Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Consolidated Statements Of Operations [Abstract]
Operating revenue	$ 826,885	$ 758,889
Operating expenses:
Salaries, wages and employee benefits	200,135	195,476
Operating supplies and expenses	55,042	57,104
Fuel	153,003	150,281
Purchased transportation	233,202	194,037
Rental expense	23,499	17,989
Insurance and claims	30,580	22,725
Depreciation and amortization of property and equipment	50,394	50,358
Amortization of intangibles	4,303	4,727
Impairments	1,065
Gain on disposal of property and equipment	(4,390)	(2,255)
Communication and utilities	6,246	6,460
Operating taxes and licenses	15,904	15,258
Total operating expenses	768,983	712,160
Operating income	57,902	46,729
Other (income) expenses:
Interest expense	32,776	37,501
Derivative interest expense	2,545	4,680
Interest income	(397)	(467)
Loss on debt extinguishment	20,940
Other	(602)	(511)
Total other (income) expenses, net	55,262	41,203
Income before income taxes	2,640	5,526
Income tax (benefit) expense	(3,548)	2,321
Net income	$ 6,188	$ 3,205
Basic earnings per share	$ 0.04	$ 0.02
Diluted earnings per share	$ 0.04	$ 0.02
Shares used in per share calculations
Basic	139,509	138,127
Diluted	140,392	138,900