Mine Closing, Reclamation, and Gas Well Closing (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Jan. 02, 2010
Asset Retirement Obligation	$ 650,073,000	$ 670,856,000	$ 533,177,000
Accretion Expense	48,120,000	46,200,000
Asset Retirement Obligation, Cash Paid to Settle	(57,584,000)	(45,961,000)
Asset Retirement Obligation, Revision of Estimate	(4,621,000)	82,742,000
Asset Retirement Obligation, Liabilities Incurred	0	62,098,000
Asset Retirement Obligation, Other Change	(6,698,000)	(7,400,000)
Bishop Mining Complex [Member]
Asset Retirement Obligation, Other Change	(6,698)
Fola [Member]
Asset Retirement Obligation, Revision of Estimate		80,525
Jones Fork Mining Complex [Member]
Asset Retirement Obligation, Other Change		$ (7,400)