Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 395,398	$ 450,781
Short term investments	198,788	200,192
Restricted cash	109,650	97,542
Trade accounts receivable (net of allowance for doubtful accounts of $7.8 million for both periods, respectively.	113,005	117,405
Other receivables	15,589	18,362
Inventories	195,987	196,720
Prepaid royalties	8,075	10,022
Coal derivative assets	5,808	8,035
Other current assets	44,830	39,866
Total current assets	1,087,130	1,138,925
Property, plant and equipment, net	3,487,109	3,619,029
Other assets
Prepaid royalties	20,997	23,671
Equity investments	201,517	201,877
Other noncurrent assets	58,657	58,379
Total other assets	281,171	283,927
Total assets	4,855,410	5,041,881
Liabilities not subject to compromise
Accounts payable	70,823	128,131
Accrued expenses and other current liabilities	102,590	329,450
Current maturities of debt	0	5,042,353
Total current liabilities	173,413	5,499,934
Long-term debt	0	30,953
Asset retirement obligations	401,569	396,659
Accrued pension benefits	20,646	27,373
Accrued postretirement benefits other than pension	89,779	99,810
Accrued workers’ compensation	113,782	112,270
Other noncurrent liabilities	18,023	119,171
Total liabilities not subject to compromise	817,212	6,286,170
Liabilities subject to compromise	5,487,326	0
Total liabilities	6,304,538	6,286,170
Stockholders' deficit
Common stock, $0.01 par value, authorized 26,000 shares, issued 21,448 shares and 21,446 shares at March 31, 2016 and December 31, 2015, respectively	2,145	2,145
Paid-in capital	3,055,214	3,054,211
Treasury stock, at cost, 152 shares at March 31, 2016 and December 31, 2015	(53,863)	(53,863)
Accumulated deficit	(4,451,669)	(4,244,967)
Accumulated other comprehensive loss	(955)	(1,815)
Total stockholders’ deficit	(1,449,128)	(1,244,289)
Total liabilities and stockholders’ deficit	$ 4,855,410	$ 5,041,881