Plant, Property, and Equipment (Schedule Of Depreciation And Amortization Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Depreciation expense - plant, property, and equipment	$ 687	$ 591	$ 551
Total depreciation and amortization expense	811	750	685
Securitized Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	25	83	75
Other Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense		2	5
Software [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	96	70	50
Other Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	3	4	4
Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense - plant, property, and equipment	680	586	546
Total depreciation and amortization expense	803	744	678
Consumers Energy Company [Member] | Securitized Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	25	83	75
Consumers Energy Company [Member] | Other Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense		2	5
Consumers Energy Company [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	95	69	49
Consumers Energy Company [Member] | Other Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	$ 3	$ 4	$ 3