Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2018	Apr. 19, 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-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Trading Symbol	SEIC
Amendment Flag	false
Entity Common Stock, Shares Outstanding		158,084,303

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 748,299	$ 744,247
Restricted cash	3,507	3,505
Receivables from investment products	54,909	56,666
Receivables, net of allowance for doubtful accounts of $788 and $695	308,270	282,706
Securities owned	21,600	21,526
Other current assets	34,722	31,158
Total Current Assets	1,171,307	1,139,808
Property and Equipment, net of accumulated depreciation of $317,245 and $309,955	145,280	146,428
Capitalized Software, net of accumulated amortization of $361,065 and $350,045	312,272	310,405
Investments Available for Sale	83,089	87,983
Investments in Affiliated Funds, at fair value	5,534	6,034
Investment in Unconsolidated Affiliate	54,482	59,492
Goodwill	52,990	52,990
Intangible Assets, net of accumulated amortization of $2,328 and $1,552	27,802	28,578
Deferred Contract Costs	19,875	0
Deferred Income Taxes	2,740	2,767
Other Assets, net	18,334	18,884
Total Assets	1,893,705	1,853,369
Current Liabilities:
Accounts payable	8,463	5,268
Accrued liabilities	168,618	265,058
Deferred revenue	4,998	4,723
Total Current Liabilities	182,079	275,049
Borrowings Under Revolving Credit Facility	20,000	30,000
Long-term Income Taxes Payable	10,629	10,629
Deferred Income Taxes	54,384	48,472
Other Long-term Liabilities	12,959	12,380
Total Liabilities	280,051	376,530
Commitments and Contingencies
Shareholders' Equity:
Common stock, $.01 par value, 750,000 shares authorized; 157,990 and 157,069 shares issued and outstanding	1,580	1,571
Capital in excess of par value	1,085,312	1,027,709
Retained earnings	544,923	467,467
Accumulated other comprehensive loss, net	(18,161)	(19,908)
Total Shareholders' Equity	1,613,654	1,476,839
Total Liabilities and Shareholders' Equity	$ 1,893,705	$ 1,853,369

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current Assets:
Receivables, allowance for doubtful accounts	$ 788	$ 695
Property and Equipment, accumulated depreciation	317,245	309,955
Capitalized software, accumulated amortization	361,065	350,045
Intangible assets, accumulated amortization	$ 2,328	$ 1,552
Stockholders' Equity:
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	157,990,000	157,069,000
Common stock, shares outstanding	157,990,000	157,069,000

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Asset management, administration and distribution fees	$ 316,209	$ 279,461
Information processing and software servicing fees	89,389	80,523
Total revenues	405,598	359,984
Expenses:
Subadvisory, distribution and other asset management costs	45,205	43,152
Software royalties and other information processing costs	8,718	11,971
Compensation, benefits and other personnel	124,277	108,943
Stock-based compensation	5,195	6,180
Consulting, outsourcing and professional fees	48,707	43,149
Data processing and computer related	20,591	18,325
Facilities, supplies and other costs	17,613	15,925
Amortization	11,854	12,022
Depreciation	7,122	6,800
Total expenses	289,282	266,467
Income from operations	116,316	93,517
Net (loss) gain from investments	(410)	347
Interest and dividend income	2,502	1,343
Interest expense	(257)	(112)
Equity in earnings of unconsolidated affiliate	40,607	33,565
Income before income taxes	158,758	128,660
Income taxes	18,920	39,923
Net income	$ 139,838	$ 88,737
Basic earnings per common share (in USD per share)	$ 0.89	$ 0.56
Shares used to compute basic earnings per share	157,434	159,091
Diluted earnings per common share (in USD per share)	$ 0.86	$ 0.55
Shares used to compute diluted earnings per share	163,424	162,742

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 139,838	$ 88,737
Other comprehensive gain (loss), net of tax:
Foreign currency translation adjustments	3,377	2,488
Unrealized loss on investments:
Unrealized losses during the period, net of income taxes of $424 and $19	(1,357)	(24)
Less: reclassification adjustment for gains realized in net income, net of income taxes of $(15) and $10	(273)	(22)
Unrealized loss on investments:	(1,630)	(46)
Total other comprehensive gain, net of tax	1,747	2,442
Comprehensive income	$ 141,585	$ 91,179

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Unrealized gains (losses) during the period, income tax (expense) benefit	$ 424	$ 19
Reclassification adjustment for losses realized in net income, income tax benefit	$ (15)	$ 10

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 139,838	$ 88,737
Adjustments to reconcile net income to net cash provided by operating activities (See Note 1)	(35,664)	(15,725)
Net cash provided by operating activities	104,174	73,012
Cash flows from investing activities:
Additions to property and equipment	(5,611)	(3,205)
Additions to capitalized software	(12,887)	(16,861)
Purchases of marketable securities	(15,466)	(20,445)
Prepayments and maturities of marketable securities	18,588	15,166
Net cash used in investing activities	(15,376)	(25,345)
Cash flows from financing activities:
Repayments under revolving credit facility	(10,000)	0
Purchase and retirement of common stock	(87,995)	(56,553)
Proceeds from issuance of common stock	57,889	16,847
Payment of dividends	(47,179)	(44,597)
Net cash used in financing activities	(87,285)	(84,303)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	2,541	2,307
Net increase (decrease) in cash, cash equivalents and restricted cash	4,054	(34,329)
Cash, cash equivalents and restricted cash, beginning of period	747,752	699,201
Cash, cash equivalents and restricted cash, end of period	$ 751,806	$ 664,872

Summary of Significant Accounting Policies

3 Months Ended

Mar. 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 various other 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.

Basis of Presentation

The accompanying Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States of America. Certain financial information and accompanying note disclosure normally included in the Company’s Annual Report on Form 10-K have been condensed or omitted. The interim financial information is unaudited but reflects all adjustments (consisting of only normal recurring adjustments) which are, in the opinion of management, necessary for a fair statement of financial position of the Company as of March 31, 2018, the results of operations for the three months ended March 31, 2018 and 2017, and cash flows for the three-month periods ended March 31, 2018 and 2017. These interim Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and the Notes to the Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017.

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 during the three months ended March 31, 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 (see following caption "Revenue Recognition"). The Company also adopted ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (see Note 6) and ASU No. 2016-18, Statement of Cash Flows, Restricted Cash (Topic 230) (see following caption "Statements of Cash Flows"). All amounts and disclosures set forth in this Form 10-Q have been updated to comply with the new standards.

Revenue Recognition

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 will continue 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 the three months ended March 31, 2018 and 2017 were $3,730 and $4,073, 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 recognized over the expected client life. 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 to retained earnings associated with the capitalization of contract costs. 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

Cash and cash equivalents includes $341,413 and $401,292 at March 31, 2018 and December 31, 2017, respectively, primarily invested in SEI-sponsored open-ended money market mutual funds. The SEI-sponsored mutual funds are Level 1 assets.

Restricted Cash

Restricted cash includes $3,000 at March 31, 2018 and December 31, 2017 segregated for regulatory purposes related to trade-execution services conducted by SEI Investments (Europe) Limited. Restricted cash also includes $507 and $505 at March 31, 2018 and December 31, 2017, respectively, segregated in special reserve accounts for the benefit of customers of the Company’s broker-dealer subsidiary, SEI Investments Distribution Co. (SIDCO), in accordance with certain rules established by the Securities and Exchange Commission (SEC) for broker-dealers.

Capitalized Software

The Company capitalized $12,887 and $16,861 of software development costs during the three months ended March 31, 2018 and 2017, respectively. The Company's software development costs primarily relate to the continued development of the SEI Wealth Platform^SM(the Platform). The Company capitalized $12,042 and $15,178 of software development costs for significant enhancements to the Platform during the three months ended March 31, 2018 and 2017, respectively. As of March 31, 2018, the net book value of the Platform was $287,530. The net book value includes $33,237 of capitalized software development costs in-progress associated with future releases. The Platform has a weighted average remaining life of 8.4 years. Amortization expense for the Platform was $9,719 and $11,972 during the three months ended March 31, 2018 and 2017, respectively.

