Consolidated Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating revenue	$ 173,159	$ 161,929
Operating expenses (income):
Salaries, wages and benefits	56,400	54,830
Purchased transportation	29,362	28,035
Fuel and fuel taxes	25,956	19,630
Supplies and maintenance	10,990	10,499
Depreciation	21,383	20,047
Operating taxes and licenses	2,247	2,185
Insurance and claims	8,914	7,355
Communications and utilities	1,581	1,620
Other	3,491	5,037
Total operating expenses	159,221	147,804
Operating income	13,938	14,125
Other	141	215
Income before income taxes	13,797	13,910
Provision for income taxes	5,583	5,717
Net income	$ 8,214	$ 8,193
Basic earnings per common share (in dollars per share)	$ 0.25	$ 0.25
Diluted earnings per common share (in dollars per share)	0.25	0.25
Dividends declared per common share (in dollars per share)	$ 0.025	$ 0.025
Revenue Equipment [Member]
Operating expenses (income):
Gain on disposition of assets	$ (1,103)	$ (1,434)