CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 95,538	$ 168,745
Accounts receivable	52,214	86,838
Due from related parties	2,473	227
Inventories, net	78,714	79,802
Deferred income taxes	21,670	21,670
Derivative financial instruments	13,086	17,111
Other assets	20,622	9,840
Total current assets	284,317	384,233
Noncurrent assets
Property, plant and equipment, net	1,543,858	1,589,138
Port access contract rights, net	51,925	53,780
Goodwill	2,280	35,634
Deferred income taxes	63,254	56,468
Other assets	47,889	40,665
Total assets	1,993,523	2,159,918
Current liabilities
Accounts payable	47,620	52,035
Royalties and production taxes	110,830	126,212
Accrued expenses	38,045	52,213
Current portion of federal coal lease obligations	0	63,970
Other liabilities	1,632	1,632
Total current liabilities	198,127	296,062
Noncurrent liabilities
Senior notes	498,603	498,480
Asset retirement obligations, net of current portion	200,175	216,241
Accumulated postretirement medical benefit obligation, net of current portion	53,691	50,276
Other liabilities	10,375	11,025
Total liabilities	$ 960,971	$ 1,072,084
Commitments and Contingencies (Note 13)
Equity
Common stock ($0.01 par value; 200,000 shares authorized; 61,510 and 61,434 shares issued and 61,034 and 61,022 outstanding at June 30, 2015 and December 31, 2014, respectively)	$ 610	$ 610
Treasury stock, at cost (475 shares and 432 shares at June 30, 2015 and December 31, 2014, respectively)	(6,492)	(6,243)
Additional paid-in capital	570,172	568,022
Retained earnings	479,167	536,744
Accumulated other comprehensive income (loss)	(10,905)	(11,299)
Total equity	1,032,552	1,087,834
Total liabilities and equity	$ 1,993,523	$ 2,159,918