Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities
Net income	$ 258,966,000	$ 221,393,000	$ 52,995,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	131,397,000	128,732,000	123,199,000
Provision for doubtful accounts	1,321,000	917,000	1,970,000
Amortization of debt issue costs	1,683,000	2,154,000	1,461,000
Stock-based compensation expense	6,391,000	6,164,000	5,638,000
Loss from disposition of fixed assets	1,375,000	581,000	2,711,000
Impairment of long-lived assets	1,975,000
Gain on involuntary conversion of assets			(455,000)
Deferred income taxes	14,114,000	14,153,000	31,207,000
Equity in income of joint ventures	(427,000)	(2,212,000)	(3,818,000)
Changes in operating assets and liabilities
Accounts receivable	(45,766,000)	(33,478,000)	5,667,000
Inventories	(40,749,000)	(80,611,000)	(41,450,000)
Prepaid expenses and other current assets	2,987,000	(7,217,000)	(236,000)
Accounts payable	20,311,000	25,644,000	67,044,000
Accrued liabilities	18,785,000	9,910,000	8,308,000
Other, net	(10,067,000)	(2,846,000)	(18,719,000)
Net cash provided by operating activities	362,296,000	283,284,000	235,522,000
Cash flows from investing activities
Acquisition of business			(6,297,000)
Additions to equity investments		(10,177,000)
Additions to property, plant and equipment	(176,843,000)	(81,269,000)	(99,769,000)
Proceeds from disposition of assets	2,880,000	914,000	3,255,000
Proceeds from insurance for involuntary conversion of assets			484,000
Proceeds from repayment of loan to affiliate	1,192,000	763,000
Purchase of securities and other investments	(30,265,000)
Settlements of derivative instruments	251,000	9,494,000	(859,000)
Net cash used for investing activities	(202,785,000)	(80,275,000)	(103,186,000)
Cash flows from financing activities
Capitalized debt issuance costs	(2,697,000)	(3,331,000)	(2,203,000)
Dividends paid	(18,265,000)	(16,014,000)	(14,510,000)
Proceeds from exercise of stock options	5,344,000	3,745,000	879,000
Repurchase of common stock for treasury	(2,518,000)
Utilization of restricted cash	54,227,000	197,298,000	38,851,000
Net cash provided by financing activities	36,091,000	181,698,000	23,017,000
Net increase in cash and cash equivalents	195,602,000	384,707,000	155,353,000
Cash and cash equivalents at beginning of the year	630,299,000	245,592,000	90,239,000
Cash and cash equivalents at end of the year	825,901,000	630,299,000	245,592,000
Supplemental cash flow information
Interest paid (net of interest capitalized)	48,431,000	33,980,000	33,394,000
Income taxes paid (refunded)	126,283,000	108,218,000	(40,741,000)
Series 2009A Revenue Bonds [Member]
Non-cash financing activity:
Proceeds from borrowings related to revenue bonds (in restricted cash)			4,900,000
6 1/2% Tax-Exempt Revenue Bonds Due 2029 [Member]
Non-cash financing activity:
Proceeds from borrowings related to revenue bonds (in restricted cash)		93,943,000
GO Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]
Non-cash financing activity:
Proceeds from borrowings related to revenue bonds (in restricted cash)		87,940,000
IKE Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]
Non-cash financing activity:
Proceeds from borrowings related to revenue bonds (in restricted cash)		$ 64,209,000