SEI Investments (SEIC) 10-Q 23 Jul 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Jul. 22, 2014
Document Information [Line Items]	'	'
Entity Registrant Name	'SEI INVESTMENTS CO	'
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	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Trading Symbol	'SEIC	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	167,765,438

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current Assets:	'	'
Cash and cash equivalents	$532,167	$578,273
Restricted cash	5,500	5,500
Receivables from regulated investment companies	44,044	39,364
Receivables, net of allowance for doubtful accounts of $878 and $651	207,682	186,664
Securities owned	21,158	21,133
Other current assets	21,558	16,166
Total Current Assets	832,109	847,100
Property and Equipment, net of accumulated depreciation of $230,899 and $220,064	126,685	118,995
Capitalized Software, net of accumulated amortization of $198,746 and $180,062	312,193	312,615
Investments Available for Sale	85,504	83,323
Trading Securities	5,270	4,849
Investment in Unconsolidated Affiliates	60,017	61,370
Other Assets, net	13,328	10,917
Total Assets	1,435,106	1,439,169
Current Liabilities:	'	'
Accounts payable	8,470	16,235
Accrued liabilities	138,022	188,123
Deferred income taxes, net	1,847	1,653
Deferred revenue	1,338	1,977
Total Current Liabilities	149,677	207,988
Deferred Income Taxes	72,367	66,572
Other Long-term Liabilities	9,720	8,607
Total Liabilities	231,764	283,167
Commitments and Contingencies	'	'
SEI Investments shareholders' equity:	'	'
Common stock, $.01 par value, 750,000 shares authorized; 167,683 and 169,242 shares issued and outstanding	1,677	1,692
Capital in excess of par value	772,386	721,219
Retained earnings	425,458	431,604
Accumulated other comprehensive income, net	3,821	1,487
Total Shareholders' Equity	1,203,342	1,156,002
Total Liabilities and Shareholders' Equity	$1,435,106	$1,439,169

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Current Assets:	'	'
Receivables, allowance for doubtful accounts	$878	$651
Property and Equipment, accumulated depreciation	230,899	220,064
Capitalized Software, accumulated amortization	$198,746	$180,062
SEI Investments shareholders' equity:	'	'
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	167,683,000	169,242,000
Common stock, shares outstanding	167,683,000	169,242,000

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues:	'	'	'	'
Asset management, administration and distribution fees	$236,191	$203,722	$461,262	$402,355
Information processing and software servicing fees	75,828	62,468	145,006	127,000
Transaction-based and trade execution fees	6,796	8,384	14,933	17,098
Total revenues	318,815	274,574	621,201	546,453
Expenses:	'	'	'	'
Subadvisory, distribution and other asset management costs	37,244	29,652	71,256	57,586
Software royalties and other information processing costs	8,417	7,884	16,970	15,371
Brokerage commissions	5,119	6,260	11,098	12,772
Compensation, benefits and other personnel	92,470	86,715	186,894	175,325
Stock-based compensation	2,872	10,607	5,695	15,900
Consulting, outsourcing and professional fees	33,404	33,451	68,337	65,300
Data processing and computer related	13,378	12,316	25,998	24,374
Facilities, supplies and other costs	17,366	15,559	33,218	33,707
Amortization	9,584	8,427	18,798	16,669
Depreciation	5,331	5,730	10,915	11,434
Total expenses	225,185	216,601	449,179	428,438
Income from operations	93,630	57,973	172,022	118,015
Net gain (loss) from investments	391	-177	527	103
Interest and dividend income	721	688	1,498	1,741
Interest expense	-114	-114	-227	-227
Equity in earnings of unconsolidated affiliates	34,226	27,588	66,117	55,176
Gain on sale of subsidiary	0	0	5,582	22,112
Other income	0	43,429	0	43,429
Income before income taxes	128,854	129,387	245,519	240,349
Income taxes	46,041	45,893	87,886	84,585
Net income	82,813	83,494	157,633	155,764
Less: Net income attributable to the noncontrolling interest	0	0	0	-350
Net income attributable to SEI Investments Company	$82,813	$83,494	$157,633	$155,414
Basic earnings per common share	$0.49	$0.48	$0.93	$0.90
Shares used to compute basic earnings per share	168,606	172,223	168,956	172,411
Diluted earnings per common share	$0.48	$0.47	$0.91	$0.88
Shares used to compute diluted earnings per share	172,304	176,058	173,066	176,032
Dividends declared per common share	$0.22	$0.20	$0.22	$0.20

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net income	$82,813	$83,494	$157,633	$155,764
Other comprehensive income (loss), net of tax:	'	'	'	'
Foreign currency translation adjustments	3,378	-1,800	1,412	-7,107
Unrealized gain (loss) on investments:	'	'	'	'
Unrealized gains during the period, net of income taxes of $(461), $(771), $(756) and $(812)	453	-1,361	991	-1,240
Less: reclassification adjustment for gains realized in net income, net of income taxes of $13, $(66), $38 and $(185)	-24	-121	-69	-342
Net unrealized gain (loss) on investments	429	-1,482	922	-1,582
Total other comprehensive income (loss), net of tax	3,807	-3,282	2,334	-8,689
Comprehensive income	86,620	80,212	159,967	147,075
Comprehensive loss attributable to the noncontrolling interest	0	0	0	101
Comprehensive income attributable to SEI Investments Company	$86,620	$80,212	$159,967	$147,176

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Unrealized gains (losses) during the period, income tax expense (benefit)	($461)	($771)	($756)	($812)
Reclassification adjustment for gains realized in net income, income tax benefit (expense)	$13	($66)	$38	($185)

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:	'	'
Net income	$157,633	$155,764
Adjustments to reconcile net income to net cash provided by operating activities (See Note 1)	-14,641	-32,450
Net cash provided by operating activities	142,992	123,314
Cash flows from investing activities:	'	'
Additions to property and equipment	-18,632	-3,564
Additions to capitalized software	-18,262	-22,186
Purchases of marketable securities	-34,675	-15,484
Prepayments and maturities of marketable securities	16,203	17,807
Sales of marketable securities	18,048	5,988
Sale of subsidiary, net of cash transferred	5,582	6,028
Purchases of other investments	-2,000	-2,604
Net cash used in investing activities	-33,736	-14,015
Cash flows from financing activities:	'	'
Purchase and retirement of common stock	-140,294	-86,376
Proceeds from issuance of common stock	51,571	39,634
Tax benefit on stock options exercised	7,617	6,655
Payment of dividends	-74,256	-34,400
Net cash used in financing activities	-155,362	-74,487
Net (decrease) increase in cash and cash equivalents	-46,106	34,812
Cash and cash equivalents, beginning of period	578,273	452,247
Cash and cash equivalents, end of period	$532,167	$487,059

Summary_of_Significant_Account

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	Summary of Significant Accounting Policies
	Nature of Operations
	SEI Investments Company (the Company), a Pennsylvania corporation, provides investment processing, investment management, and investment operations solutions 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 solutions consist of application and business process outsourcing services, professional services and transaction-based services. Revenues from investment processing solutions are recognized in Information processing and software servicing fees on the accompanying Consolidated Statements of Operations, except for fees earned associated with trade execution services which are recognized in Transaction-based and trade execution fees.
	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 solutions 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 solutions 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 solutions 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 has 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 June 30, 2014, the results of operations for the three and six months ended June 30, 2014 and 2013, and cash flows for the six month periods ended June 30, 2014 and 2013. 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, 2013.
	There have been no significant changes in significant accounting policies during the six months ended June 30, 2014 as compared to the significant accounting policies described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
	Cash and Cash Equivalents
	Cash and cash equivalents includes $328,014 and $387,201 at June 30, 2014 and December 31, 2013, respectively, primarily invested in SEI-sponsored open-ended money market mutual funds. The SEI-sponsored mutual funds are considered Level 1 assets.
	Restricted Cash
	Restricted cash includes $5,000 at June 30, 2014 and December 31, 2013 segregated for regulatory purposes related to trade-execution services conducted by SEI Investments (Europe) Limited. Restricted cash also includes $500 at June 30, 2014 and December 31, 2013, 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 for broker-dealers.
	Capitalized Software
	The Company capitalized $18,262 and $22,186 of software development costs for the continued development of the SEI Wealth PlatformSM (the Platform) during the six months ended June 30, 2014 and 2013, respectively. Included in the amount for 2013 is a one-time contractual payment of $8,812 to exercise a conversion option in lieu of periodic fee payments pertaining to a software license for the Platform. As of June 30, 2014, the net book value of the Platform was $312,193. Capitalized software development costs in-progress associated with future releases to the Platform at June 30, 2014 were $8,854. The Platform has an estimated useful life of 15 years and a weighted average remaining life of 8.0 years. Amortization expense for the Platform was $18,589 and $16,321 during the six months ended June 30, 2014 and 2013, respectively.
	Earnings per Share
	The calculations of basic and diluted earnings per share for the three months ended June 30, 2014 and 2013 are:
		For the Three Months Ended June 30, 2014
		Income			Shares			Per Share
		(Numerator)			(Denominator)			Amount
	Basic earnings per common share	$	82,813		168,606,000			$	0.49
	Dilutive effect of stock options	—			3,698,000
	Diluted earnings per common share	$	82,813		172,304,000			$	0.48
		For the Three Months Ended June 30, 2013
		Income			Shares			Per Share
		(Numerator)			(Denominator)			Amount
	Basic earnings per common share	$	83,494		172,223,000			$	0.48
	Dilutive effect of stock options	—			3,835,000
	Diluted earnings per common share	$	83,494		176,058,000			$	0.47
	Employee stock options to purchase 5,397,000 and 5,548,000 shares of common stock, with an average exercise price of $32.40 and $29.22, were outstanding during the three months ended June 30, 2014 and 2013, respectively, but not included in the computation of diluted earnings per common share because the effect on diluted earnings per common share would have been anti-dilutive.
	The calculations of basic and diluted earnings per share for the six months ended June 30, 2014 and 2013 are:
		For the Six Months Ended June 30, 2014
		Income			Shares			Per Share
		(Numerator)			(Denominator)			Amount
	Basic earnings per common share	$	157,633		168,956,000			$	0.93
	Dilutive effect of stock options	—			4,110,000
	Diluted earnings per common share	$	157,633		173,066,000			$	0.91
		For the Six Months Ended June 30, 2013
		Income			Shares			Per Share
		(Numerator)			(Denominator)			Amount
	Basic earnings per common share	$	155,414		172,411,000			$	0.9
	Dilutive effect of stock options	—			3,621,000
	Diluted earnings per common share	$	155,414		176,032,000			$	0.88
	Employee stock options to purchase 5,397,000 and 6,745,000 shares of common stock, with an average exercise price of $32.40 and $28.01, were outstanding during the six months ended June 30, 2014 and 2013, respectively, but not included in the computation of diluted earnings per common share because the effect on diluted earnings per common share would have been anti-dilutive.
	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 following table provides the details of the adjustments to reconcile net income to net cash provided by operating activities for the six months ended June 30:
		2014			2013
	Net income	$	157,633		$	155,764
	Adjustments to reconcile net income to net cash provided by operating activities:
	Depreciation	10,915			11,434
	Amortization	18,798			16,669
	Equity in earnings of unconsolidated affiliates	(66,117		)	(55,176		)
	Distributions received from unconsolidated affiliate	69,470			53,797
	Stock-based compensation	5,695			15,900
	Provision for losses on receivables	227			483
	Deferred income tax expense	5,270			(10,000		)
	Gain from sale of SEI AK	(5,582		)	(22,112		)
	Net gain from investments	(527		)	(103		)
	Change in other long-term liabilities	1,113			825
	Change in other assets	(2,564		)	559
	Other	1,443			(7,251		)
	Change in current asset and liabilities
	Decrease (increase) in
Restricted cash for broker-dealer operations	—			500
Receivables from regulated investment companies	(4,680		)	(4,874		)
Receivables	(21,245		)	(16,407		)
Other current assets	(5,392		)	344
Increase (decrease) in
Accounts payable	(7,765		)	(9,433		)
Accrued liabilities	(13,061		)	(6,467		)
Deferred revenue	(639		)	(1,138		)
Total adjustments	(14,641		)	(32,450		)
Net cash provided by operating activities	$	142,992		$	123,314
New Accounting Pronouncements
On May 28, 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09), requiring an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014-09 also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The updated standard permits the use of either the retrospective or cumulative effect transition method. Early adoption is not permitted. ASU 2014-09 becomes effective for the Company during the first quarter 2017. The Company is currently evaluating the transition method that will be elected and the effect that the updated standard will have on its consolidated financial statements and related disclosures.
Reclassifications
Certain prior year amounts have been reclassified to conform to current year presentation.

