Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	$ 95,212	$ 90,038
Accumulated Amortization	(45,391)	(38,972)
Net Carrying Amounts	49,821	51,066
Customer relationships
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	80,176	75,407
Accumulated Amortization	(37,781)	(32,307)
Net Carrying Amounts	42,395	43,100
Non-compete agreements
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	1,626	1,556
Accumulated Amortization	(789)	(707)
Net Carrying Amounts	837	849
Customer backlog
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	1,400	1,650
Accumulated Amortization	(443)	(866)
Net Carrying Amounts	957	784
Trade name
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	110	100
Accumulated Amortization	(43)	(53)
Net Carrying Amounts	67	47
Internally developed software
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amounts	11,900	11,325
Accumulated Amortization	(6,335)	(5,039)
Net Carrying Amounts	$ 5,565	$ 6,286

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 928
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6473545&loc=d3e61844-108004

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
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- References

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- Definition

Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
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-Topic 350
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