Intangible Assets and Goodwill - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 40,200	$ 40,200
Accumulated Amortization	(18,277)	(13,989)
Net Carrying Value	21,923	26,211
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	39,500	39,500
Accumulated Amortization	(17,577)	(13,329)
Net Carrying Value	21,923	26,171
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	400	400
Accumulated Amortization	(400)	(360)
Net Carrying Value	0	40
Brand name
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	300	300
Accumulated Amortization	(300)	(300)
Net Carrying Value	$ 0	$ 0