Document And Entity Information - USD ($) $ in Billions	12 Months Ended
Document And Entity Information - USD ($) $ in Billions	Dec. 31, 2018	Jan. 31, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	SEI INVESTMENTS COMPANY
Entity Central Index Key	0000350894
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	SEIC
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		153,690,105
Entity Shell Company	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 7.7

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 754,525	$ 744,247
Restricted cash	3,514	3,505
Receivables from investment products	49,869	56,666
Receivables, net of allowance for doubtful accounts of $718 and $695	315,336	282,706
Securities owned	30,892	21,526
Other current assets	36,676	31,158
Total Current Assets	1,190,812	1,139,808
Property and Equipment, net of accumulated depreciation of $338,206 and $309,955	145,863	146,428
Capitalized Software, net of accumulated amortization of $395,171 and $350,045	309,500	310,405
Investments Available for Sale	111,901	87,983
Investments in Affiliated Funds, at fair value	4,887	6,034
Investment in Unconsolidated Affiliates	52,342	59,492
Goodwill	64,489	52,990
Intangible Assets, net of accumulated amortization of $5,090 and $1,552	31,670	28,578
Deferred Contract Costs	24,007	0
Deferred Income Taxes	2,042	2,767
Other Assets, net	34,155	18,884
Total Assets	1,971,668	1,853,369
Current Liabilities:
Accounts payable	10,920	5,268
Accrued liabilities	279,634	265,058
Deferred revenue	5,154	4,723
Total Current Liabilities	295,708	275,049
Borrowings Under Revolving Credit Facility	0	30,000
Long-term Income Taxes Payable	803	10,629
Deferred Income Taxes	57,795	48,472
Other Long-term Liabilities	24,215	12,380
Total Liabilities	378,521	376,530
Commitments and Contingencies
Shareholders' Equity:
Series Preferred stock, $.05 par value, 50 shares authorized; no shares issued and outstanding	0	0
Common stock, $.01 par value, 750,000 shares authorized; 153,634 and 157,069 shares issued and outstanding	1,536	1,571
Capital in excess of par value	1,106,641	1,027,709
Retained earnings	517,970	467,467
Accumulated other comprehensive loss, net	(33,000)	(19,908)
Total Shareholders' Equity	1,593,147	1,476,839
Total Liabilities and Equity	$ 1,971,668	$ 1,853,369

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Receivables, allowance for doubtful accounts	$ 718	$ 695
Property and Equipment, accumulated depreciation	338,206	309,955
Capitalized software, accumulated amortization	395,171	350,045
Intangible assets, accumulated amortization	$ 5,090	$ 1,552
Preferred stock, par value (in USD per share)	$ 0.05	$ 0.05
Preferred stock, shares authorized	50,000	50,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	153,634,000	157,069,000
Common stock, shares outstanding	153,634,000	157,069,000

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Revenues	$ 1,624,167	$ 1,526,552	$ 1,401,545
Expenses:
Subadvisory, distribution and other asset management costs	180,488	181,509	173,615
Software royalties and other information processing costs	32,449	46,792	49,821
Compensation, benefits and other personnel	511,258	458,737	414,622
Stock-based compensation	23,805	36,366	16,017
Consulting, outsourcing and professional fees	200,862	186,357	166,769
Data processing and computer related	84,790	77,615	64,930
Facilities, supplies and other costs	70,840	66,646	68,245
Amortization	48,895	48,275	45,392
Depreciation	28,792	27,311	26,440
Total expenses	1,182,179	1,129,608	1,025,851
Income from operations	441,988	396,944	375,694
Net (loss) gain from investments	(325)	1,269	112
Interest and dividend income	13,397	7,057	4,316
Interest expense	(645)	(781)	(531)
Equity in earnings of unconsolidated affiliates	159,791	152,550	126,103
Gain on sale of subsidiary	0	0	2,791
Income before income taxes	614,206	557,039	508,485
Income taxes	108,338	152,650	174,668
Net income	$ 505,868	$ 404,389	$ 333,817
Basic earnings per common share (in USD per share)	$ 3.23	$ 2.56	$ 2.07
Shares used to compute basic earnings per share	156,579	158,177	161,350
Diluted earnings per common share (in USD per share)	$ 3.14	$ 2.49	$ 2.03
Shares used to compute diluted earnings per share	161,232	162,269	164,431
Dividends declared per common share (in USD per share)	$ 0.63	$ 0.58	$ 0.54
Asset management, administration and distribution fees
Revenues:
Revenues	$ 1,270,180	$ 1,184,157	$ 1,075,459
Information processing and software servicing fees
Revenues:
Revenues	$ 353,987	$ 342,395	$ 326,086

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 505,868	$ 404,389	$ 333,817
Other comprehensive (loss) gain, net of tax:
Foreign currency translation adjustments	(12,065)	17,597	(12,131)
Unrealized holding (loss) gain on investments:
Unrealized holding (losses) gains during the period, net of income taxes of $285, $1 and $457	(1,088)	190	(918)
Less: reclassification adjustment for losses realized in net income, net of income taxes of $(96), $(99) and $(201)	61	260	384
Total other comprehensive (loss) gain, net of taxes	(13,092)	18,047	(12,665)
Comprehensive income	$ 492,776	$ 422,436	$ 321,152

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Unrealized holding gains (losses) during the period, income taxes	$ 285	$ 1	$ 457
Reclassification adjustment for losses realized in net income, income taxes	$ (96)	$ (99)	$ (201)

Consolidated Statements of Changes in Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Capital In Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect upon adoption of ASUs			$ 0
Cumulative effect upon adoption of ASUs \| Accounting Standards Update 2014-09				$ 0
Cumulative effect upon adoption of ASUs \| Accounting Standards Update 2016-09				0
Beginning balance at Dec. 31, 2015		$ 1,637	910,513	402,860	$ (25,290)
Beginning balance, shares at Dec. 31, 2015		163,733
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Purchase and retirement of common stock		$ (66)	(28,306)	(266,002)
Purchase and retirement of common stock, shares		(6,600)
Issuance of common stock under the employee stock purchase plan		$ 1	3,357
Issuance of common stock under the employee stock purchase plan, shares		88
Issuance of common stock upon exercise of stock options		$ 18	44,896
Issuance of common stock upon exercise of stock options, shares	1,809	1,810
Stock-based compensation	$ (16,017)		16,017
Tax benefit on stock options exercised			8,984
Net income	333,817			333,817
Dividends declared ($0.63, $0.58 and $0.54 per share)	(86,657)			(86,657)
Other comprehensive (loss) gain	(12,665)				(12,665)
Ending balance at Dec. 31, 2016	$ 1,303,114	$ 1,590	955,461	384,018	(37,955)
Ending balance, shares at Dec. 31, 2016		159,031
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect upon adoption of ASUs			2,582
Cumulative effect upon adoption of ASUs \| Accounting Standards Update 2014-09				0
Cumulative effect upon adoption of ASUs \| Accounting Standards Update 2016-09				(1,669)
Purchase and retirement of common stock		$ (44)	(20,243)	(227,827)
Purchase and retirement of common stock, shares		(4,403)
Issuance of common stock under the employee stock purchase plan		$ 1	3,280
Issuance of common stock under the employee stock purchase plan, shares		71
Issuance of common stock upon exercise of stock options		$ 24	50,263
Issuance of common stock upon exercise of stock options, shares	2,370	2,370
Stock-based compensation	$ (36,366)		36,366
Tax benefit on stock options exercised			0
Net income	404,389			404,389
Dividends declared ($0.63, $0.58 and $0.54 per share)	(91,444)			(91,444)
Other comprehensive (loss) gain	18,047				18,047
Ending balance at Dec. 31, 2017	$ 1,476,839	$ 1,571	1,027,709	467,467	(19,908)
Ending balance, shares at Dec. 31, 2017	157,069	157,069
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect upon adoption of ASUs			0
Cumulative effect upon adoption of ASUs \| Accounting Standards Update 2014-09				14,402
Cumulative effect upon adoption of ASUs \| Accounting Standards Update 2016-09				0
Purchase and retirement of common stock		$ (67)	(32,823)	(371,867)
Purchase and retirement of common stock, shares		(6,744)
Issuance of common stock under the employee stock purchase plan		$ 0	4,170
Issuance of common stock under the employee stock purchase plan, shares		77
Issuance of common stock upon exercise of stock options		$ 32	83,780
Issuance of common stock upon exercise of stock options, shares	3,232	3,232
Stock-based compensation	$ (23,805)		23,805
Tax benefit on stock options exercised			0
Net income	505,868			505,868
Dividends declared ($0.63, $0.58 and $0.54 per share)	(97,900)			(97,900)
Other comprehensive (loss) gain	(13,092)				(13,092)
Ending balance at Dec. 31, 2018	$ 1,593,147	$ 1,536	$ 1,106,641	$ 517,970	$ (33,000)
Ending balance, shares at Dec. 31, 2018	153,634	153,634

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 505,868	$ 404,389	$ 333,817
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	28,792	27,311	26,440
Amortization	48,895	48,275	45,392
Equity in earnings of unconsolidated affiliates	(159,791)	(152,550)	(126,103)
Distributions received from unconsolidated affiliate	166,941	143,517	125,224
Stock-based compensation	23,805	36,366	16,017
Provision for losses on receivables	23	172	(126)
Deferred income tax expense	5,998	(21,046)	4,794
Net loss (gain) from investments	325	(1,269)	(112)
Change in long-term taxes payable	(9,826)	10,629	0
Change in other long-term liabilities	145	(2,265)	3,248
Change in other assets	(4,785)	(1,489)	(1,917)
Contract costs capitalized, net	(5,366)	0	0
Gain from sale of SEI AK	0	0	(2,791)
Tax benefit on stock options exercised	0	0	8,984
Other	(294)	(2,186)	390
Change in current assets and liabilities:
Decrease (increase) in Receivables from investment products	6,797	5,095	(13,663)
Decrease (increase) in Receivables	(32,652)	(52,726)	(4,807)
Decrease (increase) in Other current assets	(5,518)	(3,583)	(1,368)
Increase (decrease) in Accounts payable	5,652	(909)	1,455
Increase (decrease) in Accrued liabilities	13,079	20,992	18,851
Increase (decrease) in Deferred revenue	313	1,180	495
Total adjustments	82,533	55,514	100,403
Net cash provided by operating activities	588,401	459,903	434,220
Cash flows from investing activities:
Additions to property and equipment	(29,095)	(25,525)	(31,397)
Additions to capitalized software	(44,221)	(61,043)	(50,392)
Purchases of marketable securities	(203,460)	(69,525)	(73,193)
Prepayments and maturities of marketable securities	167,876	65,830	54,141
Sales of marketable securities	0	0	15,152
Cash paid for acquisition, net of cash acquired	(5,794)	(80,234)	0
Receipt of contingent payment from sale of SEI AK	0	0	2,791
Other investing activities	(8,676)	(1,805)	1,313
Net cash used in investing activities	(123,370)	(172,302)	(81,585)
Cash flows from financing activities:
Repayments under revolving credit facility	(30,000)	(10,000)	0
Borrowings under revolving credit facility	0	40,000	0
Purchase and retirement of common stock	(407,384)	(248,339)	(292,258)
Proceeds from issuance of common stock	87,982	53,568	48,272
Payment of dividends	(94,318)	(88,862)	(84,686)
Net cash used in financing activities	(443,720)	(253,633)	(328,672)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(11,024)	14,583	(9,923)
Net increase in cash, cash equivalents and restricted cash	10,287	48,551	14,040
Cash, cash equivalents and restricted cash, beginning of year	747,752	699,201	685,161
Cash, cash equivalents and restricted cash, end of year	758,039	747,752	699,201
Interest paid	806	699	531
Income taxes paid	110,203	165,049	157,255
Non-cash financing activities
Dividends declared but not paid	$ 50,761	$ 47,179	$ 44,596

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Nature of Operations

SEI Investments Company (the Company), a Pennsylvania corporation, provides investment processing, investment management, and investment operations platforms to financial institutions, financial advisors, institutional investors, investment managers and ultra-high-net-worth families in the United States, Canada, the United Kingdom, continental Europe and other various locations throughout the world. Investment processing platforms consist of application and business process outsourcing services, professional services and transaction-based services. Revenues from investment processing platforms are recognized in Information processing and software servicing fees on the accompanying Consolidated Statements of Operations.

Investment management programs consist of mutual funds, alternative investments and separate accounts. These include a series of money market, equity, fixed-income and alternative investment portfolios, primarily in the form of registered investment companies. The Company serves as the administrator and investment advisor for many of these products. Revenues from investment management programs are recognized in Asset management, administration and distribution fees on the accompanying Consolidated Statements of Operations.

Investment operations platforms offer investment managers support for traditional investment products such as mutual funds, collective investment trusts, exchange-traded funds, and institutional and separate accounts, by providing outsourcing services including fund and investment accounting, administration, reconciliation, investor servicing and client reporting. These platforms also provide support to managers focused on alternative investments who manage hedge funds, funds of hedge funds, private equity funds and real estate funds, across registered, partnership and separate account structures domiciled in the United States and overseas. Revenues from investment operations platforms are recognized in Asset management, administration and distribution fees on the accompanying Consolidated Statements of Operations.

Principles of Consolidation

The Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries and entities in which it holds a controlling financial interest. The Company determines whether it has a controlling financial interest either by its decision-making ability through voting interests or by the extent of the Company’s participation in the economic risks and rewards of the entity through variable interests. The Company’s principal subsidiaries are SEI Investments Distribution Co. (SIDCO), SEI Investments Management Corporation (SIMC), SEI Private Trust Company (SPTC), SEI Trust Company (STC), SEI Global Services, Inc. (SGSI) and SEI Investments (Europe) Limited (SIEL). All intercompany accounts and transactions have been eliminated.

The Company accounts for investments in unconsolidated entities that are 20 percent to 50 percent owned or are 20 percent or less owned and have the ability to exercise significant influence over the operating and financial policies of the entity under the equity method of accounting. Under this method of accounting, the Company’s interest in the net assets of unconsolidated entities is reflected in Investment in unconsolidated affiliates on the accompanying Consolidated Balance Sheet and its interest in the earnings or losses of unconsolidated entities is reflected in Equity in earnings of unconsolidated affiliates on the accompanying Consolidated Statement of Operations. Any investments in entities not consolidated or accounted for under the equity method are accounted for under the cost method of accounting.

Variable Interest Entities

The Company or its affiliates have created numerous investment products for its clients in various types of legal entity structures. The Company serves as the Manager, Administrator and Distributor for these investment products and may also serve as the Trustee for some of the investment products. The Company receives asset management, distribution, administration and custodial fees for these services. Clients are the equity investors and participate in proportion to their ownership percentage in the net income or loss and net capital gains or losses of the products, and, on liquidation, will participate in proportion to their ownership percentage in the remaining net assets of the products after satisfaction of outstanding liabilities.

The Company has concluded that it is not the primary beneficiary of the entities and; therefore, is not required to consolidate any of the pooled investment vehicles for which it receives asset management, distribution, administration and custodial fees under the VIE model. The entities either do not meet the definition of a VIE or the Company does not hold a variable interest in the entities. The entities either qualify for the money market scope exception, or are entities in which the Company’s asset management, distribution, administration and custodial fees are commensurate with the services provided and include fair terms and conditions, or are entities that are limited partnerships which have substantive kick-out rights. The Company acts as a fiduciary and does not hold any other interests other than insignificant seed money investments in the

pooled investment vehicles. For this reason, the Company also concluded that it is not required to consolidate the pooled investment vehicles under the voting interest entity (VOE) model.

The Company is a party to expense limitation agreements with certain SEI-sponsored money market funds subject to Rule 2a-7 of the Investment Company Act of 1940 which establish a maximum level of ordinary operating expenses incurred by the fund in any fiscal year including, but not limited to, fees of the administrator or its affiliates. Under the terms of these agreements, the Company waived $26,229, $27,434 and $41,227 in fees during 2018, 2017 and 2016, respectively.

Management’s Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States (U.S. GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Revenue Recognition

The Company adopted the requirements of Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) (Accounting Standards Codification (ASC) 606 (ASC 606)) using the modified retrospective method on January 1, 2018. As a result of the adoption of ASC 606, the Company recorded a cumulative effect adjustment of $14,402 to retained earnings as of January 1, 2018. Prior period information has not been restated.

The Company's revenues are based on contractual arrangements. Revenue is recognized when the transfer of control of promised goods or services under the terms of a contract with customers are satisfied in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those promised goods or services. Certain portions of the Company’s revenues involve a third party in providing goods or services to its customers. In such circumstances, the Company must determine whether the nature of its promise to the customer is to provide the underlying goods or services (the Company is the principal in the transaction and reports the transaction gross) or to arrange for a third party to provide the underlying goods or services (the entity is the agent in the transaction and reports the transaction net).

ASC 606 did not change the accounting for the majority of the Company’s revenue arrangements and did not have a material impact to the Company’s consolidated financial statements. The following is a summary of the impact from the adoption of ASC 606:

•The majority of the Company’s services are bundled together, and provided and completed for the client on a monthly basis. For these revenue arrangements, the Company continues to recognize revenue on a monthly basis as the client consumes the benefits continuously over time. The timing and recognition of revenues from these arrangements did not change.

•Contracts with new clients or with existing clients for new services generally include implementation fees. These fees are recognized in Information processing and software servicing fees when in connection with investment processing platforms and are recognized in Asset management, administration and distribution fees when in connection with investment operations platforms. The Company concluded that most of the current arrangements for implementation services are a distinct and separate performance obligation from the monthly recurring services. The timing and recognition of fees for most of these arrangements have not changed. However, each new revenue arrangement for implementation fees is analyzed to determine whether or not it is a distinct performance obligation. Implementation fees determined not to be a distinct performance obligation would be required to be recognized over the expected life of the client relationship along with the costs relating directly to satisfying such performance obligation. The Company will evaluate each contract in accordance with the requirements of ASC 606.

•Research services provided by SIDCO, the Company’s broker-dealer subsidiary, to customers in soft-dollar arrangements were determined to be a separate performance obligation. Research services provided by a broker-dealer may be internally generated or provided by a third party and paid directly by the broker-dealer on the customer’s behalf. It was determined that SIDCO is considered an agent since it does not control the research services before they are transferred to the customer. Therefore, fees received for research services should be recorded in revenues net of amounts paid for the soft-dollar arrangement. These amounts paid by the Company were previously recorded gross as an expense and, beginning January 1, 2018, are recorded net of any revenue recognized. The amounts related to soft-dollar arrangements during 2018, 2017 and 2016 were $16,680, $14,623 and $18,409, respectively.

•Incremental contract acquisition costs related to information processing contracts in the Private Banks segment and investment operations contracts in the Investment Managers segment will be deferred and amortized using the straight-line method over the expected client life, which ranges from 6 to 15 years. These costs primarily consist of sales compensation payments to the Company's sales personnel. As a result, incremental contract acquisition costs are capitalized and subsequently amortized. The Company recorded a cumulative effect adjustment associated with the capitalization of contract costs of $18,641 as of January 1, 2018. For the Company's other sales compensation payments, the Company either applies the practical

expedient permitting the expensing of costs to obtain a contract when the expected amortization period is one year or less or there are no contract acquisition costs required to be deferred under the requirements of ASC 606.

Cash and Cash Equivalents

The Company considers investment instruments purchased with an original maturity of three months or less to be cash equivalents. The Company adopted ASU No. 2016-18, Statement of Cash Flows, Restricted Cash (Topic 230) (ASU 2016-18) on January 1, 2018 which requires that a statement of cash flows explain the change during the period for the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. The prior periods were retrospectively adjusted to conform to the current period’s presentation. There was no material impact to net cash flows for 2017 or 2016 as a result of including restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts presented on the accompanying Consolidated Condensed Statement of Cash Flows in accordance with ASU 2016-18.

Cash and cash equivalents include $315,840 and $401,292 at December 31, 2018 and 2017, respectively, primarily invested in SEI-sponsored open-ended money market mutual funds. The SEI-sponsored mutual funds are considered Level 1 assets.

Restricted Cash

Restricted cash includes $3,000 at December 31, 2018 and 2017 segregated for regulatory purposes related to trade-execution services conducted by SIEL. Restricted cash also includes $514 and $505 at December 31, 2018 and 2017, respectively, segregated in special reserve accounts for the benefit of SIDCO customers in accordance with certain rules established by the Securities and Exchange Commission for broker-dealers.

Allowances for Doubtful Accounts

The Company provides an allowance for doubtful accounts equal to the estimated uncollectible amounts. The Company’s estimate is based on historical collection experience and a review of the current status of trade accounts receivable.

