Plant, Property, and Equipment (Schedule Of Depreciation And Amortization) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ 7,360	$ 7,037
Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	7,272	6,958
Utility plant assets
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	7,269	6,956
Utility plant assets | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	7,269	6,956
Non‑utility plant assets
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	91	81
Non‑utility plant assets | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ 3	$ 2