Statements Of Consolidated Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Statements Of Consolidated Cash Flows [Abstract]
Cash and Cash Equivalents, Beginning of Year	$ 421,420	$ 476,575	$ 278,253
Operating Activities
Net income (loss)	88,443	3,985	(107,747)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization, net of accretion	201,638	189,517	185,428
Non-cash compensation and employee benefits	22,050	20,256	34,821
Increase in deferred income taxes	52,160	68,343	7,987
Provision for uncollectible accounts	6,761	7,319	8,007
Loss (Gain) from asset impairments and purchase-price adjustment	(10,000)	19,181	134,813
Loss from restructuring activities		4,990	3,360
Loss (Gain) from sales of property and equipment, net	(7,120)	1,243	7,922
Changes in assets and liabilities:
Receivables	(42,315)	(61,264)	9,154
Prepaid expenses	(1,024)	(4,542)	(808)
Accounts payable	41,313	31,891	2,008
Accrued variable compensation	22,439	8,268	4,576
Accrued liabilities, excluding accrued variable compensation and employee benefits	3,808	(20,492)	(41,810)
Self-insurance accruals	(11,951)	30,487	(2,417)
Accrued income taxes	34,362	(39,583)	21,163
Employee benefits	(52,713)	(67,629)	327
Deferred charges and credits	(952)	(3,572)	4,418
Other	(2,189)	(3,526)	5,450
Net Cash Provided by Operating Activities	344,710	184,872	276,652
Investing Activities
Capital expenditures	(288,994)	(186,496)	(68,207)
Software expenditures	(8,667)	(8,101)	(5,593)
Proceeds from sales of property and equipment	13,213	12,403	15,398
Proceeds from sale-leaseback transactions		20,430	17,310
Proceeds from purchase-price adjustment	10,000
Purchases of marketable securities	(13,480)	(59,260)	(164,077)
Proceeds from sales of marketable securities	900	59,960	164,491
Net Cash Used in Investing Activities	(287,028)	(161,064)	(40,678)
Financing Activities
Repayment of long-term debt, guarantees and capital leases	(19,811)	(211,124)	(22,400)
Net proceeds from (repayments of) short-term borrowings	(4,691)	7,912	2,832
Payment of debt issuance costs	(661)	(2,123)
Net proceeds from issuance of common stock		143,325
Proceeds from exercise of stock options	5,532	3,459	4,171
Excess tax benefit from share-based compensation	716	433	165
Payments of common dividends	(22,177)	(20,845)	(19,079)
Payments of preferred dividends			(3,507)
Net Cash Used in Financing Activities	(41,092)	(78,963)	(37,818)
Net Cash Provided by (Used in) Continuing Operations	16,590	(55,155)	198,156
Discontinued Operations
Net Cash Provided by Operating Activities			166
Increase (Decrease) in Cash and Cash Equivalents	16,590	(55,155)	198,322
Cash and Cash Equivalents, End of Year	438,010	421,420	476,575
Supplemental Disclosure
Cash paid (refunded) for income taxes, net	(28,740)	(10,354)	(10,164)
Cash paid for interest, net of amounts capitalized	54,676	62,869	69,313
Non-cash Investing and Financing Activities
Capital lease incurred to acquire revenue equipment		55,534	49,999
Revenue equipment acquired through partial non-monetary exchanges	33,463
Repurchased common stock issued under defined contribution plan	17,307	36,763	23,316
Repurchased common stock issued for payment of preferred dividends			$ 3,189