Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities
Net income	$ 123,347	$ 87,813
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	35,356	35,394
Provision for (recovery of) doubtful accounts	393	(155)
Amortization of debt issuance costs	365	400
Stock-based compensation expense	1,499	1,651
Loss from disposition of fixed assets	2,387	481
Deferred income taxes	29,466	791
Windfall tax benefits from share-based payment arrangements	(3,844)	(4,481)
Equity in (income) loss of joint ventures	(178)	702
Changes in operating assets and liabilities
Accounts receivable	(7,917)	(37,720)
Inventories	(8,776)	68,372
Prepaid expenses and other current assets	(2,077)	(1,611)
Accounts payable	14,733	(28,138)
Accrued liabilities	(14,670)	(21,647)
Other, net	(53,832)	3,724
Net cash provided by operating activities	116,252	105,576
Cash flows from investing activities
Additions to property, plant and equipment	(150,784)	(64,902)
Proceeds from disposition of assets	2	3
Proceeds from repayment of loan to affiliate	167	167
Proceeds from Sale and Maturity of Marketable Securities	124,873	0
Purchase of securities and other investments	(94,903)	(2,961)
Settlements of derivative instruments	(679)	511
Net cash used for investing activities	(121,324)	(67,182)
Cash flows from financing activities
Dividends paid	(12,553)	(4,914)
Proceeds from exercise of stock options	1,590	480
Utilization of restricted cash	0	30,800
Windfall tax benefits from share-based payment arrangements	3,844	4,481
Net cash provided by financing activities	(7,119)	30,847
Net increase in cash and cash equivalents	(12,191)	69,241
Cash and cash equivalents at beginning of period	790,078	825,901
Cash and cash equivalents at end of period	$ 777,887	$ 895,142