Investment_In_Unconsolidated_A

Investment In Unconsolidated Affiliates	6 Months Ended
	Jun. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Investment In Unconsolidated Affiliates	'
	Investment in Unconsolidated Affiliates
	LSV Asset Management
	The Company has an investment in LSV Asset Management (LSV), a Delaware general partnership. LSV is a registered investment advisor that provides investment advisory services to institutions, including pension plans and investment companies. LSV is currently an investment sub-advisor for a small number of SEI-sponsored mutual funds. The Company accounts for its interest in LSV using the equity method because of its less than 50 percent ownership. The Company’s total partnership interest in LSV was approximately 39.3 percent during the six months ended June 30, 2014. During the six months ended June 30, 2013, the Company's total partnership interest was reduced from approximately 39.8 percent to approximately 39.3 percent. The Company’s interest in the net assets of LSV is reflected in Investment in unconsolidated affiliates on the accompanying Consolidated Balance Sheets and its interest in the earnings of LSV is reflected in Equity in earnings of unconsolidated affiliates on the accompanying Consolidated Statements of Operations.
	At June 30, 2014 and December 31, 2013, the Company’s total investment in LSV was $47,841 and $50,595, respectively. The investment in LSV exceeded the underlying equity in the net assets of LSV by $3,062 which is considered goodwill embedded in the investment. The Company receives partnership distributions from LSV on a quarterly basis. The Company received partnership distributions from LSV of $69,470 and $53,797 in the six months ended June 30, 2014 and 2013, respectively.
	The Company’s proportionate share in the earnings of LSV was $34,500 and $27,780 during the three months ended June 30, 2014 and 2013, respectively. During the six months ended June 30, 2014 and 2013, the Company’s proportionate share in the earnings of LSV was $66,716 and $55,586, respectively.
	The following table contains the condensed statements of operations of LSV for the three and six months ended June 30, 2014 and 2013:
		Three Months Ended June 30,				Six Months Ended June 30,
		2014		2013		2014		2013
	Revenues	$	105,948	$	83,682	$	201,721	$	164,598
	Net income	87,820		70,922		169,743		141,102
	Guaranty Agreement with LSV Employee Group II
	In April 2011, LSV Employee Group II agreed to purchase a partnership interest of an existing LSV employee for $4,300, of which $3,655 was financed through a term loan with Bank of America, N.A. (Bank of America). The Company provided an unsecured guaranty to the lenders of all the obligations of LSV Employee Group II. The lenders have the right to seek payment from the Company in the event of a default by LSV Employee Group II. LSV Employee Group II made the final principal payment in May 2014 for the term loan and has no further obligation regarding the Credit Agreement. LSV Employee Group II made principal payments of $716 during 2014, including the final principal payment of $365 in May 2014.
	Guaranty Agreement with LSV Employee Group III
	In October 2012, LSV Employee Group III purchased a portion of the partnership interest of three existing LSV employees for $77,700, of which $69,930 was financed through two syndicated term loan facilities contained in a credit agreement with The PrivateBank and Trust Company. The Company provided an unsecured guaranty for $45,000 of the obligations of LSV Employee Group III to the lenders through a guaranty agreement. The lenders have the right to seek payment from the Company in the event of a default by LSV Employee Group III. LSV agreed to provide an unsecured guaranty for $24,930 of the obligations of LSV Employee Group III to the lenders through a separate guaranty agreement.
	As of July 22, 2014, the remaining unpaid principal balances of the term loans guaranteed by LSV and the Company were $1,443 and $45,000, respectively. LSV Employee Group III has met all financial obligations to date regarding the scheduled repayment of the term loans since origination. The Company, in its capacity as guarantor, currently has no obligation of payment relating to the term loan of LSV Employee Group III and, furthermore, fully expects that LSV Employee Group III will meet all of their future obligations regarding the term loan.
	Investment in Gao Fu Limited
	The Company has an investment in Gao Fu Limited (Gao Fu), a wealth services firm based in Shanghai in the Republic of China. The Company accounts for its interest in Gao Fu using the equity method. At June 30, 2014 and December 31, 2013, the Company's total investment in Gao Fu was $12,176 and $10,775, respectively. The Company's proportionate share in the losses of Gao Fu was $599 and $410 during the six months ended June 30, 2014 and 2013, respectively.

Variable_Interest_Entities_Inv

Variable Interest Entities - Investment Products	6 Months Ended
	Jun. 30, 2014
Variable Interest Entities - Investment Products [Abstract]	'
Variable Interest Entities - Investment Products	'
	Variable Interest Entities – Investment Products
	The Company has 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. Clients are the equity investors and participate in proportion to their ownership percentage in the net income and net capital gains 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. Some of the Company’s investment products have been determined to be VIEs at inception.
	The Company does not have a significant equity investment in any of the VIEs and does not have an obligation to enter into any guarantee agreements with the VIEs. The Company is not the primary beneficiary of the VIEs because the expected fees and the expected return on any investment into the VIE by the Company relative to the expected returns of the VIE to the equity investor holders does not approach 50 percent of the expected losses or gains of the VIEs. Therefore, the Company is not required to consolidate any investment products that are VIEs into its financial statements. The Company’s variable interest in the VIEs, which consists of management fees and in some situations, seed capital, is not considered a significant variable interest.
	The risks to the Company associated with its involvement with any of the investment products that are VIEs are limited to the cash flows received from the revenue generated for asset management, administration and distribution services and any equity investments in the VIEs. Both of these items are not significant. The Company has no other financial obligation to the VIEs.
	Amounts relating to fees due from the VIEs included in Receivables and amounts relating to equity investments in the VIEs included in Investments Available for Sale on the Company’s Consolidated Balance Sheets are not significant to the total assets of the Company.

Composition_of_Certain_Financi

Composition of Certain Financial Statement Captions	6 Months Ended
	Jun. 30, 2014
Items Included in Consolidated Statement of Financial Condition [Abstract]	'
Composition of Certain Financial Statement Captions	'
	Composition of Certain Financial Statement Captions
	Receivables
	Receivables on the accompanying Consolidated Balance Sheets consist of:
		June 30, 2014			December 31, 2013
	Trade receivables	$	58,980		$	44,502
	Fees earned, not billed	142,847			128,248
	Other receivables	6,733			14,565
		208,560			187,315
	Less: Allowance for doubtful accounts	(878		)	(651		)
		$	207,682		$	186,664
	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 regulated investment companies on the accompanying Consolidated Balance Sheets primarily represent fees receivable for distribution, investment advisory, and administration services to various regulated investment companies sponsored by SEI.
	Property and Equipment
	Property and Equipment on the accompanying Consolidated Balance Sheets consists of:
		June 30, 2014			December 31, 2013
	Buildings	$	138,508		$	138,426
	Equipment	74,120			70,117
	Land	9,997			9,929
	Purchased software	101,936			96,268
	Furniture and fixtures	17,073			17,060
	Leasehold improvements	5,608			4,670
	Construction in progress	10,342			2,589
		357,584			339,059
	Less: Accumulated depreciation	(230,899		)	(220,064		)
	Property and Equipment, net	$	126,685		$	118,995
	The Company recognized $10,915 and $11,434 in depreciation expense related to property and equipment for the six months ended June 30, 2014 and 2013, respectively.
	Accrued Liabilities
	Accrued liabilities on the accompanying Consolidated Balance Sheets consist of:
		June 30, 2014			December 31, 2013
	Accrued employee compensation	$	40,497		$	69,256
	Accrued employee benefits and other personnel	6,380			9,647
	Accrued consulting, outsourcing and professional fees	23,006			19,311
	Accrued sub-advisory, distribution and other asset management fees	28,301			25,018
	Accrued income taxes	8,643			—
	Accrued dividend payable	—			37,314
	Other accrued liabilities	31,195			27,577
	Total accrued liabilities	$	138,022		$	188,123

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	Fair Value Measurements
	The fair value of the Company’s financial assets and liabilities 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 equity and fixed-income mutual funds that are quoted daily. Level 2 financial assets consist of Government National Mortgage Association (GNMA) mortgage-backed pass-through certificates, Federal Home Loan Bank (FHLB) and other U.S. government agency short-term notes and investment grade commercial paper. The Company's Level 2 financial assets, with the exception of the GNMA securities, were purchased as part of a cash management program requiring only short term, top-tier investment grade government and corporate securities. The GNMA mortgage-backed pass-through certificates were purchased for the sole purpose of satisfying specific regulatory requirements imposed on our wholly-owned limited purpose federal thrift subsidiary, SEI Private Trust Company (SPTC). As a result, the Company's Level 2 financial assets are limited to only these types of fixed income securities. The valuation of the Company's Level 2 financial assets are based upon securities pricing policies and procedures utilized by third-party pricing vendors. The pricing policies and procedures applied during the six months ended June 30, 2014 were consistent with those as described in our Annual Report on Form 10-K at December 31, 2013. The Company had no Level 3 financial assets or liabilities at June 30, 2014 or December 31, 2013. There were no transfers of financial assets between levels within the fair value hierarchy during the six months ended June 30, 2014.
	The fair value of certain financial assets and liabilities of the Company was determined using the following inputs:
		At June 30, 2014
		Fair Value Measurements at Reporting Date Using
	Assets	Total		Quoted Prices		Significant
				in		Other
				Active  Markets		Observable
				for Identical		Inputs
				Assets		(Level 2)
				(Level 1)
	Equity available-for-sale securities	$	12,106	$	12,106	$	—
	Fixed income available-for-sale securities	73,398		—		73,398
	Fixed income securities owned	21,158		—		21,158
	Trading securities	5,270		5,270		—
		$	111,932	$	17,376	$	94,556
		At December 31, 2013
		Fair Value Measurements at Reporting Date Using
	Assets	Total		Quoted Prices		Significant
				in		Other
				Active  Markets		Observable
				for Identical		Inputs
				Assets		(Level 2)
				(Level 1)
	Equity available-for-sale securities	$	11,633	$	11,633	$	—
	Fixed income available-for-sale securities	71,690		—		71,690
	Fixed income securities owned	21,133		—		21,133
	Trading securities	4,849		4,849		—
		$	109,305	$	16,482	$	92,823

