Acquisitions (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Apr. 02, 2011 Western Coal Corp	Apr. 02, 2011 Western Coal Corp Common stock of Walter Energy	Apr. 02, 2011 Western Coal Corp Stock options issued and warrants assumed	Dec. 31, 2013 North River Mine	May 06, 2011 North River Mine
Purchase consideration:
Cash consideration				$ 2,173,080,000				$ 1,100,000
Liabilities assumed								90,900,000
Fair value of shares of common stock issued or stock options issued and warrants					1,224,126,000	34,765,000
Fair value of consideration transferred				3,431,971,000
Fair value of equity interest in Western Coal held before the acquisition				314,231,000
Total consideration				3,746,202,000
Fair value of assets acquired and liabilities assumed
Cash and cash equivalents				34,065,000
Receivables				163,668,000
Inventories				121,229,000
Other current assets				86,498,000
Mineral interests				3,086,000,000
Property, plant and equipment				554,192,000
Goodwill				1,065,040,000			1,700,000
Other long-term assets				54,150,000
Total assets				5,164,842,000
Accounts payable and accrued liabilities				184,983,000
Other current liabilities				86,105,000
Deferred tax liability				1,046,708,000
Other long-term liabilities				100,844,000
Total liabilities				1,418,640,000
Net assets acquired				3,746,202,000
Total revenues
As reported herein			2,571,358,000
Pro forma			2,795,566,000
Income (loss) from continuing operations
As reported herein	(359,003,000)	(1,065,555,000)	363,598,000
Pro forma			$ 418,419,000