Goodwill and Identifiable Intangible Assets, Net - IdentifiableIntangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Identifiable Intangible Assets, Net
Gross Book Value	$ 95,360	$ 85,819
Accumulated Amortization	(52,925)	(44,740)
Amortization of identifiable intangible assets	8,185	7,481	$ 7,653
Future amortization expense of identifiable intangible assets
2017	5,702
2018	4,861
2019	4,246
2020	3,751
2021	3,300
Thereafter	20,575
Total	42,435
Customer relationships
Identifiable Intangible Assets, Net
Gross Book Value	57,230	53,334
Accumulated Amortization	$ (36,758)	(31,960)
Customer relationships | Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	1 year
Customer relationships | Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	15 years
Backlog
Identifiable Intangible Assets, Net
Gross Book Value	$ 3,600	1,600
Accumulated Amortization	$ (3,433)	(1,412)
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	$ (2,890)	(2,890)
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	$ 31,640	27,995
Accumulated Amortization	$ (9,844)	$ (8,478)
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