Plant, Property, and Equipment (Schedule Of Depreciation And Amortization Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense – plant, property, and equipment	$ 902	$ 842	$ 778
Total depreciation and amortization expense	1,048	992	933
Securitized regulatory assets
Property, Plant and Equipment [Line Items]
Amortization expense	26	26	25
Software
Property, Plant and Equipment [Line Items]
Amortization expense	116	121	127
Other intangible assets
Property, Plant and Equipment [Line Items]
Amortization expense	4	3	3
Consumers Energy Company
Property, Plant and Equipment [Line Items]
Depreciation expense – plant, property, and equipment	881	827	768
Total depreciation and amortization expense	1,023	975	921
Consumers Energy Company | Securitized regulatory assets
Property, Plant and Equipment [Line Items]
Amortization expense	26	26	25
Consumers Energy Company | Software
Property, Plant and Equipment [Line Items]
Amortization expense	112	119	125
Consumers Energy Company | Other intangible assets
Property, Plant and Equipment [Line Items]
Amortization expense	$ 4	$ 3	$ 3