Goodwill and Intangible Assets - Schedule of Finite-Lived Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 41,580	$ 41,580
Accumulated amortization of intangible assets	(11,668)	(7,212)
Amortized intangible assets, Net	29,912	34,368
Railcar Leases
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	3,249	3,249
Accumulated amortization of intangible assets	(2,599)	(1,950)
Amortized intangible assets, Net	650	1,299
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	6,267	6,267
Accumulated amortization of intangible assets	(4,864)	(3,540)
Amortized intangible assets, Net	1,403	2,727
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	32,064	32,064
Accumulated amortization of intangible assets	(4,205)	(1,722)
Amortized intangible assets, Net	$ 27,859	$ 30,342