Plant, Property, and Equipment (Schedule Of Depreciation And Amortization) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ 7,953	$ 7,360
Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Consumers accumulated depreciation and amortization	7,844	7,272
Non-utility plant assets
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	112	91
Non-utility plant assets | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Consumers accumulated depreciation and amortization	3	3
Utility plant assets
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	7,841	7,269
Utility plant assets | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Consumers accumulated depreciation and amortization	$ 7,841	$ 7,269