Concentration of Credit Risk

Financial instruments which potentially expose the Company to concentrations of credit risk consist primarily of cash equivalents and trade receivables. Cash equivalents are principally invested in short-term money market funds or placed with major banks and high-credit qualified financial institutions. Cash deposits maintained with institutions are in excess of federally insured limits. Concentrations of credit risk with respect to the Company's receivables are limited due to the large number of clients and their dispersion across geographic areas. No single group or customer represents greater than ten percent of total accounts receivable.

Property and Equipment

Property and Equipment are recorded at cost. Expenditures for major additions and improvements are capitalized and minor replacements, maintenance, and repairs are charged to expense as incurred. Construction in progress includes the cost of construction and other direct costs attributable to the construction. When property and equipment are retired or disposed of, the related cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations for the respective period. Depreciation is provided over the estimated useful lives using the straight line method for financial statement purposes. No provision for depreciation is made for construction in progress until such time as the relevant assets are completed and put into service. The Company uses other depreciation methods, generally accelerated, for tax purposes where appropriate. Buildings and building improvements are depreciated over 25 to 39 years. Equipment, purchased software and furniture and fixtures have useful lives ranging from 3 to 5 years. Amortization of leasehold improvements is computed using the straight line method over the shorter of the remaining lease term or the estimated useful lives of the improvements.

Marketable Securities

The classification of investments in marketable securities is determined at the time of purchase and reevaluated at each balance sheet date. Debt and equity securities classified as available-for-sale are reported at fair value as determined by the most recently traded price of each security at the balance sheet date.

The Company prospectively adopted ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01) on January 1, 2018 which requires the Company to recognize all changes in fair value of available-for-sale equity securities in current period earnings. Previously, these changes in fair value were recognized as a separate component of comprehensive income. The adoption of ASU 2016-01 did not have a material impact to the Company's consolidated financial statements.

Unrealized gains and losses associated with the Company's available for sale debt securities, net of income taxes, are reported as a separate component of comprehensive income. SIDCO, the Company’s broker-dealer subsidiary, reports changes

in fair value of marketable securities through current period earnings due to specialized accounting practices related to investments by broker-dealers. The Company records its investments in funds sponsored by LSV on the accompanying Consolidated Balance Sheets at fair value. Unrealized gains and losses from the change in fair value of these securities are recognized in current period earnings. The specific identification method is used to compute the realized gains and losses on all of the Company’s marketable securities (See Note 5).

The Company evaluates the realizable value of its marketable securities on a quarterly basis. In the event that the carrying value of an investment exceeds its fair value and the decline in value is determined to be other-than-temporary, an impairment charge is recorded and a new cost basis for the investment is established. Some of the factors considered in determining other-than-temporary impairment for equity securities include, but are not limited to, significant or prolonged declines in the fair value of the investments, the Company’s ability and intent to retain the investment for a period sufficient to allow the value to recover, and the financial condition of the investment. Some of the factors considered in determining other-than-temporary impairment for debt securities include, but are not limited to, the intent of management to sell the security, the likelihood that the Company will be required to sell the security before recovering its cost, and management’s expectation to recover the entire amortized cost basis of the security even if there is no intent to sell the security. The Company did not recognize any impairment charges related to its marketable securities in 2018, 2017 or 2016.

Fair Value of Financial Instruments

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The fair value hierarchy describes three levels of inputs that may be used by the Company to measure fair value:

Level 1 – Quoted prices in active markets for identical assets or liabilities without adjustment. The Company’s Level 1 assets primarily include investments in mutual funds sponsored by SEI that are quoted daily.

Level 2 – Observable inputs other than Level 1 prices, such as quoted prices for similar assets, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 2 financial assets consist of Government National Mortgage Association (GNMA) mortgage-backed securities, Federal Home Loan Bank (FHLB) and other U.S. government agency short-term notes. The investments in GNMA mortgage-backed securities were purchased for the sole purpose of satisfying applicable regulatory requirements imposed on our wholly-owned limited purpose federal thrift subsidiary, SPTC. The investments in FHLB and other U.S. government agency short-term notes were purchased as part of a cash management program requiring only short term, top-tier investment grade government and corporate securities.

Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, or similar techniques, as well as instruments for which the determination of fair value requires significant judgment by management. The Company had no Level 3 financial assets at December 31, 2018 or 2017 that were required to be measured at fair value on a recurring basis. The Company's Level 3 financial liabilities at December 31, 2018 consist entirely of an estimated contingent consideration resulting from the Company's acquisition of Huntington Steele, LLC (See Note 14). The Company had no Level 3 financial liabilities as of December 31, 2017 that were required to be measured at fair value on a recurring basis.

The fair value of an asset or liability may include inputs from more than one level in the fair value hierarchy. The lowest level of significant inputs used to value the asset or liability determines which level the asset or liability is classified in its entirety. Transfers between levels of the fair value hierarchy are reported at fair value as of the beginning of the period in which the transfers occur.

See Note 4 for information on related disclosures regarding fair value measurements.

Capitalized Software

Costs incurred for the development of internal use software to be offered in a hosting arrangement is capitalized during the development stage of the software application. These costs include direct external and internal costs to design the software configuration and interfaces, coding, installation, and testing. Costs incurred during the preliminary and post-implementation stages of the software application are expensed as incurred. Costs associated with significant enhancements to a software application are capitalized while costs incurred to maintain existing software applications are expensed as incurred. The capitalization of software development costs requires considerable judgment by management with respect to certain external factors, including, but not limited to, technological and economic feasibility, and estimated economic life. Amortization of capitalized software development costs begins when the product is ready for its intended use. Capitalized software development

costs are amortized on a product-by-product basis using the straight-line method over the estimated economic life of the product or enhancement.

The Company capitalized $44,221, $61,043 and $50,392 of software development costs during 2018, 2017 and 2016, respectively. The Company's capitalized software development costs primarily relate to the further development of the SEI Wealth Platform^SM(SWP). The Company capitalized $43,376, $51,353 and $39,785 of software development costs for significant enhancements to SWP during 2018, 2017 and 2016, respectively. As of December 31, 2018, the net book value of SWP was $288,666. The net book value includes $42,238 of capitalized software development costs in-progress associated with future releases.

Management continually reassesses the estimated useful life of SWP and any change in management’s estimate could result in the remaining amortization expense to be accelerated or spread out over a longer period. During the fourth quarter 2017, the Company adjusted the remaining useful life of certain components and functionality of SWP that were placed into service during the past several years. The adjustment resulted in a decrease to the Company's amortization expense of $4,347 and an increase to the Company's net income of $3,156, or $0.02 diluted earnings per share, in 2017. As of December 31, 2018, SWP has a weighted average remaining life of 8.5 years. Amortization expense for SWP was $39,917, $46,505 and $45,047 in 2018, 2017 and 2016, respectively, and is included in Amortization expense on the accompanying Consolidated Statements of Operations.

The Company also capitalized $845, $9,690 and $10,607 of software development costs during 2018, 2017 and 2016, respectively, related to an application for the Investment Managers segment. The application was placed into service during the first quarter 2018 with an estimated useful life of 5 years. The net book value of the application at December 31, 2018 was $20,834. Amortization expense for the application was $5,209 during 2018 and is included in Amortization expense on the accompanying Consolidated Statements of Operations.

The Company currently expects to recognize amortization expense related to all capitalized software development costs placed into service as of December 31, 2018 each year from 2019 through 2023 as follows:



2019	$	46,608
2020	46,608
2021	46,330
2022	31,817
2023	13,145

The Company evaluates the carrying value of capitalized software development costs when circumstances indicate the carrying value may not be recoverable. The review of capitalized software development costs for impairment requires significant assumptions about operating strategies, underlying technologies utilized, and external market factors. External market factors include, but are not limited to, expected levels of competition, barriers to entry by potential competitors, stability in the target market and governmental regulations. The Company did not recognize any impairment charges related to its capitalized software development costs in 2018, 2017 or 2016.

Business Combinations

The Company accounts for business combinations in accordance with Accounting Standards Codification Topic 805, Business Combinations (ASC 805). ASC 805 establishes principles and requirements for recognizing the total consideration transferred, assets acquired and liabilities assumed in a business combination. ASC 805 also provides guidance for recognizing and measuring goodwill acquired in a business combination and requires the acquirer to disclose information needed to evaluate and understand the financial impact of the business combination. The Company recognizes assets and liabilities acquired at their estimated fair values. Management uses judgment to identify the acquired assets and liabilities assumed; estimate the fair value of these assets and liabilities; estimate the useful life of the assets; and assess the appropriate method for recognizing depreciation or amortization expense over the estimated useful life of the assets.

Goodwill and Other Intangible Assets

The Company reviews long-lived assets and identifiable definite-lived intangible assets for impairment at least annually or whenever events or changes in circumstances indicate that the carrying amount of these assets may not be recoverable. For purposes of recognizing and measuring an impairment loss, a long-lived asset is grouped with other assets and liabilities at the lowest level for which identifiable cash flows are largely independent.

Identifiable definite-lived intangible assets on the Company’s Consolidated Balance Sheet are amortized on a straight-line basis according to their estimated useful lives. Goodwill is not amortized but is reviewed for impairment annually or more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. Current guidance require that a two-step, fair value based test be performed to assess goodwill for impairment. In the first step, the fair value of each reporting unit is compared with its carrying value, including goodwill. If the

fair value exceeds the carrying value, goodwill is not impaired and no further testing is performed. The second step is performed if the carrying value exceeds the fair value. The second step requires an allocation of fair value to the individual assets and liabilities using a purchase price allocation in order to determine the implied fair value of goodwill. If the implied fair value of goodwill is less than the carrying amount, an impairment loss is recognized. The Company did not recognize any impairment charges related to its goodwill or other intangible assets in 2018 or 2017.

Income Taxes

The Company applies the asset and liability approach to account for income taxes whereby deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.

Foreign Currency Translation

The assets and liabilities and results of operations of the Company’s foreign subsidiaries are measured using the foreign subsidiary’s local currency as the functional currency. Assets and liabilities have been translated into U.S. dollars using the rates of exchange at the balance sheet dates. The results of operations have been translated into U.S. dollars at average exchange rates prevailing during the period. The resulting translation gain and loss adjustments are recorded as a separate component of comprehensive income.

Transaction gains and losses from exchange rate fluctuations are included in the results of operations in the periods in which they occur. There were no material gains or losses from exchange rate fluctuations in 2018, 2017 or 2016.

Earnings Per Common Share

Basic earnings per common share is computed by dividing net income attributable to SEI Investments common shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per common share is computed by dividing net income attributable to SEI Investments common shareholders by the combination of the weighted average number of common shares outstanding and the dilutive potential common shares, such as stock options, outstanding during the period.

The calculations of basic and diluted earnings per share for 2018, 2017 and 2016 are:



	2018		2017		2016
Net income	$	505,868	$	404,389	$	333,817
Shares used to compute basic earnings per common share	156,579,000		158,177,000		161,350,000
Dilutive effect of stock options	4,653,000		4,092,000		3,081,000
Shares used to compute diluted earnings per common share	161,232,000		162,269,000		164,431,000
Basic earnings per common share	$	3.23	$	2.56	$	2.07
Diluted earnings per common share	$	3.14	$	2.49	$	2.03

Employee stock options to purchase approximately 6,224,000, 5,196,000 and 10,632,000 shares of common stock, with an average exercise price per share of $53.60, $45.49 and $35.02, were outstanding during 2018, 2017 and 2016, respectively, but not included in the computation of diluted earnings per common share because either the performance conditions have not been satisfied or would have been satisfied if the reporting date was the end of the contingency period or the option’s exercise price was greater than the average market price of the Company’s common stock and the effect on diluted earnings per common share would have been anti-dilutive (See Note 7).

Stock-Based Compensation

Stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which is the vesting period. The amount of stock-based compensation expense that is recognized in a given period is dependent upon management’s estimate of when the vesting targets are expected to be achieved. If this estimate proves to be inaccurate, the remaining amount of stock-based compensation expense could be accelerated, spread out over a longer period, or reversed (See Note 7).

The Company adopted ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (ASU 2016-09) during 2017. As required by ASU 2016-09, excess tax benefits recognized on stock-based compensation expense are reflected in the accompanying Consolidated Statements of Operations as a component of the provision for income taxes effective January 1, 2017 (See Note 11).

New Accounting Pronouncements

In February 2016, the FASB issued ASU No. 2016-02, Leases (ASU 2016-02), as amended, requiring lessees to recognize a right-of-use asset and a lease liability on the balance sheet for all leases with the exception of short-term leases. For lessees, leases will be classified as either operating or finance leases, with the classification affecting the pattern and classification of expense recognition in the income statement. The updated standard is effective for the Company beginning in the first quarter of 2019. Early adoption is permitted. A modified retrospective transition approach is required, applying the new standard to all leases existing at the date of initial application. An entity may choose to use either (i) its effective date or (ii) the beginning of the earliest comparative period presented in the financial statements as its date of initial application. The Company adopted the new standard on January 1, 2019 and used the effective date as the date of initial application. As a result, financial information will not be updated and the disclosures required under the new standard will not be provided for periods prior to January 1, 2019.

The new standard provides a number of optional practical expedients in transition. The Company elected the package of practical expedients which permits the Company to not reassess under the new standard its prior conclusions about lease identification, lease classification and initial direct costs. The Company did not elect the hindsight practical expedient in determining its lease terms.

As part of its project plan’s preliminary assessment and design implementation phases for the adoption of ASU 2016-02, the Company has adopted implementation controls that allow it to properly and timely adopt ASU 2016-02 on the effective date. The Company is finalizing its assessment of the adoption of ASU 2016-02. The Company expects the most significant effects will relate to the recognition of right-of-use assets and lease liabilities on the balance sheet for office space and certain office equipment and providing significant new disclosures about leasing arrangements. The Company owns its corporate headquarters and leases office space in other locations. The Company has completed the process of cataloging existing lease agreements and is finalizing the right-of-use asset and lease liability which is expected to be between $50,000 and $60,000.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13) which requires that expected credit losses relating to financial assets measured on an amortized cost basis and available-for-sale debt securities be recorded through an allowance for credit losses. ASU 2016-13 limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and also requires the reversal of previously recognized credit losses if fair value increases. ASU 2016-13 becomes effective for the Company during the first quarter of 2020. Early adoption is permitted. The Company is currently evaluating the effect that the updated standard will have on its consolidated financial statements and related disclosures.

In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment (ASU 2017-04). The objective of ASU 2017-04 is to simplify the subsequent measurement of goodwill by entities performing their annual goodwill impairment tests by comparing the fair value of a reporting unit, including income tax effects from any tax-deductible goodwill, with its carrying amount and recognizing an impairment charge for the amount by which the carrying amount exceeds fair value. ASU 2017-04 is effective for the Company beginning in the first quarter of 2020. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2017-04 on its consolidated financial statements and related disclosures.

In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting (ASU 2018-07) which simplifies the accounting for nonemployee share-based payment transactions. The amendments specify that Topic 718 applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor’s own operations by issuing share-based payment awards. ASU 2018-07 is effective for the Company beginning in the first quarter of 2019. The adoption of ASU 2018-07 will not have a material impact on the Company's consolidated financial statements and related disclosures.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (ASU 2018-13) which modifies the disclosure requirements on fair value measurements. ASU 2018-13 is effective for the Company beginning in the first quarter of 2020. The Company is currently evaluating the impact of adopting ASU 2018-13 on its consolidated financial statements and related disclosures.

In October 2018, the FASB issued ASU 2018-17, Consolidation (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities (ASU 2018-17). The new standard changes how entities evaluate decision-making fees under the variable interest entity guidance. ASU 2018-17 is effective for the Company beginning in the first quarter of 2020. The Company is currently evaluating the impact of adopting ASU 2018-17 on its consolidated financial statements and related disclosures.

Reclassifications

Certain prior year amounts have been reclassified to conform to current year presentation.

Investment in Unconsolidated Affiliates

12 Months Ended

Dec. 31, 2018

Equity Method Investments and Joint Ventures [Abstract]

Investment in Unconsolidated Affiliates

LSV Asset Management

The Company has an investment in the general partnership LSV Asset Management (LSV), a registered investment advisor that provides investment advisory services primarily to institutions, including pension plans and investment companies. LSV is currently an investment sub-advisor for a limited number of SEI-sponsored mutual funds. As of December 31, 2018, the Company's total partnership interest in LSV was approximately 38.9 percent. The Company accounts for its interest in LSV using the equity method because of its less than 50 percent ownership. The Company’s interest in the net assets of LSV is reflected in Investment in unconsolidated affiliates on the accompanying Consolidated Balance Sheets and its interest in the earnings of LSV is reflected in Equity in earnings of unconsolidated affiliates on the accompanying Consolidated Statements of Operations.

At December 31, 2018, the Company’s total investment in LSV was $52,342. The Company’s proportionate share in the earnings of LSV was $159,791, $152,550 and $126,103 in 2018, 2017 and 2016, respectively. The Company receives partnership distributions related to the earnings of LSV on a quarterly basis. As such, the Company considers these distribution payments as returns on investment rather than returns of the Company's original investment in LSV and has therefore classified the associated cash inflows as an operating activity on the Consolidated Statements of Cash Flows. The Company received partnership distribution payments from LSV of $166,941, $143,517 and $125,224 in 2018, 2017 and 2016, respectively.

These tables contain condensed financial information of LSV:



Condensed Statement of Operations Year ended December 31,	2018		2017		2016
Revenues	$	517,203	$	491,872	$	399,462
Net income	$	410,846	$	392,141	$	323,381



Condensed Balance Sheets December 31,	2018		2017
Current assets	$	138,083	$	155,239
Non-current assets	1,165		1,407
Total assets	$	139,248	$	156,646

Current liabilities	$	47,874	$	46,486
Partners’ capital	91,374		110,160
Total liabilities and partners’ capital	$	139,248	$	156,646

Composition of Certain Financial Statement Captions

12 Months Ended

Dec. 31, 2018

Items Included in Consolidated Statement of Financial Condition [Abstract]

Composition of Certain Financial Statement Captions

Receivables

Receivables on the accompanying Consolidated Balance Sheets consist of:



	2018			2017
Trade receivables	$	76,362		$	76,760
Fees earned, not billed	226,001			194,331
Other receivables	13,691			12,310
	316,054			283,401
Less: Allowance for doubtful accounts	(718		)	(695		)
Receivables, net	$	315,336		$	282,706

Fees earned, not billed represents receivables from contracts from customers earned but unbilled and results from timing differences between services provided and contractual billing schedules. These billing schedules generally provide for fees to be billed on a quarterly basis. In addition, certain fees earned from investment operations services are calculated based on assets under administration that have an extended valuation process. Billings to these clients occur once the asset valuation processes are completed.

Property and Equipment

Property and Equipment on the accompanying Consolidated Balance Sheets consists of:



	2018			2017
Buildings	$	160,796		$	153,961
Equipment	126,954			115,546
Land	10,772			10,030
Purchased software	139,245			134,610
Furniture and fixtures	18,103			18,114
Leasehold improvements	18,959			18,017
Construction in progress	9,240			6,105
	484,069			456,383
Less: Accumulated depreciation	(338,206		)	(309,955		)
Property and Equipment, net	$	145,863		$	146,428

Depreciation expense related to property and equipment for 2018, 2017 and 2016 was $28,792, $27,311 and $26,440, respectively.

Other Assets

Other assets consist of long-term prepaid expenses, deposits, other investments at cost and various other assets. Amortization expense for certain other assets for 2018, 2017 and 2016 was $231, $218 and $345, respectively.

Accrued Liabilities

Accrued Liabilities on the accompanying Consolidated Balance Sheets consist of:



	2018		2017
Accrued employee compensation	$	97,603	$	88,960
Accrued consulting, outsourcing and professional fees	31,000		29,658
Accrued sub-advisory, distribution and other asset management fees	42,583		42,365
Accrued dividend payable	50,761		47,179
Other accrued liabilities	57,687		56,896
Accrued liabilities	$	279,634	$	265,058

Fair Value Measurements

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

The fair value of the Company’s financial assets and liabilities, except for the Company's investment funds sponsored by LSV, is determined in accordance with the fair value hierarchy. The fair value of the Company’s Level 1 financial assets consists mainly of investments in open-ended mutual funds that are quoted daily. Level 2 financial assets consist of Government National Mortgage Association (GNMA) mortgage-backed securities held by the Company's wholly-owned limited purpose federal thrift subsidiary, SEI Private Trust Company (SPTC), Federal Home Loan Bank (FHLB) and other U.S. government agency short-term notes held by SIDCO. The financial assets held by SIDCO were purchased as part of a cash management program requiring only short term, top-tier investment grade government and corporate securities. The financial assets held by SPTC are debt securities issued by GNMA and are backed by the full faith and credit of the U.S. government. These securities were purchased for the sole purpose of satisfying applicable regulatory requirements and have maturity dates which range from 2021 to 2041.

