Plant, Property, and Equipment (Schedule Of Plant, Property, and Equipment) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross		$ 21,010	$ 18,943	$ 17,721
Construction work in progress		761	1,509
Less accumulated depreciation and amortization		(6,056)	(5,747)
Total plant, property, and equipment	[1]	15,715	14,705
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross		20,838	18,797	$ 17,580
Construction work in progress		759	1,467
Less accumulated depreciation and amortization		(5,994)	(5,676)
Total plant, property, and equipment	[1]	15,603	14,588
Public Utilities, Property Plant and Equipment Additions		2,300	1,400
Public Utilities, Property Plant and Equipment Disposals		$ 285	187
Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Consumers		5 years
Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Consumers		125 years
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing		$ 5,900	4,925
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Generation		22 years
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Generation		125 years
Electric Distribution [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution		$ 7,149	6,809
Electric Distribution [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		20 years
Electric Distribution [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		75 years
Electric Transmission [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Transmission		$ 59
Electric Transmission [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		46 years
Electric Transmission [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		75 years
Electric Other [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		$ 1,137	1,039
Electric Other [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		5 years
Electric Other [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		50 years
Electric Capital Leases [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation	[1]	$ 295	286
Gas Distribution [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution		$ 3,806	3,497
Gas Distribution [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		28 years
Gas Distribution [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		80 years
Gas Transmission [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Transmission		$ 1,124	981
Gas Transmission [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		17 years
Gas Transmission [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		75 years
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	[2]	$ 630	601
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other	[2]	29 years
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other	[2]	65 years
Gas Other [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		$ 708	630
Gas Other [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		5 years
Gas Other [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		50 years
Gas Capital Leases [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation		$ 15	14
Natural Gas [Member] | Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		26	26
Enterprises IPP [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross		$ 141	95
Enterprises IPP [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		3 years
Enterprises IPP [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		30 years
Enterprises Other [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross		$ 16	25
Enterprises Other [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		3 years
Enterprises Other [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		40 years
Other [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Other non-utility property		$ 15	26
Other [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		1 year
Other [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		7 years
Other [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Other non-utility property		$ 15	$ 15
Other [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		8 years
Other [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		51 years

[1] For the year ended December 31, 2016, Consumers' plant additions were $2.3 billion and plant retirements were $285 million. For the year ended December 31, 2015, Consumers' plant additions were $1.4 billion and plant retirements were $187 million.

[2] Underground storage includes base natural gas of $26 million at December 31, 2016 and 2015. Base natural gas is not subject to depreciation.