Transactions with Affiliates - Schedule of Amounts Charged to UTSI (Detail) - Affiliates [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	$ 67,249	$ 66,073	$ 51,254
Administrative support services [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	2,638	3,234	2,459
Truck fuel, tolls and maintenance [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	2,656	2,523	1,320
Real estate rent and related costs [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	17,174	13,174	10,472
Insurance and employee benefit plans [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	44,548	46,173	36,073
Contracted transportation services [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	$ 233	$ 969	$ 930