Plant, Property, and Equipment (Schedule of Finite-Lived Intangible Assets by Major Class Table) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	$ 909	[1]	$ 855	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	280		269
Public Utilities, Property Plant and Equipment Additions	1,300		999
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	906	[1]	853	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	279		269
Public Utilities, Property Plant and Equipment Additions	1,300		999
Software and Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Computer Software, Gross	508	[1]	466	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	174		172
Software and Software Development Costs [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Computer Software, Gross	506	[1]	464	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	173		172
Plant Acquisition Adjustments [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Plant Adjustments for Intangible Utility Plants	216	[1]	214	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	32		27
Plant Acquisition Adjustments [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Plant Adjustments for Intangible Utility Plants	216	[1]	214	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	32		27
Leasehold Improvements [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Leasehold Improvements, Gross	14	[1]	13	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	11		10
Leasehold Improvements [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Leasehold Improvements, Gross	14	[1]	13	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	11		10
Intangible Plant [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property Plant and Equipment Additions	53		108
Rights of Way [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Contractual Rights, Gross	135	[1]	130	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	42		40
Rights of Way [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Contractual Rights, Gross	135	[1]	130	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	42		40
Franchises and Consents [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	15	[1]	14	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	7		6
Franchises and Consents [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	15	[1]	14	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	7		6
Other Intangibles [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Other Finite-Lived Intangible Assets, Gross	21	[1]	18	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	14		14
Other Intangibles [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Other Finite-Lived Intangible Assets, Gross	20	[1]	18	[1]
Finite-Lived Intangible Assets, Accumulated Amortization	$ 14		$ 14
Minimum [Member] | Software and Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Minimum [Member] | Software and 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] | Plant Acquisition Adjustments [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life	40 years
Minimum [Member] | Plant Acquisition Adjustments [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life	40 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 and Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years
Maximum [Member] | Software and 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] | Plant Acquisition Adjustments [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life	46 years
Maximum [Member] | Plant Acquisition Adjustments [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life	46 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] Net intangible asset additions for Consumers’ utility plant were $53 million during 2013 and $108 million during 2012 and primarily represented software development costs.