Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 400,205	$ 450,781
Short term investments	111,451	200,192
Restricted cash	81,563	97,542
Trade accounts receivable (net of allowance for doubtful accounts of $0 and $7.8 million, respectively)	165,522	117,405
Other receivables	17,227	18,362
Inventories	159,410	196,720
Prepaid royalties	4,805	10,022
Coal derivative assets	2,180	8,035
Other current assets	36,960	39,866
Total current assets	979,323	1,138,925
Property, plant and equipment, net	3,434,941	3,619,029
Other assets
Prepaid royalties	20,997	23,671
Equity investments	164,232	201,877
Other noncurrent assets	58,569	58,379
Total other assets	243,798	283,927
Total assets	4,658,062	5,041,881
Liabilities not subject to compromise
Accounts payable	89,966	128,131
Accrued expenses and other current liabilities	223,780	329,450
Current maturities of debt	3,398	5,042,353
Total current liabilities	317,144	5,499,934
Long-term debt	30,037	30,953
Asset retirement obligations	394,699	396,659
Accrued pension benefits	23,716	27,373
Accrued postretirement benefits other than pension	87,123	99,810
Accrued workers’ compensation	119,828	112,270
Other noncurrent liabilities	65,824	119,171
Total liabilities not subject to compromise	1,038,371	6,286,170
Liabilities subject to compromise	5,295,785	0
Total liabilities	6,334,156	6,286,170
Stockholders' deficit
Common stock, $0.01 par value, authorized 26,000 shares, issued 21,448 shares and 21,446 shares at September 30, 2016 and December 31, 2015, respectively	2,145	2,145
Paid-in capital	3,056,307	3,054,211
Treasury stock, at cost, 152 shares at September 30, 2016 and December 31, 2015	(53,863)	(53,863)
Accumulated deficit	(4,678,977)	(4,244,967)
Accumulated other comprehensive loss	(1,706)	(1,815)
Total stockholders’ deficit	(1,676,094)	(1,244,289)
Total liabilities and stockholders’ deficit	$ 4,658,062	$ 5,041,881