Plant, Property, and Equipment (Schedule Of Plant, Property, and Equipment) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) coal_fueled_electric_generating_unit	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	$ 25,390	$ 24,400	$ 22,506
Construction work in progress	896	763
Accumulated depreciation and amortization	(7,360)	(7,037)
Total plant, property, and equipment	18,926	18,126
Regulatory assets	2,489	1,743
Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	24,963	23,963	22,318
Assets under finance leases and other financing obligations	340	309	$ 312
Construction work in progress	879	756
Accumulated depreciation and amortization	(7,272)	(6,958)
Total plant, property, and equipment	18,570	17,761
Plant additions	2,000	1,800
Plant retirements	380	190
Regulatory assets	$ 2,489	1,743
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
Independent power production1
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	$ 403	410
Independent power production1 | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	3 years
Independent power production1 | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	40 years
Other
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	$ 2	2
Other | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	3 years
Other | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	5 years
Generation | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Generation	$ 5,942	6,305
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	$ 8,519	7,957
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	$ 113	154
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	$ 1,258	1,316
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 obligations	$ 326	295
Distribution | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Distribution	$ 5,235	4,651
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	$ 1,752	1,521
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	$ 987	910
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	$ 797	823
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 obligations	$ 14	14
Other non‑utility property | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Other non‑utility property	$ 20	17
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, consumers	1 year
EnerBank | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, consumers	7 years
Costs of coal-fueled electric generating units to be retired | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Regulatory assets	$ 667	$ 0