Leases (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Leases [Line Items]
Finance Leases Lessee Balance Sheet Assets Amortization And Interest Charges	$ 20	$ 20	$ 21
Consumers Energy Company [Member]
Leases [Line Items]
Finance Lease Term	15 years
Finance Leases Lessee Balance Sheet Assets Amortization And Interest Charges	$ 20	$ 20	$ 21
Coal-Carrying Railcars [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Operating leases without extension provisions, remaining term	10 years
Operating leases with extension provisions, remaining term	13 years
Gas Transportation Pipeline into Karn [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Capital Lease Term	15 years
Capital Lease Remaining Term	8 years
Gas Transportation Pipeline into Zeeland [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Capital Lease Remaining Term	4 years
Capital lease renewal term	5 years
Minimum [Member] | Coal-Carrying Railcars [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Operating leases, term	3 years
Minimum [Member] | Long-term PPAs [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Lease term	2 years
Maximum [Member] | Coal-Carrying Railcars [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Operating leases, term	15 years
Maximum [Member] | Vehicle Fleet Operations [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Capital Lease Term	120 months
Maximum [Member] | Long-term PPAs [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Lease term	19 years