CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
OPERATING ACTIVITIES
Net income (loss)	$ (83,936)	$ 72,552
Less income from discontinued operations		(5,180)
Income (loss) from continuing operations	(83,936)	67,372
Adjustments to reconcile income (loss) from continuing operations to net cash flows provided by (used in) operating activities:
Depreciation and depletion	149,510	140,952
Deferred income tax benefit	(77,717)	(18,894)
Amortization of debt issuance costs	14,015	9,033
Other	8,402	9,327
Decrease (increase) in current assets:
Receivables	(2,302)	113,203
Inventories	(24,281)	(66,213)
Prepaid expenses and other current assets	(8,826)	(22,095)
Increase (decrease) in current liabilities:
Accounts payable	24,483	81,684
Accrued expenses and other current liabilities	(23,450)	(5,807)
Cash flows provided by (used in) operating activities	(24,102)	308,562
INVESTING ACTIVITIES
Additions to property, plant and equipment	(80,251)	(246,056)
Proceeds from sales of investments	202	12,228
Other	762	582
Cash flows used in investing activities	(79,287)	(233,246)
FINANCING ACTIVITIES
Proceeds from issuance of debt	450,000
Borrowings under revolving credit agreement	529,382	112,350
Repayments on revolving credit agreement	(529,382)	(63,341)
Retirements of debt	(259,200)	(118,003)
Dividends paid	(15,638)	(15,618)
Debt issuance costs	(15,080)
Other	(600)	288
Cash flows provided by (used in) financing activities	159,482	(84,324)
Cash flows provided by (used in) continuing operations	56,093	(9,008)
CASH FLOWS FROM DISCONTINUED OPERATIONS		9,500
Effect of foreign exchange rates on cash	(1,816)	(242)
Net increase in cash and cash equivalents	54,277	250
Cash and cash equivalents at beginning of period	116,601	128,430
Cash and cash equivalents at end of period	$ 170,878	$ 128,680