The Company also capitalized $845 and $1,683 of software development costs during the three months ended March 31, 2018 and 2017, 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 March 31, 2018 was $24,742. Amortization expense for the application was $1,301 during the three months ended March 31, 2018.

Earnings per Share

The calculations of basic and diluted earnings per share for the three months ended March 31, 2018 and 2017 are:



	Three Months Ended March 31,
	2018		2017
Net income	$	139,838	$	88,737
Shares used to compute basic earnings per common share	157,434,000		159,091,000
Dilutive effect of stock options	5,990,000		3,651,000
Shares used to compute diluted earnings per common share	163,424,000		162,742,000
Basic earnings per common share	$	0.89	$	0.56
Diluted earnings per common share	$	0.86	$	0.55

During the three months ended March 31, 2018 and 2017, employee stock options to purchase 6,054,000 and 11,279,000 shares of common stock with an average exercise price of $52.73 and $37.70, respectively, were outstanding but not included in the computation of diluted earnings per common share. These options for the three month periods were 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.

Reclassifications

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

New Accounting Pronouncements

In February 2016, the FASB issued ASU No. 2016-02, Leases (ASU 2016-02) 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 continue to be classified as either operating or finance leases in the income statement. Lessor accounting is similar to the current model but updated to align with certain changes to the lessee model. Lessors will continue to classify leases as operating, direct financing or sales-type leases. The updated standard is effective for the Company beginning in the first quarter of 2019. Early adoption is permitted. While the Company is not yet in a position to assess the full impact of the adoption of ASU 2016-02 on its consolidated financial statements and related disclosures, the Company is currently in the process of cataloging existing lease agreements and evaluating the transition method to be elected.

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.

Statements of Cash Flows

For purposes of the Consolidated Statements of Cash Flows, 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 period was retrospectively adjusted to conform to the current period’s presentation. There was no impact to net cash flows for the three months ended March 31, 2017 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.

The following table provides the details of the adjustments to reconcile net income to net cash provided by operating activities for the three months ended March 31:



	2018			2017
Net income	$	139,838		$	88,737
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	7,122			6,800
Amortization	11,854			12,022
Equity in earnings of unconsolidated affiliate	(40,607		)	(33,565		)
Distributions received from unconsolidated affiliate	45,617			35,265
Stock-based compensation	5,195			6,180
Provision for losses on receivables	93			(5		)
Deferred income tax expense	2,083			877
Net gain from investments	410			(347		)
Change in other long-term liabilities	579			965
Change in other assets	290			(849		)
Other	(784		)	56
Change in current assets and liabilities
Decrease (increase) in
Receivables from investment products	1,757			10,308
Receivables	(25,657		)	(24,243		)
Other current assets	(3,564		)	(2,298		)
Increase (decrease) in
Accounts payable	3,195			1,406
Accrued liabilities	(43,522		)	(27,754		)
Deferred revenue	275			(543		)
Total adjustments	(35,664		)	(15,725		)
Net cash provided by operating activities	$	104,174		$	73,012

Investment In Unconsolidated Affiliate

3 Months Ended

Mar. 31, 2018

Equity Method Investments and Joint Ventures [Abstract]

Investment In Unconsolidated Affiliate

Investment in Unconsolidated Affiliate

LSV Asset Management

The Company has an investment in 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 investment products. 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 affiliate on the accompanying Consolidated Balance Sheets and its interest in the earnings of LSV is reflected in Equity in earnings of unconsolidated affiliate on the accompanying Consolidated Statements of Operations.

At March 31, 2018, the Company’s total investment in LSV was $54,482. The Company receives partnership distributions from LSV on a quarterly basis. The Company received partnership distributions from LSV of $45,617 and $35,265 in the three months ended March 31, 2018 and 2017, respectively. 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’s proportionate share in the earnings of LSV was $40,607 and $33,565 during the three months ended March 31, 2018 and 2017, respectively.

These tables contain condensed financial information of LSV:



Condensed Statement of Operations	Three Months Ended March 31,
	2018		2017
Revenues	$	131,718	$	109,953
Net income	104,406		86,215



Condensed Balance Sheets	March 31, 2018		December 31, 2017
Current assets	$	143,922	$	155,239
Non-current assets	1,444		1,407
Total assets	$	145,366	$	156,646

Current liabilities	$	47,641	$	46,486
Partners’ capital	97,725		110,160
Total liabilities and partners’ capital	$	145,366	$	156,646

Variable Interest Entities - Investment Products	3 Months Ended
Variable Interest Entities - Investment Products	Mar. 31, 2018
Financial Support for Nonconsolidated Legal Entity [Abstract]
Variable Interest Entities - Investment Products	Variable Interest Entities – Investment Products 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 $6,654 and $7,072 in fees during the three months ended March 31, 2018 and 2017, respectively.

Composition of Certain Financial Statement Captions

3 Months Ended

Mar. 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:



	March 31, 2018			December 31, 2017
Trade receivables	$	72,764		$	76,760
Fees earned, not billed	220,414			194,331
Other receivables	15,880			12,310
	309,058			283,401
Less: Allowance for doubtful accounts	(788		)	(695		)
	$	308,270		$	282,706

Fees earned, not billed represents receivables 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 a prolonged valuation process which delays billings to clients.

Receivables from investment products on the accompanying Consolidated Balance Sheets primarily represent fees receivable for distribution, investment advisory, and administration services to various regulated investment companies and other investment products sponsored by SEI.

Property and Equipment

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



	March 31, 2018			December 31, 2017
Buildings	$	154,007		$	153,961
Equipment	118,823			115,546
Land	10,557			10,030
Purchased software	136,226			134,610
Furniture and fixtures	18,320			18,114
Leasehold improvements	18,851			18,017
Construction in progress	5,741			6,105
	462,525			456,383
Less: Accumulated depreciation	(317,245		)	(309,955		)
Property and Equipment, net	$	145,280		$	146,428

The Company recognized $7,122 and $6,800 in depreciation expense related to property and equipment for the three months ended March 31, 2018 and 2017, respectively.

Accrued Liabilities

Accrued liabilities on the accompanying Consolidated Balance Sheets consist of:



	March 31, 2018		December 31, 2017
Accrued employee compensation	$	28,714	$	88,960
Accrued consulting, outsourcing and professional fees	35,682		29,658
Accrued sub-advisory, distribution and other asset management fees	39,680		42,365
Accrued dividend payable	—		47,179
Accrued income taxes	19,282		5,583
Other accrued liabilities	45,260		51,313
Total accrued liabilities	$	168,618	$	265,058

Fair Value Measurements

3 Months Ended

Mar. 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 consist 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 pricing policies and procedures applied for our Level 1 and Level 2 financial assets during the three months ended March 31, 2018 were consistent with those as described in our Annual Report on Form 10-K at December 31, 2017. The Company had no Level 3 financial assets or liabilities at March 31, 2018 or 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 the three months ended March 31, 2018.

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



			Fair Value Measurements at the End of the Reporting Period Using
Assets	March 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Equity available-for-sale securities	$	11,316	$	11,316	$	—
Fixed-income available-for-sale securities	71,773		—		71,773
Fixed-income securities owned	21,600		—		21,600
Investment funds sponsored by LSV (1)	5,534
	$	110,223	$	11,316	$	93,373



			Fair Value Measurements at the End of the Reporting Period Using
Assets	December 31, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
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 6).

Marketable Securities

3 Months Ended

Mar. 31, 2018

Marketable Securities [Abstract]

Marketable Securities

Investments Available for Sale

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



	At March 31, 2018
	Cost Amount		Gross Unrealized Gains		Gross Unrealized (Losses)			Fair Value
SEI-sponsored mutual funds	$	7,382	$	96	$	(50	)	$	7,428
Equities and other mutual funds	3,483		405		—			3,888
Debt securities	74,431		—		(2,658		)	71,773
	$	85,296	$	501	$	(2,708	)	$	83,089



	At December 31, 2017
	Cost Amount		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

The Company 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.

