Income Taxes (Tax Effect Of Significant Temporary Differences Representing Deferred Tax Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred Tax Liabilities, Net [Abstract]
Difference in financial reporting and income tax depreciation methods	$ (10,104)	$ (13,600)
Reserves not currently deductible	325	374
Capitalized software currently deductible for tax purposes, net of amortization	(137,467)	(139,455)
State deferred income taxes	5,943	6,717
Revenue and expense recognized in different periods for financial reporting and income tax purpose	4,397	3,149
Unrealized holding loss (gain) on investments	(1,428)	(927)
Stock-based compensation expense	42,133	43,879
State net operating loss carryforward	13,883	14,485
Valuation allowance on deferred tax assets	(6,879)	(8,585)
Federal benefit of state tax deduction for uncertain tax positions	2,359	1,725
Foreign currency exchange	(39)	(363)
Foreign deferred including taxes on cumulative undistributed earnings of SEI AK	(4,569)	0
Net deferred income tax liability	$ (91,446)	$ (92,601)