Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 288,474	$ 208,034	$ 206,650
Depreciation	22,497	22,586	21,471
Amortization	34,602	33,258	27,288
Equity in earnings of unconsolidated affiliates	(118,076)	(98,671)	(105,818)
Distributions received from unconsolidated affiliate	137,104	92,227	109,273
Stock-based compensation	37,865	15,736	14,112
Provision for losses on receivables	(154)	(119)	(271)
Deferred income tax expense	(22,825)	(1,191)	1,001
Gain from sale of SEI AK (See Note 15)	(22,112)	0	0
Net realized gains from investments	(659)	(14,067)	(3,360)
Change in other long-term liabilities	1,575	(1,244)	2,631
Change in other assets	600	(619)	315
Other	(3,972)	6,680	(3,148)
Decrease (increase) in Restricted cash for broker-dealer operations	500	0	0
Decrease (increase) in Receivables from regulated investment companies	(8,280)	(5,284)	3,482
Decrease (increase) in Receivables	(17,513)	(30,852)	(11,474)
Decrease (increase) in Other current assets	1,971	(282)	(1,689)
Increase (decrease) in Accounts payable	5,000	9,249	(2,583)
Increase (decrease) in Accrued liabilities	15,102	21,627	(1,340)
Increase (decrease) in Deferred revenue	(475)	422	422
Total adjustments	62,750	49,456	50,312
Net cash provided by operating activities	351,224	257,490	256,962
Cash flows from investing activities:
Additions to restricted cash	0	0	(2,000)
Additions to property and equipment	(16,351)	(23,070)	(12,271)
Additions to capitalized software	(39,500)	(31,004)	(40,954)
Purchases of marketable securities	(57,560)	(33,662)	(73,960)
Prepayments and maturities of marketable securities	40,257	53,352	61,582
Sales of marketable securities	7,317	54,830	38,247
Purchases of other investments	(2,604)	(3,819)	(7,500)
Sales of other investments	0	0	4,906
Sale of subsidiary, net of cash transferred (See Note 15)	6,028	0	0
Net cash (used in) provided by investing activities	(62,413)	16,627	(31,950)
Cash flows from financing activities:
Payments on long-term debt	0	0	(95,000)
Purchase and retirement of common stock	(206,577)	(157,543)	(208,932)
Proceeds from issuance of common stock	66,367	49,439	24,221
Tax benefit on stock options exercised	11,825	583	1,434
Payment of dividends	(34,400)	(135,335)	(22,041)
Net cash used in financing activities	(162,785)	(242,856)	(300,318)
Net increase (decrease) in cash and cash equivalents	126,026	31,261	(75,306)
Cash and cash equivalents, beginning of year	452,247	420,986	496,292
Cash and cash equivalents, end of year	578,273	452,247	420,986
Interest paid	458	367	559
Income taxes paid	163,834	113,160	116,483
Non-cash financing activities
Dividends declared but not paid	$ 37,314	$ 0	$ 26,518