CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
OPERATING ACTIVITIES
Net income	$ 219,055	$ 221,800
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and other non-cash charges	159,090	130,834
Stock-based compensation expense	5,904	5,423
Loss on disposition of assets, net	4,859	2,690
Deferred income tax provision	7,294	57,587
Excess tax benefits for share-based payments	(2,584)	(3,434)
(Increase) decrease in assets:
Accounts receivable	83,234	(143,422)
Income taxes receivable	10,286	18,311
Inventories	(41,961)	(29,319)
Prepaid expenses	3,353	1,937
Other current assets	19,721	(13,281)
Other non-current assets	(4,233)	576
Increase (decrease) in liabilities:
Accounts payable	4,394	54,500
Income taxes payable	(9,152)	(1,803)
Accrued payroll and related expenses	(236)	4,197
Accrued insurance expenses	609	900
Accrued state, local and other taxes	6,249	3,151
Other accrued expenses	(1,097)	1,008
Pension liabilities	(1,371)	382
Accrued insurance expenses	1,791	400
Other non-current liabilities	65	478
Net cash provided by operating activities	465,270	312,915
INVESTING ACTIVITIES
Capital expenditures	(273,801)	(305,729)
Proceeds from sale of assets	11,873	18,897
Net cash used for investing activities	(261,928)	(286,832)
FINANCING ACTIVITIES
Payment of dividends	(52,623)	(32,501)
Borrowings from notes payable to banks	606,550	610,450
Repayments of notes payable to banks	(726,150)	(590,900)
Debt issue costs for notes payable to banks		(415)
Excess tax benefits for share-based payments	2,584	3,434
Cash paid for common stock purchased and retired	(30,224)	(18,857)
Proceeds received upon exercise of stock options	270	641
Net cash used for provided by financing activities	(199,593)	(28,148)
Net increase (decrease) in cash and cash equivalents	3,749	(2,065)
Cash and cash equivalents at beginning of period	7,393	9,035
Cash and cash equivalents at end of period	11,142	6,970
Supplemental cash flows disclosure:
Interest paid, net of amount capitalized	1,353	2,704
Income taxes paid, net	125,441	61,172
Supplemental disclosure of noncash investing activities:
Capital expenditures included in accounts payable	$ 19,369	$ 24,772