Net unrealized losses at March 31, 2018 and December 31, 2017 of the Company's available-for-sale debt securities were $2,016 (net of income tax benefit of $642) 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 no material realized gains or losses from available-for-sale securities during the three months ended March 31, 2018 and 2017. 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 in 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 primarily in securities of Canadian, Australian and Japanese companies as well as various other global securities. The underlying securities held by the funds are translated into U.S. dollars within the funds. The funds had a fair value of $5,534 and $6,034 at March 31, 2018 and December 31, 2017, respectively. The Company recognized losses of $500 and gains of $298 during the three months ended March 31, 2018 and 2017, respectively, from the change in fair value of the funds.

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 $21,600 and $21,526 at March 31, 2018 and December 31, 2017, respectively. There were no material net gains or losses related to the securities during the three months ended March 31, 2018 and 2017.

Line of Credit	3 Months Ended
Line of Credit	Mar. 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, 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 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 an acquisition. As of March 31, 2018, the outstanding balance of the Credit Facility was $20,000 and is included in Borrowings Under Revolving Credit Facility on the accompanying Consolidated Balance Sheet. The Company was in compliance with all covenants of the Credit Facility during the three months ended March 31, 2018. In April 2018, the Company made a principal payment of $20,000 to fully repay the outstanding balance of the Credit Facility. As of April 19, 2018, the amount of the Credit Facility that is available for general corporate purposes was $300,000.

Shareholders' Equity

3 Months Ended

Mar. 31, 2018

Stockholders' Equity Note [Abstract]

Shareholders' Equity

Shareholders’ Equity

Stock-Based Compensation

The Company has only non-qualified stock options outstanding under its equity compensation plans. All outstanding stock options have performance-based vesting provisions specific to each option grant that tie the vesting of the applicable 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 solely as a result of achievement of the financial vesting targets. Options granted in December 2017 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 recognized stock-based compensation expense in its Consolidated Financial Statements in the three months ended March 31, 2018 and 2017, respectively, as follows:



	Three Months Ended March 31,
	2018			2017
Stock-based compensation expense	$	5,195		$	6,180
Less: Deferred tax benefit	(1,103		)	(2,153		)
Stock-based compensation expense, net of tax	$	4,092		$	4,027

As of March 31, 2018, there was approximately $56,579 of unrecognized compensation cost remaining related to unvested employee stock options that management expects will vest and is being amortized.

The Company issues new common shares associated with the exercise of stock options. The total intrinsic value of options exercised during the three months ended March 31, 2018 was $93,668. The total options exercisable as of March 31, 2018 had an intrinsic value of $393,003. The total intrinsic value for options exercisable is calculated as the difference between the market value of the Company’s common stock as of March 31, 2018 and the weighted average exercise price of the shares. The market value of the Company’s common stock as of March 31, 2018 was $74.91 as reported by the Nasdaq Stock Market, LLC. The weighted average exercise price of the options exercisable as of March 31, 2018 was $29.20. Total options that were outstanding as of March 31, 2018 were 14,652,000. Total options that were exercisable as of March 31, 2018 were 8,598,000.

Common Stock Buyback

The Company’s Board of Directors, under multiple authorizations, has authorized the repurchase of the Company’s common stock on the open market or through private transactions. The Company purchased 1,122,000 shares at a total cost of $82,257 during the three months ended March 31, 2018, which reduced the total shares outstanding of common stock. The cost of stock purchases during the period includes the cost of certain transactions that settled in the following quarter. As of March 31, 2018, the Company had approximately $88,380 of authorization remaining for the purchase of common stock under the program.

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.

Accumulated Other Comprehensive Loss

3 Months Ended

Mar. 31, 2018

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

Accumulated Other Comprehensive Loss

The components of Accumulated other comprehensive loss, net of tax, are as follows:



	Foreign Currency Translation Adjustments			Unrealized Gains (Losses) on Investments			Accumulated Other Comprehensive Loss
Balance, January 1, 2018	$	(19,522	)	$	(386	)	$	(19,908	)

Other comprehensive gain before reclassifications	3,377			(1,357		)	2,020
Amounts reclassified from accumulated other comprehensive loss	—			(273		)	(273		)
Net current-period other comprehensive gain	3,377			(1,630		)	1,747

Balance, March 31, 2018	$	(16,145	)	$	(2,016	)	$	(18,161	)

Business Segment Information

3 Months Ended

Mar. 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 and both traditional and non-traditional investment managers worldwide; and

Investments in New Businesses – focuses on providing investment management programs 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.

The information in the following tables is derived from the Company’s internal financial reporting used for corporate management purposes. There are no inter-segment revenues for the three months ended March 31, 2018 and 2017. Management evaluates Company assets on a consolidated basis during interim periods. The accounting policies of the reportable business segments are the same as those described in Note 1 to the Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017.

The following tables highlight certain financial information about each of the Company’s business segments for the three months ended March 31, 2018 and 2017.



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Three Months Ended March 31, 2018
Revenues	$	122,164	$	99,192	$	85,491	$	96,855	$	1,896		$	405,598
Expenses	112,202		52,453		41,249		63,338		5,098			274,340
Operating profit (loss)	$	9,962	$	46,739	$	44,242	$	33,517	$	(3,202	)	$	131,258



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Three Months Ended March 31, 2017
Revenues	$	112,634	$	88,238	$	77,004	$	80,487	$	1,621		$	359,984
Expenses	108,550		47,539		38,828		52,065		4,880			251,862
Operating profit (loss)	$	4,084	$	40,699	$	38,176	$	28,422	$	(3,259	)	$	108,122

A reconciliation of the total operating profit reported for the business segments to income from operations in the Consolidated Statements of Operations for the three months ended March 31, 2018 and 2017 is as follows:



	2018			2017
Total operating profit from segments	$	131,258		$	108,122
Corporate overhead expenses	(14,942		)	(14,605		)
Income from operations	$	116,316		$	93,517

The following tables provide additional information for the three months ended March 31, 2018 and 2017 pertaining to our business segments:



	Capital Expenditures (1)				Depreciation
	2018		2017		2018		2017
Private Banks	$	10,239	$	12,850	$	3,319	$	4,410
Investment Advisors	4,260		4,532		1,105		733
Institutional Investors	967		811		448		227
Investment Managers	2,520		1,615		1,809		916
Investments in New Businesses	204		106		150		368
Total from business segments	$	18,190	$	19,914	$	6,831	$	6,654
Corporate overhead	308		152		291		146
	$	18,498	$	20,066	$	7,122	$	6,800

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



	Amortization
	2018		2017
Private Banks	$	6,627	$	8,464
Investment Advisors	2,357		2,850
Institutional Investors	427		323
Investment Managers	2,345		216
Investments in New Businesses	40		119
Total from business segments	$	11,796	$	11,972
Corporate overhead	58		50
	$	11,854	$	12,022

Income Taxes

3 Months Ended

Mar. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

The gross liability for unrecognized tax benefits at March 31, 2018 and December 31, 2017 was $14,685 and $14,480, respectively, exclusive of interest and penalties, of which $13,986 and $13,737 would affect the effective tax rate if the Company were to recognize the tax benefit.

The Company classifies interest and penalties on unrecognized tax benefits as income tax expense. As of March 31, 2018 and December 31, 2017, the combined amount of accrued interest and penalties related to tax positions taken on tax returns was $1,218 and $1,175, respectively.



	March 31, 2018		December 31, 2017
Gross liability for unrecognized tax benefits, exclusive of interest and penalties	$	14,685	$	14,480
Interest and penalties on unrecognized benefits	1,218		1,175
Total gross uncertain tax positions	$	15,903	$	15,655
Amount included in Current liabilities	$	2,944	$	3,275
Amount included in Other long-term liabilities	12,959		12,380
	$	15,903	$	15,655

The Company's effective income tax rate for the three months ended March 31, 2018 and 2017 differs from the federal income tax statutory rate due to the following:



	Three Months Ended March 31,
	2018		2017
Statutory rate	21.0	%	35.0	%
State taxes, net of federal tax benefit	2.2		1.5
Foreign tax expense and tax rate differential	(0.2	)	(0.8	)
Tax benefit from stock option exercises	(10.8	)	(4.2	)
Other, net	(0.3	)	(0.5	)
	11.9	%	31.0	%

The decrease in the tax rate for the three months ended March 31, 2018 was primarily due to the tax changes enacted in the 2017 Tax Cut and Jobs Act (The Tax Act). The Tax Act was enacted on December 22, 2017 and included a permanent reduction in the corporate tax rate from 35.0 percent to 21.0 percent. In addition, the rate was favorably impacted by an increase in the excess tax benefits recognized on stock-based compensation expense due to a higher volume of stock option exercise activity.

