Plant, Property, and Equipment (Schedule Of Depreciation And Amortization Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation expense – plant, property, and equipment	$ 778	$ 739	$ 687
Total depreciation and amortization expense	933	881	811
Securitized regulatory assets
Property, Plant and Equipment [Line Items]
Amortization expense	25	25	25
Software
Property, Plant and Equipment [Line Items]
Amortization expense	127	114	96
Other intangible assets
Property, Plant and Equipment [Line Items]
Amortization expense	3	3	3
Consumers Energy Company
Property, Plant and Equipment [Line Items]
Depreciation expense – plant, property, and equipment	768	732	680
Total depreciation and amortization expense	921	872	803
Consumers Energy Company | Securitized regulatory assets
Property, Plant and Equipment [Line Items]
Amortization expense	25	25	25
Consumers Energy Company | Software
Property, Plant and Equipment [Line Items]
Amortization expense	125	112	95
Consumers Energy Company | Other intangible assets
Property, Plant and Equipment [Line Items]
Amortization expense	$ 3	$ 3	$ 3