Plant, Property, and Equipment (Schedule of Finite-Lived Intangible Assets by Major Class Table) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	$ 1,052	$ 930
Finite-Lived Intangible Assets, Accumulated Amortization		444	368
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	1,043	925
Finite-Lived Intangible Assets, Accumulated Amortization		440	365
Public Utilities, Property Plant and Equipment Additions		2,300	1,400
Public Utilities, Property Plant and Equipment Disposals		285	187
Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	853	734
Finite-Lived Intangible Assets, Accumulated Amortization		367	294
Software Development Costs [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	845	729
Finite-Lived Intangible Assets, Accumulated Amortization		363	291
Leasehold Improvements [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1],[2]	7	7
Finite-Lived Intangible Assets, Accumulated Amortization	[2]	6	5
Leasehold Improvements [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1],[2]	7	7
Finite-Lived Intangible Assets, Accumulated Amortization	[2]	6	5
Intangible Plant [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property Plant and Equipment Additions		141	140
Public Utilities, Property Plant and Equipment Disposals		23
Rights of Way [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	155	153
Finite-Lived Intangible Assets, Accumulated Amortization		48	46
Rights of Way [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	155	153
Finite-Lived Intangible Assets, Accumulated Amortization		48	46
Franchises and Consents [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	15	15
Finite-Lived Intangible Assets, Accumulated Amortization		8	8
Franchises and Consents [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	15	15
Finite-Lived Intangible Assets, Accumulated Amortization		8	8
Other Intangible Assets [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	22	21
Finite-Lived Intangible Assets, Accumulated Amortization		15	15
Other Intangible Assets [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	21	21
Finite-Lived Intangible Assets, Accumulated Amortization		$ 15	$ 15
Minimum [Member] | Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		1 year
Minimum [Member] | Software Development Costs [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		3 years
Minimum [Member] | Rights of Way [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		50 years
Minimum [Member] | Rights of Way [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		50 years
Minimum [Member] | Franchises and Consents [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		5 years
Minimum [Member] | Franchises and Consents [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		5 years
Maximum [Member] | Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		15 years
Maximum [Member] | Software Development Costs [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		15 years
Maximum [Member] | Rights of Way [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		75 years
Maximum [Member] | Rights of Way [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		75 years
Maximum [Member] | Franchises and Consents [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		30 years
Maximum [Member] | Franchises and Consents [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		30 years

[1] For the year ended December 31, 2016, Consumers' intangible asset additions were $141 million and intangible asset retirements were $23 million. For the year ended December 31, 2015, Consumers' intangible asset additions were $140 million and there were no retirements.

[2] Leasehold improvements are amortized over the life of the lease, which may change whenever the lease is renewed or extended.