Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Operating revenues	$ 495,654	$ 492,022
Operating expenses:
Salaries, wages and benefits	151,465	134,713
Fuel	52,760	91,075
Supplies and maintenance	47,657	45,854
Taxes and licenses	21,080	20,832
Insurance and claims	22,047	20,206
Depreciation	45,720	43,123
Rent and purchased transportation	113,748	111,646
Communications and utilities	3,678	3,499
Other	(686)	(2,367)
Total operating expenses	457,469	468,581
Operating income	38,185	23,441
Other expense (income):
Interest expense	475	94
Interest income	(631)	(655)
Other	90	4
Total other income	(66)	(557)
Income before income taxes	38,251	23,998
Income taxes	15,109	9,659
Net income	$ 23,142	$ 14,339
Earnings per share:
Basic	$ 0.32	$ 0.20
Diluted	$ 0.32	$ 0.20
Dividends declared per share	$ 0.050	$ 0.050
Weighted-average common shares outstanding:
Basic	72,067	72,676
Diluted	72,542	73,169