The fair value of the Company's investment funds sponsored by LSV is measured using the net asset value per share (NAV) as a practical expedient. The NAVs of the funds are calculated by the funds' independent custodian and are derived from the fair values of the underlying investments as of the reporting date. The funds allow for investor redemptions at the end of each calendar month. This investment has not been classified in the fair value hierarchy but is presented in the tables below to permit reconciliation to the amounts presented on the accompanying Consolidated Balance Sheets.

The valuation of the Company's Level 2 financial assets held by SIDCO and SPTC are based upon securities pricing policies and procedures utilized by third-party pricing vendors. The Company had no Level 3 financial assets at December 31, 2018 or 2017 that were required to be measured at fair value on a recurring basis. The Company's Level 3 financial liabilities at December 31, 2018 consist entirely of the estimated contingent consideration of $12,120 resulting from an acquisition (See Note 14). The fair value of the contingent consideration was determined using a Monte-Carlo simulation model. Key assumptions for the Monte-Carlo simulation model include expected revenues, expected volatility, risk-free rate and correlation

coefficient. The Company had no Level 3 financial liabilities as of December 31, 2017 that were required to be measured at fair value on a recurring basis.There were no transfers of financial assets between levels within the fair value hierarchy during 2018.

Valuation of GNMA and Other U.S. Government Agency Securities

All of the Company's investments in GNMA, FHLB and other U.S. government agency securities are held in accounts at well-established financial institutions. The Company's selection of a financial institution for the purpose of purchasing securities considered a number of various factors including, but not limited to, securities pricing policies and procedures utilized by that financial institution. Each financial institution utilizes the services of independent pricing vendors. These vendors utilize evaluated and industry accepted pricing models that vary by asset class and incorporate available trade, bid and other market information to determine the fair value of the securities. The market inputs, listed in approximate order of priority, include: benchmark yields, reported trade, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data. The Company evaluated the information regarding the pricing methodologies and processes utilized by the independent pricing vendors during the selection process of the financial institution. The Company analyzed this information for the purpose of classifying the securities into the appropriate level within the fair value hierarchy and to ensure that each pricing model for each asset class provided the fair value of those specific securities in accordance with generally accepted accounting principles. The Company continually monitors the price of each security for any unanticipated deviations from the previously quoted price. In the event of any significant unanticipated deviations in a security's price, additional analysis is conducted. The Company's investments in GNMA, FHLB and other U.S. government agency securities have been recorded at the prices provided by the independent pricing vendor without adjustment.

The fair value of certain financial assets and liabilities of the Company was determined using the following inputs:



			Fair Value Measurements at Reporting Date Using
	December 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Assets
Equity available-for-sale securities	$	10,218	$	10,218	$	—
Fixed-income available-for-sale securities	101,683		—		101,683
Fixed-income securities owned	30,892		—		30,892
Investment funds sponsored by LSV (1)	4,887
	$	147,680	$	10,218	$	132,575



			Fair Value Measurements at Reporting Date Using
	December 31, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Assets
Equity available-for-sale securities	$	11,250	$	11,250	$	—
Fixed-income available-for-sale securities	76,733		—		76,733
Fixed-income securities owned	21,526		—		21,526
Investment funds sponsored by LSV (1)	6,034
	$	115,543	$	11,250	$	98,259

(1) The fair value amounts presented in the tables above are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the accompanying Consolidated Balance Sheets (See Note 5).

Marketable Securities

12 Months Ended

Dec. 31, 2018

Marketable Securities [Abstract]

Marketable Securities

Investments Available For Sale

Investments available for sale classified as non-current assets consist of:



	At December 31, 2018
	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Fair Value
SEI-sponsored mutual funds	$	7,446	$	—	$	(788	)	$	6,658
Equities and other mutual funds	3,434		126		—			3,560
Debt securities	103,518		—		(1,835		)	101,683
	$	114,398	$	126	$	(2,623	)	$	111,901



	At December 31, 2017
	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Fair Value
SEI-sponsored mutual funds	$	7,369	$	110	$	(143	)	$	7,336
Equities and other mutual funds	3,456		458		—			3,914
Debt securities	77,745		—		(1,012		)	76,733
	$	88,570	$	568	$	(1,155	)	$	87,983

Net unrealized holding losses at December 31, 2018 and 2017 of the Company's available-for-sale debt securities were $1,413 (net of income tax benefit of $422) and $779 (net of income tax benefit of $233), respectively. These net unrealized losses are reported as a separate component of Accumulated other comprehensive loss on the accompanying Consolidated Balance Sheets.

There were gross realized gains of $1,065 and gross realized losses of $1,686 from available-for-sale securities during 2018. In 2017, there were gross realized gains of $529 and gross realized losses of $888 from available-for-sale securities. There were gross realized gains of $284 and gross realized losses of $869 from available-for-sale securities during 2016. Gains and losses from available-for-sale securities, including amounts reclassified from accumulated comprehensive loss, are reflected in Net (loss) gain from investments on the accompanying Consolidated Statements of Operations.

Investments in Affiliated Funds

The Company has an investment related to the startup of investment funds sponsored by LSV. The Company records this investment on the accompanying Consolidated Balance Sheets at fair value. Unrealized gains and losses from the change in fair value of these funds are recognized in Net (loss) gain from investments on the accompanying Consolidated Statements of Operations.

The investment primarily consists of U.S. dollar denominated funds that invest in equity securities of Canadian, Australian and Japanese companies. The underlying securities held by the funds are translated into U.S. dollars within the funds. The funds had a fair value of $4,887 and $6,034 at December 31, 2018 and 2017, respectively. The Company recognized losses of $1,147 and gains of $1,176 and $819 from the change in fair value of the funds during 2018, 2017 and 2016, respectively.

Securities Owned

The Company’s broker-dealer subsidiary, SIDCO, has investments in U.S. government agency securities with maturity dates less than one year. These investments are reflected as Securities owned on the accompanying Consolidated Balance Sheets. Due to specialized accounting practices applicable to investments by broker-dealers, the securities are reported at fair value and changes in fair value are recorded in current period earnings. The securities had a fair value of $30,892 and $21,526 at December 31, 2018 and 2017, respectively. There were no material net gains or losses from the change in fair value of the securities during 2018, 2017 and 2016.

Line of Credit	12 Months Ended
Line of Credit	Dec. 31, 2018
Line of Credit Facility [Abstract]
Lines of Credit	Line of Credit The Company has a five-year $300,000 Credit Agreement (the Credit Facility) with Wells Fargo Bank, National Association (Wells Fargo) and a syndicate of other lenders. The Credit Facility is scheduled to expire in June 2021, at which time any aggregate principal amount of loans outstanding becomes payable in full. Any borrowings made under the Credit Facility will accrue interest at rates that, at the Company's option, are based on a base rate (the Base Rate) plus a premium that can range from 0.25 percent to 1.00 percent or the London InterBank Offered Rate (LIBOR) plus a premium that can range from 1.25 percent to 2.00 percent depending on the Company’s Leverage Ratio (a ratio of consolidated indebtedness to consolidated EBITDA for the four preceding fiscal quarters, all as defined in the related agreement). The Base Rate is defined as the highest of a) the Federal Funds Rate, as published by the Federal Reserve Bank of New York, plus 0.50 percent, b) the prime commercial lending rate of Wells Fargo, c) the applicable LIBOR plus 1.00 percent, or d) 0 percent. The Company also pays quarterly commitment fees based on the unused portion of the Credit Facility. The quarterly fees for the Credit Facility can range from 0.15 percent of the amount of the unused portion to 0.30 percent, depending on the Company’s Leverage Ratio. Certain wholly-owned subsidiaries of the Company have guaranteed the obligations of the Company under the agreement. The aggregate amount of the Credit Facility may be increased by an additional $100,000 under certain conditions set forth in the agreement. The Company may issue up to $15,000 in letters of credit under the terms of the Credit Facility. The Company pays a periodic commission fee of 1.250 percent plus a fronting fee of 0.175 percent of the aggregate face amount of the outstanding letters of credit issued under the Credit Facility. The Credit Facility contains covenants that restrict the ability of the Company to engage in mergers, consolidations, asset sales, investments, transactions with affiliates, or to incur liens, as defined in the agreement. In the event of a default under the Credit Facility, the Company would also be restricted from paying dividends on, or repurchasing, its common stock without the approval of the lenders. None of the covenants of the Credit Facility negatively affect the Company’s liquidity or capital resources. Upon the occurrence of certain financial or economic events, significant corporate events, or certain other events of default constituting an event of default under the Credit Facility, all loans outstanding may be declared immediately due and payable and all commitments under the agreement may be terminated. In July 2017, the Company borrowed $40,000 under the Credit Facility for the funding of the acquisition of Archway (See Note 14). The Company made principal payments of $30,000 and $10,000 during 2018 and 2017, respectively, to fully repay the outstanding balance of the Credit Facility. As of December 31, 2018, the Company had outstanding letters of credit of $13,813 under the Credit Facility. These letters of credit were issued primarily for the expansion of the Company's headquarters and are scheduled to expire in 2019. The amount of the Credit Facility that is available for general corporate purposes as of December 31, 2018 was $286,187. The Company was in compliance with all covenants of the Credit Facility during 2018. The Company considers the book value of long-term debt related to the borrowings through the Credit Facility to be representative of its fair value. The Company incurred $645, $781 and $531 in interest charges and commitment fees relating to its line of credit during 2018, 2017 and 2016, respectively, which are reflected in Interest expense on the accompanying Consolidated Statements of Operations. The weighted average interest rate applied to the outstanding balance of the Credit Facility during 2018 was 2.93 percent.

Shareholders' Equity

12 Months Ended

Dec. 31, 2018

Stockholders' Equity Note [Abstract]

Shareholders' Equity

Shareholders’ Equity

Stock-Based Compensation

The Company's active equity compensation plan, the 2014 Omnibus Equity Compensation Plan (the 2014 Plan), is the successor plan to the 2007 Equity Compensation Plan (the 2007 Plan) which was merged with and into the 2014 Plan in May 2014. The 2014 Plan provides for the grant of stock options, stock units, stock awards, stock appreciation rights, dividend equivalents and other stock-based awards.

Outstanding grants under the 2007 Plan will continue according to the terms in effect before the plan merger, but the outstanding shares will be issued or transferred under the 2014 Plan. Permitted grantees under the 2014 Plan include employees, non-employee directors and consultants who perform services for the Company. The plan is administered by the Compensation Committee of the Board of Directors of the Company. The Company has only non-qualified stock options outstanding under the 2014 Plan.

All outstanding stock options have performance-based vesting provisions that tie the vesting of stock options to the Company’s financial performance. The Company’s stock options vest at a rate of 50 percent when a specified diluted earnings per share target is achieved, and the remaining 50 percent when a second, higher-specified diluted earnings per share target is achieved. Options do not vest due to the passage of time but as a result of achievement of the financial vesting targets. Options granted in December 2017 and thereafter include a service condition which requires a minimum two or four year waiting period from the grant date along with the attainment of the applicable financial vesting target. Earnings per share targets exclude the impact of stock-based compensation and are established at time of grant. The targets are measured annually on December 31. The amount of stock-based compensation expense recognized in the period is based upon management’s estimate of when the earnings per share targets may be achieved. Any change in management’s estimate could result in the remaining amount of stock-based compensation expense to be accelerated, spread out over a longer period, or reversed. This may cause volatility in the recognition of stock-based compensation expense in future periods and could materially affect the Company’s earnings.

The Company uses the Black-Scholes option pricing model to determine the fair value of stock options. The determination of the fair value of stock options on the date of grant using an option-pricing model is affected by the price of the Company’s common stock as well as other variables. These variables include expected stock price volatility over the term of the awards, actual and projected employee stock exercise behaviors, risk-free interest rate and expected dividends. The Company primarily uses historical data to estimate the variables used in the option-pricing model except expected volatility. The Company uses a combination of historical and implied volatility.

The weighted average fair value of the Company’s stock options granted during 2018, 2017 and 2016 were $13.04, $16.78 and $12.43, respectively, using the following assumptions:



	2018		2017		2016
Expected term (in years)	6.34		6.00		6.00
Expected volatility	25.27	%	22.58	%	25.44	%
Expected dividend yield	1.35	%	0.82	%	1.10	%
Risk-free interest rate	2.75	%	2.29	%	2.18	%

The Company recognized stock-based compensation expense in its Consolidated Financial Statements in 2018, 2017 and 2016 as follows:



	2018			2017			2016
Stock-based compensation expense	$	23,805		$	36,366		$	16,017
Less: Deferred tax benefit	(5,078		)	(7,891		)	(5,612		)
Stock-based compensation expense, net of tax	$	18,727		$	28,475		$	10,405

During 2018, 2017 and 2016, the Company revised its estimates of when some vesting targets are expected to be achieved. The changes in management’s estimates during 2018 and 2017 resulted in an increase of $1,909 and $11,206 in stock-based compensation expense in 2018 and 2017, respectively. The change in management’s estimate during 2016 was not material.

As of December 31, 2018, there was approximately 6,454,000 unvested employee stock options with an unrecognized compensation cost of $68,470 that the Company expects will vest and be expensed through 2023 with a weighted average period of 2.2 years.

This table presents certain information relating to the Company’s stock option plans for 2018, 2017 and 2016:



	Number of Shares		Weighted Avg. Price
Balance as of December 31, 2015	19,237,000		$	28.71
Granted	2,310,000		49.57
Exercised	(1,809,000	)	24.82
Expired or canceled	(1,669,000	)	30.86
Balance as of December 31, 2016	18,069,000		$	31.57
Granted	2,057,000		69.87
Exercised	(2,370,000	)	21.22
Expired or canceled	(1,044,000	)	33.42
Balance as of December 31, 2017	16,712,000		$	37.63
Granted	2,468,000		49.94
Exercised	(3,232,000	)	25.93
Expired or canceled	(135,000	)	49.58
Balance as of December 31, 2018	15,813,000		$	41.84

Exercisable as of December 31, 2018	9,359,000		$	32.89
Available for future grant as of December 31, 2018	21,775,000

As of December 31, 2017 and 2016, there were 10,624,000 and 6,692,000 shares exercisable, respectively. The expiration dates for options outstanding at December 31, 2018 range from December 15, 2019 to December 11, 2028 with a weighted average remaining contractual life of 6.3 years.

Upon exercise of stock options, the Company will issue new shares of its common shares. The Company does not hold any shares in treasury. The total intrinsic value of options exercised during 2018 and 2017 was $139,087 and $83,628, respectively. The total options exercisable as of December 31, 2018 had an intrinsic value of $138,706. The total options outstanding as of December 31, 2018 had an intrinsic value of $143,939. The total intrinsic value for options outstanding and options exercisable is calculated as the difference between the market value of the Company’s common stock as of December 31, 2018 and the exercise price of the shares. The market value of the Company’s common stock as of December 31, 2018 was $46.20 as reported by the Nasdaq Stock Market, LLC.

This table summarizes information relating to all options outstanding and exercisable at December 31, 2018:



				Options Outstanding at December 31, 2018				Options Exercisable at December 31, 2018
Range of Exercise Prices (Per Share)				Number of Shares	Weighted Average Exercise Price (Per Share)		Weighted Average Remaining Contractual Life (Years)	Number of Shares	Weighted Average Exercise Price (Per Share)		Weighted Average Remaining Contractual Life (Years)
$	14.62	-	21.05	1,996,000	$	16.63	2.09	1,996,000	$	16.63	2.09
22.45		-	23.86	2,379,000	23.13		3.04	2,379,000	23.13		3.04
27.03		-	40.64	3,332,000	37.10		5.54	2,390,000	35.70		5.36
45.99		-	53.16	4,268,000	49.01		9.06	908,000	49.61		8.00
53.34		-	71.12	3,838,000	62.69		8.19	1,686,000	53.36		7.02
				15,813,000				9,359,000

Employee Stock Purchase Plan

The Company has an employee stock purchase plan that provides for offerings of common stock to eligible employees at a price equal to 85 percent of the fair market value of the stock at the end of the stock purchase period, as defined. The Company has reserved 15,600,000 shares for issuance under this plan. At December 31, 2018, 12,038,000 cumulative shares have been issued. There were no material costs incurred by the Company related to the employee stock purchase plan in 2018, 2017 and 2016.

Common Stock Buyback

The Board of Directors, under multiple authorizations, has authorized the purchase of the Company’s common stock on the open market or through private transactions. As of December 31, 2018, the Company had approximately $215,879 of authorization remaining for the purchase of common stock. The following table provides the total number of shares repurchased and the related total costs in 2018, 2017 and 2016:



Year	Total Number of Shares Repurchased	Total Cost
2018	6,744,000	$	404,759
2017	4,403,000	248,114
2016	6,600,000	294,374

The Company immediately retires its common stock when purchased. Upon retirement, the Company reduces Capital in excess of par value for the average capital per share outstanding and the remainder is charged against Retained earnings. If the Company reduces its Retained earnings to zero, any subsequent purchases of common stock will be charged entirely to Capital in excess of par value.

Rights Agreement

The Company’s Board of Directors declared a dividend distribution pursuant to a Rights Agreement (the Rights Agreement) which became effective on January 6, 2009. The Rights Agreement was not renewed and expired on January 6, 2019. The purpose of the Rights Agreement was to deter coercive or unfair takeover tactics and to prevent a person or group from acquiring control of the Company without offering a fair price to all shareholders. Under the Rights Agreement, all common shareholders would have received one Right for each common share outstanding. Each Right entitled the registered holder to purchase from the Company a unit consisting of one twenty-thousandths of a share of Series A Junior Participating Preferred Shares, $0.05 par value per share, or a combination of securities and assets of equivalent value, at a purchase price of $150.00 per unit, subject to adjustment.

Cash Dividends

On May 30, 2018, the Board of Directors declared a cash dividend of $0.30 per share on the Company’s common stock, which was paid on June 22, 2018, to shareholders of record on June 14, 2018. On December 11, 2018, the Board of Directors

declared a cash dividend of $0.33 per share on the Company’s common stock, which was paid on January 8, 2019, to shareholders of record on December 27, 2018.

The cash dividends declared in 2018, 2017 and 2016 were $97,900, $91,444 and $86,657, respectively. The Board of Directors has indicated its intention to declare future cash dividends on a semiannual basis.

Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2018

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Accumulated Other Comprehensive Income (Loss)

Other comprehensive income (loss) consists of net income and other gains and losses affecting shareholders’ equity that are excluded from net income. Other comprehensive income (loss) includes unrealized gains and losses on available for sale securities and foreign currency translation adjustments. The Company presents other comprehensive income (loss) in its Consolidated Statements of Comprehensive Income. Components of Accumulated other comprehensive income (loss), net of tax, consisted of:



	Foreign Currency Translation Adjustments			Unrealized Holding Gains (Losses) on Investments			Accumulated Other Comprehensive Income (Loss)
Balance, January 1, 2016	$	(24,988	)	$	(302	)	$	(25,290	)

Other comprehensive loss before reclassifications	(12,131		)	(918		)	(13,049		)
Amounts reclassified from accumulated other comprehensive loss	—			384			384
Net current-period other comprehensive loss	(12,131		)	(534		)	(12,665		)

Balance, December 31, 2016	$	(37,119	)	$	(836	)	$	(37,955	)

Other comprehensive gain before reclassifications	17,597			190			17,787
Amounts reclassified from accumulated other comprehensive loss	—			260			260
Net current-period other comprehensive gain	17,597			450			18,047

Balance, December 31, 2017	$	(19,522	)	$	(386	)	$	(19,908	)

Other comprehensive loss before reclassifications	(12,065		)	(1,088		)	(13,153		)
Amounts reclassified from accumulated other comprehensive loss	—			61			61
Net current-period other comprehensive loss	(12,065		)	(1,027		)	(13,092		)

Balance, December 31, 2018	$	(31,587	)	$	(1,413	)	$	(33,000	)

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

The Company leases software, facilities, and data processing equipment under non-cancelable operating leases, some which contain escalation clauses for increased taxes and operating expenses. The Company has entered into maintenance agreements primarily for its data processing equipment. Rent expense, primarily related to user licenses for software, was $34,679, $32,619 and $28,016 in 2018, 2017 and 2016, respectively.

