Plant, Property, and Equipment (Schedule Of Plant, Property, and Equipment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	$ 24,400	$ 22,506	$ 21,010
Construction work in progress	763	765
Accumulated depreciation and amortization	(7,037)	(6,510)
Total plant, property, and equipment	18,126	16,761
Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	23,963	22,318	$ 20,838
Construction work in progress	756	753
Accumulated depreciation and amortization	(6,958)	(6,441)
Total plant, property, and equipment	17,761	16,630
Plant additions	1,800	1,700
Plant retirements	$ 190	214
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 production
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	$ 410	163
Independent power production | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	3 years
Independent power production | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	35 years
Other
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross	$ 2	4
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
Other non‑utility property
Public Utility, Property, Plant and Equipment [Line Items]
Other	$ 25	21
Other non‑utility property | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	1 year
Other non‑utility property | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated depreciable life in years, other	7 years
Other non‑utility property | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Other	$ 17	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
Generation | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Generation	$ 6,305	6,025
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	$ 7,957	7,603
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	$ 154	66
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	$ 1,316	1,229
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 capital leases and financing obligation | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation	$ 295	298
Distribution | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Distribution	$ 4,651	4,182
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	$ 1,521	1,278
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	$ 910	842
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	$ 823	764
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
Capital Leases | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation	$ 14	14
Natural Gas | Underground Storage Facilities | Consumers Energy Company
Public Utility, Property, Plant and Equipment [Line Items]
Other	$ 26	$ 26