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 estimate of the one-time transition tax as of March 31, 2018 was $11,544, of which $915 is expected to be paid within one year and $10,629 is included in Long-term income taxes payable on the accompanying Consolidated Balance Sheet.

The Company files income tax returns in the United States on a consolidated basis and in many U.S. state and foreign jurisdictions. The Company is subject to examination of income tax returns by the Internal Revenue Service (IRS) and other domestic and foreign tax authorities. The Company is no longer subject to U.S. federal income tax examination for years before 2014 and is no longer subject to state, local or foreign income tax examinations by authorities for years before 2013.

The Company estimates it will recognize $2,944 of gross unrecognized tax benefits. This amount is expected to be paid within one year or to be removed at the expiration of the statute of limitations and resolution of income tax audits and is netted against the current payable account. These unrecognized tax benefits are related to tax positions taken on certain federal, state, and foreign tax returns. However, the timing of the resolution of income tax examinations is highly uncertain, and the amounts ultimately paid, if any, upon resolution of the issues raised by the taxing authorities may differ materially from the amounts accrued for each year. While it is reasonably possible that some issues under examination could be resolved in the next twelve months, based upon the current facts and circumstances, the Company cannot reasonably estimate the timing of such resolution or the total range of potential changes as it relates to the current unrecognized tax benefits that are recorded as part of the Company’s financial statements.

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies In the normal course of business, the Company is party to various claims and legal proceedings. 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 still pending before the District Court 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, alleging claims essentially the same as those in Lillie. In January 2017, the Judicial Panel on Multidistrict Litigation transferred the proceeding to the Northern District of Texas and the Stanford MDL. During February 2017, SEI filed its response to the 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. Another one of the cases, 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. The plaintiffs in two of the cases remaining in the Parish of East Baton Rouge have granted SEI and SPTC indefinite extensions to respond to the petitions. In the 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 subjection matter jurisdiction under the federal Securities Litigation Uniform Standards Act (SLUSA). After the matter was removed to the United States District Court for the Northern District of Texas, that court 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 matter was 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.

Goodwill and Intangible Assets

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets

In July 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. The total purchase price was allocated to Archway’s net tangible and intangible assets based upon their estimated fair values at the date of purchase. The excess purchase price over the 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 identified intangible assets related to Archway that met the contractual-legal criterion for recognition apart from goodwill. The identifiable intangible assets included on the accompanying Consolidated Balance Sheets consist of:



	March 31, 2018			December 31, 2017
Acquired technology	$	13,510		$	13,510
Client relationships	10,760			10,760
Non-competition agreements	3,470			3,470
Trade name	2,390			2,390
	30,130			30,130
Less: Accumulated amortization	(2,328		)	(1,552		)
Intangible assets, net	$	27,802		$	28,578

The Company recognized $776 of amortization expense related to the intangible assets during the three months ended March 31, 2018. Goodwill and the identifiable intangible assets related to Archway have been allocated to the Investment Managers segment.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Revenues from Contracts with Customers

3 Months Ended

Mar. 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 the three months ended March 31, 2018:



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses		Total
Major Product Lines:	For the Three Months Ended March 31, 2018
Investment management fees from pooled investment products	$	35,190	$	72,418	$	15,858	$	—	$	225	$	123,691
Investment management fees from investment management agreements	198		22,764		69,276		83		1,634		93,955
Investment operations fees	382		—		—		87,455		—		87,837
Investment processing fees - PaaS	44,585		—		—		483		—		45,068
Investment processing fees - SaaS	34,602		—		—		2,365		—		36,967
Professional services fees	5,419		—		—		1,887		—		7,306
Account fees and other	1,788		4,010		357		4,582		37		10,774
Total revenues	$	122,164	$	99,192	$	85,491	$	96,855	$	1,896	$	405,598

Primary Geographic Markets:
United States	$	78,133	$	99,192	$	64,768	$	91,759	$	1,896	$	335,748
United Kingdom	27,525		—		14,787		—		—		42,312
Canada	11,601		—		2,671		—		—		14,272
Ireland	4,905		—		2,427		5,096		—		12,428
Other	—		—		838		—		—		838
Total revenues	$	122,164	$	99,192	$	85,491	$	96,855	$	1,896	$	405,598

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 that offer traditional and alternative products. The Company contracts directly with the investment management firm. 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 - 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.

Deferred Contract Costs

Deferred contract costs, which primarily consist of deferred sales commissions, were $19,875 as of March 31, 2018. The expense related to the deferred contract costs during the three months ended March 31, 2018 was immaterial. There was no impairment loss in relation to the costs capitalized during the three months ended March 31, 2018.

Summary of Significant Accounting Policies (Policy)	3 Months Ended
Summary of Significant Accounting Policies (Policy)	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States of America. Certain financial information and accompanying note disclosure normally included in the Company’s Annual Report on Form 10-K have been condensed or omitted. The interim financial information is unaudited but reflects all adjustments (consisting of only normal recurring adjustments) which are, in the opinion of management, necessary for a fair statement of financial position of the Company as of March 31, 2018, the results of operations for the three months ended March 31, 2018 and 2017, and cash flows for the three-month periods ended March 31, 2018 and 2017. These interim Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and the Notes to the Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017. 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 during the three months ended March 31, 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 (see following caption "Revenue Recognition"). The Company also adopted ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (see Note 6) and ASU No. 2016-18, Statement of Cash Flows, Restricted Cash (Topic 230) (see following caption "Statements of Cash Flows"). All amounts and disclosures set forth in this Form 10-Q have been updated to comply with the new standards.
Revenue Recognition	Revenue Recognition 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 will continue 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 the three months ended March 31, 2018 and 2017 were $3,730 and $4,073, 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 recognized over the expected client life. 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 to retained earnings associated with the capitalization of contract costs. 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	Cash and Cash EquivalentsCash and cash equivalents includes $341,413 and $401,292 at March 31, 2018 and December 31, 2017, respectively, primarily invested in SEI-sponsored open-ended money market mutual funds. The SEI-sponsored mutual funds are Level 1 assets.For purposes of the Consolidated Statements of Cash Flows, the Company considers investment instruments purchased with an original maturity of three months or less to be cash equivalents.
Restricted Cash	Restricted CashRestricted cash includes $3,000 at March 31, 2018 and December 31, 2017 segregated for regulatory purposes related to trade-execution services conducted by SEI Investments (Europe) Limited. Restricted cash also includes $507 and $505 at March 31, 2018 and December 31, 2017, respectively, segregated in special reserve accounts for the benefit of customers of the Company’s broker-dealer subsidiary, SEI Investments Distribution Co. (SIDCO), in accordance with certain rules established by the Securities and Exchange Commission (SEC) for broker-dealers.
Reclassifications	ReclassificationsCertain prior year amounts have been reclassified to conform to current year presentation.
New Accounting Pronouncements	New Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (ASU 2016-02) 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 continue to be classified as either operating or finance leases in the income statement. Lessor accounting is similar to the current model but updated to align with certain changes to the lessee model. Lessors will continue to classify leases as operating, direct financing or sales-type leases. The updated standard is effective for the Company beginning in the first quarter of 2019. Early adoption is permitted. While the Company is not yet in a position to assess the full impact of the adoption of ASU 2016-02 on its consolidated financial statements and related disclosures, the Company is currently in the process of cataloging existing lease agreements and evaluating the transition method to be elected. 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.
Equity Method Investments	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 affiliate on the accompanying Consolidated Balance Sheets and its interest in the earnings of LSV is reflected in Equity in earnings of unconsolidated affiliate on the accompanying Consolidated Statements of Operations.
Variable Interest Entities	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.
Fair Value of Financial Instruments	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 consist 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 pricing policies and procedures applied for our Level 1 and Level 2 financial assets during the three months ended March 31, 2018 were consistent with those as described in our Annual Report on Form 10-K at December 31, 2017. The Company had no Level 3 financial assets or liabilities at March 31, 2018 or December 31, 2017 that were required to be measured at fair value on a recurring basis.
Investments in Affiliated Funds	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.
Available-for-sale Securities	These net unrealized losses are reported as a separate component of Accumulated other comprehensive loss on the accompanying Consolidated Balance Sheets.
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.

Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2018

Accounting Policies [Abstract]

Calculation Of Basic And Diluted Earnings Per Share

The calculations of basic and diluted earnings per share for the three months ended March 31, 2018 and 2017 are:



	Three Months Ended March 31,
	2018		2017
Net income	$	139,838	$	88,737
Shares used to compute basic earnings per common share	157,434,000		159,091,000
Dilutive effect of stock options	5,990,000		3,651,000
Shares used to compute diluted earnings per common share	163,424,000		162,742,000
Basic earnings per common share	$	0.89	$	0.56
Diluted earnings per common share	$	0.86	$	0.55

Adjustments To Reconcile Net Income To Net Cash Provided By Operating Activities

The following table provides the details of the adjustments to reconcile net income to net cash provided by operating activities for the three months ended March 31:



	2018			2017
Net income	$	139,838		$	88,737
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	7,122			6,800
Amortization	11,854			12,022
Equity in earnings of unconsolidated affiliate	(40,607		)	(33,565		)
Distributions received from unconsolidated affiliate	45,617			35,265
Stock-based compensation	5,195			6,180
Provision for losses on receivables	93			(5		)
Deferred income tax expense	2,083			877
Net gain from investments	410			(347		)
Change in other long-term liabilities	579			965
Change in other assets	290			(849		)
Other	(784		)	56
Change in current assets and liabilities
Decrease (increase) in
Receivables from investment products	1,757			10,308
Receivables	(25,657		)	(24,243		)
Other current assets	(3,564		)	(2,298		)
Increase (decrease) in
Accounts payable	3,195			1,406
Accrued liabilities	(43,522		)	(27,754		)
Deferred revenue	275			(543		)
Total adjustments	(35,664		)	(15,725		)
Net cash provided by operating activities	$	104,174		$	73,012

Investment In Unconsolidated Affiliate (Tables)

3 Months Ended

Mar. 31, 2018

Equity Method Investments and Joint Ventures [Abstract]

Condensed financial information of LSV

These tables contain condensed financial information of LSV:



Condensed Statement of Operations	Three Months Ended March 31,
	2018		2017
Revenues	$	131,718	$	109,953
Net income	104,406		86,215



Condensed Balance Sheets	March 31, 2018		December 31, 2017
Current assets	$	143,922	$	155,239
Non-current assets	1,444		1,407
Total assets	$	145,366	$	156,646

Current liabilities	$	47,641	$	46,486
Partners’ capital	97,725		110,160
Total liabilities and partners’ capital	$	145,366	$	156,646

Composition of Certain Financial Statement Captions (Tables)

3 Months Ended

Mar. 31, 2018

Items Included in Consolidated Statement of Financial Condition [Abstract]

Receivables

Receivables on the accompanying Consolidated Balance Sheets consist of:



	March 31, 2018			December 31, 2017
Trade receivables	$	72,764		$	76,760
Fees earned, not billed	220,414			194,331
Other receivables	15,880			12,310
	309,058			283,401
Less: Allowance for doubtful accounts	(788		)	(695		)
	$	308,270		$	282,706

Property And Equipment

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



	March 31, 2018			December 31, 2017
Buildings	$	154,007		$	153,961
Equipment	118,823			115,546
Land	10,557			10,030
Purchased software	136,226			134,610
Furniture and fixtures	18,320			18,114
Leasehold improvements	18,851			18,017
Construction in progress	5,741			6,105
	462,525			456,383
Less: Accumulated depreciation	(317,245		)	(309,955		)
Property and Equipment, net	$	145,280		$	146,428

Accrued Liabilities

Accrued liabilities on the accompanying Consolidated Balance Sheets consist of:



	March 31, 2018		December 31, 2017
Accrued employee compensation	$	28,714	$	88,960
Accrued consulting, outsourcing and professional fees	35,682		29,658
Accrued sub-advisory, distribution and other asset management fees	39,680		42,365
Accrued dividend payable	—		47,179
Accrued income taxes	19,282		5,583
Other accrued liabilities	45,260		51,313
Total accrued liabilities	$	168,618	$	265,058

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Of Certain Financial Assets And Liabilities

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



			Fair Value Measurements at the End of the Reporting Period Using
Assets	March 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Equity available-for-sale securities	$	11,316	$	11,316	$	—
Fixed-income available-for-sale securities	71,773		—		71,773
Fixed-income securities owned	21,600		—		21,600
Investment funds sponsored by LSV (1)	5,534
	$	110,223	$	11,316	$	93,373



			Fair Value Measurements at the End of the Reporting Period Using
Assets	December 31, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
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

Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2018

Marketable Securities [Abstract]

Investments Available For Sale

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



	At March 31, 2018
	Cost Amount		Gross Unrealized Gains		Gross Unrealized (Losses)			Fair Value
SEI-sponsored mutual funds	$	7,382	$	96	$	(50	)	$	7,428
Equities and other mutual funds	3,483		405		—			3,888
Debt securities	74,431		—		(2,658		)	71,773
	$	85,296	$	501	$	(2,708	)	$	83,089



	At December 31, 2017
	Cost Amount		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

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Shareholders' Equity (Tables)

3 Months Ended

Mar. 31, 2018

Stockholders' Equity Note [Abstract]

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan

The Company recognized stock-based compensation expense in its Consolidated Financial Statements in the three months ended March 31, 2018 and 2017, respectively, as follows:



	Three Months Ended March 31,
	2018			2017
Stock-based compensation expense	$	5,195		$	6,180
Less: Deferred tax benefit	(1,103		)	(2,153		)
Stock-based compensation expense, net of tax	$	4,092		$	4,027

Accumulated Other Comprehensive Income (Loss) (Tables)

3 Months Ended

Mar. 31, 2018

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

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

The components of Accumulated other comprehensive loss, net of tax, are as follows:



	Foreign Currency Translation Adjustments			Unrealized Gains (Losses) on Investments			Accumulated Other Comprehensive Loss
Balance, January 1, 2018	$	(19,522	)	$	(386	)	$	(19,908	)

Other comprehensive gain before reclassifications	3,377			(1,357		)	2,020
Amounts reclassified from accumulated other comprehensive loss	—			(273		)	(273		)
Net current-period other comprehensive gain	3,377			(1,630		)	1,747

Balance, March 31, 2018	$	(16,145	)	$	(2,016	)	$	(18,161	)

Business Segment Information (Tables)

3 Months Ended

Mar. 31, 2018

Segment Reporting [Abstract]

Schedule Of Financial Information About Business Segments

The following tables highlight certain financial information about each of the Company’s business segments for the three months ended March 31, 2018 and 2017.



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Three Months Ended March 31, 2018
Revenues	$	122,164	$	99,192	$	85,491	$	96,855	$	1,896		$	405,598
Expenses	112,202		52,453		41,249		63,338		5,098			274,340
Operating profit (loss)	$	9,962	$	46,739	$	44,242	$	33,517	$	(3,202	)	$	131,258



	Private Banks		Investment Advisors		Institutional Investors		Investment Managers		Investments In New Businesses			Total
	For the Three Months Ended March 31, 2017
Revenues	$	112,634	$	88,238	$	77,004	$	80,487	$	1,621		$	359,984
Expenses	108,550		47,539		38,828		52,065		4,880			251,862
Operating profit (loss)	$	4,084	$	40,699	$	38,176	$	28,422	$	(3,259	)	$	108,122

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



	2018			2017
Total operating profit from segments	$	131,258		$	108,122
Corporate overhead expenses	(14,942		)	(14,605		)
Income from operations	$	116,316		$	93,517

Reconciliation of Other Significant Reconciling Items from Segments to Consolidated

The following tables provide additional information for the three months ended March 31, 2018 and 2017 pertaining to our business segments:



