Summary of Significant Accounting Policies (Details 5)	12 Months Ended
	Dec. 31, 2011 Y
Non-contractual customer relationships [Member]
Amortization of intangible assets estimated useful lives
Minimum	4
Maximum	25
Covenants not-to-compete [Member]
Amortization of intangible assets estimated useful lives
Minimum	3
Maximum	10
Favorable lease asset [Member]
Amortization of intangible assets estimated useful lives
Minimum	1
Maximum	14
Technology [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	5
Trademarks [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	10
Contracts [Member]
Amortization of intangible assets estimated useful lives
Minimum	6
Maximum	9
Client lists [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	3