Condensed Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current assets
Cash and cash equivalents	$ 648.0	$ 799.1
Accounts receivable, net of allowance for doubtful accounts of $15.2 at September 30, 2012 and $17.0 at December 31, 2011	682.2	922.5
Inventories	554.9	444.4
Assets from coal trading activities, net	56.2	44.6
Deferred income taxes	15.8	27.3
Other current assets	697.6	768.0
Total current assets	2,654.7	3,005.9
Property, plant, equipment and mine development
Land and coal interests	11,875.2	10,630.5
Buildings and improvements	1,268.3	1,084.2
Machinery and equipment	3,175.8	2,857.3
Less: accumulated depreciation, depletion and amortization	(3,808.2)	(3,320.4)
Property, plant, equipment and mine development, net	12,511.1	11,251.6
Investments and other assets	1,684.6	2,475.5
Total assets	16,850.4	16,733.0
Current liabilities
Current maturities of long-term debt	124.8	101.1
Liabilities from coal trading activities, net	19.9	10.3
Accounts payable and accrued expenses	1,645.1	1,712.3
Total current liabilities	1,789.8	1,823.7
Long-term debt, less current maturities	6,238.3	6,556.4
Deferred income taxes	385.0	523.2
Asset retirement obligations	662.4	615.2
Accrued postretirement benefit costs	1,054.3	1,053.1
Other noncurrent liabilities	743.6	645.6
Total liabilities	10,873.4	11,217.2
Stockholders' equity
Additional paid-in capital	2,284.9	2,234.0
Retained earnings	4,095.2	3,744.0
Accumulated other comprehensive Income (Loss)	23.2	(142.4)
Treasury shares, at cost: 13.7 shares as of September 30, 2012 and 9.2 shares as of December 31, 2011	461.5	(353.3)
Peabody Energy Corporation's stockholders' equity	5,944.6	5,485.1
Noncontrolling interests	32.4	30.7
Total stockholders' equity	5,977.0	5,515.8
Total liabilities and stockholders' equity	16,850.4	16,733.0
Preferred Stock [Member]
Stockholders' equity
Preferred Stock	0	0
Series A Junior Participating Preferred Stock [Member]
Stockholders' equity
Preferred Stock		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
Noncontrolling Interest [Member]
Stockholders' equity
Noncontrolling interests	32.4
Total stockholders' equity		$ 30.7