Goodwill and Identifiable Intangible Assets, Net (Details 2) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Identifiable Intangible Assets, Net
Gross Book Value	73,504	68,501
Accumulated Amortization	(24,298)	(20,152)
Customer relationships
Identifiable Intangible Assets, Net
Gross Book Value	40,404	36,351
Accumulated Amortization	(12,715)	(9,880)
Customer relationships | Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	1 year	1 year
Customer relationships | Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	15 years	15 years
Backlog
Identifiable Intangible Assets, Net
Gross Book Value	6,515	5,890
Accumulated Amortization	(5,430)	(4,999)
Backlog | Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	1 year	1 year
Backlog | Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years	2 years
Noncompete agreements
Identifiable Intangible Assets, Net
Gross Book Value	2,890	2,890
Accumulated Amortization	(2,159)	(1,932)
Noncompete agreements | Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years	2 years
Noncompete agreements | Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	7 years	7 years
Tradenames
Identifiable Intangible Assets, Net
Gross Book Value	23,695	23,370
Accumulated Amortization	(3,994)	(3,341)
Tradenames | Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years	2 years
Tradenames | Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	25 years	25 years