Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible assets
Gross Carrying Amount		$ 84,250	$ 66,314
Accumulated Amorization		(39,450)	(33,473)
Amortization expense of intangible assets		8,689	6,597	$ 6,793
Estimated future amortization expense for intangible assets
2018		9,541
2019		9,193
2020		6,442
2021		5,203
2022		4,048
Thereafter		10,373
Total		$ 44,800	32,841
Tradename
Intangible assets
Amortization Period		9 years
Gross Carrying Amount		$ 32,175	30,485
Accumulated Amorization		$ (22,238)	(18,733)
Impairment of intangible asset	$ 500
Customer relationships
Intangible assets
Amortization Period		10 years
Gross Carrying Amount		$ 49,900	33,579
Accumulated Amorization		$ (16,338)	(13,439)
Non-compete agreements
Intangible assets
Amortization Period		5 years
Gross Carrying Amount		$ 1,900	2,250
Accumulated Amorization		$ (820)	$ (1,301)
Other
Intangible assets
Amortization Period		3 years
Gross Carrying Amount		$ 275
Accumulated Amorization		$ (54)