Plant, Property, and Equipment (Schedule of Finite-Lived Intangible Assets by Major Class Table) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	$ 1,114	$ 1,242
Accumulated Amortization	615	686
Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	1,100	1,226
Accumulated Amortization	607	678
Plant additions	2,000	1,800
Plant retirements	380	190
Software development
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	882	1,024
Accumulated Amortization	529	603
Software development | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	869	1,009
Accumulated Amortization	521	595
Leasehold improvements
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	9	9
Accumulated Amortization	7	7
Leasehold improvements | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	9	9
Accumulated Amortization	7	7
Intangible Plant | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Plant additions	67	90
Plant retirements	193	7
Rights of way
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	180	167
Accumulated Amortization	55	52
Rights of way | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	180	167
Accumulated Amortization	55	52
Franchises and consents
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	16	15
Accumulated Amortization	9	9
Franchises and consents | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	16	15
Accumulated Amortization	9	9
Other intangible assets
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	27	27
Accumulated Amortization	15	15
Other intangible assets | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	26	26
Accumulated Amortization	$ 15	$ 15
Minimum | Software development
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	1 year
Minimum | Software development | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	3 years
Minimum | Rights of way
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	50 years
Minimum | Rights of way | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	50 years
Minimum | Franchises and consents
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	5 years
Minimum | Franchises and consents | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	5 years
Maximum | Software development
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	15 years
Maximum | Software development | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	15 years
Maximum | Rights of way
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	85 years
Maximum | Rights of way | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	85 years
Maximum | Franchises and consents
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	50 years
Maximum | Franchises and consents | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Amortization Life in Years	50 years