Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities
Net income	$ 87,813	$ 83,544
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	35,394	32,578
(Recovery of) provision for doubtful accounts	(155)	783
Amortization of debt issue costs	400	438
Stock-based compensation expense	1,651	1,503
Loss from disposition of fixed assets	481	44
Deferred income taxes	791	7,416
Equity in loss (income) of joint ventures	702	(485)
Changes in operating assets and liabilities
Accounts receivable	(37,720)	(47,340)
Inventories	68,372	3,771
Prepaid expenses and other current assets	(1,611)	1,604
Accounts payable	(28,138)	(22,481)
Accrued liabilities	(21,647)	(25,351)
Other, net	3,724	4,636
Net cash provided by operating activities	110,057	40,660
Cash flows from investing activities
Additions to property, plant and equipment	(64,902)	(28,808)
Proceeds from disposition of assets	3	630
Proceeds from repayment of loan to affiliate	167	167
Purchase of investments	(2,961)
Settlements of derivative instruments	511	(222)
Net cash used for investing activities	(67,182)	(28,233)
Cash flows from financing activities
Dividends paid	(4,914)	(4,218)
Proceeds from exercise of stock options	480	4,820
Utilization of restricted cash	30,800	11,175
Net cash provided by financing activities	26,366	11,777
Net increase in cash and cash equivalents	69,241	24,204
Cash and cash equivalents at beginning of period	825,901	630,299
Cash and cash equivalents at end of period	$ 895,142	$ 654,503