Condensed Consolidated Balance Sheets (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Current assets    
Cash and cash equivalents $ 689,972 $ 734,231
Short term investments 249,518 248,954
Trade accounts receivable 198,314 211,506
Other receivables 15,435 20,511
Inventories 240,113 190,253
Prepaid royalties 12,841 11,118
Deferred income taxes 50,414 52,728
Coal derivative assets 14,777 13,257
Other current assets 59,605 60,193
Total current assets 1,530,989 1,542,751
Property, plant and equipment, net 6,371,335 6,453,458
Other assets    
Prepaid royalties 63,622 66,806
Equity investments 225,030 235,842
Other noncurrent assets 123,964 130,866
Total other assets 412,616 433,514
Total assets 8,314,940 8,429,723
Current liabilities    
Accounts payable 167,480 180,113
Accrued expenses and other current liabilities 321,503 302,396
Current maturities of debt 34,368 36,885
Total current liabilities 523,351 519,394
Long-term debt 5,117,982 5,123,485
Asset retirement obligations 404,844 398,896
Accrued pension benefits 14,436 16,260
Accrued postretirement benefits other than pension 34,453 32,668
Accrued workers’ compensation 98,683 94,291
Deferred income taxes 419,064 422,809
Other noncurrent liabilities 141,804 153,766
Total liabilities 6,754,617 6,761,569
Stockholders' equity    
Common stock, $0.01 par value, authorized 260,000 shares, issued 214,179 shares and 213,791 shares at March 31, 2015 and December 31, 2014, respectively 2,145 2,141
Paid-in capital 3,050,216 3,048,460
Treasury stock, at cost, 1,517 shares at March 31, 2015 and December 31, 2014 (53,863) (53,863)
Accumulated deficit (1,445,020) (1,331,825)
Accumulated other comprehensive income 6,845 3,241
Total stockholders’ equity 1,560,323 1,668,154
Total liabilities and stockholders’ equity $ 8,314,940 $ 8,429,723