Marketable_Securities

Marketable Securities	6 Months Ended
	Jun. 30, 2014
Marketable Securities [Abstract]	'
Marketable Securities	'
	Marketable Securities
	Investments Available for Sale
	Investments available for sale classified as non-current assets consist of:
		At June 30, 2014
		Cost		Gross		Gross		Fair
		Amount		Unrealized		Unrealized		Value
				Gains		Losses
	SEI-sponsored mutual funds	$	7,686	$	1,559	$	—	$	9,245
	Equities and other mutual funds	2,764		97		—		2,861
	Debt securities	71,598		1,800		—		73,398
		$	82,048	$	3,456	$	—	$	85,504
		At December 31, 2013
		Cost		Gross		Gross		Fair
		Amount		Unrealized		Unrealized		Value
				Gains		Losses
	SEI-sponsored mutual funds	$	7,612	$	1,242	$	—	$	8,854
	Equities and other mutual funds	2,615		164		—		2,779
	Debt securities	71,280		410		—		71,690
		$	81,507	$	1,816	$	—	$	83,323
	Net unrealized gains at June 30, 2014 and December 31, 2013 were $2,308 (net of income tax expense of $1,148) and $1,386 (net of income tax expense of $430), respectively. These net unrealized gains are reported as a separate component of Accumulated other comprehensive income on the accompanying Consolidated Balance Sheets.
	There were gross realized gains of $230 and gross realized losses of $123 from available-for-sale securities during the six months ended June 30, 2014. There were gross realized gains of $703 and gross realized losses of $175 from available-for-sale securities during the six months ended June 30, 2013. Gains and losses from available-for-sale securities, including amounts reclassified from accumulated comprehensive income, are reflected in Net gain (loss) from investments on the accompanying Consolidated Statements of Operations.
	The Company’s investments in debt securities are issued by GNMA and are backed by the full faith and credit of the U.S. government. These securities were purchased to satisfy applicable regulatory requirements of SPTC and have maturity dates which range from 2020 to 2043.
	Trading Securities
	The Company records all of its trading securities on the accompanying Consolidated Balance Sheets at fair value. Unrealized gains and losses from the change in fair value of these securities are recognized in Net gain (loss) from investments on the accompanying Consolidated Statements of Operations.
	Trading securities of the Company primarily consist of an investment related to the startup of mutual funds sponsored by LSV. These mutual funds are 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 $5,270 and $4,849 at June 30, 2014 and December 31, 2013, respectively. The Company recognized gains of $421 and losses of $475 from the change in fair value of the funds during the six months ended June 30, 2014 and 2013, respectively. During the three months ended June 30, 2014 and 2013, the Company recognized gains of $356 and losses of $460, 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 and commercial paper 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 $21,158 and $21,133 at June 30, 2014 and December 31, 2013, respectively. There were no material net gains or losses from the change in fair value of the securities during the three and six months ended June 30, 2014 and 2013.

Lines_of_Credit

Lines of Credit	6 Months Ended
	Jun. 30, 2014
Line of Credit Facility [Abstract]	'
Lines of Credit	'
	Lines 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 February 2017, 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 1.25 percent above LIBOR. There is also a commitment fee equal to 0.15 percent per annum on the daily unused portion of the facility. 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. Both the interest rate and commitment fee prices may increase if the Company’s leverage ratio reaches certain levels. 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. The Company had no borrowings under the Credit Facility at June 30, 2014. The Company was in compliance with all covenants of the Credit Facility during the six months ended June 30, 2014.
	The Company’s Canadian subsidiary maintained a credit facility agreement (the Canadian Credit Facility) for the purpose of facilitating the settlement of mutual fund transactions. The amount of the facility was limited to $2,000 Canadian dollars or the equivalent amount in U.S. dollars. On June 9, 2014, the Company terminated the agreement. The Company was in compliance with all covenants of the Canadian Credit Facility during 2014.

Shareholders_Equity

Shareholders' Equity	6 Months Ended
	Jun. 30, 2014
Stockholders' Equity Note [Abstract]	'
Shareholders' Equity	'
	Shareholders’ Equity
	Stock-Based Compensation
	On March 19, 2014, the Company’s Board of Directors approved the 2014 Omnibus Equity Compensation Plan (the 2014 Plan), which was later approved by the shareholders of the Company on May 21, 2014. The 2014 Plan became effective upon receipt of the shareholders' approval on May 21, 2014 and is the successor equity compensation plan to the 2007 Equity Compensation Plan (the 2007 Plan) which was merged with and into the 2014 Plan. The 2014 Plan provides for the grant of stock options, stock units, stock awards, stock appreciation rights and other stock-based awards.
	No further grants will be made under the 2007 Plan, and shares with respect to all grants outstanding under the 2007 Plan will be issued or transferred under the 2014 Plan. Permitted grantees under the 2014 Plan include employees, non-employee directors and consultants who perform services for the Company. The plan is administered by the Compensation Committee of the Board of Directors of the Company. There were no grants of stock options, stock units, stock awards, stock appreciation rights or other stock-based awards made under the 2014 Plan as of June 30, 2014.
	The Company has only non-qualified stock options outstanding under the merged plan. 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 specified diluted earnings per share targets are achieved, and the remaining 50 percent when secondary, higher specified diluted earnings per share targets are achieved. The amount of stock-based compensation expense is based upon management’s estimate of when the earnings per share targets may be achieved.
	The Company recognized stock-based compensation expense in its Consolidated Financial Statements in the three and six months ended June 30, 2014 and 2013, respectively, as follows:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Stock-based compensation expense	$	2,872		$	10,607		$	5,695		$	15,900
	Less: Deferred tax benefit	(939		)	(3,867		)	(1,950		)	(5,783		)
	Stock-based compensation expense, net of tax	$	1,933		$	6,740		$	3,745		$	10,117
	As of June 30, 2014, there was approximately $33,865 of unrecognized compensation cost remaining, adjusted for estimated forfeitures, 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 six months ended June 30, 2014 was $50,471. The total options exercisable as of June 30, 2014 had an intrinsic value of $158,021. The total intrinsic value for options exercisable is calculated as the difference between the market value of the Company’s common stock as of June 30, 2014 and the weighted average exercise price of the shares. The market value of the Company’s common stock as of June 30, 2014 was $32.77 as reported by the Nasdaq Stock Market, LLC. The weighted average exercise price of the options exercisable as of June 30, 2014 was $19.57. Total options that were outstanding and exercisable as of June 30, 2014 were 20,994,000 and 11,974,000, respectively.
	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 4,261,000 shares at a total cost of $140,568 during the six months ended June 30, 2014. The cost of stock purchases during the period includes the cost of certain transactions that settled in the following quarter. As of July 22, 2014, the Company has $140,502 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.
	Cash Dividend
	On May 21, 2014, the Board of Directors declared a cash dividend of $0.22 per share on the Company's common stock, which was paid on June 24, 2014, to shareholders of record on June 16, 2014. Cash dividends declared during the six months ended June 30, 2014 and 2013 were $36,942 and $34,400, respectively.

Accumulated_Comprehensive_Inco

Accumulated Comprehensive Income	6 Months Ended
	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Accumulated Comprehensive Income	'
	Accumulated Other Comprehensive Income
	The components of Accumulated other comprehensive income, net of tax, are as follows:
		Foreign		Unrealized			Total
		Currency		Gains (Losses)
		Translation		on Investments
		Adjustments
	Balance, January 1, 2014	$	101	$	1,386		$	1,487
	Other comprehensive income before reclassifications	1,412		991			2,403
	Amounts reclassified from accumulated other comprehensive income	—		(69		)	(69		)
	Net current-period other comprehensive income	1,412		922			2,334
	Balance, June 30, 2014	$	1,513	$	2,308		$	3,821

Business_Segment_Information

Business Segment Information	6 Months Ended
	Jun. 30, 2014
Segment Reporting [Abstract]	'
Business Segment Information	'
	Business Segment Information
	The Company’s reportable business segments are:
	Private Banks – provides investment processing and investment management programs to banks and trust institutions, independent wealth advisers and financial advisors worldwide;
	Investment Advisors – provides investment management programs 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 programs and administrative outsourcing solutions to retirement plan sponsors, hospitals and not-for-profit organizations worldwide;
	Investment Managers – provides investment operations outsourcing solutions 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 solutions; 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 and six months ended June 30, 2014 and 2013. 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, 2013.
	The following tables highlight certain unaudited financial information about each of the Company’s business segments for the three months ended June 30, 2014 and 2013.
		Private			Investment			Institutional		Investment		Investments			Total
		Banks			Advisors			Investors		Managers		In New
												Businesses
		For the Three Months Ended June 30, 2014
	Revenues	$	114,182		$	70,046		$	70,994	$	62,451	$	1,142		$	318,815
	Expenses	98,957			35,679			35,025		39,449		4,451			213,561
	Operating profit (loss)	$	15,225		$	34,367		$	35,969	$	23,002	$	(3,309	)	$	105,254
		Private			Investment			Institutional		Investment		Investments			Total
		Banks			Advisors			Investors		Managers		In New
												Businesses
		For the Three Months Ended June 30, 2013
	Revenues	$	95,142		$	59,284		$	63,684	$	55,456	$	1,008		$	274,574
	Expenses	97,755			32,898			33,028		36,507		3,890			204,078
	Operating profit (loss)	$	(2,613	)	$	26,386		$	30,656	$	18,949	$	(2,882	)	$	70,496
	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 June 30, 2014 and 2013 is as follows:
		2014			2013
	Total operating profit from segments above	$	105,254		$	70,496
	Corporate overhead expenses	(11,624		)	(12,523		)
	Income from operations	$	93,630		$	57,973
	The following tables provide additional information for the three months ended June 30, 2014 and 2013 pertaining to our business segments:
		Capital Expenditures						Depreciation
		2014			2013			2014		2013
	Private Banks	$	9,510		$	11,852		$	3,557	$	3,947
	Investment Advisors	4,061			4,192			512		517
	Institutional Investors	1,642			781			209		222
	Investment Managers	3,087			852			512		474
	Investments in New Businesses	616			187			420		454
	Total from business segments	$	18,916		$	17,864		$	5,210	$	5,614
	Corporate overhead	943			94			121		116
		$	19,859		$	17,958		$	5,331	$	5,730
		Amortization
		2014			2013
	Private Banks	$	6,192		$	5,457
	Investment Advisors	2,286			2,001
	Institutional Investors	355			309
	Investment Managers	236			206
	Investments in New Businesses	458			397
	Total from business segments	$	9,527		$	8,370
	Corporate overhead	57			57
		$	9,584		$	8,427
	The following tables highlight certain unaudited financial information about each of the Company’s business segments for the six months ended June 30, 2014 and 2013.
		Private			Investment			Institutional		Investment		Investments			Total
		Banks			Advisors			Investors		Managers		In New
												Businesses
		For the Six Months Ended June 30, 2014
	Revenues	$	219,361		$	136,470		$	139,651	$	123,459	$	2,260		$	621,201
	Expenses	199,147			70,256			69,120		78,633		8,700			425,856
	Operating profit (loss)	$	20,214		$	66,214		$	70,531	$	44,826	$	(6,440	)	$	195,345
	Gain on sale of subsidiary	5,582			—			—		—		—			5,582
	Total profit (loss)	$	25,796		$	66,214		$	70,531	$	44,826	$	(6,440	)	$	200,927
		Private			Investment			Institutional		Investment		Investments			Total
		Banks			Advisors			Investors		Managers		In New
												Businesses
		For the Six Months Ended June 30, 2013
Revenues	$	193,888		$	114,475		$	126,846	$	109,276	$	1,968		$	546,453
Expenses	194,053			64,523			64,537		71,669		7,628			402,410
Operating profit (loss)	$	(165	)	$	49,952		$	62,309	$	37,607	$	(5,660	)	$	144,043
Gain on sale of subsidiary	22,112			—			—		—		—			22,112
Total profit (loss)	$	21,947		$	49,952		$	62,309	$	37,607	$	(5,660	)	$	166,155
A reconciliation of the total operating profit reported for the business segments to income from operations in the Consolidated Statements of Operations for the six months ended June 30, 2014 and 2013 is as follows:
	2014			2013
Total operating profit from segments above	$	195,345		$	144,043
Corporate overhead expenses	(23,323		)	(26,317		)
Noncontrolling interest reflected in segments	—			289
Income from operations	$	172,022		$	118,015
The following tables provide additional information for the six months ended June 30, 2014 and 2013 pertaining to our business segments:
	Capital Expenditures						Depreciation
	2014			2013			2014		2013
Private Banks	$	18,308		$	16,703		$	7,289	$	7,880
Investment Advisors	7,650			5,967			1,003		1,026
Institutional Investors	2,930			1,144			419		452
Investment Managers	5,222			1,475			1,024		936
Investments in New Businesses	1,196			275			950		908
Total from business segments	$	35,306		$	25,564		$	10,685	$	11,202
Corporate Overhead	1,588			186			230		232
	$	36,894		$	25,750		$	10,915	$	11,434
	Amortization
	2014			2013
Private Banks	$	12,143		$	10,793
Investment Advisors	4,484			3,958
Institutional Investors	695			611
Investment Managers	464			408
Investments in New Businesses	898			785
Total from business segments	$	18,684		$	16,555
Corporate Overhead	114			114
	$	18,798		$	16,669

