Statements Of Consolidated Operations (USD $) In Thousands, except Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Statements Of Consolidated Operations [Abstract]
Revenues	$ 1,377,079	$ 1,270,183	$ 3,971,255	$ 3,738,357
Costs and Expenses
Salaries, wages and employee benefits	516,083	517,221	1,516,597	1,530,630
Purchased transportation	365,306	331,137	1,030,822	952,817
Fuel and fuel-related taxes	142,185	112,863	428,322	349,547
Other operating expenses	145,298	137,563	417,998	411,505
Depreciation and amortization	50,814	50,568	151,668	143,532
Maintenance	35,711	30,640	97,692	94,141
Rents and leases	30,423	29,622	86,944	88,673
Purchased labor	30,134	31,654	83,226	85,998
Loss from impairment of goodwill and other intangible assets		16,414		19,181
Total Costs and Expenses	1,315,954	1,257,682	3,813,269	3,676,024
Operating Income	61,125	12,501	157,986	62,333
Other Income (Expense)
Investment income	163	352	712	1,059
Interest expense	(13,909)	(13,818)	(41,751)	(44,906)
Miscellaneous, net	227	(568)	(2,536)	(2,622)
Total Other Income (Expense)	(13,519)	(14,034)	(43,575)	(46,469)
Income (Loss) before Income Tax Provision	47,606	(1,533)	114,411	15,864
Income Tax Provision	18,478	6,695	48,939	14,266
Net Income (Loss) Applicable to Common Shareholders	$ 29,128	$ (8,228)	$ 65,472	$ 1,598
Weighted-Average Common Shares Outstanding
Basic	55,535,074	54,286,677	55,331,170	51,780,610
Diluted	56,117,334	54,286,677	56,054,059	52,410,846
Basic
Net Income (Loss) Applicable to Common Shareholders	$ 0.52	$ (0.15)	$ 1.18	$ 0.03
Diluted
Net Income (Loss) Applicable to Common Shareholders	$ 0.52	$ (0.15)	$ 1.17	$ 0.03