The aggregate noncancellable minimum commitments at December 31, 2018 are:



2019	$	10,322
2020	8,476
2021	7,855
2022	7,616
2023 and thereafter	25,573
	$	59,842

Stanford Trust Company Litigation

SEI has been named in seven lawsuits filed in Louisiana courts; four of the cases also name SPTC as a defendant. The underlying allegations in all actions relate to the purported role of SPTC in providing back-office services to Stanford Trust Company. The complaints allege that SEI and SPTC participated in some manner in the sale of “certificates of deposit” issued by Stanford International Bank so as to be a “seller” of the certificates of deposit for purposes of primary liability under the Louisiana Securities Law or so as to be secondarily liable under that statute for sales of certificates of deposit made by Stanford Trust Company. Two of the actions also include claims for violations of the Louisiana Racketeering Act and possibly conspiracy, and a third also asserts claims of negligence, breach of contract, breach of fiduciary duty, violations of the uniform fiduciaries law, negligent misrepresentation, detrimental reliance, violations of the Louisiana Racketeering Act, and conspiracy.

The procedural status of the seven cases varies. The Lillie case, filed originally in the 19th Judicial District Court for the Parish of East Baton Rouge, was brought as a class action and is procedurally the most advanced of the cases. SEI and SPTC filed exceptions, which the Court granted in part, dismissing claims under the Louisiana Unfair Trade Practices Act and permitting the claims under the Louisiana Securities Law to go forward. On March 11, 2013, newly-added insurance carrier defendants removed the case to the United States District Court for the Middle District of Louisiana. On August 7, 2013, the Judicial Panel on Multidistrict Litigation transferred the matter to the Northern District of Texas where MDL 2099, In re: Stanford Entities Securities Litigation (“the Stanford MDL”), is pending. On September 22, 2015, the District Court on the motion of SEI and SPTC dismissed plaintiffs’ claims for primary liability under Section 714(A) of the Louisiana Securities Law, but declined to dismiss plaintiffs’ claims for secondary liability under Section 714(B) of the Louisiana Securities Law based on the allegations pled by plaintiffs. On November 4, 2015, the District Court granted SEI and SPTC's motion to dismiss plaintiffs' claims under Section 712(D) of the Louisiana Securities Law. Consequently, the only claims of plaintiffs remaining in Lillie are plaintiffs' claims for secondary liability against SEI and SPTC under Section 714(B) of the Louisiana Securities Law. On May 2, 2016, the District Court certified the class as being "all persons for whom Stanford Trust Company purchased or renewed Stanford Investment Bank Limited certificates of deposit in Louisiana between January 1, 2007 and February 13, 2009". Notice of the pendency of the class action was mailed to potential class members on October 4, 2016.

On December 1, 2016, a group of plaintiffs who opted out of the Lillie class filed a complaint against SEI and SPTC in the United States District Court in the Middle District of Louisiana (“Ahders Complaint”), alleging claims essentially the same as those in Lillie. In January 2017, the Judicial Panel on Multidistrict Litigation transferred the Ahders proceeding to the Northern District of Texas and the Stanford MDL. During February 2017, SEI filed its response to the Ahders Complaint, and in March 2017 the District Court for the Northern District of Texas approved the stipulated dismissal of all claims in this Complaint predicated on Section 712(D) or Section 714(A) of the Louisiana Securities Law. In both cases, as a result of the proceedings in the Northern District of Texas, only the plaintiffs’ secondary liability claims under Section 714(B) of the Louisiana Securities Law remain. Limited discovery and motions practice have occurred, including SEI and SPTC’s filing of a dispositive summary judgment motion in the Lillie proceeding. On January 31, 2019, the Judicial Panel on Multidistrict Litigation remanded the Lillie and Ahders proceedings to the Middle District of Louisiana. No material activity has taken place since remand.

Another case, filed in the 23rd Judicial District Court for the Parish of Ascension, also was removed to federal court and transferred by the Judicial Panel on Multidistrict Litigation to the Northern District of Texas and the Stanford MDL. The schedule for responding to that Complaint has not yet been established.

Two additional cases remain in the Parish of East Baton Rouge. Plaintiffs filed petitions in 2010 and have granted SEI and SPTC indefinite extensions to respond. No material activity has taken place since.

In two additional cases, filed in East Baton Rouge and brought by the same counsel who filed the Lillie action, virtually all of the litigation to date has involved motions practice and appellate litigation regarding the existence of federal subject matter jurisdiction under the federal Securities Litigation Uniform Standards Act (SLUSA). The matters were removed to the United States District Court for the Northern District of Texas and consolidated. The court then dismissed the action under SLUSA. The Court of Appeals for the Fifth Circuit reversed that order, and the Supreme Court of the United States affirmed the

Court of Appeals judgment on February 26, 2014. The matters were remanded to state court and no material activity has taken place since that date.

While the outcome of this litigation remains uncertain, SEI and SPTC believe that they have valid defenses to plaintiffs' claims and intend to defend the lawsuits vigorously. Because of uncertainty in the make-up of the Lillie class, the specific theories of liability that may survive a motion for summary judgment or other dispositive motion, the relative lack of discovery regarding damages, causation, mitigation and other aspects that may ultimately bear upon loss, the Company is not reasonably able to provide an estimate of loss, if any, with respect to the foregoing lawsuits.

SEI Capital Accumulation Plan Litigation

On September 28, 2018, a class action complaint was filed in the United States District Court for the Eastern District of Pennsylvania by Gordon Stevens, individually and as the representative of similarly situated persons, and on behalf of the SEI Capital Accumulation Plan (the “Plan”) naming the Company and its affiliated and/or related entities SEI Investments Management Corporation, SEI Capital Accumulation Plan Design Committee, SEI Capital Accumulation Plan Investment Committee, SEI Capital Accumulation Plan Administration Committee, and John Does 1-30 as defendants (the “Stevens Complaint”). The Stevens Compliant seeks unspecified damages for defendants’ breach of fiduciary duties under ERISA with respect to selecting and monitoring the Plan’s investment options and by retaining affiliated investment products in the Plan.

All parties to the matter have agreed to participate in non-binding mediation with the goal of resolving the matter in an efficient and satisfactory manner, while avoiding protracted litigation costs. The court granted a motion to stay the litigation pending the outcome of mediation, which is scheduled for May 7, 2019, in Atlanta, Georgia.

While the outcome of this litigation remains uncertain, the defendants believe that they have valid defenses to plaintiffs’ claims and intend to defend the allegations contained in the Stevens Complaint vigorously. Because of uncertainty in the make-up of the purported class named in the Stevens Complaint, the specific theories of liability that may survive a motion for summary judgment or other dispositive motion, the lack of specificity or discovery regarding damages, causation, mitigation and other aspects that may ultimately bear upon loss, the Company is not reasonably able to provide an estimate of loss, if any, with respect to the matters set forth in the Stevens Complaint.

Other Matters

The Company is also a party to various other actions and claims arising in the normal course of business that the Company does not believe are material. The Company believes that the ultimate resolution of these matters will not have a material adverse effect on the Company's financial position or the manner in which the Company conducts its business. Currently, the Company does not believe the amount of losses associated with these matters can be estimated. While the Company does not believe that the amount of such losses will, when liquidated or estimable, be material to its financial position, the assumptions may be incorrect and any such loss could have a material adverse effect on the Company's results of operations or the manner in which the Company conducts its business in the period(s) during which the underlying matters are resolved.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

The federal and state and foreign income tax provision is summarized as follows:



Year Ended December 31,	2018		2017			2016
Current
Federal	$	82,493	$	154,776		$	158,411
State	13,709		11,645			10,500
Foreign	8,405		8,002			5,137
	104,607		174,423			174,048
Deferred
Federal	2,550		(26,350		)	788
State	1,166		1,378			(168		)
Foreign	15		3,199			—
	3,731		(21,773		)	620
Total income taxes	$	108,338	$	152,650		$	174,668

Annual tax provisions include amounts considered sufficient to pay assessments that may result from examination of prior year tax returns; however, the amount ultimately paid upon resolution of issues raised may differ materially from the amount accrued. The examination and the resolution process may last longer than one year.

The components of Income before income taxes are summarized as follows:



Year Ended December 31,	2018		2017		2016
Domestic	$	579,622	$	523,044	$	481,760
Foreign	34,584		33,995		26,725
	$	614,206	$	557,039	$	508,485

The Company's foreign income is primarily earned in Canada and the Republic of Ireland.

The effective income tax rate differs from the federal income tax statutory rate due to the following:



Year Ended December 31,	2018		2017		2016
Statutory rate	21.0	%	35.0	%	35.0	%
State taxes, net of federal tax benefit	1.9		1.3		1.3
Foreign tax expense and tax rate differential	(0.1	)	(1.1	)	(0.8	)
Tax benefit from stock option exercises	(3.8	)	(3.9	)	—
Enactment of the Tax Cuts and Jobs Act:
Re-measurement of deferred taxes	—		(4.9	)	—
One-time transition tax on repatriation of foreign earnings and withholding tax	(0.1	)	2.6		—
Research and development tax credit	(0.8	)	(0.9	)	(0.8	)
Domestic Production Activities Deduction	—		(0.5	)	(0.6	)
Foreign Derived Intangible Income Deduction	(0.2	)	—		—
Other, net	(0.3	)	(0.2	)	0.2
	17.6	%	27.4	%	34.3	%

The Company's effective income tax rate in 2018 included the new 21.0 percent corporate tax rate under the Tax Cut and Jobs Act (the Tax Act). The Tax Act also provided for a Foreign Derived Intangible Income (FDII) deduction. For 2018, the Company estimated a federal FDII benefit of $1,206. The Tax Act also repealed the Section 199 Deduction for businesses that perform domestic manufacturing and certain other production activities which had an unfavorable impact on the Company's tax rate in 2018.

The Company's effective income tax rate in 2017 included the adoption of ASU 2016-09 and the estimated impact of the Tax Act. As required by ASU 2016-09, the Company no longer records excess tax benefits from stock option exercises as an increase to additional paid in capital, but records such excess tax benefits as a reduction of income tax expense in the reporting period in which the exercises occur.

The impact to the Company's effective tax rate in 2017 from the Tax Act was a combination of a $27,153 tax benefit from the re-measurement of the Company's estimated net deferred tax liability as of December 31, 2017 based upon the new 21.0 percent corporate tax rate offset by expense of $14,743 from the preliminary estimate of the one-time transition tax relating to the impact of the deemed repatriation and withholding tax of the Company's previously undistributed foreign earnings. The net impact to the Company's tax rate in 2017 from the Tax Act was a net tax benefit of $12,410, or $0.08 diluted earnings per share. The favorable impact to the Company's effective income tax rate in 2018 from the Tax Act related to the finalization of the estimated one-time transition tax. This adjustment to the one-time transition tax represents what the Company believes is its final liability under the changes from the Tax Act.

The Tax Act also imposed a territorial rather than worldwide system which requires a one-time transition tax on the repatriation of previously deferred foreign earnings. The Company's one-time transition tax as of the filing of the Company's 2017 Federal Tax Return was $10,711. After the Company made a payment of $1,000 and its estimated tax payments relating to its 2017 tax liability, the IRS issued guidance informing taxpayers that they may not receive a refund or credit of any portion of properly applied 2017 tax payments unless and until the amount of payments exceeds the entire unpaid 2017 repatriation tax liability, including all amounts to be paid in installments in subsequent years. In accordance with this guidance, the Company was required to apply $8,908 from an overpayment of federal taxes against the transition tax payable during 2018. The remaining amount payable related to the transition tax of $803 is included in Long-term income taxes payable on the accompanying Consolidated Balance Sheet.

Deferred income taxes for 2018 and 2017 reflect the impact of temporary differences between the amount of assets and liabilities for financial reporting purposes and such amounts as measured by tax laws and regulations. Significant components of our deferred tax assets and liabilities at December 31, 2018 and 2017 are as follows:



	2018			2017
Deferred Tax Assets:
Stock-based compensation expense	$	24,125		$	24,725
Foreign and state net operating loss carryforward and FTC	74,358			71,236
Basis differences in investments	4,118			4,191
Federal benefit of state tax deduction for uncertain tax positions	1,882			1,918
Revenue and expense recognized in different periods for financial reporting and income tax purposes	1,657			2,631
Other assets	1,049			273
Total deferred income tax assets	107,189			104,974
Less: valuation allowance	(72,316		)	(68,469		)
Net deferred income tax assets	$	34,873		$	36,505

Deferred Tax Liabilities:
Capitalized software currently deductible for tax purposes, net of amortization	$	(71,067	)	$	(70,575	)
Difference in financial reporting and income tax depreciation methods	(6,545		)	(3,182		)
Difference between book and tax basis of other assets	(4,429		)	(3,549		)
Goodwill and other intangibles	(1,823		)	(1,001		)
Foreign Dividend Withholding Tax	(312		)	(3,199		)
Capitalized contract costs	(5,490		)	—
Other liabilities	(960		)	(704		)
Total deferred income tax liabilities	$	(90,626	)	$	(82,210	)
Net deferred income tax liabilities	$	(55,753	)	$	(45,705	)

The valuation allowances against deferred tax assets at December 31, 2018 and 2017 are related to state net operating losses from certain domestic subsidiaries, foreign net operating losses from certain foreign subsidiaries and The Tax Act restriction of use of the foreign tax credit placed by The Tax Act. Certain state and foreign tax statutes significantly limit the utilization of net operating losses for domestic and foreign subsidiaries. Furthermore, these net operating losses cannot be used to offset the net income of other subsidiaries.

The Company recognizes uncertain tax positions in accordance with the applicable accounting guidance and adjusts these liabilities when management’s judgment changes as a result of the evaluation of new information not previously available. Due to the complexity of some of these uncertainties, the ultimate resolution may result in a payment that is materially different from our current estimate of the tax liabilities. The Company’s total unrecognized tax benefit, not including interest and penalties, as of December 31, 2018 was $14,367, of which $13,774 would affect the effective tax rate if the Company were to recognize the tax benefit. The gross amount of uncertain tax liability of $3,131 is expected to be paid within one year is netted against the current payable account while the remaining amount of $12,525 is included in Other long-term liabilities on the accompanying Consolidated Balance Sheets. During the year ended December 31, 2018, the Company recognized $2,621 of previously unrecognized tax benefits relating to the lapse of the statute of limitation.

The Company files a consolidated federal income tax return and separate income tax returns with various states. Certain subsidiaries of the Company file tax returns in foreign jurisdictions. The Company is no longer subject to U.S. federal income tax examination for years before 2015 and is no longer subject to state, local or foreign income tax examinations by authorities for years before 2014.

A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows:



	2018			2017			2016
Balance as of January 1	$	14,480		$	17,287		$	14,517
Tax positions related to current year:
Gross additions	2,446			3,180			3,756
Tax positions related to prior years:
Gross additions	340			211			1,762
Settlements	(278		)	(352		)	(378		)
Lapses on statute of limitations	(2,621		)	(5,846		)	(2,370		)
Balance as of December 31	$	14,367		$	14,480		$	17,287

The above reconciliation of the gross unrecognized tax benefit will differ from the amount which would affect the effective tax rate because of the recognition of the federal and state tax benefits.

The Company classifies all interest and penalties as income tax expense. The Company has recorded $1,289, $1,175 and $1,227 in liabilities for tax-related interest and penalties in 2018, 2017 and 2016, respectively.

The Company estimates it will recognize $3,131 of unrecognized tax benefits within the next twelve months due to lapses on the statute of limitation.

The Company includes its direct and indirect subsidiaries in its U.S. consolidated federal income tax return. The Company’s tax sharing allocation agreement provides that any subsidiary having taxable income will pay a tax liability equivalent to what that subsidiary would have paid if it filed a separate income tax return. If the separately calculated federal income tax provision for any subsidiary results in a tax loss, the current benefit resulting from such loss, to the extent utilizable on a separate return basis, is accrued and paid to that subsidiary.

Business Segment Information

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Business Segment Information

The Company’s reportable business segments are:

Private Banks – provides outsourced investment processing and investment management platforms to banks and trust institutions, independent wealth advisers and financial advisors worldwide;

Investment Advisors – provides investment management and investment processing platforms to affluent investors through a network of independent registered investment advisors, financial planners and other investment professionals in the United States;

Institutional Investors – provides investment management and administrative outsourcing platforms to retirement plan sponsors, healthcare systems and not-for-profit organizations worldwide;

Investment Managers – provides investment operations outsourcing platforms to fund companies, banking institutions, traditional and non-traditional investment managers worldwide and family offices in the United States; and

Investments in New Businesses – focuses on providing investment management solutions to ultra-high-net-worth families residing in the United States; developing internet-based investment services and advice platforms; entering new markets; and conducting other research and development activities.

In 2018, 2017 and 2016, no single customer accounted for more than ten percent of revenues in any business segment.

The following tables highlight certain financial information about each of the Company’s business segments for the years ended December 31, 2018, 2017 and 2016:



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Year Ended December 31, 2018
Revenues	$	483,097	$	399,089	$	333,299	$	398,076	$	10,606		$	1,624,167
Expenses	457,894		212,439		163,536		259,693		22,971			1,116,533
Operating profit (loss)	$	25,203	$	186,650	$	169,763	$	138,383	$	(12,365	)	$	507,634



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Year Ended December 31, 2017
Revenues	$	474,272	$	373,473	$	322,457	$	349,444	$	6,906		$	1,526,552
Expenses	455,119		201,833		161,640		226,504		20,678			1,065,774
Operating profit (loss)	$	19,153	$	171,640	$	160,817	$	122,940	$	(13,772	)	$	460,778



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Year Ended December 31, 2016
Revenues	$	457,886	$	330,677	$	312,584	$	294,390	$	6,008		$	1,401,545
Expenses	421,188		180,140		153,117		191,127		20,962			966,534
Operating profit (loss)	$	36,698	$	150,537	$	159,467	$	103,263	$	(14,954	)	$	435,011
Gain on sale of subsidiary	2,791		—		—		—		—			2,791
Total profit (loss)	$	39,489	$	150,537	$	159,467	$	103,263	$	(14,954	)	$	437,802

A reconciliation of the total reported for the business segments to income from operations in the Consolidated Statements of Operations for the years ended December 31, 2018, 2017 and 2016 is as follows:



Year Ended December 31,	2018			2017			2016
Total operating profit from segments above	$	507,634		$	460,778		$	435,011
Corporate overhead expenses	(65,646		)	(63,834		)	(59,317		)
Income from operations	$	441,988		$	396,944		$	375,694

The following tables provide additional information for the years ended December 31, 2018, 2017 and 2016 pertaining to our business segments:



	Capital Expenditures (1)						Depreciation
Year Ended December 31,	2018		2017		2016		2018		2017		2016
Private Banks	$	36,763	$	47,526	$	45,940	$	13,773	$	16,479	$	13,222
Investment Advisors	16,572		17,450		17,610		4,607		3,364		3,880
Institutional Investors	3,863		4,020		4,319		1,672		1,121		1,367
Investment Managers	13,639		15,863		11,209		6,988		4,698		4,877
Investments in New Businesses	972		546		726		547		826		2,197
Total from business segments	$	71,809	$	85,405	$	79,804	$	27,587	$	26,488	$	25,543
Corporate Overhead	1,507		1,163		1,985		1,205		823		897
	$	73,316	$	86,568	$	81,789	$	28,792	$	27,311	$	26,440

(1) Capital expenditures include additions to property and equipment and capitalized software.



	Amortization
Year Ended December 31,	2018		2017		2016
Private Banks	$	27,312	$	32,696	$	31,675
Investment Advisors	9,668		10,930		10,458
Institutional Investors	1,707		1,599		1,674
Investment Managers	9,382		2,593		1,092
Investments in New Businesses	595		239		146
Total from business segments	$	48,664	$	48,057	$	45,045
Corporate Overhead	231		218		347
	$	48,895	$	48,275	$	45,392



	Total Assets
	2018		2017
Private Banks	$	558,451	$	523,214
Investment Advisors	143,042		139,697
Institutional Investors	109,081		117,286
Investment Managers	318,342		278,540
Investments in New Businesses	33,142		19,269
Total from business segments	$	1,162,058	$	1,078,006
Corporate Overhead (2)	809,610		775,363
	$	1,971,668	$	1,853,369

(2) Unallocated assets primarily consist of cash and cash equivalents, marketable securities, and certain other shared services assets.

