Intangible Assets - Schedule of Goodwill, Customer Relationships and Trademarks (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 120,343	$ 120,343
Total	45,674
Customer relationships—Acquired
Finite-Lived Intangible Assets [Line Items]
Cost	84,248	99,402
Accumulated amortization	(55,336)	(63,208)
Total	28,912	36,194
Customer relationships—Other
Finite-Lived Intangible Assets [Line Items]
Cost	17,885	16,155
Accumulated amortization	(7,520)	(9,290)
Total	10,365	6,865
Trademarks
Finite-Lived Intangible Assets [Line Items]
Cost	9,770	9,770
Accumulated amortization	(3,373)	(2,483)
Total	$ 6,397	$ 7,287