Income_Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The gross liability for unrecognized tax benefits at June 30, 2014 and December 31, 2013 was $13,019 and $12,028, respectively, exclusive of interest and penalties, of which $11,119 and $10,139 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 June 30, 2014 and December 31, 2013, the combined amount of accrued interest and penalties related to tax positions taken on tax returns was $919 and $754, respectively.
		June 30, 2014		December 31, 2013
	Gross liability for unrecognized tax benefits, exclusive of interest and penalties	$	13,019	$	12,028
	Interest and penalties on unrecognized benefits	919		754
	Total gross uncertain tax positions	$	13,938	$	12,782
	Amount included in Current liabilities	$	4,218	$	4,175
	Amount included in Other long-term liabilities	9,720		8,607
		$	13,938	$	12,782
	The Company’s effective tax rate was 35.7 percent and 35.5 percent for the three months ended June 30, 2014 and 2013, respectively. For the six months ended June 30, 2014 and 2013, the Company's tax rate was 35.8 percent and 35.2 percent, respectively. The increase in the tax rate for the six months ended June 30, 2014 was primarily due to the research and development tax credit. The Company's 2014 tax rate reflects no benefit for the tax credit due to the expiration of the credit on December 31, 2013, whereas the Company's 2013 tax rate reflects the benefit of the tax credit for 2012 and 2013.
	On January 2, 2013, the American Taxpayer Relief Act of 2012 (the Act) was signed into law which reinstated the research and development tax credit retroactively from January 1, 2012 through December 31, 2013. Current accounting guidance requires the determination of current and deferred taxes be based upon the provisions of the enacted tax law as of the balance sheet date. Since the Act was not signed into law until January 2, 2013, the effect of the 2012 research and development tax credit was therefore reflected in the Company's 2013 tax rate. Since the research and development tax credit expired as of December 31, 2013, no credit was reflected in the Company's 2014 tax rate. The increase in tax rate was partially offset by an increase in the portion of pre-tax income in certain foreign jurisdictions which is taxed at a lower rate during the six months ended June 30, 2014.
	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 2010 and is no longer subject to state, local or foreign income tax examinations by authorities for years before 2007.
	The Company estimates it will recognize $4,218 of unrecognized tax benefits within the next twelve months due to the expiration of the statute of limitations and resolution of income tax audits. 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 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

Commitments And Contingencies	6 Months Ended
	Jun. 30, 2014
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 six lawsuits filed in Louisiana. Five lawsuits were filed in the 19th Judicial District Court for the Parish of East Baton Rouge, State of Louisiana. One of the five actions purports to set forth claims on behalf of a class and also names SPTC as a defendant and, as described below, was certified as a class in December 2012. Two of the other actions also name SPTC as a defendant. All five actions name various defendants in addition to SEI, and, in all five actions, the plaintiffs purport to bring a cause of action against SEI and SPTC under the Louisiana Securities Act. The class action originally included a claim against SEI and SPTC for an alleged violation of the Louisiana Unfair Trade Practices Act. Two of the other five actions include claims for violations of the Louisiana Racketeering Act and possibly conspiracy. In addition, another group of plaintiffs filed a lawsuit in the 23rd Judicial District Court for the Parish of Ascension, State of Louisiana, against SEI and SPTC and other defendants asserting claims of negligence, breach of contract, breach of fiduciary duty, violations of the uniform fiduciaries law, negligent misrepresentation, detrimental reliance, violations of the Louisiana Securities Act and Louisiana Racketeering Act and conspiracy. The underlying allegations in all the actions are purportedly related to the role of SPTC in providing back-office services to Stanford Trust Company. The petitions allege that SEI and SPTC aided and abetted or otherwise participated in the sale of “certificates of deposit” issued by Stanford International Bank.
	Two of the five actions filed in East Baton Rouge were removed to federal court and transferred by the Judicial Panel on Multidistrict Litigation to United States District Court for the Northern District of Texas. On August 31, 2011, the United States District Court for the Northern District of Texas issued an order and judgment that the causes of action alleged against SEI in the two removed actions were preempted by federal law and the court dismissed these cases with prejudice. Plaintiffs appealed this ruling, and on March 19, 2012, a panel of the Court of Appeals for the Fifth Circuit reversed the decision of the United States District Court and remanded the actions for further proceedings. On July 18, 2012, SEI filed a petition for a writ of certiorari in the United States Supreme Court, seeking review of the decision by the United States Court of Appeals in the Fifth Circuit to permit the claims against SEI to proceed. SEI believes that the trial court correctly concluded that the claims against SEI were barred by the federal Securities Litigation Uniform Standards Act and requested that the Supreme Court reinstate that dismissal. On January 18, 2013, the Supreme Court granted the petition for a writ of certiorari. On October 7, 2013, the Supreme Court heard oral argument on the appeal and on February 26, 2014 the Supreme Court affirmed the judgment of the Court of Appeals.
	The case filed in Ascension was also removed to federal court and transferred by the Judicial Panel on Multidistrict Litigation to the Northern District of Texas. The schedule for responding to that complaint has not yet been established. The plaintiffs in the remaining two cases in East Baton Rouge have granted SEI and SPTC an extension to respond to the filings. SEI and SPTC filed exceptions in the class action pending in East Baton Rouge, which the Court granted in part and dismissed the claims under the Louisiana Unfair Trade Practices Act and denied in part as to the other exceptions.
	SEI and SPTC filed an answer to the East Baton Rouge class action, plaintiffs filed a motion for class certification; and SEI and SPTC also filed a motion for summary judgment against certain named plaintiffs which the Court stated would not be set for hearing until after the hearing on the class certification motion. The Court in the East Baton Rouge action held a hearing on class certification on September 20, 2012. By oral decision on December 5, 2012 and later entered in a judgment signed on December 17, 2012 that was subsequently amended, the Court in East Baton Rouge certified a class to be composed of persons who purchased any Stanford International Bank certificates of deposit (SIB CDs) in Louisiana between January 1, 2007 and February 13, 2009; persons who renewed any SIB CD in Louisiana between January 1, 2007 and February 13, 2009; or any person for whom the Stanford Trust Company purchased SIB CDs in Louisiana between January 1, 2007 and February 13, 2009. On January 30, 2013, SEI and SPTC filed motions for appeal from the judgments that stated SEI's and SPTC's intention to move to stay the litigation. On February 1, 2013, plaintiffs filed a motion for Leave to File First Amended and Restated Class Action Petition in which they ask the Court to allow them to amend the petition in this case to add additional facts that were developed during discovery and adding claims against certain of SEI's insurance carriers. On February 5, 2013, the Court granted two of the motions for appeal and the motion for leave to amend. On February 15, 2013, SEI filed a motion for new trial, or, in the alternative, for reconsideration of the Court's order allowing amendment. On February 22, 2013, SEI filed a motion to stay proceedings in view of the pending Supreme Court case. On February 28, 2013, SEI responded to the First Amended and Restated Class Action Petition by filing an exception. On March 11, 2013, the insurance carrier defendants filed a notice of removal removing the case to the Middle District of Louisiana and on March 18, 2013, the insurance carrier defendants filed answers. On March 13, 2013, SEI notified the Judicial Panel on Multidistrict Litigation (MDL) of this case as a potential tag-along action. On March 19, 2013, plaintiffs filed a motion to remand, a motion for expedited briefing schedule, expedited status conference and expedited consideration of their motion to remand, a motion for leave to file under seal and a motion for order pursuant to 28 U.S.C. 1447(b) requiring removing defendants to supplement federal court record with certified copy of state court record. These motions are now fully briefed. On March 25, 2013, SEI filed a motion that the court decline to adopt the state court's order regarding class certification, which the court dismissed without prejudice to renew upon a determination of removal jurisdiction in an April 12, 2013 order that also dismissed without prejudice a motion to dismiss for lack of jurisdiction and improper venue filed on April 9, 2013 by one of the insurers. On April 1, 2013, the Louisiana Office of Financial Institutions (OFI) filed a motion to remand and sever claims, and a response to that motion by the insurers and opposition to that motion by the plaintiffs were filed on April 22, 2013. Along with the briefing in the Middle District of Louisiana, on March 13, 2013, SEI notified the MDL of this case as a potential tag-along action. On March 19, 2013, plaintiffs notified the MDL that they had filed a motion to remand and asked the panel to decline to issue a conditional transfer order. On March 29, 2013, the MDL issued a conditional transfer order (CTO). On April 18, 2013, OFI filed a motion to vacate the CTO or, in the alternative, stay any ruling to transfer the matter until after the Middle District of Louisiana ruled on OFI's motion to remand and sever. Plaintiffs filed a motion to vacate the CTO on April 19, 2013. SEI's responses to those motions were filed on May 9, 2013. On June 12, 2013, the MDL Panel issued an order notifying the parties that on July 25, 2013, it would consider, without oral argument, Plaintiffs' and OFI's motions to vacate the CTO. On August 7, 2013, the MDL Panel affirmed the CTO and transferred the matter against SEI to the United States District Court for the Northern District of Texas; the MDL Panel also severed the claims against OFI and remanded those claims to the Middle District of Louisiana. On September 11, 2013, defendants filed a motion requesting a status conference with the Court to address the status of all pending motions. On October 4, 2013, Plaintiffs filed a petition for a writ of mandamus asking the United States Court of Appeals for the Fifth Circuit to review the MDL Panel’s transfer Order and on February 14, 2014, the Court denied the petition.
	While the outcome of this litigation is uncertain given its early phase, SEI and SPTC believe that they have valid defenses to plaintiffs' claims and intend to defend the lawsuits vigorously. Because of the uncertainty of the make-up of the classes, the specific theories of liability that may survive a motion for summary judgment or other dispositive motion, the 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.
	A lawsuit entitled Steven Curd and Rebel Curd v. SEI Investments Management Corporation (SIMC) was filed against SIMC in the United States District Court for the Eastern District of Pennsylvania on December 11, 2013. The plaintiffs bring the case as a shareholder derivative action against SIMC on behalf of certain SEI funds. The claims are based on Section 36(b) of the Investment Company Act of 1940, as amended, which allows shareholders of a mutual fund to sue the investment adviser of the fund for an alleged breach of fiduciary duty with respect to compensation received by the adviser. The plaintiffs have brought the suit against SIMC with respect to five specific SEI Funds: the High Yield Bond, Tax-Managed Large Cap, and Tax-Managed Small/Mid Cap Funds, each of which is a series of the SEI Institutional Managed Trust, the Intermediate Term Municipal Fund, which is a series of the SEI Tax Exempt Trust, and the International Equity Fund, which is a series of the SEI Institutional International Trust ("the SEI Funds"). The plaintiffs seek: (1) damages for the SEI Funds in the amount of the alleged “excessive” fees earned by SIMC beginning from the one year period prior to the filing of the lawsuit, plus interest, costs, and fees; (2) orders declaring that SIMC allegedly violated Section 36(b) and enjoining SIMC from further alleged violations; and (3) rescission of the advisory contracts between SIMC and the funds, and restitution of all allegedly excessive fees paid beginning from the one year period prior to the filing of the lawsuit, plus interest, costs, and fees. On February 24, 2014, SIMC filed a motion to dismiss the complaint in this lawsuit. The plaintiffs named the SEI Funds as nominal defendants, and the SEI Funds moved to dismiss on May 23, 2014. While the outcome of this litigation is uncertain given its early phase, SIMC believes that it has valid defenses to plaintiffs' claims and intends to defend the lawsuit vigorously and SIMC is not reasonably able to provide an estimate of the ultimate loss, if any, with respect to this lawsuit.