The following table presents revenues based on the location of the use of the products or services:



For the Year Ended December 31,	2018		2017		2016
United States	$	1,348,130	$	1,298,381	$	1,191,640
International operations	276,037		228,171		209,905
	$	1,624,167	$	1,526,552	$	1,401,545

The following table presents assets based on their location:



	2018		2017
United States	$	1,612,202	$	1,471,260
International operations	359,466		382,109
	$	1,971,668	$	1,853,369

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company, either by itself or through its wholly-owned subsidiaries, serves as the sponsor, administrator, investment advisor, distributor and shareholder servicer for SEI-sponsored investment products. These investment products are offered to clients of the Company and its subsidiaries. Fees earned by the Company for the related services are recognized pursuant to the provisions of investment advisory, fund administration, distribution, and shareholder services agreements directly with the investment products. These fees totaled $462,101, $453,438 and $431,318 in 2018, 2017 and 2016, respectively. The Company also serves as an introducing broker-dealer for securities transactions of SEI-sponsored investment products. The Company recognized $2,001, $1,216 and $561 in commissions during 2018, 2017 and 2016, respectively. Both of these fees are reflected in Asset management, administration and distribution fees on the accompanying Consolidated Statements of Operations. Receivables from investment products on the accompanying Consolidated Balance Sheets primarily represent fees receivable for distribution, investment advisory, and administration services to various investment products sponsored by SEI.

Business Acquisitions

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Business Acquisitions

Huntington Steele

On April 2, 2018, the Company acquired all ownership interests of Huntington Steele, LLC (Huntington Steele), a registered investment advisor based in Seattle, Washington servicing the ultra-high-net-worth market, to enhance the Company's business development and research efforts in an additional geographic region. Under the acquisition method of accounting, the total purchase price was allocated to Huntington Steele's net tangible and intangible assets based upon their estimated fair values as of April 2, 2018. The total purchase price for Huntington Steele was $17,914, which includes $5,794 in cash consideration, net of $125 in cash acquired, and a contingent purchase price of $12,120. The contingent purchase price consists of amounts payable to the sellers upon the attainment of specified financial measures determined at various intervals over the next five years. The current portion of the contingent purchase price of $430 is included in Accrued liabilities on the accompanying Balance Sheet. The long-term portion of the contingent consideration of $11,690 is included in Other long-term liabilities on the accompanying Balance Sheet.

The purchase price allocation for the Huntington Steele acquisition is as follows:



	Estimated Fair Value			Estimated Useful Life
Cash	$	125
Goodwill	11,499
Identifiable intangible assets
Client relationships	6,180			12.0 years
Trade names	450			7.0 years
Other assets	15
Current liabilities	(230		)
Contingent consideration	(12,120		)
Net cash consideration	$	5,794

The results of operations of Huntington Steele are included in the Investments in New Businesses segment and are reflected in the Company's Consolidated Statement of Operations since the completion of the acquisition on April 2, 2018. Any goodwill generated for income tax purposes from the acquisition is fully deductible (See Note 15).

Pro forma information has not been presented because the effect of the Huntington Steele acquisition is not material to the Company's consolidated financial results.

Archway

On July 3, 2017, the Company acquired all ownership interests of Archway Technology Partners, LLC, Archway Finance & Operations, Inc. and Keystone Capital Holdings, LLC (collectively, Archway), a provider of operating technologies and services to the family office industry, from Keystone International Holdings, Inc. With this acquisition, the Company expands its position in the single and multi-family office services market by diversifying its technology and operating solutions.

Under the acquisition method of accounting, the total purchase price was allocated to Archway's net tangible and intangible assets based upon their estimated fair values as of July 3, 2017. The total purchase price for Archway was $81,635 in cash consideration with up to an additional $8,000 payable to the seller as a contingent purchase price with respect to two one-year periods ended December 31, 2017 and 2018 depending upon whether Archway achieved specified financial measures during such periods. The fair value of the contingent consideration was estimated to be $4,800 on the acquisition date. Archway did not attain the specified financial measure for the periods ended December 31, 2017 or December 31, 2018. As a result, as of December 31, 2017, the Company reversed the value allocated to the contingent consideration established at the acquisition date. Additionally, the Company recognized a liability for post-acquisition obligations to the members of Archway. The net adjustment of $3,800 was recorded as a reduction in expense and is reflected in Facilities, supplies and other costs on the accompanying Consolidated Statement of Operations in 2017. At December 31, 2018, the Company reversed the liability for the post-acquisition obligations to the members of Archway as the specified financial measure was not achieved.

The Company acquired $1,401 in cash during the acquisition, resulting in $80,234 net cash paid for Archway. According to the terms of the purchase agreement, a portion of the purchase price was placed into escrow to indemnify the Company of any pre-acquisition damages. As of December 31, 2018, the balance available in escrow was $8,000. During January 2019, the entire amount placed into escrow was released to the seller. As of January 31, 2019, the Company has no further obligation related to the acquisition of Archway.

The purchase price allocation for the Archway acquisition is as follows:



	Estimated Fair Value			Estimated Useful Life
Current assets, net of current liabilities	$	2,539
Property and equipment	776
Goodwill	52,990
Identifiable intangible assets
Acquired technology	13,510			10.0 years
Client relationships	10,760			15.0 years
Non-competition agreements	3,470			5.0 years
Trade names	2,390			7.0 years
Contingent consideration	(4,800		)
Total purchase price allocation	$	81,635

The results of operations of Archway and any adjustments related to the acquisition are included in the Investment Managers business segment and are reflected in the Company's Consolidated Statement of Operations since the completion of the acquisition on July 3, 2017. All tangible and intangible assets resulting from the Archway transaction have been allocated to the Investment Managers business segment. Any goodwill generated for income tax purposes from the acquisition is fully deductible (See Note 15).

Pro forma information has not been presented because the effect of the Archway acquisition is not material to the Company's consolidated financial results.

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets

The changes in the carrying amount of the Company's goodwill by segment are as follows:



	Investment Managers		Investments In New Businesses		Total
Balance, January 1, 2017	$	—	$	—	$	—
Acquisition of Archway	52,990		—		52,990
Balance, December 31, 2017	$	52,990	$	—	$	52,990
Acquisition of Huntington Steele	—		11,499		11,499
Balance, December 31, 2018	$	52,990	$	11,499	$	64,489

In April 2018, the Company acquired all ownership interests of Huntington Steele (See Note 14). The excess purchase price over the estimated value of the net tangible and identifiable intangible assets was allocated to goodwill. The total amount of goodwill from this transaction amounted to $11,499 and is included on the accompanying Consolidated Balance Sheet.

In July 2017, the Company acquired all ownership interests of Archway (See Note 14). The excess purchase price over the estimated value of the net tangible and identifiable intangible assets was recorded as goodwill. The total amount of goodwill from this transaction amounted to $52,990 and is included on the accompanying Consolidated Balance Sheets.

The Company's intangible assets consist of:



	December 31, 2018			Weighted Average Estimated Useful Life	December 31, 2017			Weighted Average Estimated Useful Life
Acquired technology	$	13,510		10.0 years	$	13,510		10.0 years
Client relationships	16,940			13.9 years	10,760			15.0 years
Non-competition agreements	3,470			5.0 years	3,470			5.0 years
Trade name	2,840			7.0 years	2,390			7.0 years
	36,760				30,130
Less: Accumulated amortization	(5,090		)		(1,552		)
Intangible assets, net	$	31,670			$	28,578

The Company recognized $3,538 and $1,552 of amortization expense related to intangible assets during 2018 and 2017, respectively.

The Company currently expects to recognize amortization expense related to intangible assets as of December 31, 2018 each year from 2019 through 2023 as follows:



2019	$	3,683
2020	3,683
2021	3,683
2022	3,336
2023	2,989

Revenues from Contracts with Customers

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

Revenues from Contracts with Customers

The Company’s principal sources of revenues are: (1) asset management, administration and distribution fees primarily earned based upon a contractual percentage of net assets under management or administration; and (2) information processing and software servicing fees that are either recurring and primarily earned based upon the number of trust accounts being serviced or a percentage of the total average daily market value of the clients' assets processed on the Company's platforms, or non-recurring and based upon project-oriented contractual agreements related to client implementations.

Disaggregation of Revenue

The following tables provide additional information pertaining to our revenues disaggregated by major product line and primary geographic market based on the location of the use of the products or services for each of the Company’s business segments for 2018:



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses		Total
Major Product Lines:	For the Year Ended December 31, 2018
Investment management fees from pooled investment products	$	138,616	$	288,030	$	59,739	$	928	$	1,017	$	488,330
Investment management fees from investment management agreements	793		94,526		271,600		331		9,457		376,707
Investment operations fees	1,517		—		—		360,382		—		361,899
Investment processing fees - PaaS	182,068		—		—		2,519		—		184,587
Investment processing fees - SaaS	136,222		—		—		9,598		—		145,820
Professional services fees	16,643		—		—		7,280		—		23,923
Account fees and other	7,238		16,533		1,960		17,038		132		42,901
Total revenues	$	483,097	$	399,089	$	333,299	$	398,076	$	10,606	$	1,624,167

Primary Geographic Markets:
United States	$	304,762	$	399,089	$	257,080	$	376,593	$	10,606	$	1,348,130
United Kingdom	112,980		—		55,471		—		—		168,451
Canada	45,941		—		8,526		—		—		54,467
Ireland	19,414		—		10,419		21,483		—		51,316
Other	—		—		1,803		—		—		1,803
Total revenues	$	483,097	$	399,089	$	333,299	$	398,076	$	10,606	$	1,624,167

Investment management fees from pooled investment products - Revenues associated with clients' assets invested in Company-sponsored pooled investment products. Contractual fees are stated as a percentage of the average market value of assets under management and collected on a monthly basis. Revenues are recognized in Asset management, administration and distribution fees on the accompanying Consolidated Statements of Operations.

Investment management fees from investment management agreements - Revenues based on assets of clients of the Institutional Investors segment primarily invested in Company-sponsored products. Each client is charged an investment management fee that is stated as a percentage of the average market value of all assets under management. The client is billed directly on a quarterly basis. Revenues are recognized in Asset management, administration and distribution fees on the accompanying Consolidated Statements of Operations.

Revenues associated with the separately managed account program offered through registered investment advisors located throughout the United States. The contractual fee is stated as a percentage of the average market value of all assets invested in the separately managed account and collected on a quarterly basis. Revenues are recognized in Asset management, administration and distribution fees on the accompanying Consolidated Statements of Operations.

Investment operations fees - Revenues earned from accounting and administrative services, distribution support services and regulatory and compliance services to investment management firms and family offices. The Company contracts directly with the investment management firm or family office. The contractual fees are stated as a percentage of net assets under administration and billed when asset valuations are finalized. Revenues are recognized in Asset management, administration and distribution fees on the accompanying Consolidated Statements of Operations.

Investment processing fees - Software as a Service - Revenues associated with clients that outsource investment processing technology software and computer processing by accessing our proprietary software and data center remotely but retain responsibility for all investment operations, client administration and other back-office trust operations. The contractual fee is based on a monthly fee plus additional fees determined on a per-account or per-transaction basis. The client is billed directly on a monthly basis. Revenues are recognized in Information processing and software servicing fees on the accompanying Consolidated Statements of Operations.

Investment processing fees - Platform as a Service - Revenues associated with clients that outsource their entire investment operation and back-office processing functions. Through the use of the Company's proprietary platforms, the Company assumes all back-office investment processing services including investment processing, custody and safekeeping of assets, income collections, securities settlement and other related trust activities. The contractual fee is based on a monthly fee plus additional fees determined on a per-account or per-transaction basis. Contractual fees can also be stated as a percentage of the value of assets processed on the Company's platforms each month as long as the fee is in excess of a monthly contractual minimum. The client is billed directly on a monthly basis. Revenues are recognized in Information processing and software servicing fees on the accompanying Consolidated Statements of Operations.

Professional services fees - Revenues associated with the business services migration for investment processing clients of the Private Banks segment and investment operations clients of the Investment Managers segment. In addition, Professional services include other services such as business transformation consulting. Typically, fees are stated as a contractual fixed fee. The client is billed directly and fees are collected according to the terms of the agreement.

Other - Revenues associated with custody account servicing, account terminations, reimbursements received for out-of-pocket expenses, and other fees for the provision of ancillary services.

Revenue is recognized by the Company when the performance obligations are satisfied and transfer of control to the client is completed. The majority of the Company’s performance obligations are satisfied and control is transferred to the client continuously. Therefore, revenue is recognized on a monthly basis. The amount of revenue recognized reflects the amount of consideration expected to be received by the Company in exchange for satisfied performance obligations.

The Company does not disclose the value of unsatisfied performance obligations as the majority of its contracts relate to either: contracts with an original term of one year or less; contracts for which the Company recognizes revenue at the amount to which it has the right to invoice for services performed; or contracts that are based on the value of assets under management or administration.

Deferred Contract Costs

Deferred contract costs, which primarily consist of deferred sales commissions, were $24,007 as of December 31, 2018. The Company recorded a cumulative effect adjustment on January 1, 2018 of $18,641 associated with the capitalization of contract costs upon the adoption of ASC 606 (See Note 1). The Company deferred expenses related to contract costs of $8,122 during 2018. Amortization expense related to deferred contract costs were $2,756 during 2018 and is included in Compensation, benefits and other personnel on the accompanying Consolidated Statements of Operations. There was no impairment loss in relation to deferred contract costs during 2018.

Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Data [Abstract]

Quarterly Financial Data (Unaudited)



	For the Three Months Ended
2018	March 31			June 30			September 30			December 31
Revenues	$	405,598		$	404,830		$	408,682		$	405,057
Income before income taxes	$	158,758		$	154,254		$	157,595		$	143,599
Net income	$	139,838		$	121,677		$	128,319		$	116,034
Basic earnings per share	$	0.89		$	0.77		$	0.82		$	0.75
Diluted earnings per share	$	0.86		$	0.75		$	0.80		$	0.73

Effective income tax rate	11.9		%	21.1		%	18.6		%	19.2		%



	For the Three Months Ended
2017	March 31			June 30			September 30			December 31(1)
Revenues	$	359,984		$	372,331		$	386,018		$	408,219
Income before income taxes	$	128,660		$	135,158		$	140,769		$	152,452
Net income	$	88,737		$	91,769		$	101,739		$	122,144
Basic earnings per share	$	0.56		$	0.58		$	0.64		$	0.78
Diluted earnings per share (2)	$	0.55		$	0.57		$	0.63		$	0.75

Effective income tax rate	31.0		%	32.1		%	27.7		%	19.9		%

(1) During the fourth quarter 2017, the Company recognized an estimated net tax benefit of $12,410, or $0.08 diluted earnings per share, resulting from the impacts of the enactment of the Tax Act in December 2017 (See Note 11).

(2) The sum of the individual quarterly earnings per share amounts may not agree with the annual earnings per share amount as each quarterly computation is based on the weighted average number of shares outstanding during that period.

Summary of Significant Accounting Policies (Policy)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Principles of Consolidation

Variable Interest Entities

pooled investment vehicles. For this reason, the Company also concluded that it is not required to consolidate the pooled investment vehicles under the voting interest entity (VOE) model.

Management's Use of Estimates

Management’s Use of EstimatesThe preparation of financial statements in conformity with accounting principles generally accepted in the United States (U.S. GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Revenue Recognition

Cash and Cash Equivalents

Cash and Cash EquivalentsThe Company considers investment instruments purchased with an original maturity of three months or less to be cash equivalents.

Allowance for Doubtful Accounts

Allowances for Doubtful AccountsThe Company provides an allowance for doubtful accounts equal to the estimated uncollectible amounts. The Company’s estimate is based on historical collection experience and a review of the current status of trade accounts receivable.

Concentration of Credit Risk

Concentration of Credit RiskFinancial instruments which potentially expose the Company to concentrations of credit risk consist primarily of cash equivalents and trade receivables. Cash equivalents are principally invested in short-term money market funds or placed with major banks and high-credit qualified financial institutions. Cash deposits maintained with institutions are in excess of federally insured limits. Concentrations of credit risk with respect to the Company's receivables are limited due to the large number of clients and their dispersion across geographic areas. No single group or customer represents greater than ten percent of total accounts receivable.

Property and Equipment

Property and EquipmentProperty and Equipment are recorded at cost. Expenditures for major additions and improvements are capitalized and minor replacements, maintenance, and repairs are charged to expense as incurred. Construction in progress includes the cost of construction and other direct costs attributable to the construction. When property and equipment are retired or disposed of, the related cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations for the respective period. Depreciation is provided over the estimated useful lives using the straight line method for financial statement purposes. No provision for depreciation is made for construction in progress until such time as the relevant assets are completed and put into service. The Company uses other depreciation methods, generally accelerated, for tax purposes where appropriate. Buildings and building improvements are depreciated over 25 to 39 years. Equipment, purchased software and furniture and fixtures have useful lives ranging from 3 to 5 years. Amortization of leasehold improvements is computed using the straight line method over the shorter of the remaining lease term or the estimated useful lives of the improvements.

Marketable Securities

Fair Value of Financial Instruments

Capitalized Software

costs are amortized on a product-by-product basis using the straight-line method over the estimated economic life of the product or enhancement.



2019	$	46,608
2020	46,608
2021	46,330
2022	31,817
2023	13,145

Business Combinations

Business CombinationsThe Company accounts for business combinations in accordance with Accounting Standards Codification Topic 805, Business Combinations (ASC 805). ASC 805 establishes principles and requirements for recognizing the total consideration transferred, assets acquired and liabilities assumed in a business combination. ASC 805 also provides guidance for recognizing and measuring goodwill acquired in a business combination and requires the acquirer to disclose information needed to evaluate and understand the financial impact of the business combination. The Company recognizes assets and liabilities acquired at their estimated fair values. Management uses judgment to identify the acquired assets and liabilities assumed; estimate the fair value of these assets and liabilities; estimate the useful life of the assets; and assess the appropriate method for recognizing depreciation or amortization expense over the estimated useful life of the assets.

Goodwill and Other Intangible Assets

Income Taxes

Income TaxesThe Company applies the asset and liability approach to account for income taxes whereby deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.Annual tax provisions include amounts considered sufficient to pay assessments that may result from examination of prior year tax returns; however, the amount ultimately paid upon resolution of issues raised may differ materially from the amount accrued. The examination and the resolution process may last longer than one year.

Foreign Currency Translation

Transaction gains and losses from exchange rate fluctuations are included in the results of operations in the periods in which they occur.

Earnings Per Common Share

Earnings Per Common ShareBasic earnings per common share is computed by dividing net income attributable to SEI Investments common shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per common share is computed by dividing net income attributable to SEI Investments common shareholders by the combination of the weighted average number of common shares outstanding and the dilutive potential common shares, such as stock options, outstanding during the period.

Stock-based Compensation

Stock-Based Compensation

New Accounting Pronouncements

Reclassifications

ReclassificationsCertain prior year amounts have been reclassified to conform to current year presentation.

Investments in Unconsolidated Affiliates

The Company accounts for its interest in LSV using the equity method because of its less than 50 percent ownership. The Company’s interest in the net assets of LSV is reflected in Investment in unconsolidated affiliates on the accompanying Consolidated Balance Sheets and its interest in the earnings of LSV is reflected in Equity in earnings of unconsolidated affiliates on the accompanying Consolidated Statements of Operations.

