Asset Retirement Obligations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended							12 Months Ended					12 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Consumers Energy Company [Member]	Dec. 31, 2010 Consumers Energy Company [Member]	Dec. 31, 2011 Close Gas Treating Plant and Gas Wells [Member]	Dec. 31, 2010 Close Gas Treating Plant and Gas Wells [Member]	Dec. 31, 2009 Close Gas Treating Plant and Gas Wells [Member]	Dec. 31, 2011 Coal Ash Disposal Areas [Member] Consumers Energy Company [Member]	Dec. 31, 2010 Coal Ash Disposal Areas [Member] Consumers Energy Company [Member]	Dec. 31, 2011 Wells at Gas Storage Fields [Member] Consumers Energy Company [Member]	Dec. 31, 2010 Wells at Gas Storage Fields [Member] Consumers Energy Company [Member]	Dec. 31, 2009 Wells at Gas Storage Fields [Member] Consumers Energy Company [Member]	Dec. 31, 2011 Indoor Gas Services Relocations [Member] Consumers Energy Company [Member]	Dec. 31, 2009 Indoor Gas Services Relocations [Member] Consumers Energy Company [Member]	Dec. 31, 2011 Asbestos Abatement [Member] Consumers Energy Company [Member]	Dec. 31, 2010 Asbestos Abatement [Member] Consumers Energy Company [Member]	Dec. 31, 2011 Gas Distribution Cut, Purge, Cap [Member] Consumers Energy Company [Member]	Dec. 31, 2010 Gas Distribution Cut, Purge, Cap [Member] Consumers Energy Company [Member]
Asset Retirement Obligations Assumed Market Risk Premium	5.00%		5.00%
Hypothetical Asset Retirement Obligations Liability Increase	$ 13	$ 12	$ 13	$ 12
Asset Retirement Obligation, Beginning Balance	245	229	244	228	1	1	1	66	64	1	1	1	1	1	40	38	136	124
Asset Retirement Obligation, Liabilities Incurred	(2)	6	(2)	6													(2)	6
Asset Retirement Obligation, Liabilities Settled	(7)	(7)	(7)	(7)				(2)	(4)				(1)		(1)	(1)	(3)	(2)
Asset Retirement Obligation, Accretion Expense	18	17	18	17				6	6						3	3	9	8
Asset Retirement Obligation, Ending Balance	$ 254	$ 245	$ 253	$ 244	$ 1	$ 1	$ 1	$ 70	$ 66	$ 1	$ 1	$ 1		$ 1	$ 42	$ 40	$ 140	$ 136