CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
ASSETS
Cash and cash equivalents	$ 116,601	$ 128,430
Receivables, net	256,967	313,343
Inventories	306,018	240,437
Deferred income taxes	58,526	61,079
Prepaid expenses	53,776	49,974
Other current assets	23,928	45,649
Total current assets	815,816	838,912
Mineral interests, net	2,965,557	3,056,258
Property, plant and equipment, net	1,732,131	1,631,333
Deferred income taxes	160,422	109,300
Goodwill		1,066,754
Other long-term assets	94,494	153,951
Total assets	5,768,420	6,856,508
LIABILITIES AND STOCKHOLDERS' EQUITY
Current debt	18,793	56,695
Accounts payable	114,913	112,661
Accrued expenses	184,875	229,067
Accumulated postretirement benefits obligation	29,200	27,247
Other current liabilities	206,473	63,757
Total current liabilities	554,254	489,427
Long-term debt	2,397,372	2,269,020
Deferred income taxes	921,687	1,029,336
Accumulated postretirement benefits obligation	633,264	550,671
Other long-term liabilities	251,272	381,537
Total liabilities	4,757,849	4,719,991
Commitments and Contingencies (Note 18)
Stockholders' equity:
Common stock, $0.01 par value per share: Authorized-200,000,000 shares; issued-62,521,300 and 62,444,905 shares, respectively	625	624
Preferred stock, $0.01 par value per share: Authorized-20,000,000 shares; issued-0 shares
Capital in excess of par value	1,628,244	1,620,430
Retained earnings (accumulated deficit)	(347,448)	744,939
Accumulated other comprehensive income (loss):
Pension and other post-retirement benefit plans, net of tax	(266,042)	(225,541)
Foreign currency translation adjustment	(1,502)	(3,276)
Unrealized loss on hedges, net of tax	(4,203)	(787)
Unrealized investment gain, net of tax	897	128
Total stockholders' equity	1,010,571	2,136,517
Total liabilities and stockholders' equity	$ 5,768,420	$ 6,856,508