Leases - Lessee Leases Narrative (Details)	Jun. 30, 2019
Lessee, Lease, Description [Line Items]
Finance leases	12 years
Real Estate
Lessee, Lease, Description [Line Items]
Operating lease remaining term without extension provisions	42 years
Minimum | Real Estate
Lessee, Lease, Description [Line Items]
Operating lease term	3 years
Maximum | Real Estate
Lessee, Lease, Description [Line Items]
Operating lease term	60 years
Consumers Energy Company
Lessee, Lease, Description [Line Items]
Finance leases	12 years
Consumers Energy Company | Railcars
Lessee, Lease, Description [Line Items]
Operating lease remaining term without extension provisions	4 years
Consumers Energy Company | Real Estate
Lessee, Lease, Description [Line Items]
Operating lease remaining term without extension provisions	42 years
Consumers Energy Company | Service Vehicles
Lessee, Lease, Description [Line Items]
Finance lease remaining term	7 years
Consumers Energy Company | Minimum | Railcars
Lessee, Lease, Description [Line Items]
Operating lease term	5 years
Consumers Energy Company | Minimum | Real Estate
Lessee, Lease, Description [Line Items]
Operating lease term	3 years
Consumers Energy Company | Minimum | Service Vehicles
Lessee, Lease, Description [Line Items]
Finance lease term	5 years
Consumers Energy Company | Minimum | PPAs
Lessee, Lease, Description [Line Items]
Operating and finance lease remaining term	1 year
Consumers Energy Company | Maximum | Railcars
Lessee, Lease, Description [Line Items]
Operating lease term	15 years
Consumers Energy Company | Maximum | Real Estate
Lessee, Lease, Description [Line Items]
Operating lease term	60 years
Consumers Energy Company | Maximum | Service Vehicles
Lessee, Lease, Description [Line Items]
Finance lease term	10 years
Consumers Energy Company | Maximum | PPAs
Lessee, Lease, Description [Line Items]
Operating and finance lease remaining term	14 years
D.E. Karn Generating Complex | Consumers Energy Company | Gas Pipelines
Lessee, Lease, Description [Line Items]
Finance lease term	15 years
Finance leases	3 years
Zeeland | Consumers Energy Company | Gas Pipelines
Lessee, Lease, Description [Line Items]
Finance lease term	5 years
Zeeland | Consumers Energy Company | Minimum | Gas Pipelines
Lessee, Lease, Description [Line Items]
Finance lease renewal term	5 years
Zeeland | Consumers Energy Company | Maximum | Gas Pipelines
Lessee, Lease, Description [Line Items]
Finance lease renewal term	10 years