Regulatory Matters (Schedule of PSCR Reconciliation Filings Pending with the MPSC) (Details) (Power Supply Cost Recover (PSCR) [Member], Consumers Energy Company [Member], USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Power Supply Cost Recover (PSCR) [Member] | Consumers Energy Company [Member]
Date of Filing	March 2012
Net Over/(Under) Recovery, Including Interest, Requested by Consumers	$ 8,000,000
PSCR Cost of Power Sold	$ 1,800,000,000	$ 1,700,000,000