Consolidated Statements of Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating Revenue	$ 134,273	$ 134,833
Operating Expenses
Salaries, wages, and benefits	40,598	41,996
Rent and purchased transportation	1,298	1,662
Fuel	42,978	42,705
Operations and maintenance	5,441	5,652
Operating taxes and licenses	2,416	2,075
Insurance and claims	2,860	2,514
Communications and utilities	774	747
Depreciation	15,066	13,939
Other operating expenses	3,813	3,979
Gain on disposal of property and equipment	(11,178)	(4,214)
Total operating expenses	104,066	111,055
Operating income	30,207	23,778
Interest income	123	142
Income before income taxes	30,330	23,920
Federal and state income taxes	10,596	7,332
Net income	19,734	16,588
Other comprehensive income, net of tax	0	0
Comprehensive income	$ 19,734	$ 16,588
Net income per share
Basic	$ 0.23	$ 0.19
Diluted	$ 0.23	$ 0.19
Weighted average shares outstanding
Basic	84,770	86,475
Diluted	85,046	86,826
Dividends declared per share	$ 0.02	$ 0.02