Transactions with Affiliates - Schedule of Amounts Charged to UTSI (Detail) - Affiliates [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	$ 66,073	$ 51,254	$ 48,514
Administrative support services [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	3,774	2,459	2,367
Truck fueling and maintenance [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	1,983	1,320	1,774
Real estate rent and related costs [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	13,174	10,472	11,352
Insurance and employee benefit plans [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	46,173	36,073	32,710
Contracted transportation services [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	$ 969	$ 930	$ 311