Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Operating revenues	$ 506,504	$ 509,587	$ 1,526,692	$ 1,494,913
Operating expenses:
Salaries, wages and benefits	134,923	132,128	407,283	400,256
Fuel	98,805	103,777	301,064	312,210
Supplies and maintenance	44,589	44,334	131,167	128,608
Taxes and licenses	22,251	23,932	67,750	70,372
Insurance and claims	14,469	15,603	48,796	50,194
Depreciation	41,901	40,197	124,078	119,161
Rent and purchased transportation	107,495	100,081	316,501	287,183
Communications and utilities	3,382	3,846	10,545	11,612
Other	(3,116)	(4,377)	(8,812)	(8,958)
Total operating expenses	464,699	459,521	1,398,372	1,370,638
Operating income	41,805	50,066	128,320	124,275
Other expense (income):
Interest expense	18	5	225	43
Interest income	(461)	(337)	(1,316)	(1,027)
Other	16	52	(90)	341
Total other income	(427)	(280)	(1,181)	(643)
Income before income taxes	42,232	50,346	129,501	124,918
Income taxes	17,104	20,768	52,448	51,529
Net income	$ 25,128	$ 29,578	$ 77,053	$ 73,389
Earnings per share:
Basic	$ 0.34	$ 0.41	$ 1.06	$ 1.01
Diluted	$ 0.34	$ 0.40	$ 1.05	$ 1.00
Dividends declared per share	$ 0.050	$ 0.050	$ 0.150	$ 0.150
Weighted-average common shares outstanding:
Basic	72,879	72,811	72,864	72,770
Diluted	73,445	73,231	73,414	73,203