Condensed Consolidated Balance Sheets (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 82,345	$ 93,593
Restricted cash	350,966
Trade accounts receivable	335,052	208,060
Other receivables	91,064	44,260
Inventories	350,201	235,616
Prepaid royalties	38,119	33,932
Deferred income taxes	7,015
Coal derivative assets	12,780	15,191
Other	121,123	104,262
Total current assets	1,388,665	734,914
Property, plant and equipment, net	7,726,456	3,308,892
Other assets:
Prepaid royalties	94,382	66,525
Goodwill	539,963	114,963
Deferred income taxes		361,556
Equity investments	207,646	177,451
Other	194,333	116,468
Total other assets	1,036,324	836,963
Total assets	10,151,445	4,880,769
Current liabilities:
Accounts payable	286,437	198,216
Coal derivative liabilities	5,791	4,947
Deferred income taxes		7,775
Accrued expenses and other current liabilities	395,020	245,411
Current maturities of debt and short-term borrowings	428,610	70,997
Total current liabilities	1,115,858	527,346
Long-term debt	3,773,923	1,538,744
Asset retirement obligations	412,324	334,257
Accrued pension benefits	36,047	49,154
Accrued postretirement benefits other than pension	87,626	37,793
Accrued workers' compensation	65,027	35,290
Deferred income taxes	863,970
Other noncurrent liabilities	258,261	110,234
Total liabilities	6,613,036	2,632,818
Redeemable noncontrolling interest	11,032	10,444
Stockholders' equity:
Common stock, $0.01 par value, authorized 260,000 shares, issued 212,312 shares and 164,117 shares, respectively	2,127	1,645
Paid-in capital	2,991,550	1,734,709
Treasury stock, 1,512 shares at June 30, 2011 and December 31, 2010, at cost	(53,848)	(53,848)
Retained earnings	593,896	561,418
Accumulated other comprehensive loss	(6,348)	(6,417)
Total stockholders' equity	3,527,377	2,237,507
Total liabilities and stockholders' equity	$ 10,151,445	$ 4,880,769