Note 4 - Income Taxes - Reconciliation of Income Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Federal income tax at statutory rate	$ 7,132	$ (7,437)	$ (8,714)
State income taxes, net of federal income tax benefit	1,319	(597)	(727)
Nondeductible per diem paid to drivers	1,182	2,476	2,556
Xpress Internacional activity	1,616	76	466
Tax credits	(1,611)	(970)	(1,005)
Provision to return adjustment	35	248	(1,659)
Valuation allowance	2,433	950	(22)
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	(3,278)	146	100
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	(651)
Deferred Mexican withholding tax	(876)	876
Other, net	(149)	676	557
Income tax provision (benefit)	$ 7,860	$ (17,187)	$ (8,448)