Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
ASSETS
Cash and cash equivalents	$ 454,989	$ 438,010
Marketable securities	5,000	13,255
Trade accounts receivable, net	665,713	577,522
Other accounts receivable	52,087	43,849
Operating supplies, at lower of average cost or market	25,810	22,822
Prepaid expenses	47,773	48,369
Deferred income taxes	21,288	46,563
Total Current Assets	1,272,660	1,190,390
Property, Plant and Equipment
Land	189,737	194,078
Buildings and leasehold improvements	825,669	827,910
Revenue equipment	1,697,720	1,613,806
Other equipment	322,611	318,313
Total Property, Plant and Equipment	3,035,737	2,954,107
Accumulated depreciation	(1,500,166)	(1,458,074)
Net Property, Plant and Equipment	1,535,571	1,496,033
Other Assets
Deferred charges and other assets	35,826	36,743
Capitalized software, net	19,272	19,829
Marketable securities	5,185	5,354
Intangible assets, net	12,327	13,951
Goodwill	337,820	337,716
Total Noncurrent Assets	410,430	413,593
Total Assets	3,218,661	3,100,016
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable	402,875	345,489
Accrued liabilities	256,605	235,146
Self-insurance accruals	101,740	104,328
Short-term borrowings	14,215	14,481
Current maturities of long-term debt and capital leases	21,531	24,026
Total Current Liabilities	796,966	723,470
Long-Term Liabilities
Long-term debt	718,950	718,336
Long-term obligations under capital leases	44,190	51,902
Self-insurance accruals	150,530	158,889
Employee benefits	590,299	610,850
Other liabilities and deferred credits	37,032	39,120
Deferred income taxes	57,783	38,195
Total Liabilities	2,395,750	2,340,762
Commitments and Contingencies (Note 8)
Shareholders' Equity
Common stock, $0.625 par value; authorized 100,000,000 shares; issued 63,475,232 and 63,065,931 shares, respectively	39,645	39,394
Additional paid-in capital, common stock	606,861	595,992
Retained earnings	935,437	884,758
Cost of repurchased common stock (7,569,248 and 7,468,869 shares, respectively)	(325,695)	(322,454)
Accumulated other comprehensive loss	(433,337)	(438,436)
Total Shareholders' Equity	822,911	759,254
Total Liabilities and Shareholders' Equity	$ 3,218,661	$ 3,100,016