Intangible Assets (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Intangible assets
Intangible assets, gross	$ 140,587,000		$ 140,587,000		$ 169,438,000
Less accumulated amortization	(40,085,000)		(40,085,000)		(50,319,000)
Intangible assets, net	100,502,000		100,502,000		119,119,000
Amortization of intangibles
Remainder of 2013	5,190,000		5,190,000
2014	20,733,000		20,733,000
2015	20,270,000		20,270,000
2016	19,934,000		19,934,000
2017	16,613,000		16,613,000
Thereafter	17,762,000		17,762,000
Amortization expense related to intangible assets
Amortization expense	5,900,000	6,100,000	18,600,000	18,300,000
Client relationships
Intangible assets
Intangible assets, gross	102,755,000		102,755,000		130,105,000
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	19,532,000		19,532,000		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	$ 18,300,000		$ 18,300,000		$ 19,600,000
Restrictive covenant | Minimum
Intangible assets
Useful Life			2 years
Restrictive covenant | Maximum
Intangible assets
Useful Life			5 years