Intangible Assets (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Intangible assets
Intangible assets, gross	$ 160,238,000		$ 160,238,000
Less accumulated amortization	(56,256,000)		(50,319,000)
Total	103,982,000		109,919,000
Amortization of intangibles
Remainder of 2013	16,330,000
2014	19,325,000
2015	18,998,000
2016	18,662,000
2017	15,342,000
Thereafter	15,325,000
Amortization expense related to intangible assets
Amortization expense	5,900,000	6,100,000
Goodwill	370,774,000		370,774,000
Client relationships
Intangible assets
Intangible assets, gross	121,205,000		121,205,000
Client relationships | Minimum
Intangible assets
Useful Life	5 years
Client relationships | Maximum
Intangible assets
Useful Life	10 years
Trade name
Intangible assets
Intangible assets, gross	19,733,000		19,733,000
Trade name | Minimum
Intangible assets
Useful Life	3 years
Trade name | Maximum
Intangible assets
Useful Life	7 years
Restrictive covenant
Intangible assets
Intangible assets, gross	$ 19,300,000		$ 19,300,000
Restrictive covenant | Minimum
Intangible assets
Useful Life	3 years
Restrictive covenant | Maximum
Intangible assets
Useful Life	5 years