Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 668,102	$ 730,723
Trade accounts receivable, net	299,950	418,166
Inventories, net	333,111	398,060
Prepaid expenses and other current assets	826,320	786,273
Total current assets	2,127,483	2,333,222
Property, equipment and mine development costs (net of accumulated depreciation and amortization of $1,752,754 and $1,355,937, respectively)	1,897,685	2,219,016
Owned and leased mineral rights and land (net of accumulated depletion of $839,833 and $522,207 respectively)	7,194,116	7,428,192
Goodwill, net	308,651	567,665
Other acquired intangibles (net of accumulated amortization of $630,518 and $551,584, respectively)	177,345	228,552
Other non-current assets	391,725	313,159
Total assets	12,097,005	13,089,806
Current liabilities:
Current portion of long-term debt	29,016	95,015
Trade accounts payable	224,893	255,191
Accrued expenses and other current liabilities	1,002,415	872,402
Total current liabilities	1,256,324	1,222,608
Long-term debt	3,344,736	3,291,037
Pension and postretirement medical benefit obligations	1,005,163	1,195,187
Asset retirement obligations	813,443	763,482
Deferred income taxes	790,529	971,001
Other non-current liabilities	514,120	678,676
Total liabilities	7,724,315	8,121,991
Commitments and Contingencies
Stockholders' Equity
Preferred stock - par value $0.01	0	0
Common stock - par value $0.01	2,328	2,322
Additional paid-in capital	8,130,733	8,075,694
Accumulated other comprehensive income (loss)	(60,706)	(166,598)
Treasury stock, at cost	(271,654)	(270,302)
Accumulated deficit	(3,428,011)	(2,673,301)
Total stockholders' equity	4,372,690	4,967,815
Total liabilities and stockholders' equity	$ 12,097,005	$ 13,089,806