CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
ASSETS
Cash and cash equivalents	$ 293,472	$ 260,818
Receivables, net	231,032	281,763
Inventories	274,482	312,647
Deferred income taxes	32,079	37,067
Prepaid expenses	45,361	39,022
Assets held for sale	24,150
Other current assets	12,504	18,031
Total current assets	913,080	949,348
Mineral interests, net	2,887,612	2,905,002
Property, plant and equipment, net	1,547,280	1,637,552
Other long-term assets	113,926	98,958
Total assets	5,461,898	5,590,860
LIABILITIES AND STOCKHOLDERS' EQUITY
Current debt	15,353	9,210
Accounts payable	60,451	92,712
Accrued expenses	142,831	133,870
Accumulated other postretirement benefits obligation	30,887	30,036
Other current liabilities	225,713	214,073
Total current liabilities	475,235	479,901
Long-term debt	2,880,951	2,769,622
Accumulated other postretirement benefits obligation	574,856	570,712
Deferred income taxes	783,591	822,867
Other long-term liabilities	189,930	195,064
Total liabilities	4,904,563	4,838,166
Stockholders' equity:
Common stock, $0.01 par value per share: Authorized-200,000,000 shares; issued-65,824,776 and 62,577,924 shares, respectively	658	626
Capital in excess of par value	1,639,310	1,613,256
Accumulated deficit	(942,499)	(698,930)
Accumulated other comprehensive loss	(140,134)	(162,258)
Total stockholders' equity	557,335	752,694
Total liabilities and stockholders' equity	$ 5,461,898	$ 5,590,860