CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
OPERATING ACTIVITIES
Net income	$ 80,755	$ 65,524
Adjustments to reconcile net income to net cash provided by (used for) operating activities:
Depreciation, amortization and other non-cash charges	51,605	39,249
Stock-based compensation expense	1,901	2,215
Loss (gain) on disposition of assets, net	1,404	(1,411)
Deferred income tax benefit	(11,290)	(2,210)
Excess tax benefits for share-based payments	(2,067)	(2,278)
(Increase) decrease in assets:
Accounts receivable	35,600	(62,909)
Income taxes receivable	12,311	18,793
Inventories	(11,291)	(7,218)
Prepaid expenses	1,153	1,090
Other current assets	578	(1,993)
Other non-current assets	(4,197)	(157)
Increase (decrease) in liabilities:
Accounts payable	12,583	15,438
Income taxes payable	24,698	20,509
Accrued payroll and related expenses	(6,929)	(882)
Accrued insurance expenses	394	783
Accrued state, local and other taxes	635	1,671
Other accrued expenses	(908)	(69)
Pension liabilities	(2,027)	417
Accrued insurance expenses	254	(193)
Other non-current liabilities	(1,542)	(737)
Net cash provided by operating activities	183,620	85,632
INVESTING ACTIVITIES
Capital expenditures	(121,408)	(92,318)
Proceeds from sale of assets	3,680	6,030
Net cash used for investing activities	(117,728)	(86,288)
FINANCING ACTIVITIES
Payment of dividends	(17,571)	(10,354)
Borrowings from notes payable to banks	282,100	190,300
Repayments of notes payable to banks	(304,600)	(161,750)
Excess tax benefits for share-based payments	2,067	2,278
Cash paid for common stock purchased and retired	(29,675)	(17,499)
Proceeds received upon exercise of stock options	128	324
Net cash (used for) provided by financing activities	(67,551)	3,299
Net (decrease) increase in cash and cash equivalents	(1,659)	2,643
Cash and cash equivalents at beginning of period	7,393	9,035
Cash and cash equivalents at end of period	5,734	11,678
Supplemental Information:
Interest paid, net	678	1,200
Income taxes paid, net	24,879	2,826
Change in accounts payable for capital expenditures	$ (3,190)	$ 3,519