Transactions with Affiliates - Schedule of Amounts Charged to UTSI (Detail) - Affiliates [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	$ 87,257	$ 63,535	$ 69,889
Administrative support services [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	4,215	2,629	4,085
Truck fuel, maintenance and other operating costs [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	3,887	826	895
Real estate rent and related costs [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	12,384	12,925	11,794
Insurance [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	65,076	47,133	53,050
Contracted transportation services [Member]
Related Party Transaction [Line Items]
Cost incurred for services provided by CenTra and affiliates	$ 1,695	$ 22	$ 65