v3.19.3.a.u2
Cover
Dec. 09, 2019
Cover page.  
Document Type 8-K
Document Period End Date Dec. 09, 2019
Entity Registrant Name SEI INVESTMENTS COMPANY
Entity Central Index Key 0000350894
Amendment Flag false
Entity Incorporation, State or Country Code PA
Entity File Number 0-10200
Entity Tax Identification Number 23-1707341
Entity Address, Address Line One 1 Freedom Valley Drive
Entity Address, City or Town Oaks
Entity Address, State or Province PA
Entity Address, Postal Zip Code 19456
City Area Code 610
Local Phone Number 676-1000
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Stock, par value $0.01 per share
Trading Symbol SEIC
Security Exchange Name NASDAQ
Entity Emerging Growth Company false