	Capital Expenditures (1)				Depreciation
	2018		2017		2018		2017
Private Banks	$	10,239	$	12,850	$	3,319	$	4,410
Investment Advisors	4,260		4,532		1,105		733
Institutional Investors	967		811		448		227
Investment Managers	2,520		1,615		1,809		916
Investments in New Businesses	204		106		150		368
Total from business segments	$	18,190	$	19,914	$	6,831	$	6,654
Corporate overhead	308		152		291		146
	$	18,498	$	20,066	$	7,122	$	6,800

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



	Amortization
	2018		2017
Private Banks	$	6,627	$	8,464
Investment Advisors	2,357		2,850
Institutional Investors	427		323
Investment Managers	2,345		216
Investments in New Businesses	40		119
Total from business segments	$	11,796	$	11,972
Corporate overhead	58		50
	$	11,854	$	12,022

Income Taxes (Tables)

3 Months Ended

Mar. 31, 2018

Income Tax Disclosure [Abstract]

Schedule Of Interest And Penalties



	March 31, 2018		December 31, 2017
Gross liability for unrecognized tax benefits, exclusive of interest and penalties	$	14,685	$	14,480
Interest and penalties on unrecognized benefits	1,218		1,175
Total gross uncertain tax positions	$	15,903	$	15,655
Amount included in Current liabilities	$	2,944	$	3,275
Amount included in Other long-term liabilities	12,959		12,380
	$	15,903	$	15,655

Schedule of Effective Income Tax Rate Reconciliation

The Company's effective income tax rate for the three months ended March 31, 2018 and 2017 differs from the federal income tax statutory rate due to the following:



	Three Months Ended March 31,
	2018		2017
Statutory rate	21.0	%	35.0	%
State taxes, net of federal tax benefit	2.2		1.5
Foreign tax expense and tax rate differential	(0.2	)	(0.8	)
Tax benefit from stock option exercises	(10.8	)	(4.2	)
Other, net	(0.3	)	(0.5	)
	11.9	%	31.0	%

Goodwill and Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Identifiable Intangible Assets

The identifiable intangible assets included on the accompanying Consolidated Balance Sheets consist of:



	March 31, 2018			December 31, 2017
Acquired technology	$	13,510		$	13,510
Client relationships	10,760			10,760
Non-competition agreements	3,470			3,470
Trade name	2,390			2,390
	30,130			30,130
Less: Accumulated amortization	(2,328		)	(1,552		)
Intangible assets, net	$	27,802		$	28,578

Revenues from Contracts with Customers (Tables)

3 Months Ended

Mar. 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 Three Months Ended March 31, 2018
Investment management fees from pooled investment products	$	35,190	$	72,418	$	15,858	$	—	$	225	$	123,691
Investment management fees from investment management agreements	198		22,764		69,276		83		1,634		93,955
Investment operations fees	382		—		—		87,455		—		87,837
Investment processing fees - PaaS	44,585		—		—		483		—		45,068
Investment processing fees - SaaS	34,602		—		—		2,365		—		36,967
Professional services fees	5,419		—		—		1,887		—		7,306
Account fees and other	1,788		4,010		357		4,582		37		10,774
Total revenues	$	122,164	$	99,192	$	85,491	$	96,855	$	1,896	$	405,598

Primary Geographic Markets:
United States	$	78,133	$	99,192	$	64,768	$	91,759	$	1,896	$	335,748
United Kingdom	27,525		—		14,787		—		—		42,312
Canada	11,601		—		2,671		—		—		14,272
Ireland	4,905		—		2,427		5,096		—		12,428
Other	—		—		838		—		—		838
Total revenues	$	122,164	$	99,192	$	85,491	$	96,855	$	1,896	$	405,598

Summary of Significant Accounting Policies (New Accounting Pronouncements and Changes in Accounting Principle) (Details) $ in Thousands	Jan. 01, 2018 USD ($)
Accounting Standards Update 2014-09 [Member] \| Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cumulative effect adjustment	$ 14,402

Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Expense related to soft dollar arrangement	$ 3,730	$ 4,073
Cash and cash equivalents invested in SEI-sponsored money market funds	748,299		$ 744,247
Restricted cash	3,507		3,505
Capitalized software development costs	12,887	$ 16,861
Net book value of capitalized software	$ 312,272		310,405
Anti-dilutive employee stock options	6,054	11,279
Anti-dilutive employee stock options, per share	$ 52.73	$ 37.70
SEI Wealth Platform [Member]
Capitalized software development costs	$ 12,042	$ 15,178
Net book value of capitalized software	287,530
Capitalized software in progress	33,237
Amortization expense of capitalized software	$ 9,719	11,972
SEI Wealth Platform [Member] \| Weighted Average [Member]
Estimated useful life of capitalized software	8 years 4 months 24 days
Application for Investment Managers segment [Member]
Capitalized software development costs	$ 845	$ 1,683
Net book value of capitalized software	$ 24,742
Estimated useful life of capitalized software	5 years
Amortization expense of capitalized software	$ 1,301
SEI Investments (Europe) Limited [Member]
Restricted cash	3,000		3,000
SEI Investments Distribution Co. (SIDCO) [Member]
Restricted cash	507		505
SEI-Sponsored Open-Ended Money Market Mutual Funds [Member]
Cash and cash equivalents invested in SEI-sponsored money market funds	$ 341,413		$ 401,292

Summary of Significant Accounting Policies (Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounting Policies [Abstract]
Net income	$ 139,838	$ 88,737
Shares used to compute basic earnings per common share	157,434	159,091
Dilutive effect of stock options (in shares)	5,990	3,651
Shares used to compute diluted earnings per common share	163,424	162,742
Basic earnings per common share (in USD per share)	$ 0.89	$ 0.56
Diluted earnings per common share (in USD per share)	$ 0.86	$ 0.55

Summary of Significant Accounting Policies (Net Cash Provided by Operating Activities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounting Policies [Abstract]
Net income	$ 139,838	$ 88,737
Depreciation	7,122	6,800
Amortization	11,854	12,022
Equity in earnings of unconsolidated affiliate	(40,607)	(33,565)
Distributions received from unconsolidated affiliate	45,617	35,265
Stock-based compensation	5,195	6,180
Provision for losses on receivables	93	(5)
Deferred income tax expense	2,083	877
Net gain from investments	410	(347)
Change in other long-term liabilities	579	965
Change in other assets	290	(849)
Other	(784)	56
Decrease (increase) in Receivables from investment products	1,757	10,308
Decrease (increase) in Receivables	(25,657)	(24,243)
Decrease (increase) in Other current assets	(3,564)	(2,298)
Increase (decrease) in Accounts payable	3,195	1,406
Increase (decrease) in Accrued liabilities	(43,522)	(27,754)
Increase (decrease) in Deferred revenue	275	(543)
Total adjustments	(35,664)	(15,725)
Net cash provided by operating activities	$ 104,174	$ 73,012

Investment In Unconsolidated Affiliate (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Investments in and Advances to Affiliates [Line Items]
Distributions received from unconsolidated affiliate	$ 45,617	$ 35,265
Company's share in the earnings of equity method investee	40,607	33,565
L S V Asset Management [Member]
Investments in and Advances to Affiliates [Line Items]
Total investment in equity method investee	54,482
Distributions received from unconsolidated affiliate	45,617	35,265
Company's share in the earnings of equity method investee	$ 40,607	$ 33,565
Maximum [Member]
Investments in and Advances to Affiliates [Line Items]
Equity method investment, ownership percentage	50.00%

Investment In Unconsolidated Affiliate (Statement of Operations) (Details) - L S V Asset Management [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule of Equity Method Investments [Line Items]
Revenues	$ 131,718	$ 109,953
Net income	$ 104,406	$ 86,215

Investment in Unconsolidated Affiliate (Balance Sheets) (Details) - L S V Asset Management [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Current assets	$ 143,922	$ 155,239
Non-current assets	1,444	1,407
Total assets	145,366	156,646
Current liabilities	47,641	46,486
Partners’ capital	97,725	110,160
Total liabilities and partners’ capital	$ 145,366	$ 156,646

Variable Interest Entities - Investment Products (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
SEI-Sponsored Open-Ended Money Market Mutual Funds [Member]
Financial Support for Nonconsolidated Legal Entity [Line Items]
Fees waived according to expense limitation agreements	$ 6,654	$ 7,072

