Property and Equipment, Net (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 645,563,000		$ 645,563,000		$ 622,998,000
Less: accumulated depreciation	(463,834,000)		(463,834,000)		(436,381,000)
Property and equipment, net	181,729,000		181,729,000		186,617,000
Depreciation and amortization	18,600,000	17,400,000	37,500,000	33,400,000
Land [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,000,000		4,000,000		4,000,000
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10,780,000		10,780,000		10,780,000
Furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	91,478,000		91,478,000		89,870,000
Capitalized software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	492,473,000		492,473,000		470,469,000
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 46,832,000		$ 46,832,000		$ 47,879,000