CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATING ACTIVITIES
Net income (loss)	$ 296,381	$ 146,742	$ (22,745)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, amortization and other non-cash charges	179,787	133,253	130,581
Stock-based compensation expense	8,075	4,909	4,440
Loss (gain) on disposition of assets, net	3,831	(3,758)	(1,143)
Deferred income tax provision	77,074	22,262	1,669
Excess tax benefits for share-based payments	(3,371)	(651)	(1,421)
Changes in current assets and liabilities:
Accounts receivable	(167,312)	(163,162)	80,035
Income taxes receivable	9,817	1,584	(1,159)
Inventories	(36,511)	(8,130)	(5,798)
Prepaid expenses	(2,783)	(1,041)	2,567
Other current assets	(30,524)	189	8
Accounts payable	30,102	14,191	(5,711)
Income taxes payable	4,917	5,141	(2,712)
Accrued payroll and related expenses	9,799	13,173	(9,690)
Accrued insurance expenses	603	826	(325)
Accrued state, local and other taxes	2,078	987	(394)
Other accrued expenses	958	112	(167)
Changes in working capital	(178,856)	(136,130)	56,654
Changes in other assets and liabilities:
Pension liabilities	1,249	1,628	4,882
Accrued insurance expenses	511	(108)	199
Other non-current assets	294	(920)	(2,597)
Other non-current liabilities	1,032	1,430	(1,779)
Net cash provided by operating activities	386,007	168,657	168,740
INVESTING ACTIVITIES
Capital expenditures	(416,400)	(187,486)	(67,830)
Proceeds from sale of assets	24,763	15,717	6,686
Net cash used for investing activities	(391,637)	(171,769)	(61,144)
FINANCING ACTIVITIES
Payment of dividends	(47,327)	(20,647)	(21,556)
Borrowings from notes payable to banks	940,850	516,600	276,100
Repayments of notes payable to banks	(858,800)	(485,650)	(360,250)
Debt issue costs for notes payable to banks	(415)	(1,886)	(234)
Excess tax benefits for share-based payments	3,371	651	1,421
Cash paid for common stock purchased and retired	(34,419)	(1,650)	(1,747)
Proceeds received upon exercise of stock options	728	240	122
Net cash provided by (used for) financing activities	3,988	7,658	(106,144)
Net (decrease) increase in cash and cash equivalents	(1,642)	4,546	1,452
Cash and cash equivalents at beginning of year	9,035	4,489	3,037
Cash and cash equivalents at end of year	$ 7,393	$ 9,035	$ 4,489