Other Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	$ 78,146	$ 76,177
Less accumulated amortization	(50,583)	(44,639)
Intangible assets, net	27,563	31,538
Customer lists
Acquired Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	$ 74,615	72,667
Weighted Average Life	13 years 7 months
Non-competition agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	$ 964	943
Weighted Average Life	4 years 1 month
Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	$ 2,510	2,510
Weighted Average Life	13 years 4 months
Patents
Acquired Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	$ 57	$ 57
Weighted Average Life	9 years