Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues
Revenue	$ 413,862	$ 449,758	$ 829,225	$ 875,466
Operating expenses
Salaries, wages, and benefits	130,521	139,701	255,084	272,625
Fuel and fuel taxes	47,374	57,704	94,278	116,093
Vehicle rents	18,579	19,393	37,555	39,415
Depreciation and amortization, net of (gain) loss on sale of property	24,752	24,149	47,814	48,855
Operating expenses and supplies	29,968	29,073	57,913	58,864
Insurance premiums and claims	19,266	19,165	43,619	39,335
Operating taxes and licenses	3,406	3,509	6,579	6,910
Communications and utilities	2,185	2,425	4,450	4,891
General and other operating expenses	17,115	15,940	34,594	33,149
Gain on sale of subsidiary	(670)		(670)
Total operating expenses	405,075	429,740	807,800	840,594
Operating income	8,787	20,018	21,425	34,872
Other expense (income)
Interest expense, net	5,296	12,298	10,899	24,956
Early extinguishment of debt		7,753		7,753
Equity in loss of affiliated companies	90	(119)	179	177
Other, net		242	26	167
Other expense (income)	5,386	20,174	11,104	33,053
Income before income tax provision	3,401	(156)	10,321	1,819
Income tax provision	415	(1,191)	2,316	(598)
Net total and comprehensive income	2,986	1,035	8,005	2,417
Net total and comprehensive income attributable to noncontrolling interest	314	420	612	643
Net total and comprehensive income attributable to controlling interest	$ 2,672	$ 615	$ 7,393	$ 1,774
Earnings per share
Basic earnings per share (in dollars per share)	$ 0.05	$ 0.04	$ 0.15	$ 0.17
Basic weighted average shares outstanding (in shares)	48,742	14,214	48,569	10,321
Diluted earnings per share (in dollars per share)	$ 0.05	$ 0.04	$ 0.15	$ 0.17
Diluted weighted average shares outstanding (in shares)	49,312	14,456	49,184	10,443
Cargo and Freight [Member]
Revenues
Revenue	$ 371,184	$ 402,808	$ 746,496	$ 785,666
Fuel Surcharge [Member]
Revenues
Revenue	42,678	46,950	82,729	89,800
Shipping and Handling [Member]
Operating expenses
Purchased transportation	$ 112,579	$ 118,681	$ 226,584	$ 220,457