Consolidated Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenue Equipment [Member]
Operating expenses (income):
Gain on disposition of assets	$ (1,434)	$ (1,161)
Facility [Member]
Operating expenses (income):
Gain on disposition of assets		(3,712)
Operating revenue	$ 161,929	161,287
Salaries, wages and benefits	54,830	48,808
Purchased transportation	28,035	29,504
Fuel and fuel taxes	19,630	26,476
Supplies and maintenance	10,499	10,442
Depreciation	20,047	17,827
Operating taxes and licenses	2,185	1,876
Insurance and claims	7,355	8,090
Communications and utilities	$ 1,620	1,528
Gain on disposition of assets		(3,712)
Other	$ 5,037	4,298
Total operating expenses	147,804	143,976
Operating income	14,125	17,311
Other	215	15
Income before income taxes	13,910	17,296
Provision for income taxes	5,717	7,108
Net income	$ 8,193	$ 10,188
Basic earnings per common share (in dollars per share)	$ 0.25	$ 0.30
Diluted earnings per common share (in dollars per share)	0.25	0.30
Dividends declared per common share (in dollars per share)	$ 0.025	$ 0.025