Summary of Significant Accounting Policies (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Other Intangible Assets
Gross Carrying Amount	$ 129,075	$ 74,604
Accumulated Amortization	(36,672)	(27,618)
Net Carrying Amount	92,403	46,986
Non-contractual customer relationships [Member]
Other Intangible Assets
Gross Carrying Amount	82,891	48,686
Accumulated Amortization	(21,147)	(14,188)
Net Carrying Amount	61,744	34,498
Covenants not-to-compete [Member]
Other Intangible Assets
Gross Carrying Amount	13,035	14,459
Accumulated Amortization	(8,067)	(8,311)
Net Carrying Amount	4,968	6,148
Favorable lease asset [Member]
Other Intangible Assets
Gross Carrying Amount	5,571	5,486
Accumulated Amortization	(3,210)	(2,672)
Net Carrying Amount	2,361	2,814
Technology [Member]
Other Intangible Assets
Gross Carrying Amount	16,589	2,189
Accumulated Amortization	(2,342)	(1,447)
Net Carrying Amount	14,247	742
Trademarks [Member]
Other Intangible Assets
Gross Carrying Amount	7,405	3,749
Accumulated Amortization	(1,686)	(986)
Net Carrying Amount	5,719	2,763
Contracts [Member]
Other Intangible Assets
Gross Carrying Amount	3,500
Accumulated Amortization	(185)
Net Carrying Amount	3,315
Client lists [Member]
Other Intangible Assets
Gross Carrying Amount	84	35
Accumulated Amortization	(35)	(14)
Net Carrying Amount	$ 49	$ 21