Consolidated Statements Of Cash Flows (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities
Net income	$ 232,523	$ 137,320
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	98,244	96,322
Provision for doubtful accounts	917	651
Amortization of debt issue costs	1,289	1,748
Stock-based compensation expense	4,762	4,566
Loss from disposition of fixed assets	1,022	612
Impairment of long-lived assets	1,975
Deferred income taxes	19,435	13,292
Equity in (income) loss of joint ventures	(2,443)	42
Changes in operating assets and liabilities
Accounts receivable	(100,524)	(30,595)
Inventories	(16,220)	13,614
Prepaid expenses and other current assets	4,039	(7,902)
Accounts payable	(9,558)	(30,222)
Accrued liabilities	14,330	17,360
Other, net	(5,438)	(1,827)
Net cash provided by operating activities	244,353	214,981
Cash flows from investing activities
Additions to property, plant and equipment	(111,823)	(51,237)
Proceeds from disposition of assets	2,456	849
Proceeds from repayment of loan to affiliate	763	333
Purchase of investments	(29,877)
Settlements of derivative instruments	(331)	7,136
Net cash used for investing activities	(138,812)	(42,919)
Cash flows from financing activities
Capitalized debt issuance costs	(2,540)	(1,419)
Dividends paid	(13,359)	(11,807)
Proceeds from exercise of stock options	5,323	1,280
Repurchase of common stock for treasury	(19)
Utilization of restricted cash	33,694	22,625
Net cash provided by financing activities	23,099	10,679
Net increase in cash and cash equivalents	128,640	182,741
Cash and cash equivalents at beginning of period	630,299	245,592
Cash and cash equivalents at end of period	758,939	428,333
Supplemental cash flow information
Proceeds from borrowings related to series 2009A revenue bonds (in restricted cash)		$ 93,943