Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 452,247	$ 420,986
Restricted cash	6,000	6,000
Receivables from regulated investment companies	31,084	25,800
Receivables, net of allowance for doubtful accounts of $805 and $924 (Note 4)	171,734	142,109
Deferred income taxes, net	2,012	1,150
Securities owned	20,088	20,949
Other current assets	18,239	17,957
Total Current Assets	701,404	634,951
Property and Equipment, net of accumulated depreciation of $201,418 and $182,453 (Note 4)	127,581	129,548
Capitalized Software, net of accumulated amortization of $149,747 and $117,100	307,490	309,133
Investments Available for Sale (Note 6)	75,869	83,008
Trading Securities (Note 6)	5,909	56,325
Investment in Unconsolidated Affiliates (Note 2)	77,398	68,454
Other Assets, net	14,173	13,140
Total Assets	1,309,824	1,294,559
Current Liabilities:
Accounts payable	11,248	1,999
Accrued liabilities (Note 4)	138,305	147,044
Deferred revenue	2,452	2,030
Total Current Liabilities	152,005	151,073
Deferred Income Taxes	93,458	93,751
Other Long-term Liabilities (Note 12)	7,032	8,276
Total Liabilities	252,495	253,100
Commitments and Contingencies (Note 11)
SEI Investments shareholders' equity:
Series Preferred stock, $.05 par value, 50 shares authorized; no shares issued and outstanding	0	0
Common stock, $.01 par value, 750,000 shares authorized; 172,220 and 176,506 shares issued and outstanding	1,722	1,765
Capital in excess of par value	624,305	577,949
Retained earnings	405,914	443,702
Accumulated other comprehensive income, net	6,239	1,900
Total SEI Investments Shareholders’ Equity	1,038,180	1,025,316
Noncontrolling Interest	19,149	16,143
Total Equity	1,057,329	1,041,459
Total Liabilities and Equity	$ 1,309,824	$ 1,294,559