Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue
Operating revenue	$ 135,381	$ 107,358	$ 260,394	$ 209,028
Operating expenses
Salaries, wages and employee benefits	31,645	29,221	63,882	59,860
Fuel and fuel taxes	13,984	10,479	27,463	21,253
Depreciation and amortization	7,477	6,879	14,657	14,523
Insurance and claims	5,341	5,561	10,943	13,893
Equipment rent	2,151	2,633	4,869	4,747
Operations and maintenance	8,913	7,950	16,874	14,521
Purchased transportation	55,817	41,005	104,855	78,408
Operating taxes and licenses	1,262	1,024	1,764	1,974
Communications and utilities	677	598	1,390	1,264
Gain on disposal of assets, net	(395)	(77)	(564)	(337)
Restructuring, impairment and other costs (reversal)			(639)
Other	4,198	5,051	8,197	8,287
Total operating expenses	131,070	110,324	253,691	218,393
Operating income (loss)	4,311	(2,966)	6,703	(9,365)
Other expenses
Interest expense, net	833	950	1,651	1,953
Other, net	113	128	233	226
Total other expenses, net	946	1,078	1,884	2,179
Income (loss) before income taxes	3,365	(4,044)	4,819	(11,544)
Income tax expense (benefit)	821	(1,198)	1,240	(3,808)
Consolidated net income (loss) and comprehensive income (loss)	$ 2,544	$ (2,846)	$ 3,579	$ (7,736)
Net earnings (loss) per share
Average shares outstanding (basic) (in shares)	8,205	8,028	8,141	8,028
Basic earnings (loss) per share (in dollars per share)	$ 0.31	$ (0.35)	$ 0.44	$ (0.96)
Average shares outstanding (diluted) (in shares)	8,227	8,028	8,167	8,028
Diluted earnings (loss) per share (in dollars per share)	$ 0.31	$ (0.35)	$ 0.44	$ (0.96)