Regulatory Matters (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Regulatory Matters [Line Items]
Accrued Power Supply	$ 188
Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Reduction of income tax expense	16
Accrued Power Supply	188
Energy optimization incentive requested for exceeding savings targets		18
Electric Utility [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Income tax benefits, to be returned to customers	211
Tax benefit, distribution to customers, term	5 years
Gas Utility [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Income tax benefits, to be returned to customers	264
Tax benefit, distribution to customers, term	12 years
Gas Cost Recover (GCR) [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Accrued Power Supply	84
Power Supply Cost Recover (PSCR) [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Accrued Power Supply	$ 104