Sale_of_SEI_Asset_Korea

Sale of SEI Asset Korea	6 Months Ended
	Jun. 30, 2014
Disposal Group, Not Discontinued Operation, Disposal Disclosures [Abstract]	'
Sale of SEI Asset Korea	'
	Sale of SEI Asset Korea
	On July 31, 2012, the Company, MetLife International Holdings, Inc. (MetLife) and International Finance Corporation (IFC) entered into a definitive agreement with Baring Asset Management Limited to sell all ownership interest in SEI Asset Korea (SEI AK). SEI AK was located in South Korea and provided domestic equity and fixed income investment management services to financial institutions and pension funds.
	On March 28, 2013, all conditions subject to closing the transaction were satisfied and all ownership interests in SEI AK were transferred to Baring Asset Management Limited. The net working capital of SEI AK at closing in excess of required regulatory capital, and subject to certain other adjustments, was distributed to the Company, MetLife and IFC in accordance with the ownership interests. The Company recognized a pre-tax gain of $22,112, or $0.08 diluted earnings per share, during the six months ended June 30, 2013 as a result of the sale. Under the terms of the agreement, a portion of the purchase price was paid upon closing with up to an additional $11,220 payable to the Company as a contingent purchase price with respect to three one-year periods ending on December 31, 2013, 2014, and 2015 depending upon whether SEI AK achieves specified revenue measures during such periods. The Company recognized a pre-tax gain of $5,582, or $0.02 diluted earnings per share, with respect to the one-year period ended December 31, 2013 during the six months ended June 30, 2014. The Company received the payment for this portion of the contingent purchase price in April 2014. The Company's gains from the sale of SEI AK are included in Gain on sale of subsidiary on the accompanying Consolidated Statement of Operations.
	The operating results of SEI AK were included in the Private Banks business segment. SEI AK revenues and net income included in the Company's Consolidated Statement of Operations were as follows:
		For the Period January 1, 2013 through March 28, 2013
	Revenues	$	2,889
	Net income	$	796
	Less: Income attributable to the noncontrolling interests	(350		)
	Net income attributable to SEI AK	$	446

Settlement_Agreement

Settlement Agreement	6 Months Ended
	Jun. 30, 2014
Litigation Settlement [Abstract]	'
Settlement Agreement	'
	Settlement Agreement
	On April 24, 2013, the Company entered into a Settlement Agreement with respect to litigation captioned Abu Dhabi Commercial Bank, et. al. v. Morgan Stanley & Co., Incorporated, et. al., brought by a group of plaintiffs, including the Company, related to the purchase of securities by the Company and others of Cheyne Finance LLC, a SIV security. In accordance with the Settlement Agreement, the Company received a cash settlement payment of $43,429 after fees and expenses during the three months ended June 30, 2013. The income related to the cash settlement payment is reflected in Other income on the accompanying Consolidated Statements of Operations.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policy)	6 Months Ended
	Jun. 30, 2014
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 has 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 June 30, 2014, the results of operations for the three and six months ended June 30, 2014 and 2013, and cash flows for the six month periods ended June 30, 2014 and 2013. 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, 2013.
	There have been no significant changes in significant accounting policies during the six months ended June 30, 2014 as compared to the significant accounting policies described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
Cash and Cash Equivalents	'
	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.
New Accounting Pronouncements	'
	New Accounting Pronouncements
	On May 28, 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09), requiring an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014-09 also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The updated standard permits the use of either the retrospective or cumulative effect transition method. Early adoption is not permitted. ASU 2014-09 becomes effective for the Company during the first quarter 2017. The Company is currently evaluating the transition method that will be elected and the effect that the updated standard will have on its consolidated financial statements and related disclosures.
Reclassifications	'
	Reclassifications
	Certain prior year amounts have been reclassified to conform to current year presentation.
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 total partnership interest in LSV was approximately 39.3 percent during the six months ended June 30, 2014. During the six months ended June 30, 2013, the Company's total partnership interest was reduced from approximately 39.8 percent to approximately 39.3 percent. The Company’s interest in the net assets of LSV is reflected in Investment in unconsolidated affiliates on the accompanying Consolidated Balance Sheets and its interest in the earnings of LSV is reflected in Equity in earnings of unconsolidated affiliates on the accompanying Consolidated Statements of Operations.
Variable Interest Entities	'
	The Company does not have a significant equity investment in any of the VIEs and does not have an obligation to enter into any guarantee agreements with the VIEs. The Company is not the primary beneficiary of the VIEs because the expected fees and the expected return on any investment into the VIE by the Company relative to the expected returns of the VIE to the equity investor holders does not approach 50 percent of the expected losses or gains of the VIEs. Therefore, the Company is not required to consolidate any investment products that are VIEs into its financial statements. The Company’s variable interest in the VIEs, which consists of management fees and in some situations, seed capital, is not considered a significant variable interest.
	The risks to the Company associated with its involvement with any of the investment products that are VIEs are limited to the cash flows received from the revenue generated for asset management, administration and distribution services and any equity investments in the VIEs. Both of these items are not significant. The Company has no other financial obligation to the VIEs.
	Amounts relating to fees due from the VIEs included in Receivables and amounts relating to equity investments in the VIEs included in Investments Available for Sale on the Company’s Consolidated Balance Sheets are not significant to the total assets of the Company.
Fair Value of Financial Instruments	'
	The fair value of the Company’s financial assets and liabilities 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 equity and fixed-income mutual funds that are quoted daily. Level 2 financial assets consist of Government National Mortgage Association (GNMA) mortgage-backed pass-through certificates, Federal Home Loan Bank (FHLB) and other U.S. government agency short-term notes and investment grade commercial paper. The Company's Level 2 financial assets, with the exception of the GNMA securities, were purchased as part of a cash management program requiring only short term, top-tier investment grade government and corporate securities. The GNMA mortgage-backed pass-through certificates were purchased for the sole purpose of satisfying specific regulatory requirements imposed on our wholly-owned limited purpose federal thrift subsidiary, SEI Private Trust Company (SPTC). As a result, the Company's Level 2 financial assets are limited to only these types of fixed income securities. The valuation of the Company's Level 2 financial assets are based upon securities pricing policies and procedures utilized by third-party pricing vendors. The pricing policies and procedures applied during the six months ended June 30, 2014 were consistent with those as described in our Annual Report on Form 10-K at December 31, 2013.
Available-for-sale Securities	'
	These net unrealized gains are reported as a separate component of Accumulated other comprehensive income on the accompanying Consolidated Balance Sheets.
Trading Securities	'
	The Company records all of its trading securities on the accompanying Consolidated Balance Sheets at fair value. Unrealized gains and losses from the change in fair value of these securities are recognized in Net gain (loss) from investments on the accompanying Consolidated Statements of Operations.
Securities Owned	'
	The Company’s broker-dealer subsidiary, SIDCO, has investments in U.S. government agency and commercial paper 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_Account2

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Calculation Of Basic And Diluted Earnings Per Share	'
	The calculations of basic and diluted earnings per share for the six months ended June 30, 2014 and 2013 are:
		For the Six Months Ended June 30, 2014
		Income			Shares			Per Share
		(Numerator)			(Denominator)			Amount
	Basic earnings per common share	$	157,633		168,956,000			$	0.93
	Dilutive effect of stock options	—			4,110,000
	Diluted earnings per common share	$	157,633		173,066,000			$	0.91
		For the Six Months Ended June 30, 2013
		Income			Shares			Per Share
		(Numerator)			(Denominator)			Amount
	Basic earnings per common share	$	155,414		172,411,000			$	0.9
	Dilutive effect of stock options	—			3,621,000
	Diluted earnings per common share	$	155,414		176,032,000			$	0.88
	The calculations of basic and diluted earnings per share for the three months ended June 30, 2014 and 2013 are:
		For the Three Months Ended June 30, 2014
		Income			Shares			Per Share
		(Numerator)			(Denominator)			Amount
	Basic earnings per common share	$	82,813		168,606,000			$	0.49
	Dilutive effect of stock options	—			3,698,000
	Diluted earnings per common share	$	82,813		172,304,000			$	0.48
		For the Three Months Ended June 30, 2013
		Income			Shares			Per Share
		(Numerator)			(Denominator)			Amount
	Basic earnings per common share	$	83,494		172,223,000			$	0.48
	Dilutive effect of stock options	—			3,835,000
	Diluted earnings per common share	$	83,494		176,058,000			$	0.47
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 six months ended June 30:
		2014			2013
	Net income	$	157,633		$	155,764
	Adjustments to reconcile net income to net cash provided by operating activities:
	Depreciation	10,915			11,434
	Amortization	18,798			16,669
	Equity in earnings of unconsolidated affiliates	(66,117		)	(55,176		)
	Distributions received from unconsolidated affiliate	69,470			53,797
	Stock-based compensation	5,695			15,900
	Provision for losses on receivables	227			483
	Deferred income tax expense	5,270			(10,000		)
	Gain from sale of SEI AK	(5,582		)	(22,112		)
	Net gain from investments	(527		)	(103		)
	Change in other long-term liabilities	1,113			825
	Change in other assets	(2,564		)	559
	Other	1,443			(7,251		)
	Change in current asset and liabilities
	Decrease (increase) in
	Restricted cash for broker-dealer operations	—			500
	Receivables from regulated investment companies	(4,680		)	(4,874		)
	Receivables	(21,245		)	(16,407		)
	Other current assets	(5,392		)	344
	Increase (decrease) in
	Accounts payable	(7,765		)	(9,433		)
	Accrued liabilities	(13,061		)	(6,467		)
	Deferred revenue	(639		)	(1,138		)
	Total adjustments	(14,641		)	(32,450		)
	Net cash provided by operating activities	$	142,992		$	123,314