Composition of Certain Financial Statement Captions (Receivables) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Items Included in Consolidated Statement of Financial Condition [Abstract]
Trade receivables	$ 72,764	$ 76,760
Fees earned, not billed	220,414	194,331
Other receivables	15,880	12,310
Receivables, Gross, Current	309,058	283,401
Less: Allowance for doubtful accounts	(788)	(695)
Receivables, net	$ 308,270	$ 282,706

Composition of Certain Financial Statement Captions (Property And Equipment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Property and Equipment [Line Items]
Property and Equipment, gross	$ 462,525		$ 456,383
Less: Accumulated depreciation	(317,245)		(309,955)
Property and Equipment, net	145,280		146,428
Depreciation expense	7,122	$ 6,800
Building [Member]
Property and Equipment [Line Items]
Property and Equipment, gross	154,007		153,961
Equipment [Member]
Property and Equipment [Line Items]
Property and Equipment, gross	118,823		115,546
Land [Member]
Property and Equipment [Line Items]
Property and Equipment, gross	10,557		10,030
Purchased Software [Member]
Property and Equipment [Line Items]
Property and Equipment, gross	136,226		134,610
Furniture and Fixtures [Member]
Property and Equipment [Line Items]
Property and Equipment, gross	18,320		18,114
Leasehold Improvements [Member]
Property and Equipment [Line Items]
Property and Equipment, gross	18,851		18,017
Construction in Progress [Member]
Property and Equipment [Line Items]
Property and Equipment, gross	$ 5,741		$ 6,105

Composition of Certain Financial Statement Captions (Accrued Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Items Included in Consolidated Statement of Financial Condition [Abstract]
Accrued employee compensation	$ 28,714	$ 88,960
Accrued consulting, outsourcing and professional fees	35,682	29,658
Accrued sub-advisory, distribution and other asset management fees	39,680	42,365
Accrued dividend payable	0	47,179
Accrued income taxes	19,282	5,583
Other accrued liabilities	45,260	51,313
Total accrued liabilities	$ 168,618	$ 265,058

Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity available-for-sale securities	$ 11,316	$ 11,250
Fixed-income available-for-sale securities	71,773	76,733
Fixed-income securities owned	21,600	21,526
Investment funds sponsored by LSV	5,534	6,034
Assets, fair value	110,223	115,543
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity available-for-sale securities	11,316	11,250
Fixed-income available-for-sale securities	0	0
Fixed-income securities owned	0	0
Assets, fair value	11,316	11,250
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity available-for-sale securities	0	0
Fixed-income available-for-sale securities	71,773	76,733
Fixed-income securities owned	21,600	21,526
Assets, fair value	$ 93,373	$ 98,259

Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule of Investments [Line Items]
Net unrealized losses	$ 2,016		$ 779
Unrealized losses during the period, income tax benefit	642		233
Fair value of investment funds sponsored by LSV	5,534		6,034
Securities owned	21,600		21,526
Investment Funds Sponsored by LSV [Member]
Schedule of Investments [Line Items]
Fair value of investment funds sponsored by LSV	5,534		$ 6,034
Gains (losses) from investment funds sponsored by LSV	$ (500)	$ 298

Marketable Securities (Investments Available For Sale) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Cost Amount	$ 85,296	$ 88,570
Gross Unrealized Gains	501	568
Gross Unrealized (Losses)	(2,708)	(1,155)
Fair Value	83,089	87,983
SEI-Sponsored Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Amount	7,382	7,369
Gross Unrealized Gains	96	110
Gross Unrealized (Losses)	(50)	(143)
Fair Value	7,428	7,336
Equities and Other Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Amount	3,483	3,456
Gross Unrealized Gains	405	458
Gross Unrealized (Losses)	0	0
Fair Value	3,888	3,914
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Amount	74,431	77,745
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	(2,658)	(1,012)
Fair Value	$ 71,773	$ 76,733

Line of Credit (Details) - Revolving Credit Facility [Member] - USD ($)		1 Months Ended
	Jun. 13, 2016	Apr. 19, 2018	Jul. 31, 2017	Mar. 31, 2018
Line of Credit Facility [Line Items]
Credit facility term of agreement	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 amount outstanding at reporting date				$ 20,000,000
Subsequent Event [Member]
Line of Credit Facility [Line Items]
Credit facility principal payment		$ 20,000,000
Credit facility remaining borrowing capacity		$ 300,000,000
London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	1.00%
Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	0.50%
Minimum [Member]
Line of Credit Facility [Line Items]
Credit facility commitment fee per annum on daily unused portion (as a percent)	0.15%
Minimum [Member] \| Lender's Base Rate Plus Market Spread [Member]
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	0.25%
Minimum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	1.25%
Maximum [Member]
Line of Credit Facility [Line Items]
Credit facility commitment fee per annum on daily unused portion (as a percent)	0.30%
Maximum [Member] \| Lender's Base Rate Plus Market Spread [Member]
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	1.00%
Maximum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Credit facility variable interest rate basis spread (as a percent)	2.00%

Shareholders' Equity (Narrative) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 56,579
Total intrinsic value of options exercised	93,668
Aggregate intrinsic value of options exercisable	$ 393,003
Market value of Company's common stock \| $ / shares	$ 74.91
Weighted average exercise price per share \| $ / shares	$ 29.20
Total options outstanding \| shares	14,652
Total options exercisable \| shares	8,598
Common Stock Buyback [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchased and retired \| shares	1,122
Company purchased, cost	$ 82,257
Remaining stock repurchase authorization amount	$ 88,380
2014 Plan [Member] \| Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	50.00%
2014 Plan [Member] \| Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	50.00%

Shareholders' Equity (Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Stockholders' Equity Note [Abstract]
Stock-based compensation expense	$ 5,195	$ 6,180
Less: Deferred tax benefit	(1,103)	(2,153)
Stock-based compensation expense, net of tax	$ 4,092	$ 4,027

Accumulated Other Comprehensive Income (Loss) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 1,476,839
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Other comprehensive gain before reclassifications	2,020
Amounts reclassified from accumulated other comprehensive loss	(273)
Net current-period other comprehensive gain	1,747
Ending balance	1,613,654
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(19,522)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Other comprehensive gain before reclassifications	3,377
Amounts reclassified from accumulated other comprehensive loss	0
Net current-period other comprehensive gain	3,377
Ending balance	(16,145)
Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(386)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Other comprehensive gain before reclassifications	(1,357)
Amounts reclassified from accumulated other comprehensive loss	(273)
Net current-period other comprehensive gain	(1,630)
Ending balance	(2,016)
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(19,908)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Ending balance	$ (18,161)

Business Segment Information (Schedule of Financial Information About Business Segments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 405,598	$ 359,984
Expenses	274,340	251,862
Operating profit (loss)	131,258	108,122
Private Banks [Member]
Segment Reporting Information [Line Items]
Revenues	122,164	112,634
Expenses	112,202	108,550
Operating profit (loss)	9,962	4,084
Investment Advisors [Member]
Segment Reporting Information [Line Items]
Revenues	99,192	88,238
Expenses	52,453	47,539
Operating profit (loss)	46,739	40,699
Institutional Investors [Member]
Segment Reporting Information [Line Items]
Revenues	85,491	77,004
Expenses	41,249	38,828
Operating profit (loss)	44,242	38,176
Investment Managers [Member]
Segment Reporting Information [Line Items]
Revenues	96,855	80,487
Expenses	63,338	52,065
Operating profit (loss)	33,517	28,422
Investments In New Businesses [Member]
Segment Reporting Information [Line Items]
Revenues	1,896	1,621
Expenses	5,098	4,880
Operating profit (loss)	$ (3,202)	$ (3,259)

Business Segment Information (Reconciliation of Total Operating Profit) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Total operating profit from segments	$ 131,258	$ 108,122
Income from operations	116,316	93,517
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total operating profit from segments	131,258	108,122
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Corporate overhead expenses	$ (14,942)	$ (14,605)

