Condensed Consolidated Balance Sheets (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Current assets
Cash and cash equivalents	$ 1,401.6	$ 1,295.2
Accounts receivable, net of allowance for doubtful accounts of $23.3 at September 30, 2011 and $30.3 at December 31, 2010	591.4	558.2
Inventories	351.9	332.9
Assets from coal trading activities, net	66.0	192.5
Deferred income taxes	90.9	120.4
Other current assets	503.2	459.0
Total current assets	3,005.0	2,958.2
Property, plant, equipment and mine development
Land and coal interests	7,841.3	7,657.0
Buildings and improvements	1,087.7	1,079.8
Machinery and equipment	2,175.8	1,699.3
Less: accumulated depreciation, depletion and amortization	(3,296.7)	(3,010.0)
Property, plant, equipment and mine development, net	7,808.1	7,426.1
Investments and other assets	878.5	978.8
Total assets	11,691.6	11,363.1
Current liabilities
Current maturities of long-term debt	43.8	43.2
Liabilities from coal trading activities, net	62.6	181.7
Accounts payable and accrued expenses	1,334.9	1,288.8
Total current liabilities	1,441.3	1,513.7
Long-term debt, less current maturities	2,458.6	2,706.8
Deferred income taxes	499.6	539.8
Asset retirement obligations	537.3	501.3
Accrued postretirement benefit costs	965.6	963.9
Other noncurrent liabilities	466.7	448.3
Total liabilities	6,369.1	6,673.8
Stockholders' equity
Additional paid-in capital	2,231.3	2,182.0
Retained earnings	3,544.7	2,878.4
Accumulated other comprehensive loss	(139.1)	(67.9)
Treasury shares, at cost: 9,167,639 shares as of September 30, 2011 and 8,912,772 shares as of December 31, 2010	(350.7)	(334.6)
Peabody Energy Corporation's stockholders' equity	5,289.0	4,660.7
Noncontrolling interests	33.5	28.6
Total stockholders' equity	5,322.5	4,689.3
Total liabilities and stockholders' equity	11,691.6	11,363.1
Preferred Stock [Member]
Stockholders' equity
Preferred Stock	0	0
Series A Junior Participating Preferred Stock [Member]
Stockholders' equity
Preferred Stock	0	0
Perpetual Preferred Stock
Stockholders' equity
Preferred Stock	0	0
Series Common Stock
Stockholders' equity
Common Stock	0	0
Common Stock [Member]
Stockholders' equity
Common Stock	$ 2.8	$ 2.8