Investment_In_Unconsolidated_A1

Investment In Unconsolidated Affiliates (Tables)	6 Months Ended
	Jun. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Condensed Statement of Operations of LSV	'
	The following table contains the condensed statements of operations of LSV for the three and six months ended June 30, 2014 and 2013:
		Three Months Ended June 30,				Six Months Ended June 30,
		2014		2013		2014		2013
	Revenues	$	105,948	$	83,682	$	201,721	$	164,598
	Net income	87,820		70,922		169,743		141,102

Composition_of_Certain_Financi1

Composition of Certain Financial Statement Captions (Tables)	6 Months Ended
	Jun. 30, 2014
Items Included in Consolidated Statement of Financial Condition [Abstract]	'
Receivables	'
	Receivables on the accompanying Consolidated Balance Sheets consist of:
		June 30, 2014			December 31, 2013
	Trade receivables	$	58,980		$	44,502
	Fees earned, not billed	142,847			128,248
	Other receivables	6,733			14,565
		208,560			187,315
	Less: Allowance for doubtful accounts	(878		)	(651		)
		$	207,682		$	186,664
Property And Equipment	'
	Property and Equipment on the accompanying Consolidated Balance Sheets consists of:
		June 30, 2014			December 31, 2013
	Buildings	$	138,508		$	138,426
	Equipment	74,120			70,117
	Land	9,997			9,929
	Purchased software	101,936			96,268
	Furniture and fixtures	17,073			17,060
	Leasehold improvements	5,608			4,670
	Construction in progress	10,342			2,589
		357,584			339,059
	Less: Accumulated depreciation	(230,899		)	(220,064		)
	Property and Equipment, net	$	126,685		$	118,995
Accrued Liabilities	'
	Accrued liabilities on the accompanying Consolidated Balance Sheets consist of:
		June 30, 2014			December 31, 2013
	Accrued employee compensation	$	40,497		$	69,256
	Accrued employee benefits and other personnel	6,380			9,647
	Accrued consulting, outsourcing and professional fees	23,006			19,311
	Accrued sub-advisory, distribution and other asset management fees	28,301			25,018
	Accrued income taxes	8,643			—
	Accrued dividend payable	—			37,314
	Other accrued liabilities	31,195			27,577
	Total accrued liabilities	$	138,022		$	188,123

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Of Certain Financial Assets And Liabilities	'
	The fair value of certain financial assets and liabilities of the Company was determined using the following inputs:
		At June 30, 2014
		Fair Value Measurements at Reporting Date Using
	Assets	Total		Quoted Prices		Significant
				in		Other
				Active  Markets		Observable
				for Identical		Inputs
				Assets		(Level 2)
				(Level 1)
	Equity available-for-sale securities	$	12,106	$	12,106	$	—
	Fixed income available-for-sale securities	73,398		—		73,398
	Fixed income securities owned	21,158		—		21,158
	Trading securities	5,270		5,270		—
		$	111,932	$	17,376	$	94,556
		At December 31, 2013
		Fair Value Measurements at Reporting Date Using
	Assets	Total		Quoted Prices		Significant
				in		Other
				Active  Markets		Observable
				for Identical		Inputs
				Assets		(Level 2)
				(Level 1)
	Equity available-for-sale securities	$	11,633	$	11,633	$	—
	Fixed income available-for-sale securities	71,690		—		71,690
	Fixed income securities owned	21,133		—		21,133
	Trading securities	4,849		4,849		—
		$	109,305	$	16,482	$	92,823

Marketable_Securities_Tables

Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2014
Marketable Securities [Abstract]	'
Investments Available For Sale	'
	Investments available for sale classified as non-current assets consist of:
		At June 30, 2014
		Cost		Gross		Gross		Fair
		Amount		Unrealized		Unrealized		Value
				Gains		Losses
	SEI-sponsored mutual funds	$	7,686	$	1,559	$	—	$	9,245
	Equities and other mutual funds	2,764		97		—		2,861
	Debt securities	71,598		1,800		—		73,398
		$	82,048	$	3,456	$	—	$	85,504
		At December 31, 2013
		Cost		Gross		Gross		Fair
		Amount		Unrealized		Unrealized		Value
				Gains		Losses
	SEI-sponsored mutual funds	$	7,612	$	1,242	$	—	$	8,854
	Equities and other mutual funds	2,615		164		—		2,779
	Debt securities	71,280		410		—		71,690
		$	81,507	$	1,816	$	—	$	83,323

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2014
Stockholders' Equity Note [Abstract]	'
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]	'
	The Company recognized stock-based compensation expense in its Consolidated Financial Statements in the three and six months ended June 30, 2014 and 2013, respectively, as follows:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Stock-based compensation expense	$	2,872		$	10,607		$	5,695		$	15,900
	Less: Deferred tax benefit	(939		)	(3,867		)	(1,950		)	(5,783		)
	Stock-based compensation expense, net of tax	$	1,933		$	6,740		$	3,745		$	10,117

Accumulated_Comprehensive_Inco1

Accumulated Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Schedule Of Accumulated Other Comprehensive Income, Net Of Tax	'
	The components of Accumulated other comprehensive income, net of tax, are as follows:
		Foreign		Unrealized			Total
		Currency		Gains (Losses)
		Translation		on Investments
		Adjustments
	Balance, January 1, 2014	$	101	$	1,386		$	1,487
	Other comprehensive income before reclassifications	1,412		991			2,403
	Amounts reclassified from accumulated other comprehensive income	—		(69		)	(69		)
	Net current-period other comprehensive income	1,412		922			2,334
	Balance, June 30, 2014	$	1,513	$	2,308		$	3,821

Business_Segment_Information_T

Business Segment Information (Tables)	6 Months Ended
	Jun. 30, 2014
Segment Reporting [Abstract]	'
Schedule Of Financial Information About Business Segments	'
	The following tables highlight certain unaudited financial information about each of the Company’s business segments for the six months ended June 30, 2014 and 2013.
		Private			Investment			Institutional		Investment		Investments			Total
		Banks			Advisors			Investors		Managers		In New
												Businesses
		For the Six Months Ended June 30, 2014
	Revenues	$	219,361		$	136,470		$	139,651	$	123,459	$	2,260		$	621,201
	Expenses	199,147			70,256			69,120		78,633		8,700			425,856
	Operating profit (loss)	$	20,214		$	66,214		$	70,531	$	44,826	$	(6,440	)	$	195,345
	Gain on sale of subsidiary	5,582			—			—		—		—			5,582
	Total profit (loss)	$	25,796		$	66,214		$	70,531	$	44,826	$	(6,440	)	$	200,927
		Private			Investment			Institutional		Investment		Investments			Total
		Banks			Advisors			Investors		Managers		In New
												Businesses
		For the Six Months Ended June 30, 2013
	Revenues	$	193,888		$	114,475		$	126,846	$	109,276	$	1,968		$	546,453
	Expenses	194,053			64,523			64,537		71,669		7,628			402,410
	Operating profit (loss)	$	(165	)	$	49,952		$	62,309	$	37,607	$	(5,660	)	$	144,043
	Gain on sale of subsidiary	22,112			—			—		—		—			22,112
	Total profit (loss)	$	21,947		$	49,952		$	62,309	$	37,607	$	(5,660	)	$	166,155
	The following tables highlight certain unaudited financial information about each of the Company’s business segments for the three months ended June 30, 2014 and 2013.
		Private			Investment			Institutional		Investment		Investments			Total
		Banks			Advisors			Investors		Managers		In New
												Businesses
		For the Three Months Ended June 30, 2014
	Revenues	$	114,182		$	70,046		$	70,994	$	62,451	$	1,142		$	318,815
	Expenses	98,957			35,679			35,025		39,449		4,451			213,561
	Operating profit (loss)	$	15,225		$	34,367		$	35,969	$	23,002	$	(3,309	)	$	105,254
		Private			Investment			Institutional		Investment		Investments			Total
		Banks			Advisors			Investors		Managers		In New
												Businesses
		For the Three Months Ended June 30, 2013
	Revenues	$	95,142		$	59,284		$	63,684	$	55,456	$	1,008		$	274,574
	Expenses	97,755			32,898			33,028		36,507		3,890			204,078
	Operating profit (loss)	$	(2,613	)	$	26,386		$	30,656	$	18,949	$	(2,882	)	$	70,496
Reconciliation Of Total Operating Profit Reported For Business Segments To Income From Operations In Consolidated Statements Of Operations	'
	A reconciliation of the total operating profit reported for the business segments to income from operations in the Consolidated Statements of Operations for the six months ended June 30, 2014 and 2013 is as follows:
		2014			2013
	Total operating profit from segments above	$	195,345		$	144,043
	Corporate overhead expenses	(23,323		)	(26,317		)
	Noncontrolling interest reflected in segments	—			289
	Income from operations	$	172,022		$	118,015
	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 June 30, 2014 and 2013 is as follows:
		2014			2013
	Total operating profit from segments above	$	105,254		$	70,496
	Corporate overhead expenses	(11,624		)	(12,523		)
	Income from operations	$	93,630		$	57,973
Reconciliation of Other Significant Reconciling Items from Segments to Consolidated [Table Text Block]	'
	The following tables provide additional information for the six months ended June 30, 2014 and 2013 pertaining to our business segments:
		Capital Expenditures						Depreciation
		2014			2013			2014		2013
	Private Banks	$	18,308		$	16,703		$	7,289	$	7,880
	Investment Advisors	7,650			5,967			1,003		1,026
	Institutional Investors	2,930			1,144			419		452
	Investment Managers	5,222			1,475			1,024		936
	Investments in New Businesses	1,196			275			950		908
	Total from business segments	$	35,306		$	25,564		$	10,685	$	11,202
	Corporate Overhead	1,588			186			230		232
		$	36,894		$	25,750		$	10,915	$	11,434
		Amortization
		2014			2013
	Private Banks	$	12,143		$	10,793
	Investment Advisors	4,484			3,958
	Institutional Investors	695			611
	Investment Managers	464			408
	Investments in New Businesses	898			785
	Total from business segments	$	18,684		$	16,555
	Corporate Overhead	114			114
		$	18,798		$	16,669
	The following tables provide additional information for the three months ended June 30, 2014 and 2013 pertaining to our business segments:
		Capital Expenditures						Depreciation
		2014			2013			2014		2013
	Private Banks	$	9,510		$	11,852		$	3,557	$	3,947
	Investment Advisors	4,061			4,192			512		517
	Institutional Investors	1,642			781			209		222
	Investment Managers	3,087			852			512		474
	Investments in New Businesses	616			187			420		454
	Total from business segments	$	18,916		$	17,864		$	5,210	$	5,614
	Corporate overhead	943			94			121		116
		$	19,859		$	17,958		$	5,331	$	5,730
		Amortization
		2014			2013
	Private Banks	$	6,192		$	5,457
	Investment Advisors	2,286			2,001
	Institutional Investors	355			309
	Investment Managers	236			206
	Investments in New Businesses	458			397
	Total from business segments	$	9,527		$	8,370
	Corporate overhead	57			57
		$	9,584		$	8,427

Income_Taxes_Tables

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'
Schedule Of Interest And Penalties	'
		June 30, 2014		December 31, 2013
	Gross liability for unrecognized tax benefits, exclusive of interest and penalties	$	13,019	$	12,028
	Interest and penalties on unrecognized benefits	919		754
	Total gross uncertain tax positions	$	13,938	$	12,782
	Amount included in Current liabilities	$	4,218	$	4,175
	Amount included in Other long-term liabilities	9,720		8,607
		$	13,938	$	12,782

