Regulatory Matters (Schedule of Components of the Increase in Revenue) (Details) (Electric Rate Case [Member], Consumers Energy Company [Member], USD $) In Millions	Jun. 30, 2011
Annual Rate Increase Requested by Consumers	$ 195
Investment in Rate Base [Member]
Annual Rate Increase Requested by Consumers	81
Recovery Of Depreciation And Property Taxes [Member]
Annual Rate Increase Requested by Consumers	70
Impact Of Sales Declines [Member]
Annual Rate Increase Requested by Consumers	50
Reduced Operating And Maintenance Costs [Member]
Annual Rate Increase Requested by Consumers	(4)
Cost Of Capital [Member]
Annual Rate Increase Requested by Consumers	$ (2)