Plant, Property, and Equipment (Summary of Finite-Lived Intangible Assets by Major Class) (Details) - Consumers Energy Company - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	$ 987	$ 989
Accumulated Amortization	602	583
Plant additions	3,100	2,100
Plant retirements	387	390
Software development
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	649	679
Accumulated Amortization	492	481
Rights of way
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	274	253
Accumulated Amortization	72	68
Franchises and consents
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	16	16
Accumulated Amortization	12	11
Leasehold improvements
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	15	13
Accumulated Amortization	9	7
Other intangible assets
Public Utility, Property, Plant and Equipment [Line Items]
Gross cost	33	28
Accumulated Amortization	17	16
Intangible plant
Public Utility, Property, Plant and Equipment [Line Items]
Plant additions	62	90
Plant retirements	$ 64	$ 153
Minimum \| Software development
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 \| Franchises and consents
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 \| Rights of way
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

CMS ENERGY CORP 10-K