Sale_of_SEI_Asset_Korea_Tables

Sale of SEI Asset Korea (Tables)	6 Months Ended
	Jun. 30, 2014
Disposal Group, Not Discontinued Operation, Disposal Disclosures [Abstract]	'
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block]	'
	SEI AK revenues and net income included in the Company's Consolidated Statement of Operations were as follows:
		For the Period January 1, 2013 through March 28, 2013
	Revenues	$	2,889
	Net income	$	796
	Less: Income attributable to the noncontrolling interests	(350		)
	Net income attributable to SEI AK	$	446

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Cash and cash equivalents invested in SEI-sponsored money market funds	$532,167	$487,059	$532,167	$487,059	$578,273	$452,247
Restricted cash	5,500	'	5,500	'	5,500	'
Net book value of the SEI Wealth Platform	312,193	'	312,193	'	312,615	'
Anti-dilutive employee stock options	5,397,000	5,548,000	5,397,000	6,745,000	'	'
Antidilutive securities excluded from computation of net income, per outstanding unit, amount	$32.40	$29.22	$32.40	$28.01	'	'
SEI Investments Distribution Co. (SIDCO) [Member]	'	'	'	'	'	'
Restricted cash	500	'	500	'	500	'
SEI Investments (Europe) Limited [Member]	'	'	'	'	'	'
Restricted cash	5,000	'	5,000	'	5,000	'
SEI-Sponsored Open-Ended Money Market Mutual Funds [Member]	'	'	'	'	'	'
Cash and cash equivalents invested in SEI-sponsored money market funds	328,014	'	328,014	'	387,201	'
SEI Wealth Platform [Member]	'	'	'	'	'	'
Capitalized software development costs related to the SEI Wealth Platform	'	'	18,262	22,186	'	'
One-time contractual payment for conversion option included in software development costs	'	'	'	8,812	'	'
Net book value of the SEI Wealth Platform	312,193	'	312,193	'	'	'
Capitalized software development costs in-progress associated with future releases	8,854	'	8,854	'	'	'
Estimated useful life of the SEI Wealth Platform	'15 years	'	'	'	'	'
Amortization expense related to the SEI Wealth Platform	'	'	$18,589	$16,321	'	'
Weighted Average [Member] | SEI Wealth Platform [Member]	'	'	'	'	'	'
Estimated useful life of the SEI Wealth Platform	'8 years	'	'	'	'	'

Summary_of_Significant_Account4

Summary of Significant Accounting Policies (Calculation Of Basic And Diluted Earnings Per Share) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Accounting Policies [Abstract]	'	'	'	'
Basic earnings per common share, Income (Numerator)	$82,813	$83,494	$157,633	$155,414
Shares used to compute basic earnings per share	168,606	172,223	168,956	172,411
Basic earnings per common share	$0.49	$0.48	$0.93	$0.90
Dilutive effect of stock options, income	0	0	0	0
Dilutive effect of stock options, shares	3,698	3,835	4,110	3,621
Diluted earnings per common share, Income (Numerator)	$82,813	$83,494	$157,633	$155,414
Shares used to compute diluted earnings per share	172,304	176,058	173,066	176,032
Diluted earnings per common share	$0.48	$0.47	$0.91	$0.88

Summary_of_Significant_Account5

Summary of Significant Accounting Policies (Adjustments To Reconcile Net Income To Net Cash Provided By Operating Activities) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Accounting Policies [Abstract]	'	'	'	'
Net income	$82,813	$83,494	$157,633	$155,764
Depreciation	5,331	5,730	10,915	11,434
Amortization	9,584	8,427	18,798	16,669
Equity in earnings of unconsolidated affiliates	-34,226	-27,588	-66,117	-55,176
Distributions received from unconsolidated affiliate	'	'	69,470	53,797
Stock-based compensation	2,872	10,607	5,695	15,900
Provision for losses on receivables	'	'	227	483
Deferred income tax expense	'	'	5,270	-10,000
Gain on sale of SEI AK	0	0	-5,582	-22,112
Net gain from investments	'	'	-527	-103
Change in other long-term liabilities	'	'	1,113	825
Change in other assets	'	'	-2,564	559
Other	'	'	1,443	-7,251
Decrease (increase) in Restricted cash for broker-dealer operations	'	'	0	500
Decrease (increase) in Receivables from regulated investment companies	'	'	-4,680	-4,874
Decrease (increase) in Receivables	'	'	-21,245	-16,407
Decrease (increase) in Other current assets	'	'	-5,392	344
Increase (decrease) in Accounts payable	'	'	-7,765	-9,433
Increase (decrease) in Accrued liabilities	'	'	-13,061	-6,467
Increase (decrease) in Deferred revenue	'	'	-639	-1,138
Total adjustments	'	'	-14,641	-32,450
Net cash provided by operating activities	'	'	$142,992	$123,314

Investment_In_Unconsolidated_A2

Investment In Unconsolidated Affiliates (Narrative) (Details) (USD $)

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

6 Months Ended

In Thousands, unless otherwise specified

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2014

Apr. 30, 2011

Oct. 31, 2012

Oct. 31, 2012

Jul. 22, 2014

Apr. 30, 2011

Oct. 31, 2012

Jul. 22, 2014

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

Jun. 30, 2014

LSV Employee Group II [Member]

LSV Employee Group II [Member]

LSV Employee Group II [Member]

LSV Employee Group III [Member]

Financial Guarantee [Member]

Financial Guarantee [Member]

Financial Guarantee [Member]

Financial Guarantee [Member]

Financial Guarantee [Member]

L S V Asset Management [Member]

L S V Asset Management [Member]

L S V Asset Management [Member]

L S V Asset Management [Member]

L S V Asset Management [Member]

L S V Asset Management [Member]

Gao Fu [Member]

Gao Fu [Member]

Gao Fu [Member]

Maximum [Member]

L S V Asset Management [Member]

L S V Asset Management [Member]

LSV Employee Group II [Member]

LSV Employee Group III [Member]

LSV Employee Group III [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Investments in and Advances to Affiliates [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity method investment, ownership percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

39.30%

'

39.30%

'

39.80%

'

'

'

50.00%

Total investment in equity method investee

'

'

'

'

'

'

'

'

'

'

'

'

'

$47,841

'

$47,841

'

$50,595

'

$12,176

'

$10,775

'

Investment in equity method investee in excess of the underlying equity in net assets

'

'

'

'

'

'

'

'

'

'

'

'

'

3,062

'

3,062

'

'

'

'

'

'

'

Distributions received from unconsolidated affiliate

'

'

69,470

53,797

'

'

'

'

'

'

'

'

'

'

'

69,470

53,797

'

'

'

'

'

'

Company's share in the earnings of equity method investee

34,226

27,588

66,117

55,176

'

'

'

'

'

'

'

'

'

34,500

27,780

66,716

55,586

'

'

-599

-410

'

'

Purchase price paid for partnership interest in LSV

'

'

'

'

'

'

4,300

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount of guarantor's obligation, maximum exposure

'

'

'

'

'

'

'

'

24,930

1,443

3,655

45,000

45,000

'

'

'

'

'

'

'

'

'

'

Principal payment

'

'

'

'

365

716

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount of guarantor's obligation, current carrying value

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

'

Purchase of partnership interest value

'

'

'

'

'

'

'

77,700

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount of purchase price financed through term loans

'

'

'

'

'

'

'

$69,930

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Investment_In_Unconsolidated_A3

Investment In Unconsolidated Affiliates (Condensed Statement Of Operations Of LSV) (Details) (L S V Asset Management [Member], USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
L S V Asset Management [Member]	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Equity Method Investment, Summarized Financial Information, Revenue	$105,948	$83,682	$201,721	$164,598
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	$87,820	$70,922	$169,743	$141,102

Variable_Interest_Entities_Inv1

Variable Interest Entities - Investment Products (Details)	6 Months Ended
	Jun. 30, 2014
Variable Interest Entities - Investment Products [Abstract]	'
Percentage not approached by expected return on any VIE investment	50.00%

Composition_of_Certain_Financi2

Composition of Certain Financial Statement Captions (Receivables) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Items Included in Consolidated Statement of Financial Condition [Abstract]	'	'
Trade receivables	$58,980	$44,502
Fees earned, not billed	142,847	128,248
Other receivables	6,733	14,565
Receivables, Gross, Current	208,560	187,315
Less: Allowance for doubtful accounts	878	651
Receivables, net	$207,682	$186,664

Composition_of_Certain_Financi3

Composition of Certain Financial Statement Captions (Property And Equipment) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Property, Plant and Equipment [Line Items]	'	'	'	'	'
Property and Equipment, gross	$357,584	'	$357,584	'	$339,059
Less: Accumulated depreciation	-230,899	'	-230,899	'	-220,064
Property and Equipment, net	126,685	'	126,685	'	118,995
Depreciation expense	5,331	5,730	10,915	11,434	'
Building [Member]	'	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'	'
Property and Equipment, gross	138,508	'	138,508	'	138,426
Equipment [Member]	'	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'	'
Property and Equipment, gross	74,120	'	74,120	'	70,117
Land [Member]	'	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'	'
Property and Equipment, gross	9,997	'	9,997	'	9,929
Purchased Software [Member]	'	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'	'
Property and Equipment, gross	101,936	'	101,936	'	96,268
Furniture and Fixtures [Member]	'	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'	'
Property and Equipment, gross	17,073	'	17,073	'	17,060
Leasehold Improvements [Member]	'	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'	'
Property and Equipment, gross	5,608	'	5,608	'	4,670
Construction in Progress [Member]	'	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'	'
Property and Equipment, gross	$10,342	'	$10,342	'	$2,589

Composition_of_Certain_Financi4

Composition of Certain Financial Statement Captions (Accrued Liabilities) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Items Included in Consolidated Statement of Financial Condition [Abstract]	'	'
Accrued employee compensation	$40,497	$69,256
Accrued employee benefits and other personnel	6,380	9,647
Accrued consulting, outsourcing and professional fees	23,006	19,311
Accrued sub-advisory, distribution and other asset management fees	28,301	25,018
Accrued income taxes	8,643	0
Accrued dividend payable	0	37,314
Other accrued liabilities	31,195	27,577
Total accrued liabilities	$138,022	$188,123

Fair_Value_Measurements_Fair_V

Fair Value Measurements (Fair Value Of Certain Financial Assets And Liabilities) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Fixed income securities owned	$21,158	$21,133
Trading securities	5,270	4,849
Estimate of Fair Value Measurement [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Equity available-for-sale securities	12,106	11,633
Fixed income available-for-sale securities	73,398	71,690
Fixed income securities owned	21,158	21,133
Trading securities	5,270	4,849
Assets, fair value	111,932	109,305
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	12,106	11,633
Fixed income available-for-sale securities	0	0
Fixed income securities owned	0	0
Trading securities	5,270	4,849
Assets, fair value	17,376	16,482
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	73,398	71,690
Fixed income securities owned	21,158	21,133
Trading securities	0	0
Assets, fair value	$94,556	$92,823

Marketable_Securities_Narrativ

Marketable Securities (Narrative) (Details) (USD $)	6 Months Ended			3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Dec. 31, 2013
				Trading Securities [Member]	Trading Securities [Member]	Trading Securities [Member]	Trading Securities [Member]
Schedule of Investments [Line Items]	'	'	'	'	'	'	'
Net unrealized gains	$2,308	'	$1,386	'	'	'	'
Unrealized gains during the period, income tax expense	1,148	'	430	'	'	'	'
Available-for-sale securities, gross realized gains	230	703	'	'	'	'	'
Available-for-sale securities, gross realized losses	123	175	'	'	'	'	'
Trading securities	5,270	'	4,849	5,270	'	5,270	4,849
Trading securities, realized gains	'	'	'	356	'	421	'
Trading securities, realized losses	'	'	'	'	460	475	'
Securities owned	$21,158	'	$21,133	'	'	'	'

