Goodwill and Intangible Assets, Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	$ 90,399	$ 90,038
Accumulated Amortization	(41,404)	(38,972)
Net Carrying Amounts	48,995	51,066
Customer relationships
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	76,666	75,407
Accumulated Amortization	(34,693)	(32,307)
Net Carrying Amounts	41,973	43,100
Non-compete agreements
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	1,606	1,556
Accumulated Amortization	(705)	(707)
Net Carrying Amounts	901	849
Customer backlog
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	680	1,650
Accumulated Amortization	(170)	(866)
Net Carrying Amounts	510	784
Trade name
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	70	100
Accumulated Amortization	(18)	(53)
Net Carrying Amounts	52	47
Internally developed software
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	11,377	11,325
Accumulated Amortization	(5,818)	(5,039)
Net Carrying Amounts	$ 5,559	$ 6,286