Investments in Affiliated Funds

Securities Owned

Accumulated Other Comprehensive Income (Loss)

Uncertain Tax Positions

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Amortization Expense Related to the SEI Wealth Platform



2019	$	46,608
2020	46,608
2021	46,330
2022	31,817
2023	13,145

Calculation Of Basic And Diluted Earnings Per Share

The calculations of basic and diluted earnings per share for 2018, 2017 and 2016 are:



	2018		2017		2016
Net income	$	505,868	$	404,389	$	333,817
Shares used to compute basic earnings per common share	156,579,000		158,177,000		161,350,000
Dilutive effect of stock options	4,653,000		4,092,000		3,081,000
Shares used to compute diluted earnings per common share	161,232,000		162,269,000		164,431,000
Basic earnings per common share	$	3.23	$	2.56	$	2.07
Diluted earnings per common share	$	3.14	$	2.49	$	2.03

Composition of Certain Financial Statement Captions (Tables)

12 Months Ended

Dec. 31, 2018

Items Included in Consolidated Statement of Financial Condition [Abstract]

Receivables

Receivables on the accompanying Consolidated Balance Sheets consist of:



	2018			2017
Trade receivables	$	76,362		$	76,760
Fees earned, not billed	226,001			194,331
Other receivables	13,691			12,310
	316,054			283,401
Less: Allowance for doubtful accounts	(718		)	(695		)
Receivables, net	$	315,336		$	282,706

Property And Equipment

Property and Equipment on the accompanying Consolidated Balance Sheets consists of:



	2018			2017
Buildings	$	160,796		$	153,961
Equipment	126,954			115,546
Land	10,772			10,030
Purchased software	139,245			134,610
Furniture and fixtures	18,103			18,114
Leasehold improvements	18,959			18,017
Construction in progress	9,240			6,105
	484,069			456,383
Less: Accumulated depreciation	(338,206		)	(309,955		)
Property and Equipment, net	$	145,863		$	146,428

Accrued Liabilities

Accrued Liabilities on the accompanying Consolidated Balance Sheets consist of:



	2018		2017
Accrued employee compensation	$	97,603	$	88,960
Accrued consulting, outsourcing and professional fees	31,000		29,658
Accrued sub-advisory, distribution and other asset management fees	42,583		42,365
Accrued dividend payable	50,761		47,179
Other accrued liabilities	57,687		56,896
Accrued liabilities	$	279,634	$	265,058

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Of Certain Financial Assets And Liabilities

The fair value of certain financial assets and liabilities of the Company was determined using the following inputs:



			Fair Value Measurements at Reporting Date Using
	December 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Assets
Equity available-for-sale securities	$	10,218	$	10,218	$	—
Fixed-income available-for-sale securities	101,683		—		101,683
Fixed-income securities owned	30,892		—		30,892
Investment funds sponsored by LSV (1)	4,887
	$	147,680	$	10,218	$	132,575



			Fair Value Measurements at Reporting Date Using
	December 31, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Assets
Equity available-for-sale securities	$	11,250	$	11,250	$	—
Fixed-income available-for-sale securities	76,733		—		76,733
Fixed-income securities owned	21,526		—		21,526
Investment funds sponsored by LSV (1)	6,034
	$	115,543	$	11,250	$	98,259

Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2018

Stockholders' Equity Note [Abstract]

Assumptions Used In The Weighted Average Fair Value Of The Stock Options Granted

The weighted average fair value of the Company’s stock options granted during 2018, 2017 and 2016 were $13.04, $16.78 and $12.43, respectively, using the following assumptions:



	2018		2017		2016
Expected term (in years)	6.34		6.00		6.00
Expected volatility	25.27	%	22.58	%	25.44	%
Expected dividend yield	1.35	%	0.82	%	1.10	%
Risk-free interest rate	2.75	%	2.29	%	2.18	%

Stock-based Compensation Expense

The Company recognized stock-based compensation expense in its Consolidated Financial Statements in 2018, 2017 and 2016 as follows:



	2018			2017			2016
Stock-based compensation expense	$	23,805		$	36,366		$	16,017
Less: Deferred tax benefit	(5,078		)	(7,891		)	(5,612		)
Stock-based compensation expense, net of tax	$	18,727		$	28,475		$	10,405

Stock Option Plans

This table presents certain information relating to the Company’s stock option plans for 2018, 2017 and 2016:



	Number of Shares		Weighted Avg. Price
Balance as of December 31, 2015	19,237,000		$	28.71
Granted	2,310,000		49.57
Exercised	(1,809,000	)	24.82
Expired or canceled	(1,669,000	)	30.86
Balance as of December 31, 2016	18,069,000		$	31.57
Granted	2,057,000		69.87
Exercised	(2,370,000	)	21.22
Expired or canceled	(1,044,000	)	33.42
Balance as of December 31, 2017	16,712,000		$	37.63
Granted	2,468,000		49.94
Exercised	(3,232,000	)	25.93
Expired or canceled	(135,000	)	49.58
Balance as of December 31, 2018	15,813,000		$	41.84

Exercisable as of December 31, 2018	9,359,000		$	32.89
Available for future grant as of December 31, 2018	21,775,000

Stock Options Outstanding And Exercisable

This table summarizes information relating to all options outstanding and exercisable at December 31, 2018:



				Options Outstanding at December 31, 2018				Options Exercisable at December 31, 2018
Range of Exercise Prices (Per Share)				Number of Shares	Weighted Average Exercise Price (Per Share)		Weighted Average Remaining Contractual Life (Years)	Number of Shares	Weighted Average Exercise Price (Per Share)		Weighted Average Remaining Contractual Life (Years)
$	14.62	-	21.05	1,996,000	$	16.63	2.09	1,996,000	$	16.63	2.09
22.45		-	23.86	2,379,000	23.13		3.04	2,379,000	23.13		3.04
27.03		-	40.64	3,332,000	37.10		5.54	2,390,000	35.70		5.36
45.99		-	53.16	4,268,000	49.01		9.06	908,000	49.61		8.00
53.34		-	71.12	3,838,000	62.69		8.19	1,686,000	53.36		7.02
				15,813,000				9,359,000

Common Stock Buyback

The following table provides the total number of shares repurchased and the related total costs in 2018, 2017 and 2016:



Year	Total Number of Shares Repurchased	Total Cost
2018	6,744,000	$	404,759
2017	4,403,000	248,114
2016	6,600,000	294,374

Accumulated Other Comprehensive Income (Loss), Net of Tax (Tables)

12 Months Ended

Dec. 31, 2018

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Schedule Of Accumulated Other Comprehensive Income (Loss), Net Of Tax

Components of Accumulated other comprehensive income (loss), net of tax, consisted of:



	Foreign Currency Translation Adjustments			Unrealized Holding Gains (Losses) on Investments			Accumulated Other Comprehensive Income (Loss)
Balance, January 1, 2016	$	(24,988	)	$	(302	)	$	(25,290	)

Other comprehensive loss before reclassifications	(12,131		)	(918		)	(13,049		)
Amounts reclassified from accumulated other comprehensive loss	—			384			384
Net current-period other comprehensive loss	(12,131		)	(534		)	(12,665		)

Balance, December 31, 2016	$	(37,119	)	$	(836	)	$	(37,955	)

Other comprehensive gain before reclassifications	17,597			190			17,787
Amounts reclassified from accumulated other comprehensive loss	—			260			260
Net current-period other comprehensive gain	17,597			450			18,047

Balance, December 31, 2017	$	(19,522	)	$	(386	)	$	(19,908	)

Other comprehensive loss before reclassifications	(12,065		)	(1,088		)	(13,153		)
Amounts reclassified from accumulated other comprehensive loss	—			61			61
Net current-period other comprehensive loss	(12,065		)	(1,027		)	(13,092		)

Balance, December 31, 2018	$	(31,587	)	$	(1,413	)	$	(33,000	)

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Federal and State and Foreign Income Tax Provision

The federal and state and foreign income tax provision is summarized as follows:



Year Ended December 31,	2018		2017			2016
Current
Federal	$	82,493	$	154,776		$	158,411
State	13,709		11,645			10,500
Foreign	8,405		8,002			5,137
	104,607		174,423			174,048
Deferred
Federal	2,550		(26,350		)	788
State	1,166		1,378			(168		)
Foreign	15		3,199			—
	3,731		(21,773		)	620
Total income taxes	$	108,338	$	152,650		$	174,668

Components of Net Income Before Income Taxes

The components of Income before income taxes are summarized as follows:



Year Ended December 31,	2018		2017		2016
Domestic	$	579,622	$	523,044	$	481,760
Foreign	34,584		33,995		26,725
	$	614,206	$	557,039	$	508,485

Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate

The effective income tax rate differs from the federal income tax statutory rate due to the following:



Year Ended December 31,	2018		2017		2016
Statutory rate	21.0	%	35.0	%	35.0	%
State taxes, net of federal tax benefit	1.9		1.3		1.3
Foreign tax expense and tax rate differential	(0.1	)	(1.1	)	(0.8	)
Tax benefit from stock option exercises	(3.8	)	(3.9	)	—
Enactment of the Tax Cuts and Jobs Act:
Re-measurement of deferred taxes	—		(4.9	)	—
One-time transition tax on repatriation of foreign earnings and withholding tax	(0.1	)	2.6		—
Research and development tax credit	(0.8	)	(0.9	)	(0.8	)
Domestic Production Activities Deduction	—		(0.5	)	(0.6	)
Foreign Derived Intangible Income Deduction	(0.2	)	—		—
Other, net	(0.3	)	(0.2	)	0.2
	17.6	%	27.4	%	34.3	%

Schedule of Deferred Tax Assets and Liabilities

Significant components of our deferred tax assets and liabilities at December 31, 2018 and 2017 are as follows:



	2018			2017
Deferred Tax Assets:
Stock-based compensation expense	$	24,125		$	24,725
Foreign and state net operating loss carryforward and FTC	74,358			71,236
Basis differences in investments	4,118			4,191
Federal benefit of state tax deduction for uncertain tax positions	1,882			1,918
Revenue and expense recognized in different periods for financial reporting and income tax purposes	1,657			2,631
Other assets	1,049			273
Total deferred income tax assets	107,189			104,974
Less: valuation allowance	(72,316		)	(68,469		)
Net deferred income tax assets	$	34,873		$	36,505

Deferred Tax Liabilities:
Capitalized software currently deductible for tax purposes, net of amortization	$	(71,067	)	$	(70,575	)
Difference in financial reporting and income tax depreciation methods	(6,545		)	(3,182		)
Difference between book and tax basis of other assets	(4,429		)	(3,549		)
Goodwill and other intangibles	(1,823		)	(1,001		)
Foreign Dividend Withholding Tax	(312		)	(3,199		)
Capitalized contract costs	(5,490		)	—
Other liabilities	(960		)	(704		)
Total deferred income tax liabilities	$	(90,626	)	$	(82,210	)
Net deferred income tax liabilities	$	(55,753	)	$	(45,705	)

Schedule of Unrecognized Tax Benefits Roll Forward

A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows:



	2018			2017			2016
Balance as of January 1	$	14,480		$	17,287		$	14,517
Tax positions related to current year:
Gross additions	2,446			3,180			3,756
Tax positions related to prior years:
Gross additions	340			211			1,762
Settlements	(278		)	(352		)	(378		)
Lapses on statute of limitations	(2,621		)	(5,846		)	(2,370		)
Balance as of December 31	$	14,367		$	14,480		$	17,287

Business Segment Information (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Financial Information About Business Segments

The following tables highlight certain financial information about each of the Company’s business segments for the years ended December 31, 2018, 2017 and 2016:



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Year Ended December 31, 2018
Revenues	$	483,097	$	399,089	$	333,299	$	398,076	$	10,606		$	1,624,167
Expenses	457,894		212,439		163,536		259,693		22,971			1,116,533
Operating profit (loss)	$	25,203	$	186,650	$	169,763	$	138,383	$	(12,365	)	$	507,634



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Year Ended December 31, 2017
Revenues	$	474,272	$	373,473	$	322,457	$	349,444	$	6,906		$	1,526,552
Expenses	455,119		201,833		161,640		226,504		20,678			1,065,774
Operating profit (loss)	$	19,153	$	171,640	$	160,817	$	122,940	$	(13,772	)	$	460,778



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Year Ended December 31, 2016
Revenues	$	457,886	$	330,677	$	312,584	$	294,390	$	6,008		$	1,401,545
Expenses	421,188		180,140		153,117		191,127		20,962			966,534
Operating profit (loss)	$	36,698	$	150,537	$	159,467	$	103,263	$	(14,954	)	$	435,011
Gain on sale of subsidiary	2,791		—		—		—		—			2,791
Total profit (loss)	$	39,489	$	150,537	$	159,467	$	103,263	$	(14,954	)	$	437,802

Reconciliation Of Total Operating Profit Reported For Business Segments To Income From Operations In Consolidated Statements Of Operations



Year Ended December 31,	2018			2017			2016
Total operating profit from segments above	$	507,634		$	460,778		$	435,011
Corporate overhead expenses	(65,646		)	(63,834		)	(59,317		)
Income from operations	$	441,988		$	396,944		$	375,694

Additional Information Pertaining To Business Segments

The following tables provide additional information for the years ended December 31, 2018, 2017 and 2016 pertaining to our business segments:



	Capital Expenditures (1)						Depreciation
Year Ended December 31,	2018		2017		2016		2018		2017		2016
Private Banks	$	36,763	$	47,526	$	45,940	$	13,773	$	16,479	$	13,222
Investment Advisors	16,572		17,450		17,610		4,607		3,364		3,880
Institutional Investors	3,863		4,020		4,319		1,672		1,121		1,367
Investment Managers	13,639		15,863		11,209		6,988		4,698		4,877
Investments in New Businesses	972		546		726		547		826		2,197
Total from business segments	$	71,809	$	85,405	$	79,804	$	27,587	$	26,488	$	25,543
Corporate Overhead	1,507		1,163		1,985		1,205		823		897
	$	73,316	$	86,568	$	81,789	$	28,792	$	27,311	$	26,440

(1) Capital expenditures include additions to property and equipment and capitalized software.



	Amortization
Year Ended December 31,	2018		2017		2016
Private Banks	$	27,312	$	32,696	$	31,675
Investment Advisors	9,668		10,930		10,458
Institutional Investors	1,707		1,599		1,674
Investment Managers	9,382		2,593		1,092
Investments in New Businesses	595		239		146
Total from business segments	$	48,664	$	48,057	$	45,045
Corporate Overhead	231		218		347
	$	48,895	$	48,275	$	45,392



	Total Assets
	2018		2017
Private Banks	$	558,451	$	523,214
Investment Advisors	143,042		139,697
Institutional Investors	109,081		117,286
Investment Managers	318,342		278,540
Investments in New Businesses	33,142		19,269
Total from business segments	$	1,162,058	$	1,078,006
Corporate Overhead (2)	809,610		775,363
	$	1,971,668	$	1,853,369

(2) Unallocated assets primarily consist of cash and cash equivalents, marketable securities, and certain other shared services assets.

Revenues And Assets Based On Location

The following table presents revenues based on the location of the use of the products or services:



For the Year Ended December 31,	2018		2017		2016
United States	$	1,348,130	$	1,298,381	$	1,191,640
International operations	276,037		228,171		209,905
	$	1,624,167	$	1,526,552	$	1,401,545

The following table presents assets based on their location:



	2018		2017
United States	$	1,612,202	$	1,471,260
International operations	359,466		382,109
	$	1,971,668	$	1,853,369

Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The changes in the carrying amount of the Company's goodwill by segment are as follows:



	Investment Managers		Investments In New Businesses		Total
Balance, January 1, 2017	$	—	$	—	$	—
Acquisition of Archway	52,990		—		52,990
Balance, December 31, 2017	$	52,990	$	—	$	52,990
Acquisition of Huntington Steele	—		11,499		11,499
Balance, December 31, 2018	$	52,990	$	11,499	$	64,489

Schedule of Intangible Assets

The Company's intangible assets consist of:



	December 31, 2018			Weighted Average Estimated Useful Life	December 31, 2017			Weighted Average Estimated Useful Life
Acquired technology	$	13,510		10.0 years	$	13,510		10.0 years
Client relationships	16,940			13.9 years	10,760			15.0 years
Non-competition agreements	3,470			5.0 years	3,470			5.0 years
Trade name	2,840			7.0 years	2,390			7.0 years
	36,760				30,130
Less: Accumulated amortization	(5,090		)		(1,552		)
Intangible assets, net	$	31,670			$	28,578

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

The Company currently expects to recognize amortization expense related to intangible assets as of December 31, 2018 each year from 2019 through 2023 as follows:



2019	$	3,683
2020	3,683
2021	3,683
2022	3,336
2023	2,989

Revenues from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses		Total
Major Product Lines:	For the Year Ended December 31, 2018
Investment management fees from pooled investment products	$	138,616	$	288,030	$	59,739	$	928	$	1,017	$	488,330
Investment management fees from investment management agreements	793		94,526		271,600		331		9,457		376,707
Investment operations fees	1,517		—		—		360,382		—		361,899
Investment processing fees - PaaS	182,068		—		—		2,519		—		184,587
Investment processing fees - SaaS	136,222		—		—		9,598		—		145,820
Professional services fees	16,643		—		—		7,280		—		23,923
Account fees and other	7,238		16,533		1,960		17,038		132		42,901
Total revenues	$	483,097	$	399,089	$	333,299	$	398,076	$	10,606	$	1,624,167

Primary Geographic Markets:
United States	$	304,762	$	399,089	$	257,080	$	376,593	$	10,606	$	1,348,130
United Kingdom	112,980		—		55,471		—		—		168,451
Canada	45,941		—		8,526		—		—		54,467
Ireland	19,414		—		10,419		21,483		—		51,316
Other	—		—		1,803		—		—		1,803
Total revenues	$	483,097	$	399,089	$	333,299	$	398,076	$	10,606	$	1,624,167

Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Data [Abstract]

Quarterly Financial Data



	For the Three Months Ended
2018	March 31			June 30			September 30			December 31
Revenues	$	405,598		$	404,830		$	408,682		$	405,057
Income before income taxes	$	158,758		$	154,254		$	157,595		$	143,599
Net income	$	139,838		$	121,677		$	128,319		$	116,034
Basic earnings per share	$	0.89		$	0.77		$	0.82		$	0.75
Diluted earnings per share	$	0.86		$	0.75		$	0.80		$	0.73

Effective income tax rate	11.9		%	21.1		%	18.6		%	19.2		%



	For the Three Months Ended
2017	March 31			June 30			September 30			December 31(1)
Revenues	$	359,984		$	372,331		$	386,018		$	408,219
Income before income taxes	$	128,660		$	135,158		$	140,769		$	152,452
Net income	$	88,737		$	91,769		$	101,739		$	122,144
Basic earnings per share	$	0.56		$	0.58		$	0.64		$	0.78
Diluted earnings per share (2)	$	0.55		$	0.57		$	0.63		$	0.75

Effective income tax rate	31.0		%	32.1		%	27.7		%	19.9		%

Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	Dec. 31, 2015
Summary of Significant Accounting Policies [Line Items]
Expense related to soft dollar arrangement									$ 16,680,000	$ 14,623,000	$ 18,409,000
Cash and cash equivalents	$ 754,525,000				$ 744,247,000				754,525,000	744,247,000
Restricted cash	3,514,000				3,505,000				3,514,000	3,505,000
Impairment charges related to marketable securities									0	0	0
Net book value of capitalized software	$ 309,500,000				$ 310,405,000				309,500,000	310,405,000
Increase in net income from change in estimate									$ 505,868,000	$ 404,389,000	$ 333,817,000
Increase in diluted earnings per share from change in estimate	$ 0.73	$ 0.80	$ 0.75	$ 0.86	$ 0.75	$ 0.63	$ 0.57	$ 0.55	$ 3.14	$ 2.49	$ 2.03
Capitalized software development costs									$ 44,221,000	$ 61,043,000	$ 50,392,000
Impairment charges related to capitalized software development costs									0	0	$ 0
Goodwill and intangible assets impairment									$ 0	$ 0
Anti-dilutive employee stock options									6,224	5,196	10,632
Anti-dilutive employee stock options, average exercise price per share									$ 53.60	$ 45.49	$ 35.02
SEI Wealth Platform
Summary of Significant Accounting Policies [Line Items]
Net book value of capitalized software	$ 288,666,000								$ 288,666,000
Capitalized software development costs in progress	42,238,000								42,238,000
Capitalized software development costs									43,376,000	$ 51,353,000	$ 39,785,000
Amortization expense related to the SEI Wealth Platform									39,917,000	46,505,000	45,047,000
Application for the Investment Managers segment
Summary of Significant Accounting Policies [Line Items]
Net book value of capitalized software	20,834,000								20,834,000
Capitalized software development costs									$ 845,000	9,690,000	10,607,000
Estimated useful life of the SEI Wealth Platform									5 years
Amortization expense related to the SEI Wealth Platform									$ 5,209,000
SEI Sponsored Open Ended Money Market Mutual Funds
Summary of Significant Accounting Policies [Line Items]
Cash and cash equivalents	315,840,000				$ 401,292,000				315,840,000	401,292,000
SEI Investments Europe Limited
Summary of Significant Accounting Policies [Line Items]
Restricted cash	3,000,000				3,000,000				3,000,000	3,000,000
SEI Investments Distribution Co
Summary of Significant Accounting Policies [Line Items]
Restricted cash	$ 514,000				505,000				$ 514,000	505,000
Minimum
Summary of Significant Accounting Policies [Line Items]
Contract acquisition costs, amortization period	6 years								6 years
Maximum
Summary of Significant Accounting Policies [Line Items]
Ownership interest in unconsolidated affiliate	50.00%								50.00%
Contract acquisition costs, amortization period	15 years								15 years
Weighted Average \| SEI Wealth Platform
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of the SEI Wealth Platform									8 years 6 months
Building and Building Improvements \| Minimum
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment									25 years
Building and Building Improvements \| Maximum
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment									39 years
Computer Equipment \| Minimum
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment									3 years
Computer Equipment \| Maximum
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment									5 years
Furniture and fixtures \| Minimum
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment									3 years
Furniture and fixtures \| Maximum
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment									5 years
Equity Method Investee \| Minimum
Summary of Significant Accounting Policies [Line Items]
Ownership interest in unconsolidated affiliate	20.00%								20.00%
Equity Method Investee \| Maximum
Summary of Significant Accounting Policies [Line Items]
Ownership interest in unconsolidated affiliate	50.00%								50.00%
Remaining Useful Life of SEI Wealth Platform \| SEI Wealth Platform
Summary of Significant Accounting Policies [Line Items]
Decrease in amortization expense from change in estimate										4,347,000
Increase in net income from change in estimate										$ 3,156,000
Increase in diluted earnings per share from change in estimate										$ 0.02
Retained Earnings
Summary of Significant Accounting Policies [Line Items]
Increase in net income from change in estimate									$ 505,868,000	$ 404,389,000	333,817,000
Accounting Standards Update 2014-09 \| Retained Earnings
Summary of Significant Accounting Policies [Line Items]
Cumulative effect upon adoption of ASUs					$ 14,402,000					14,402,000	0	$ 14,402,000	$ 0
Cumulative effect adjustment, before tax												$ 18,641,000
SEI Sponsored Open Ended Money Market Mutual Funds
Summary of Significant Accounting Policies [Line Items]
Fees waived according to expense limitation agreements									$ 26,229,000	$ 27,434,000	$ 41,227,000

