Regulatory Matters (Schedule of Components of the Increase in Electric Revenue) (Details) (2011 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
Depreciation And Property Taxes [Member]
Annual Rate Increase Requested by Consumers	70
Impact Of Sales Declines [Member]
Annual Rate Increase Requested by Consumers	50
Impact of Reduced Funding for Customers Assistance Programs [Member]
Annual Rate Increase Requested by Consumers	13	[1]
Reduced Operating And Maintenance Costs [Member]
Annual Rate Increase Requested by Consumers	(17)
Cost Of Capital [Member]
Annual Rate Increase Requested by Consumers	$ (2)

[1] 1 Consumers projects electric uncollectible expense to increase by $13 million in 2012 due to an anticipated reduction in federal funding for customer assistance programs. Due to the uncertainty surrounding federal funding for such programs and the resulting impact on uncollectible expense, Consumers also requested that the MPSC approve an uncollectible expense true-up mechanism.