Business Segment Information (Schedule Of Additional Information Pertaining To Business Segments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Capital Expenditures	$ 18,498	$ 20,066
Depreciation	7,122	6,800
Amortization	11,854	12,022
Operating Segments [Member]
Segment Reporting Information [Line Items]
Capital Expenditures	18,190	19,914
Depreciation	6,831	6,654
Amortization	11,796	11,972
Operating Segments [Member] \| Private Banks [Member]
Segment Reporting Information [Line Items]
Capital Expenditures	10,239	12,850
Depreciation	3,319	4,410
Amortization	6,627	8,464
Operating Segments [Member] \| Investment Advisors [Member]
Segment Reporting Information [Line Items]
Capital Expenditures	4,260	4,532
Depreciation	1,105	733
Amortization	2,357	2,850
Operating Segments [Member] \| Institutional Investors [Member]
Segment Reporting Information [Line Items]
Capital Expenditures	967	811
Depreciation	448	227
Amortization	427	323
Operating Segments [Member] \| Investment Managers [Member]
Segment Reporting Information [Line Items]
Capital Expenditures	2,520	1,615
Depreciation	1,809	916
Amortization	2,345	216
Operating Segments [Member] \| Investments In New Businesses [Member]
Segment Reporting Information [Line Items]
Capital Expenditures	204	106
Depreciation	150	368
Amortization	40	119
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Capital Expenditures	308	152
Depreciation	291	146
Amortization	$ 58	$ 50

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Gross liability for unrecognized tax benefits, exclusive of interest and penalties	$ 14,685	$ 14,480
Unrecognized tax benefits that would affect effective tax rate	13,986	13,737
Interest and penalties on unrecognized benefits	1,218	$ 1,175
Estimated one-time transition tax	11,544
Estimated one-time transition tax, current	915
Estimated one-time transition tax, noncurrent	10,629
Settlement and Lapse of Statute [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits within the next twelve months	$ 2,944

Income Taxes (Interest And Penalties) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Gross liability for unrecognized tax benefits, exclusive of interest and penalties	$ 14,685	$ 14,480
Interest and penalties on unrecognized benefits	1,218	1,175
Gross uncertain tax positions	15,903	15,655
Amount included in Current liabilities	2,944	3,275
Amount included in Other long-term liabilities	$ 12,959	$ 12,380

Income Taxes (Effective Income Tax Rate Reconciliation) (Details)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate [Abstract]
Statutory rate	21.00%	35.00%
State taxes, net of federal tax benefit	2.20%	1.50%
Foreign tax expense and tax rate differential	(0.20%)	(0.80%)
Tax benefit from stock option exercises	(10.80%)	(4.20%)
Other, net	(0.30%)	(0.50%)
Effective income tax rate	11.90%	31.00%

Commitments and Contingencies (Details)	Mar. 31, 2018 Lawsuit
Loss Contingencies [Line Items]
Number of lawsuits filed	7
Cases with SPTC as Defendant [Member]
Loss Contingencies [Line Items]
Number of lawsuits filed	4
Claims for Violations of Louisiana Racketeering Act [Member]
Loss Contingencies [Line Items]
Number of lawsuits filed	2
Cases Remaining in Parish Of East Baton Rouge Granted Indefinite Extensions to Respond [Member]
Loss Contingencies [Line Items]
Number of lawsuits filed	2
Cases Filed in East Baton Rouge [Member]
Loss Contingencies [Line Items]
Number of lawsuits filed	2

Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jul. 03, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 52,990		$ 52,990
Intangible assets, gross	30,130		30,130
Less: Accumulated amortization	(2,328)		(1,552)
Intangible assets, net	27,802		28,578
Amortization expense	11,854	$ 12,022
Acquired technology [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	13,510		13,510
Client relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	10,760		10,760
Non-competition agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	3,470		3,470
Trade name [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	2,390		$ 2,390
Archway [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill				$ 52,990
Amortization expense	$ 776

Revenues from Contracts with Customers (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 405,598,000
Deferred contract costs	19,875,000	$ 0
Capitalized contract cost impairment	0
United States [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	335,748,000
United Kingdom [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	42,312,000
Canada [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14,272,000
Ireland [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12,428,000
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	838,000
Investment Management Fees From Investment Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	123,691,000
Investment Management Fees From Investment Management Agreements [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	93,955,000
Investment Operations Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	87,837,000
Investment Processing Fees, PaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	45,068,000
Investment Processing Fees, SaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	36,967,000
Professional Services Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7,306,000
Account Fees And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	10,774,000
Private Banks [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	122,164,000
Private Banks [Member] \| United States [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	78,133,000
Private Banks [Member] \| United Kingdom [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	27,525,000
Private Banks [Member] \| Canada [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11,601,000
Private Banks [Member] \| Ireland [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,905,000
Private Banks [Member] \| Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Private Banks [Member] \| Investment Management Fees From Investment Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	35,190,000
Private Banks [Member] \| Investment Management Fees From Investment Management Agreements [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	198,000
Private Banks [Member] \| Investment Operations Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	382,000
Private Banks [Member] \| Investment Processing Fees, PaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	44,585,000
Private Banks [Member] \| Investment Processing Fees, SaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	34,602,000
Private Banks [Member] \| Professional Services Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,419,000
Private Banks [Member] \| Account Fees And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,788,000
Investment Advisors [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	99,192,000
Investment Advisors [Member] \| United States [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	99,192,000
Investment Advisors [Member] \| United Kingdom [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Advisors [Member] \| Canada [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Advisors [Member] \| Ireland [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Advisors [Member] \| Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Advisors [Member] \| Investment Management Fees From Investment Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	72,418,000
Investment Advisors [Member] \| Investment Management Fees From Investment Management Agreements [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	22,764,000
Investment Advisors [Member] \| Investment Operations Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Advisors [Member] \| Investment Processing Fees, PaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Advisors [Member] \| Investment Processing Fees, SaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Advisors [Member] \| Professional Services Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Advisors [Member] \| Account Fees And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,010,000
Institutional Investors [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	85,491,000
Institutional Investors [Member] \| United States [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	64,768,000
Institutional Investors [Member] \| United Kingdom [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14,787,000
Institutional Investors [Member] \| Canada [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,671,000
Institutional Investors [Member] \| Ireland [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,427,000
Institutional Investors [Member] \| Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	838,000
Institutional Investors [Member] \| Investment Management Fees From Investment Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	15,858,000
Institutional Investors [Member] \| Investment Management Fees From Investment Management Agreements [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	69,276,000
Institutional Investors [Member] \| Investment Operations Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Institutional Investors [Member] \| Investment Processing Fees, PaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Institutional Investors [Member] \| Investment Processing Fees, SaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Institutional Investors [Member] \| Professional Services Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Institutional Investors [Member] \| Account Fees And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	357,000
Investment Managers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	96,855,000
Investment Managers [Member] \| United States [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	91,759,000
Investment Managers [Member] \| United Kingdom [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Managers [Member] \| Canada [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Managers [Member] \| Ireland [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,096,000
Investment Managers [Member] \| Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Managers [Member] \| Investment Management Fees From Investment Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investment Managers [Member] \| Investment Management Fees From Investment Management Agreements [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	83,000
Investment Managers [Member] \| Investment Operations Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	87,455,000
Investment Managers [Member] \| Investment Processing Fees, PaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	483,000
Investment Managers [Member] \| Investment Processing Fees, SaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,365,000
Investment Managers [Member] \| Professional Services Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,887,000
Investment Managers [Member] \| Account Fees And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,582,000
Investments In New Businesses [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,896,000
Investments In New Businesses [Member] \| United States [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,896,000
Investments In New Businesses [Member] \| United Kingdom [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investments In New Businesses [Member] \| Canada [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investments In New Businesses [Member] \| Ireland [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investments In New Businesses [Member] \| Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investments In New Businesses [Member] \| Investment Management Fees From Investment Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	225,000
Investments In New Businesses [Member] \| Investment Management Fees From Investment Management Agreements [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,634,000
Investments In New Businesses [Member] \| Investment Operations Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investments In New Businesses [Member] \| Investment Processing Fees, PaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investments In New Businesses [Member] \| Investment Processing Fees, SaaS [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investments In New Businesses [Member] \| Professional Services Fees [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Investments In New Businesses [Member] \| Account Fees And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 37,000