Summary of Significant Accounting Policies (Expected Amortization Expenses) (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Finite-Lived Intangible Assets [Line Items]
Estimated amortization expense related to all capitalized software in 2019	$ 3,683
Estimated amortization expense related to all capitalized software in 2020	3,683
Estimated amortization expense related to all capitalized software in 2021	3,683
Estimated amortization expense related to all capitalizes software in 2022	3,336
Estimated amortization expense related to all capitalized software in 2023	2,989
Software development
Finite-Lived Intangible Assets [Line Items]
Estimated amortization expense related to all capitalized software in 2019	46,608
Estimated amortization expense related to all capitalized software in 2020	46,608
Estimated amortization expense related to all capitalized software in 2021	46,330
Estimated amortization expense related to all capitalizes software in 2022	31,817
Estimated amortization expense related to all capitalized software in 2023	$ 13,145

Summary of Significant Accounting Policies (Calculation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income									$ 505,868	$ 404,389	$ 333,817
Shares used to compute basic earnings per common share									156,579	158,177	161,350
Dilutive effect of stock options									4,653	4,092	3,081
Shares used to compute diluted earnings per common share									161,232	162,269	164,431
Basic earnings per common share (in USD per share)	$ 0.75	$ 0.82	$ 0.77	$ 0.89	$ 0.78	$ 0.64	$ 0.58	$ 0.56	$ 3.23	$ 2.56	$ 2.07
Diluted earnings per common share (in USD per share)	$ 0.73	$ 0.80	$ 0.75	$ 0.86	$ 0.75	$ 0.63	$ 0.57	$ 0.55	$ 3.14	$ 2.49	$ 2.03

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Investment in Unconsolidated Affiliates (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments in and Advances to Affiliates [Line Items]
Company's share in the earnings of LSV	$ 159,791	$ 152,550	$ 126,103
Distributions received from LSV	$ 166,941	143,517	125,224
LSV Asset Management
Investments in and Advances to Affiliates [Line Items]
Ownership interest in LSV	38.90%
Total investment in LSV	$ 52,342
Company's share in the earnings of LSV	159,791	152,550	126,103
Distributions received from LSV	$ 166,941	$ 143,517	$ 125,224
Maximum
Investments in and Advances to Affiliates [Line Items]
Ownership interest in LSV	50.00%

- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References + Details

Investment in Unconsolidated Affiliates (Condensed Statements of Operations of LSV) (Details) - LSV Asset Management - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Revenues	$ 517,203	$ 491,872	$ 399,462
Net income	$ 410,846	$ 392,141	$ 323,381

Investment in Unconsolidated Affiliates (Condensed Balance Sheets of LSV) (Details) - LSV Asset Management - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Current assets	$ 138,083	$ 155,239
Non-current assets	1,165	1,407
Total assets	139,248	156,646
Current liabilities	47,874	46,486
Partners’ capital	91,374	110,160
Total liabilities and partners’ capital	$ 139,248	$ 156,646

Composition of Certain Financial Statement Captions (Receivables) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Items Included in Consolidated Statement of Financial Condition [Abstract]
Trade receivables	$ 76,362	$ 76,760
Fees earned, not billed	226,001	194,331
Other receivables	13,691	12,310
Gross receivables	316,054	283,401
Less: Allowance for doubtful accounts	(718)	(695)
Receivables, net	$ 315,336	$ 282,706

Composition of Certain Financial Statement Captions (Property And Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 484,069	$ 456,383
Less: Accumulated depreciation	(338,206)	(309,955)
Property and Equipment, net	145,863	146,428
Depreciation expense	28,792	27,311	$ 26,440
Buildings
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	160,796	153,961
Equipment
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	126,954	115,546
Land
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	10,772	10,030
Purchased software
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	139,245	134,610
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	18,103	18,114
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	18,959	18,017
Construction in progress
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 9,240	$ 6,105

Composition of Certain Financial Statement Captions (Accrued Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Items Included in Consolidated Statement of Financial Condition [Abstract]
Accrued employee compensation	$ 97,603	$ 88,960
Accrued consulting, outsourcing and professional fees	31,000	29,658
Accrued sub-advisory, distribution and other asset management fees	42,583	42,365
Accrued dividend payable	50,761	47,179
Other accrued liabilities	57,687	56,896
Accrued liabilities	$ 279,634	$ 265,058

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Apr. 02, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity available-for-sale securities	$ 10,218		$ 11,250
Fixed income available-for-sale securities	101,683		76,733
Fixed income securities owned	30,892		21,526
Investment funds sponsored by LSV	4,887		6,034
Assets, fair value	147,680		115,543
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity available-for-sale securities	10,218		11,250
Fixed income available-for-sale securities	0		0
Fixed income securities owned	0		0
Assets, fair value	10,218		11,250
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity available-for-sale securities	0		0
Fixed income available-for-sale securities	101,683		76,733
Fixed income securities owned	30,892		21,526
Assets, fair value	$ 132,575		$ 98,259
Huntington Steele, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent purchase price		$ 12,120
Huntington Steele, LLC \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent purchase price		$ 12,120

Marketable Securities (Investments Available For Sale) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Equity Securities:
Fair Value	$ 10,218	$ 11,250
Debt Securities:
Fair Value	101,683	76,733
Cost Amount	114,398	88,570
Gross Unrealized Gains	126	568
Gross Unrealized (Losses)	(2,623)	(1,155)
Fair Value	111,901	87,983
SEI-sponsored mutual funds
Equity Securities:
Cost Amount	7,446	7,369
Gross Unrealized Gains	0	110
Gross Unrealized (Losses)	(788)	(143)
Fair Value	6,658	7,336
Equities and other mutual funds
Equity Securities:
Cost Amount	3,434	3,456
Gross Unrealized Gains	126	458
Gross Unrealized (Losses)	0	0
Fair Value	3,560	3,914
Debt securities
Debt Securities:
Cost Amount	103,518	77,745
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	(1,835)	(1,012)
Fair Value	$ 101,683	$ 76,733

Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Net unrealized holding losses	$ 1,413	$ 779
Net unrealized holding losses, income tax benefit	422	233
Gross realized gains from available-for-sale securities	1,065	529	$ 284
Gross realized losses from available-for-sale securities	1,686	888	869
Investment funds sponsored by LSV	4,887	6,034
Securities owned	30,892	21,526
Investment funds sponsored by LSV
Schedule of Investments [Line Items]
Investment funds sponsored by LSV	4,887	6,034
Change in fair value of investment funds sponsored by LSV	$ (1,147)	$ 1,176	$ 819

Line of Credit (Details) - USD ($)		1 Months Ended	12 Months Ended
Line of Credit (Details) - USD ($)	Jun. 13, 2016	Jul. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Credit facility principal payment			$ 30,000,000	$ 10,000,000	$ 0
Letters of credit outstanding amount			13,813,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument, term	5 years
Credit facility maximum borrowing capacity	$ 300,000,000
Credit facility stated percentage	0.00%
Credit facility accordion feature, increase limit	$ 100,000,000
Credit facility borrowings		$ 40,000,000
Credit facility principal payment			30,000,000	10,000,000
Credit facility remaining borrowing capacity			286,187,000
Credit facility commitment fees			645,000	$ 781,000	$ 531,000
Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	1.00%
Revolving Credit Facility \| Federal Funds Rate
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	0.50%
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity			$ 15,000,000
Credit facility, commitment fee percentage			1.25%
Credit facility, fronting fee percentage			0.175%
Minimum \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility commitment fee per annum on daily unused portion (as a percent)	0.15%
Minimum \| Revolving Credit Facility \| Base Rate
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	0.25%
Minimum \| Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	1.25%
Maximum \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility commitment fee per annum on daily unused portion (as a percent)	0.30%
Maximum \| Revolving Credit Facility \| Base Rate
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	1.00%
Maximum \| Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	2.00%
Weighted Average \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility interest rate during the period			2.93%

Shareholders' Equity (Narrative) (Details) $ / shares in Units, $ in Thousands					12 Months Ended
	Jan. 08, 2019 $ / shares	Dec. 11, 2018 $ / shares	Jun. 22, 2018 $ / shares	May 30, 2018 $ / shares	Dec. 31, 2018 USD ($) right / shares $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of stock options granted \| $ / shares					$ 13.04	$ 16.78	$ 12.43
Increase in stock-based compensation from change in management estimate \| $					$ 1,909	$ 11,206
Unvested employee stock options outstanding \| shares					6,454,000
Unrecognized compensation cost from employee stock options \| $					$ 68,470
Weighted average period for recognition of unrecognized compensation cost					2 years 2 months 13 days
Total options that were exercisable (in shares) \| shares					9,359,000	10,624,000	6,692,000
Options outstanding weighted average remaining contractual life, years					6 years 3 months 26 days
Total intrinsic value of options exercised \| $					$ 139,087	$ 83,628
Aggregate intrinsic value of options exercisable \| $					138,706
Total intrinsic value of options outstanding \| $					$ 143,939
Share price of SEI common stock (in USD per share) \| $ / shares					$ 46.20
Rights received by common shareholder for each common share outstanding, rights \| right / shares					1
Series A Junior Participating Preferred stock, par value (in USD per share) \| $ / shares					$ 0.05	$ 0.05
Securities and assets of equivalent value, purchase price (in USD per unit) \| $ / shares					$ 150.00
Number of days, rights become exercisable following public announcement					10 days
Dividends declared per common share (in USD per share) \| $ / shares		$ 0.33		$ 0.30	$ 0.63	$ 0.58	$ 0.54
Dividends paid per common share (in USD per share) \| $ / shares			$ 0.30
Dividends declared \| $					$ 97,900	$ 91,444	$ 86,657
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends paid per common share (in USD per share) \| $ / shares	$ 0.33
Common Stock Buyback
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining stock repurchase authorization amount \| $					$ 215,879
2014 Equity Compensation Plan \| Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate					50.00%
2014 Equity Compensation Plan \| Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate					50.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock purchase plan, employee eligible percentage on offerings of common stock					85.00%
Shares reserved under the plan \| shares					15,600,000
Issuance of common stock under the employee stock purchase plan, shares \| shares					12,038,000

Shareholders' Equity (Assumptions Used In The Weighted Average Fair Value Of Stock Options Granted) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Expected term (in years)	6 years 4 months 2 days	6 years	6 years
Expected volatility	25.27%	22.58%	25.44%
Expected dividend yield	1.35%	0.82%	1.10%
Risk-free interest rate	2.75%	2.29%	2.18%

Shareholders' Equity (Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Stock-based compensation expense	$ 23,805	$ 36,366	$ 16,017
Less: Deferred tax benefit	(5,078)	(7,891)	(5,612)
Stock-based compensation expense, net of tax	$ 18,727	$ 28,475	$ 10,405

Shareholders' Equity (Stock Option Plans) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Beginning balance (in shares)	16,712,000	18,069,000	19,237,000
Granted (in shares)	2,468,000	2,057,000	2,310,000
Exercised (in shares)	(3,232,000)	(2,370,000)	(1,809,000)
Expired or canceled (in shares)	(135,000)	(1,044,000)	(1,669,000)
Ending balance (in shares)	15,813,000	16,712,000	18,069,000
Weighted Avg. Price
Beginning balance (in USD per share)	$ 37.63	$ 31.57	$ 28.71
Granted, weighted avg. price (in USD per share)	49.94	69.87	49.57
Exercised, weighted avg. price (in USD per share)	25.93	21.22	24.82
Expired or canceled, weighted avg. price (in USD per share)	49.58	33.42	30.86
Ending balance (in USD per share)	$ 41.84	$ 37.63	$ 31.57
Total options that were exercisable (in shares)	9,359,000	10,624,000	6,692,000
Exercisable shares, weighted avg. price (in USD per share)	$ 32.89
Available for future grant as of December 31, 2018 (in shares)	21,775,000

Shareholders' Equity (Stock Options Outstanding And Exercisable) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options outstanding (in shares)	15,813,000	16,712,000	18,069,000	19,237,000
Options outstanding, weighted average exercise price (in USD per share)	$ 41.84	$ 37.63	$ 31.57	$ 28.71
Options outstanding weighted average remaining contractual life, years	6 years 3 months 26 days
Number of options exercisable (in shares)	9,359,000	10,624,000	6,692,000
Exercisable shares, weighted avg. price (in USD per share)	$ 32.89
Exercise Price $14.62-21.05
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range	14.62
Upper range	$ 21.05
Number of options outstanding (in shares)	1,996,000
Options outstanding, weighted average exercise price (in USD per share)	$ 16.63
Options outstanding weighted average remaining contractual life, years	2 years 32 days
Number of options exercisable (in shares)	1,996,000
Exercisable shares, weighted avg. price (in USD per share)	$ 16.63
Options exercisable, weighted average remaining contractual life, years	2 years 32 days
Exercise Price $22.45-23.86
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range	$ 22.45
Upper range	$ 23.86
Number of options outstanding (in shares)	2,379,000
Options outstanding, weighted average exercise price (in USD per share)	$ 23.13
Options outstanding weighted average remaining contractual life, years	3 years 15 days
Number of options exercisable (in shares)	2,379,000
Exercisable shares, weighted avg. price (in USD per share)	$ 23.13
Options exercisable, weighted average remaining contractual life, years	3 years 15 days
Exercise Price $27.03-40.64
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range	$ 27.03
Upper range	$ 40.64
Number of options outstanding (in shares)	3,332,000
Options outstanding, weighted average exercise price (in USD per share)	$ 37.10
Options outstanding weighted average remaining contractual life, years	5 years 6 months 15 days
Number of options exercisable (in shares)	2,390,000
Exercisable shares, weighted avg. price (in USD per share)	$ 35.70
Options exercisable, weighted average remaining contractual life, years	5 years 4 months 10 days
Exercise Price $45.99-53.16
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range	$ 45.99
Upper range	$ 53.16
Number of options outstanding (in shares)	4,268,000
Options outstanding, weighted average exercise price (in USD per share)	$ 49.01
Options outstanding weighted average remaining contractual life, years	9 years 23 days
Number of options exercisable (in shares)	908,000
Exercisable shares, weighted avg. price (in USD per share)	$ 49.61
Options exercisable, weighted average remaining contractual life, years	8 years
Exercise Price $53.34-71.12
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range	$ 53.34
Upper range	$ 71.12
Number of options outstanding (in shares)	3,838,000
Options outstanding, weighted average exercise price (in USD per share)	$ 62.69
Options outstanding weighted average remaining contractual life, years	8 years 1 month 40 days
Number of options exercisable (in shares)	1,686,000
Exercisable shares, weighted avg. price (in USD per share)	$ 53.36
Options exercisable, weighted average remaining contractual life, years	7 years 7 days

Shareholders' Equity (Common Stock Buyback) (Details) - Common Stock Buyback - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity, Class of Treasury Stock [Line Items]
Shares repurchased and retired during period	6,744	4,403	6,600
Value of shares repurchased during period	$ 404,759	$ 248,114	$ 294,374

Accumulated Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 1,476,839	$ 1,303,114
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Other comprehensive gain(loss) before reclassifications	(13,153)	17,787	$ (13,049)
Amounts reclassified from accumulated other comprehensive loss	61	260	384
Net current-period other comprehensive loss	(13,092)	18,047	(12,665)
Ending balance	1,593,147	1,476,839	1,303,114
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(19,522)	(37,119)	(24,988)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Other comprehensive gain(loss) before reclassifications	(12,065)	17,597	(12,131)
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Net current-period other comprehensive loss	(12,065)	17,597	(12,131)
Ending balance	(31,587)	(19,522)	(37,119)
Unrealized Holding Gains (Losses) on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(386)	(836)	(302)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Other comprehensive gain(loss) before reclassifications	(1,088)	190	(918)
Amounts reclassified from accumulated other comprehensive loss	61	260	384
Net current-period other comprehensive loss	(1,027)	450	(534)
Ending balance	(1,413)	(386)	(836)
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(19,908)	(37,955)	(25,290)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Ending balance	$ (33,000)	$ (19,908)	$ (37,955)

Commitments and Contingencies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Lawsuit	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Rent expense \| $	$ 34,679	$ 32,619	$ 28,016
Loss Contingencies [Line Items]
Number of lawsuits filed	7
Cases with SPTC as Defendant
Loss Contingencies [Line Items]
Number of lawsuits filed	4
Claims for Violations of Louisiana Racketeering Act
Loss Contingencies [Line Items]
Number of lawsuits filed	2
Cases Remaining in Parish of East Baton Rouge Granted Indefinite Extensions to Respond
Loss Contingencies [Line Items]
Number of lawsuits filed	2
Cases Filed in East Baton Rouge
Loss Contingencies [Line Items]
Number of lawsuits filed	2

Commitments and Contingencies (Schedule Of Noncancellable Minimum Commitments) (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Future minimum operating lease payments due in 2019	$ 10,322
Future minimum operating lease payments due in 2020	8,476
Future minimum operating lease payments due in 2021	7,855
Future minimum operating lease payments due in 2022	7,616
Future minimum operating lease payments due in 2023 and thereafter	25,573
Operating leases, future minimum payments due	$ 59,842

Income Taxes (Schedule Of Federal And State And Foreign Income Tax Provision) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current
Federal	$ 82,493	$ 154,776	$ 158,411
State	13,709	11,645	10,500
Foreign	8,405	8,002	5,137
Current federal, state and foreign income tax	104,607	174,423	174,048
Deferred
Federal	2,550	(26,350)	788
State	1,166	1,378	(168)
Foreign	15	3,199	0
Deferred income tax expense (benefit)	3,731	(21,773)	620
Total income taxes	$ 108,338	$ 152,650	$ 174,668

Income Taxes (Components Of Net Income Before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic									$ 579,622	$ 523,044	$ 481,760
Foreign									34,584	33,995	26,725
Income before income taxes	$ 143,599	$ 157,595	$ 154,254	$ 158,758	$ 152,452	$ 140,769	$ 135,158	$ 128,660	$ 614,206	$ 557,039	$ 508,485

Income Taxes (Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate) (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory rate									21.00%	35.00%	35.00%
State taxes, net of federal tax benefit									1.90%	1.30%	1.30%
Foreign tax expense and tax rate differential									(0.10%)	(1.10%)	(0.80%)
Tax benefit from stock option exercises									(3.80%)	(3.90%)	0.00%
Enactment of the Tax Cuts and Jobs Act:
Re-measurement of deferred taxes									0.00%	(4.90%)	0.00%
One-time transition tax on repatriation of foreign earnings and withholding tax									(0.10%)	2.60%	0.00%
Research and development tax credit									(0.80%)	(0.90%)	(0.80%)
Domestic Production Activities Deduction									0.00%	(0.50%)	(0.60%)
Foreign Derived Intangible Income Deduction									(0.20%)	0.00%	0.00%
Other, net									(0.30%)	(0.20%)	0.20%
Effective income tax rate	19.20%	18.60%	21.10%	11.90%	19.90%	27.70%	32.10%	31.00%	17.60%	27.40%	34.30%

Income Taxes (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Foreign derived intangible income deduction benefit provided by the Tax Act		$ 1,206
Foreign withholding tax included in Deferred income taxes	$ 3,199	312	$ 3,199
Tax benefit from remeasurement of estimated net deferred tax liability			27,153
Tax expense (benefit) from preliminary estimate of one-time transition tax and withholding tax			14,743
Net tax benefit from enactment of the Tax Act	$ 12,410
Net tax benefit from enactment of the Tax Act, per diluted share	$ 0.08
One-time transition tax on repatriation of previously deferred foreign earnings		10,711
Payment of transition tax		1,000
Overpayment of federal taxes against the transition tax payable		8,908
Transition tax, noncurrent		803
Unrecognized tax benefit, excluding interest and penalties	$ 14,480	14,367	14,480	$ 17,287	$ 14,517
Unrecognized tax benefits that would affect effective tax rate		13,774
Amount of previously unrecognized tax benefits recognized		2,621
Liabilities for tax-related interest and penalties		1,289	$ 1,175	$ 1,227
Current liabilities
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Amount of uncertain tax liability expected to be paid within one year		3,131
Other long-term liabilities
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Amount of uncertain tax liability included in Other long-term liabilities		12,525
Settlement and Lapse of Statute
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized tax benefits within the next 12 months		$ 3,131

