Leases And Palisades Financing (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) MW	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Consumers Energy Company
Leases [Line Items]
Finance lease term	15 years
Coal-Carrying Railcars | Consumers Energy Company
Leases [Line Items]
Operating leases without extension provisions, remaining term	5 years
Operating leases with extension provisions, remaining term	8 years
Gas Transportation Pipeline into Karn | Consumers Energy Company
Leases [Line Items]
Capital lease term	15 years
Capital lease remaining term	3 years
Gas Transportation Pipeline into Zeeland | Consumers Energy Company
Leases [Line Items]
Capital lease term	5 years
Minimum | Coal-Carrying Railcars | Consumers Energy Company
Leases [Line Items]
Operating leases, term	7 years
Minimum | Gas Transportation Pipeline into Zeeland | Consumers Energy Company
Leases [Line Items]
Capital lease renewal term	5 years
Minimum | Long-term PPAs | Consumers Energy Company
Leases [Line Items]
Lease term	1 year
Maximum | Coal-Carrying Railcars | Consumers Energy Company
Leases [Line Items]
Operating leases, term	15 years
Maximum | Vehicle Fleet Operations | Consumers Energy Company
Leases [Line Items]
Capital lease term	120 months
Maximum | Gas Transportation Pipeline into Zeeland | Consumers Energy Company
Leases [Line Items]
Capital lease renewal term	10 years
Maximum | Long-term PPAs | Consumers Energy Company
Leases [Line Items]
Lease term	15 years
Palisades Financing
Leases [Line Items]
Amortization and interest charges	$ 16	$ 17	$ 17
Asset and financing obligation	42
Palisades Financing | Consumers Energy Company
Leases [Line Items]
Asset and financing obligation	$ 42
Palisades PPA | Consumers Energy Company
Leases [Line Items]
Annual average capacity (in MW) | MW	798