Significant Accounting Policies (Schedule of Property and Equipment) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Accounting Policies [Abstract]
Buildings	$ 72,100	$ 72,100
Computer equipment	152,795	158,947
Software	224,750	187,842
Equipment and furniture	64,493	39,722
Leasehold improvements	131,586	104,312
Property and equipment, gross	645,724	562,923
Less accumulated depreciation and amortization	(384,179)	(328,325)
Land	15,884	15,884
Property and equipment, net	$ 277,429	$ 250,482