Income Taxes Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets:
Stock-based compensation expense	$ 24,125	$ 24,725
Foreign and state net operating loss carryforward and FTC	74,358	71,236
Basis differences in investments	4,118	4,191
Federal benefit of state tax deduction for uncertain tax positions	1,882	1,918
Revenue and expense recognized in different periods for financial reporting and income tax purposes	1,657	2,631
Other assets	1,049	273
Total deferred income tax assets	107,189	104,974
Less: valuation allowance	(72,316)	(68,469)
Net deferred income tax assets	34,873	36,505
Deferred Tax Liabilities:
Capitalized software currently deductible for tax purposes, net of amortization	(71,067)	(70,575)
Difference in financial reporting and income tax depreciation methods	(6,545)	(3,182)
Difference between book and tax basis of other assets	(4,429)	(3,549)
Goodwill and other intangibles	(1,823)	(1,001)
Foreign Dividend Withholding Tax	(312)	(3,199)
Capitalized contract costs	(5,490)	0
Other liabilities	(960)	(704)
Total deferred income tax liabilities	(90,626)	(82,210)
Net deferred income tax liabilities	$ (55,753)	$ (45,705)

Income Taxes (Unrecognized Tax Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 14,480	$ 17,287	$ 14,517
Tax positions related to current year:
Gross additions	2,446	3,180	3,756
Tax positions related to prior years:
Gross additions	340	211	1,762
Settlements	(278)	(352)	(378)
Lapses on statute of limitations	(2,621)	(5,846)	(2,370)
Ending balance	$ 14,367	$ 14,480	$ 17,287

Business Segment Information (Schedule Of Financial Information About Business Segments) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 405,057	$ 408,682	$ 404,830	$ 405,598	$ 408,219	$ 386,018	$ 372,331	$ 359,984	$ 1,624,167	$ 1,526,552	$ 1,401,545
Expenses									1,116,533	1,065,774	966,534
Operating profit (loss)									507,634	460,778	435,011
Gain on sale of subsidiary											2,791
Total profit (loss)											437,802
Private Banks
Segment Reporting Information [Line Items]
Revenues									483,097	474,272	457,886
Expenses									457,894	455,119	421,188
Operating profit (loss)									25,203	19,153	36,698
Gain on sale of subsidiary											2,791
Total profit (loss)											39,489
Investment Advisors
Segment Reporting Information [Line Items]
Revenues									399,089	373,473	330,677
Expenses									212,439	201,833	180,140
Operating profit (loss)									186,650	171,640	150,537
Gain on sale of subsidiary											0
Total profit (loss)											150,537
Institutional Investors
Segment Reporting Information [Line Items]
Revenues									333,299	322,457	312,584
Expenses									163,536	161,640	153,117
Operating profit (loss)									169,763	160,817	159,467
Gain on sale of subsidiary											0
Total profit (loss)											159,467
Investment Managers
Segment Reporting Information [Line Items]
Revenues									398,076	349,444	294,390
Expenses									259,693	226,504	191,127
Operating profit (loss)									138,383	122,940	103,263
Gain on sale of subsidiary											0
Total profit (loss)											103,263
Investments In New Businesses
Segment Reporting Information [Line Items]
Revenues									10,606	6,906	6,008
Expenses									22,971	20,678	20,962
Operating profit (loss)									$ (12,365)	$ (13,772)	(14,954)
Gain on sale of subsidiary											0
Total profit (loss)											$ (14,954)

Business Segment Information (Reconciliation Of Total Operating Profit Reported For Business Segments To Income From Operations In Consolidated Statements Of Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total operating profit from segments above	$ 507,634	$ 460,778	$ 435,011
Income from operations	441,988	396,944	375,694
Operating Segments
Segment Reporting Information [Line Items]
Total operating profit from segments above	507,634	460,778	435,011
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Corporate overhead expenses	$ (65,646)	$ (63,834)	$ (59,317)

Business Segment Information (Schedule Of Additional Information Pertaining To Business Segments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Capital Expenditures	$ 73,316	$ 86,568	$ 81,789
Depreciation	28,792	27,311	26,440
Amortization	48,895	48,275	45,392
Assets	1,971,668	1,853,369
Private Banks
Segment Reporting Information [Line Items]
Assets	558,451	523,214
Investment Advisors
Segment Reporting Information [Line Items]
Assets	143,042	139,697
Institutional Investors
Segment Reporting Information [Line Items]
Assets	109,081	117,286
Investment Managers
Segment Reporting Information [Line Items]
Assets	318,342	278,540
Investments In New Businesses
Segment Reporting Information [Line Items]
Assets	33,142	19,269
Operating Segments
Segment Reporting Information [Line Items]
Capital Expenditures	71,809	85,405	79,804
Depreciation	27,587	26,488	25,543
Amortization	48,664	48,057	45,045
Assets	1,162,058	1,078,006
Operating Segments \| Private Banks
Segment Reporting Information [Line Items]
Capital Expenditures	36,763	47,526	45,940
Depreciation	13,773	16,479	13,222
Amortization	27,312	32,696	31,675
Operating Segments \| Investment Advisors
Segment Reporting Information [Line Items]
Capital Expenditures	16,572	17,450	17,610
Depreciation	4,607	3,364	3,880
Amortization	9,668	10,930	10,458
Operating Segments \| Institutional Investors
Segment Reporting Information [Line Items]
Capital Expenditures	3,863	4,020	4,319
Depreciation	1,672	1,121	1,367
Amortization	1,707	1,599	1,674
Operating Segments \| Investment Managers
Segment Reporting Information [Line Items]
Capital Expenditures	13,639	15,863	11,209
Depreciation	6,988	4,698	4,877
Amortization	9,382	2,593	1,092
Operating Segments \| Investments In New Businesses
Segment Reporting Information [Line Items]
Capital Expenditures	972	546	726
Depreciation	547	826	2,197
Amortization	595	239	146
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Capital Expenditures	1,507	1,163	1,985
Depreciation	1,205	823	897
Amortization	231	218	$ 347
Assets	$ 809,610	$ 775,363

Business Segment Information (Schedule of Revenues And Assets Based On Location) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues	$ 405,057	$ 408,682	$ 404,830	$ 405,598	$ 408,219	$ 386,018	$ 372,331	$ 359,984	$ 1,624,167	$ 1,526,552	$ 1,401,545
Assets	1,971,668				1,853,369				1,971,668	1,853,369
United States
Revenues									1,348,130	1,298,381	1,191,640
Assets	1,612,202				1,471,260				1,612,202	1,471,260
International operations
Revenues									276,037	228,171	$ 209,905
Assets	$ 359,466				$ 382,109				$ 359,466	$ 382,109

Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Asset management, administration and distribution fees
Related Party Transaction [Line Items]
Revenue from related parties	$ 462,101	$ 453,438	$ 431,318
Transaction-based and trade execution fees
Related Party Transaction [Line Items]
Revenue from related parties	$ 2,001	$ 1,216	$ 561

Business Acquisitions (Narrative) (Details) - USD ($) $ in Thousands			12 Months Ended
	Apr. 02, 2018	Jul. 03, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Net cash consideration			$ 5,794	$ 80,234	$ 0
Huntington Steele, LLC
Business Acquisition [Line Items]
Total purchase price	$ 17,914
Net cash consideration	5,794
Cash acquired from acquisition	125
Contingent purchase price	$ 12,120
Contingent liability, recognition period	5 years
Cash acquired during transaction	$ 125
Archway
Business Acquisition [Line Items]
Net cash consideration		$ 80,234
Contingent purchase price		4,800
Total purchase price allocation		81,635
Maximum contingent purchase price		8,000
Net adjustment to contingent consideration			3,800
Cash acquired during transaction		$ 1,401
Escrow account balance			$ 8,000
Other long-term liabilities \| Huntington Steele, LLC
Business Acquisition [Line Items]
Contingent purchase price, noncurrent	11,690
Accrued liabilities \| Huntington Steele, LLC
Business Acquisition [Line Items]
Contingent purchase price, current	$ 430

Business Acquisitions (Purchase Price Allocation) (Details) - USD ($) $ in Thousands			12 Months Ended
	Apr. 02, 2018	Jul. 03, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill			$ 64,489	$ 52,990	$ 0
Net cash consideration			$ 5,794	$ 80,234	$ 0
Archway
Business Acquisition [Line Items]
Cash		$ 1,401
Goodwill		52,990
Current assets, net		2,539
Property and equipment		776
Contingent consideration		(4,800)
Net cash consideration		80,234
Total purchase price allocation		81,635
Archway \| Acquired technology
Business Acquisition [Line Items]
Identifiable intangible assets		$ 13,510
Weighted average useful life of acquired intangible assets		10 years
Archway \| Client relationships
Business Acquisition [Line Items]
Identifiable intangible assets		$ 10,760
Weighted average useful life of acquired intangible assets		15 years
Archway \| Non-competition agreements
Business Acquisition [Line Items]
Identifiable intangible assets		$ 3,470
Weighted average useful life of acquired intangible assets		5 years
Archway \| Trade names
Business Acquisition [Line Items]
Identifiable intangible assets		$ 2,390
Weighted average useful life of acquired intangible assets		7 years
Huntington Steele, LLC
Business Acquisition [Line Items]
Cash	$ 125
Goodwill	11,499
Other assets	15
Current liabilities	(230)
Contingent consideration	(12,120)
Net cash consideration	5,794
Huntington Steele, LLC \| Client relationships
Business Acquisition [Line Items]
Identifiable intangible assets	$ 6,180
Weighted average useful life of acquired intangible assets	12 years
Huntington Steele, LLC \| Trade names
Business Acquisition [Line Items]
Identifiable intangible assets	$ 450
Weighted average useful life of acquired intangible assets	7 years

Goodwill and Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Apr. 02, 2018	Jul. 03, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill	$ 64,489	$ 52,990			$ 0
Amortization of intangible assets	$ 3,538	$ 1,552
Huntington Steele, LLC
Goodwill [Line Items]
Goodwill			$ 11,499
Archway
Goodwill [Line Items]
Goodwill				$ 52,990

Goodwill and Intangible Assets (Schedule of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Beginning balance	$ 52,990	$ 0
Business acquisition	11,499	52,990
Ending balance	64,489	52,990
Investment Managers
Goodwill [Roll Forward]
Beginning balance	52,990	0
Business acquisition	0	52,990
Ending balance	52,990	52,990
Investments In New Businesses
Goodwill [Roll Forward]
Beginning balance	0	0
Business acquisition	11,499	0
Ending balance	$ 11,499	$ 0

Goodwill and Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 36,760	$ 30,130
Less: Accumulated amortization	(5,090)	(1,552)
Intangible assets, net	31,670	28,578
Acquired technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 13,510	$ 13,510
Weighted Average Estimated Useful Life	10 years	10 years
Client relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 16,940	$ 10,760
Weighted Average Estimated Useful Life	13 years 11 months	15 years
Non-competition agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 3,470	$ 3,470
Weighted Average Estimated Useful Life	5 years	5 years
Trade names
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 2,840	$ 2,390
Weighted Average Estimated Useful Life	7 years	7 years

Goodwill and Intangible Assets (Future Amortization Expenses) (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Estimated amortization expense in 2019	$ 3,683
Estimated amortization expense in 2020	3,683
Estimated amortization expense in 2021	3,683
Estimated amortization expense in 2022	3,336
Estimated amortization expense in 2023	$ 2,989

Revenues from Contracts with Customers (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 405,057,000	$ 408,682,000	$ 404,830,000	$ 405,598,000	$ 408,219,000	$ 386,018,000	$ 372,331,000	$ 359,984,000	$ 1,624,167,000	$ 1,526,552,000	$ 1,401,545,000
Deferred contract costs	$ 24,007,000				$ 0				24,007,000	0
Capitalized contract cost, amount capitalized during period									8,122,000
Amortization of deferred contract costs									2,756,000
Capitalized contract cost impairment									0
United States
Disaggregation of Revenue [Line Items]
Revenues									1,348,130,000	1,298,381,000	1,191,640,000
United Kingdom
Disaggregation of Revenue [Line Items]
Revenues									168,451,000
Canada
Disaggregation of Revenue [Line Items]
Revenues									54,467,000
Ireland
Disaggregation of Revenue [Line Items]
Revenues									51,316,000
Other
Disaggregation of Revenue [Line Items]
Revenues									1,803,000
Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues									488,330,000
Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues									376,707,000
Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues									361,899,000
Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues									184,587,000
Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues									145,820,000
Professional services fees
Disaggregation of Revenue [Line Items]
Revenues									23,923,000
Account fees and other
Disaggregation of Revenue [Line Items]
Revenues									42,901,000
Private Banks
Disaggregation of Revenue [Line Items]
Revenues									483,097,000	474,272,000	457,886,000
Private Banks \| United States
Disaggregation of Revenue [Line Items]
Revenues									304,762,000
Private Banks \| United Kingdom
Disaggregation of Revenue [Line Items]
Revenues									112,980,000
Private Banks \| Canada
Disaggregation of Revenue [Line Items]
Revenues									45,941,000
Private Banks \| Ireland
Disaggregation of Revenue [Line Items]
Revenues									19,414,000
Private Banks \| Other
Disaggregation of Revenue [Line Items]
Revenues									0
Private Banks \| Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues									138,616,000
Private Banks \| Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues									793,000
Private Banks \| Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues									1,517,000
Private Banks \| Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues									182,068,000
Private Banks \| Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues									136,222,000
Private Banks \| Professional services fees
Disaggregation of Revenue [Line Items]
Revenues									16,643,000
Private Banks \| Account fees and other
Disaggregation of Revenue [Line Items]
Revenues									7,238,000
Investment Advisors
Disaggregation of Revenue [Line Items]
Revenues									399,089,000	373,473,000	330,677,000
Investment Advisors \| United States
Disaggregation of Revenue [Line Items]
Revenues									399,089,000
Investment Advisors \| United Kingdom
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Advisors \| Canada
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Advisors \| Ireland
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Advisors \| Other
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Advisors \| Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues									288,030,000
Investment Advisors \| Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues									94,526,000
Investment Advisors \| Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Advisors \| Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Advisors \| Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Advisors \| Professional services fees
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Advisors \| Account fees and other
Disaggregation of Revenue [Line Items]
Revenues									16,533,000
Institutional Investors
Disaggregation of Revenue [Line Items]
Revenues									333,299,000	322,457,000	312,584,000
Institutional Investors \| United States
Disaggregation of Revenue [Line Items]
Revenues									257,080,000
Institutional Investors \| United Kingdom
Disaggregation of Revenue [Line Items]
Revenues									55,471,000
Institutional Investors \| Canada
Disaggregation of Revenue [Line Items]
Revenues									8,526,000
Institutional Investors \| Ireland
Disaggregation of Revenue [Line Items]
Revenues									10,419,000
Institutional Investors \| Other
Disaggregation of Revenue [Line Items]
Revenues									1,803,000
Institutional Investors \| Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues									59,739,000
Institutional Investors \| Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues									271,600,000
Institutional Investors \| Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues									0
Institutional Investors \| Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues									0
Institutional Investors \| Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues									0
Institutional Investors \| Professional services fees
Disaggregation of Revenue [Line Items]
Revenues									0
Institutional Investors \| Account fees and other
Disaggregation of Revenue [Line Items]
Revenues									1,960,000
Investment Managers
Disaggregation of Revenue [Line Items]
Revenues									398,076,000	349,444,000	294,390,000
Investment Managers \| United States
Disaggregation of Revenue [Line Items]
Revenues									376,593,000
Investment Managers \| United Kingdom
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Managers \| Canada
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Managers \| Ireland
Disaggregation of Revenue [Line Items]
Revenues									21,483,000
Investment Managers \| Other
Disaggregation of Revenue [Line Items]
Revenues									0
Investment Managers \| Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues									928,000
Investment Managers \| Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues									331,000
Investment Managers \| Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues									360,382,000
Investment Managers \| Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues									2,519,000
Investment Managers \| Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues									9,598,000
Investment Managers \| Professional services fees
Disaggregation of Revenue [Line Items]
Revenues									7,280,000
Investment Managers \| Account fees and other
Disaggregation of Revenue [Line Items]
Revenues									17,038,000
Investments In New Businesses
Disaggregation of Revenue [Line Items]
Revenues									10,606,000	$ 6,906,000	$ 6,008,000
Investments In New Businesses \| United States
Disaggregation of Revenue [Line Items]
Revenues									10,606,000
Investments In New Businesses \| United Kingdom
Disaggregation of Revenue [Line Items]
Revenues									0
Investments In New Businesses \| Canada
Disaggregation of Revenue [Line Items]
Revenues									0
Investments In New Businesses \| Ireland
Disaggregation of Revenue [Line Items]
Revenues									0
Investments In New Businesses \| Other
Disaggregation of Revenue [Line Items]
Revenues									0
Investments In New Businesses \| Investment management fees from pooled investment products
Disaggregation of Revenue [Line Items]
Revenues									1,017,000
Investments In New Businesses \| Investment management fees from investment management agreements
Disaggregation of Revenue [Line Items]
Revenues									9,457,000
Investments In New Businesses \| Investment operations fees
Disaggregation of Revenue [Line Items]
Revenues									0
Investments In New Businesses \| Investment processing fees - PaaS
Disaggregation of Revenue [Line Items]
Revenues									0
Investments In New Businesses \| Investment processing fees - SaaS
Disaggregation of Revenue [Line Items]
Revenues									0
Investments In New Businesses \| Professional services fees
Disaggregation of Revenue [Line Items]
Revenues									0
Investments In New Businesses \| Account fees and other
Disaggregation of Revenue [Line Items]
Revenues									$ 132,000
Retained Earnings \| Accounting Standards Update 2014-09
Disaggregation of Revenue [Line Items]
Cumulative effect adjustment, before tax												$ 18,641,000

Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Revenues	$ 405,057	$ 408,682	$ 404,830	$ 405,598	$ 408,219	$ 386,018	$ 372,331	$ 359,984	$ 1,624,167	$ 1,526,552	$ 1,401,545
Income before income taxes	143,599	157,595	154,254	158,758	152,452	140,769	135,158	128,660	$ 614,206	$ 557,039	$ 508,485
Net income	$ 116,034	$ 128,319	$ 121,677	$ 139,838	$ 122,144	$ 101,739	$ 91,769	$ 88,737
Basic earnings per common share (in USD per share)	$ 0.75	$ 0.82	$ 0.77	$ 0.89	$ 0.78	$ 0.64	$ 0.58	$ 0.56	$ 3.23	$ 2.56	$ 2.07
Diluted earnings per common share (in USD per share)	$ 0.73	$ 0.80	$ 0.75	$ 0.86	$ 0.75	$ 0.63	$ 0.57	$ 0.55	$ 3.14	$ 2.49	$ 2.03
Effective income tax rate	19.20%	18.60%	21.10%	11.90%	19.90%	27.70%	32.10%	31.00%	17.60%	27.40%	34.30%
Net tax benefit from enactment of the Tax Act					$ 12,410
Net tax benefit from enactment of the Tax Act, per diluted share					$ 0.08

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

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+ Details

Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 695	$ 523	$ 649
Additions, Charged to Costs and Expenses	23	172	0
Additions, Charged to Other Accounts	0	0	0
(Deductions)	0	0	(126)
Balance at End of Year	718	695	523
Deferred income tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	68,469	17,922	14,548
Additions, Charged to Costs and Expenses	0	0	0
Additions, Charged to Other Accounts	3,847	50,547	3,374
(Deductions)	0	0	0
Balance at End of Year	$ 72,316	$ 68,469	$ 17,922

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit PlanThe Company has a tax-qualified defined contribution plan (the Plan). The Plan provides retirement benefits, including provisions for early retirement and disability benefits, as well as a tax-deferred savings feature. After satisfying certain requirements, participants are vested in employer contributions at the time the contributions are made. All Company contributions are discretionary and are made from available profits. The Company contributed $12,362, $10,929 and $9,665 to the Plan in 2018, 2017 and 2016, respectively.

Employee Benefit Plan (Details) - USD ($) $ in Thousands	12 Months Ended
Employee Benefit Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Defined contribution plan, cost recognized	$ 12,362	$ 10,929	$ 9,665