Income Taxes - Reconciliation of Income Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory income tax rate, as a percent	21.00%	21.00%	35.00%
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal income tax at statutory rate	$ (558)	$ 7,132	$ (7,437)
State income taxes, net of federal income tax benefit	1,633	1,319	(597)
Nondeductible per diem paid to drivers	1,173	1,182	2,476
Xpress Internacional activity	(71)	1,616	76
Tax credits	(1,341)	(1,611)	(970)
Provision to return adjustment	(138)	35	248
Valuation allowance	567	2,433	950
Foreign transition tax on deemed distribution		(30)	2,315
Global intangible low-taxed income (GILTI)		1,217
Tax Act impact of federal rate change			(14,723)
Basis difference on assets held for sale		(2,524)
Change in reserve for uncertain tax positions and settlements	(755)	(3,278)	146
Affirmative issue - imputed interest expense		1,223	(1,223)
Non-taxable life insurance death benefit		(1,004)
Expiration of federal capital loss carryforward		1,826
Excess tax benefits on share-based compensation	(459)	(651)
Deferred Mexican withholding tax		(876)	876
Other, net	338	(149)	676
Income Tax Expense (Benefit), Total	389	7,860	(17,187)
Adjustment to original provision for Tax Cut and Jobs Act		$ 200
Deferred tax liability, foreign undistributed earnings	$ 0		$ 900