Marketable_Securities_Investme

Marketable Securities (Investments Available For Sale) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Investment Available for Sale, Cost Amount	$82,048	$81,507
Investment Available for Sale, Gross Unrealized Gains	3,456	1,816
Investment Available for Sale, Gross Unrealized Losses	0	0
Investment Available for Sale, Fair Value	85,504	83,323
SEI-Sponsored Mutual Funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Investment Available for Sale, Cost Amount	7,686	7,612
Investment Available for Sale, Gross Unrealized Gains	1,559	1,242
Investment Available for Sale, Gross Unrealized Losses	0	0
Investment Available for Sale, Fair Value	9,245	8,854
Equity Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Investment Available for Sale, Cost Amount	2,764	2,615
Investment Available for Sale, Gross Unrealized Gains	97	164
Investment Available for Sale, Gross Unrealized Losses	0	0
Investment Available for Sale, Fair Value	2,861	2,779
Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Investment Available for Sale, Cost Amount	71,598	71,280
Investment Available for Sale, Gross Unrealized Gains	1,800	410
Investment Available for Sale, Gross Unrealized Losses	0	0
Investment Available for Sale, Fair Value	$73,398	$71,690

Lines_of_Credit_Details

Lines of Credit (Details) (Line of Credit [Member])	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 09, 2014
	2012 Credit Facility [Member]	2012 Credit Facility [Member]	Canadian Subsidiary [Member]	Canadian Subsidiary [Member]
	USD ($)	London Interbank Offered Rate (LIBOR) [Member]		CAD
Line of Credit Facility [Line Items]	'	'	'	'
Debt Instrument, Term	'5 years	'	'	'
Credit facility maximum borrowing capacity	$300,000	'	'	2,000
Credit facility expiration date	2-Feb-17	'	9-Jun-14	'
Credit facility variable interest rate basis spread	'	1.25%	'	'
Credit facility commitment fee per annum on daily unused portion	0.15%	'	'	'
Aggregate amount that may increase under credit facility	$100,000	'	'	'

Shareholders_Equity_Narrative_

Shareholders' Equity (Narrative) (Details) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended			3 Months Ended		0 Months Ended
In Thousands, except Share data, unless otherwise specified	21-May-14	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jul. 22, 2014
						Common Stock Buyback [Member]	2007 Plan [Member]	2007 Plan [Member]	Subsequent Event [Member]
							Tranche One [Member]	Tranche Two [Member]	Common Stock Buyback [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'
Vesting rate	'	'	'	'	'	'	50.00%	50.00%	'
Unrecognized compensation cost	'	$33,865	'	$33,865	'	'	'	'	'
Total intrinsic value of options exercised	'	'	'	50,471	'	'	'	'	'
Aggregate intrinsic value of options exercisable	'	158,021	'	158,021	'	'	'	'	'
Share Price	'	$32.77	'	$32.77	'	'	'	'	'
Weighted average exercise price per share	'	$19.57	'	$19.57	'	'	'	'	'
Total options that were outstanding	'	20,994,000	'	20,994,000	'	'	'	'	'
Total options that were exercisable	'	11,974,000	'	11,974,000	'	'	'	'	'
Shares purchased and retired	'	'	'	'	'	4,261,000	'	'	'
Company purchased, cost	'	'	'	'	'	140,568	'	'	'
Remaining stock repurchase authorization amount	'	'	'	'	'	'	'	'	140,502
Dividends declared per common share	$0.22	$0.22	$0.20	$0.22	$0.20	'	'	'	'
Cash dividends declared on the Company's common stock	'	'	'	$36,942	$34,400	'	'	'	'

Shareholders_Equity_StockBased

Shareholders' Equity (Stock-Based Compensation Expense) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Stockholders' Equity Note [Abstract]	'	'	'	'
Stock-based compensation expense	$2,872	$10,607	$5,695	$15,900
Less: Deferred tax benefit	-939	-3,867	-1,950	-5,783
Stock-based compensation expense, net of tax	$1,933	$6,740	$3,745	$10,117

Accumulated_Comprehensive_Inco2

Accumulated Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income (Loss), Net Of Tax) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Accumulated other comprehensive income, Unrealized Holding Gains on Investments	$2,308	'	$2,308	'	$1,386
Accumulated Other Comprehensive Income	3,821	'	3,821	'	1,487
Other Comprehensive Income, Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	'	'	1,412	'	'
Other Comprehensive Income, Available-for-sale Securities Adjustment, before Reclassification Adjustments, Net of Tax	'	'	991	'	'
Other Comprehensive Income before Reclassification, Net of Tax	'	'	2,403	'	'
Other Comprehensive Income, Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	'	'	0	'	'
Other Comprehensive Income, Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	24	121	69	342	'
Other Comprehensive Income, Reclassification Adjustment, Net of Tax	'	'	69	'	'
Total comprehensive income, Foreign Currency Translation Adjustments	3,378	-1,800	1,412	-7,107	'
Total comprehensive income, Unrealized Holding Gains (Losses) on Investments	'	'	922	'	'
Total other comprehensive income (loss), net of tax	3,807	-3,282	2,334	-8,689	'
SEI Investments Company [Member]	'	'	'	'	'
Accumulated other comprehensive income, Foreign Currency Translation Adjustments	1,513	'	1,513	'	101
Accumulated other comprehensive income, Unrealized Holding Gains on Investments	2,308	'	2,308	'	1,386
Accumulated Other Comprehensive Income	$3,821	'	$3,821	'	$1,487

Business_Segment_Information_S

Business Segment Information (Schedule Of Financial Information About Business Segments) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Revenues	$318,815	$274,574	$621,201	$546,453
Expenses	213,561	204,078	425,856	402,410
Operating profit (loss)	105,254	70,496	195,345	144,043
Gain on sale of subsidiary	'	'	5,582	22,112
Total profit (loss)	'	'	200,927	166,155
Private Banks [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenues	114,182	95,142	219,361	193,888
Expenses	98,957	97,755	199,147	194,053
Operating profit (loss)	15,225	-2,613	20,214	-165
Gain on sale of subsidiary	'	'	5,582	22,112
Total profit (loss)	'	'	25,796	21,947
Investment Advisors [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenues	70,046	59,284	136,470	114,475
Expenses	35,679	32,898	70,256	64,523
Operating profit (loss)	34,367	26,386	66,214	49,952
Gain on sale of subsidiary	'	'	0	0
Total profit (loss)	'	'	66,214	49,952
Institutional Investors [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenues	70,994	63,684	139,651	126,846
Expenses	35,025	33,028	69,120	64,537
Operating profit (loss)	35,969	30,656	70,531	62,309
Gain on sale of subsidiary	'	'	0	0
Total profit (loss)	'	'	70,531	62,309
Investment Managers [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenues	62,451	55,456	123,459	109,276
Expenses	39,449	36,507	78,633	71,669
Operating profit (loss)	23,002	18,949	44,826	37,607
Gain on sale of subsidiary	'	'	0	0
Total profit (loss)	'	'	44,826	37,607
Investments In New Businesses [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenues	1,142	1,008	2,260	1,968
Expenses	4,451	3,890	8,700	7,628
Operating profit (loss)	-3,309	-2,882	-6,440	-5,660
Gain on sale of subsidiary	'	'	0	0
Total profit (loss)	'	'	($6,440)	($5,660)

Business_Segment_Information_R

Business Segment Information (Reconciliation Of Total Operating Profit Reported For Business Segments To Income From Operations In Consolidated Statements Of Operations) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Total operating profit from segments above	$105,254	$70,496	$195,345	$144,043
Noncontrolling interest reflected in segments	0	0	0	350
Income from operations	93,630	57,973	172,022	118,015
Operating Segments [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total operating profit from segments above	105,254	70,496	195,345	144,043
Corporate, Non-Segment [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Corporate overhead expenses	-11,624	-12,523	-23,323	-26,317
Segment Reconciling Items [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Noncontrolling interest reflected in segments	'	'	$0	$289

Business_Segment_Information_S1

Business Segment Information (Schedule Of Additional Information Pertaining To Business Segments) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Capital Expenditures	$19,859	$17,958	$36,894	$25,750
Depreciation	5,331	5,730	10,915	11,434
Amortization	9,584	8,427	18,798	16,669
Private Banks [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Capital Expenditures	9,510	11,852	18,308	16,703
Depreciation	3,557	3,947	7,289	7,880
Amortization	6,192	5,457	12,143	10,793
Investment Advisors [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Capital Expenditures	4,061	4,192	7,650	5,967
Depreciation	512	517	1,003	1,026
Amortization	2,286	2,001	4,484	3,958
Institutional Investors [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Capital Expenditures	1,642	781	2,930	1,144
Depreciation	209	222	419	452
Amortization	355	309	695	611
Investment Managers [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Capital Expenditures	3,087	852	5,222	1,475
Depreciation	512	474	1,024	936
Amortization	236	206	464	408
Investments In New Businesses [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Capital Expenditures	616	187	1,196	275
Depreciation	420	454	950	908
Amortization	458	397	898	785
Total From Business Segments [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Capital Expenditures	18,916	17,864	35,306	25,564
Depreciation	5,210	5,614	10,685	11,202
Amortization	9,527	8,370	18,684	16,555
Corporate Overhead [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Capital Expenditures	943	94	1,588	186
Depreciation	121	116	230	232
Amortization	$57	$57	$114	$114

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Income Tax Contingency [Line Items]	'	'	'	'	'
Gross liability for unrecognized tax benefits, exclusive of interest and penalties	$13,019	'	$13,019	'	$12,028
Unrecognized tax benefits that would affect effective tax rate	11,119	'	11,119	'	10,139
Interest and penalties on unrecognized benefits	919	'	919	'	754
Effective tax rates	35.70%	35.50%	35.80%	35.20%	'
Settlement and Lapse of Statute [Member]	'	'	'	'	'
Income Tax Contingency [Line Items]	'	'	'	'	'
Unrecognized tax benefits within the next twelve months	$4,218	'	$4,218	'	'

Income_Taxes_Interest_And_Pena

Income Taxes (Interest And Penalties) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Income Tax Contingency [Line Items]	'	'
Gross liability for unrecognized tax benefits, exclusive of interest and penalties	$13,019	$12,028
Interest and penalties on unrecognized benefits	919	754
Gross uncertain tax positions	13,938	12,782
Amount included in Current liabilities	4,218	4,175
Amount included in Other long-term liabilities	$9,720	$8,607

Sale_of_SEI_Asset_Korea_Narrat

Sale of SEI Asset Korea (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Mar. 28, 2013
					SEI Asset Korea Co., Ltd. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'
Gain on sale of subsidiary	$0	$0	$5,582	$22,112	'
Gain on sale of subsidiary, diluted earnings per share impact, net	'	'	$0.02	$0.08	'
Contingent purchase price from sale of SEI AK	'	'	'	'	11,220
Revenues and Net Income Included on Company's Consolidated Statement of Operations	'	'	'	'	'
Revenues	'	'	'	'	2,889
Net income	'	'	'	'	796
Less: Income attributable to the noncontrolling interests	'	'	'	'	350
Net income attributable to SEI AK	'	'	'	'	$446

Settlement_Agreement_Details

Settlement Agreement (Details) (Positive Outcome of Litigation [Member], Other Income [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013
Positive Outcome of Litigation [Member] | Other Income [Member]	'
Gain Contingencies [Line Items]	'
Cash settlement payment	$43,429