CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 123,519	$ 168,745
Accounts receivable	62,029	86,838
Due from related parties	4,152	227
Inventories, net	75,503	79,802
Deferred income taxes	21,670	21,670
Derivative financial instruments	7,258	17,111
Prepaid taxes	9,388	3
Other assets	16,668	9,837
Total current assets	320,187	384,233
Noncurrent assets
Property, plant and equipment, net	1,514,762	1,589,138
Port access contract rights, net	50,997	53,780
Goodwill	2,280	35,634
Deferred income taxes	65,918	56,468
Other assets	44,540	31,900
Total assets	1,998,684	2,151,153
Current liabilities
Accounts payable	54,189	52,035
Royalties and production taxes	126,139	126,212
Accrued expenses	45,989	52,213
Current portion of federal coal lease obligations	0	63,970
Other liabilities	1,803	1,632
Total current liabilities	228,120	296,062
Noncurrent liabilities
Senior notes	490,792	489,715
Asset retirement obligations, net of current portion	167,790	216,241
Accumulated postretirement medical benefit obligation, net of current portion	55,401	50,276
Other liabilities	12,370	11,025
Total liabilities	$ 954,473	$ 1,063,319
Commitments and Contingencies (Note 13)
Equity
Common stock ($0.01 par value; 200,000 shares authorized; 61,647 and 61,454 shares issued and 61,172 and 61,022 outstanding at September 30, 2015 and December 31, 2014, respectively)	$ 612	$ 610
Treasury stock, at cost (475 shares and 432 shares at September 30, 2015 and December 31, 2014, respectively)	(6,493)	(6,243)
Additional paid-in capital	572,758	568,022
Retained earnings	488,041	536,744
Accumulated other comprehensive income (loss)	(10,707)	(11,299)
Total equity	1,044,211	1,087,834
Total liabilities and equity	$ 1,998,684	$ 2,151,153