Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating revenues	$ 492,022	$ 492,887
Operating expenses:
Salaries, wages and benefits	134,713	133,105
Fuel	91,075	96,793
Supplies and maintenance	45,854	43,128
Taxes and licenses	20,832	21,624
Insurance and claims	20,206	19,801
Depreciation	43,123	42,331
Rent and purchased transportation	111,646	106,318
Communications and utilities	3,499	3,142
Other	(2,367)	(2,048)
Total operating expenses	468,581	464,194
Operating income	23,441	28,693
Other expense (income):
Interest expense	94	144
Interest income	(655)	(505)
Other	4	(10)
Total other income	(557)	(371)
Income before income taxes	23,998	29,064
Income taxes	9,659	11,553
Net income	$ 14,339	$ 17,511
Earnings per share:
Basic	$ 0.20	$ 0.24
Diluted	$ 0.20	$ 0.24
Dividends declared per share	$ 0.050	$ 0.050
Weighted-average common shares outstanding:
Basic	72,676	73,260
Diluted	73,169	73,782