Plant, Property, and Equipment (Schedule of Finite Lived Intangible Assets Amortization Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Public Utility, Property, Plant and Equipment [Line Items]
Amortization of Intangible Assets	$ 48	$ 39	$ 32
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Amortization of Intangible Assets	47	38	32
Software and Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Amortization of Intangible Assets	39	31	24
Software and Software Development Costs [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Amortization of Intangible Assets	39	30	24
Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Expected future amortization expense of intangible assets, per year	54
Minimum [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Expected future amortization expense of intangible assets, per year	54
Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Expected future amortization expense of intangible assets, per year	73
Maximum [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Expected future amortization expense of intangible assets, per year	$ 73