Goodwill and Identifiable Intangible Assets, Net (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Identifiable Intangible Assets, Net
Gross Book Value	$ 73,504	$ 68,501
Accumulated Amortization	(28,989)	(20,152)
Amortization expense	8,837	7,462	6,217
Future amortization expense of identifiable intangible assets
2013	7,120
2014	6,106
2015	4,873
2016	3,748
2017	2,997
Thereafter	19,671
Total	44,515
Customer relationships
Identifiable Intangible Assets, Net
Gross Book Value	40,404	36,351
Accumulated Amortization	(15,579)	(9,880)
Customer relationships | Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years
Customer relationships | Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	15 years
Backlog
Identifiable Intangible Assets, Net
Gross Book Value	6,515	5,890
Accumulated Amortization	(6,375)	(4,999)
Backlog | Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	1 year
Backlog | Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years
Noncompete agreements
Identifiable Intangible Assets, Net
Gross Book Value	2,890	2,890
Accumulated Amortization	(2,380)	(1,932)
Noncompete agreements | Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years
Noncompete agreements | Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	7 years
Tradenames
Identifiable Intangible Assets, Net
Gross Book Value	23,695	23,370
Accumulated Amortization	$ (4,655)	$ (3,341)
Tradenames | Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years
Tradenames | Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	25 years