Plant, Property, and Equipment (Schedule Of Plant, Property, and Equipment) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) coal_fueled_electric_generating_unit	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	$ 27,907	$ 25,390	$ 24,400
Construction work in progress	1,085	896
Accumulated depreciation and amortization	(7,953)	(7,360)
Total plant, property, and equipment	21,039	18,926
Regulatory assets	2,653	2,489
Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	26,757	24,963	23,963
Assets under finance leases and other financing	336	340	$ 309
Construction work in progress	1,058	879
Accumulated depreciation and amortization	(7,844)	(7,272)
Total plant, property, and equipment	19,971	18,570
Plant additions	2,000	2,000
Plant retirements	220	380
Regulatory assets	$ 2,653	2,489
Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, consumers	3 years
Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, consumers	125 years
Generation | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Generation	$ 6,376	5,942
Generation | Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, generation	22 years
Generation | Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, generation	125 years
Distribution | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Distribution	$ 9,130	8,519
Distribution | Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, distribution	20 years
Distribution | Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, distribution	75 years
Transmission | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Transmission	$ 0	113
Transmission | Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, transmission	46 years
Transmission | Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, transmission	75 years
Other | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Other	$ 1,326	1,258
Other | Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	5 years
Other | Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	50 years
Assets under finance leases and other financing obligations | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Assets under finance leases and other financing	$ 323	326
Distribution | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Distribution	$ 5,702	5,235
Distribution | Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, distribution	20 years
Distribution | Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, distribution	85 years
Transmission | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Transmission	$ 2,003	1,752
Transmission | Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, transmission	17 years
Transmission | Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, transmission	75 years
Underground Storage Facilities | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Other	$ 1,046	987
Underground Storage Facilities | Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	27 years
Underground Storage Facilities | Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	75 years
Other | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Other	$ 817	797
Other | Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	5 years
Other | Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	50 years
Finance leases | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Assets under finance leases and other financing	$ 13	14
Other non-utility property | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Other non-utility property	$ 21	20
Other non-utility property | Consumers Energy Company | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	3 years
Other non-utility property | Consumers Energy Company | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	51 years
Costs of coal-fueled electric generating units to be retired | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Number of units | coal_fueled_electric_generating_unit	2
Natural Gas | Underground Storage Facilities | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Other	$ 26	26
EnerBank | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, Enterprises and EnerBank	1 year
EnerBank | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, Enterprises and EnerBank	7 years
Enterprises independent power production
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	$ 1,112	403
Enterprises independent power production | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, Enterprises and EnerBank	3 years
Enterprises independent power production | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, Enterprises and EnerBank	40 years
Enterprises Other
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	$ 1	2
Enterprises Other | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, Enterprises and EnerBank	3 years
Enterprises Other | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, Enterprises and EnerBank	5 years
Costs of coal-fueled electric generating units to be retired | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Regulatory assets	$ 678	$ 667