Regulatory Matters (Narrative) (Details) (USD $) In Millions, unless otherwise specified			9 Months Ended				9 Months Ended				3 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Consumers Energy Company [Member]	May 31, 2014 Consumers Energy Company [Member]	Dec. 31, 2013 Consumers Energy Company [Member]	Jul. 31, 2014 Consumers Energy Company [Member] Securitization Bonds [Member]	Sep. 30, 2014 Coal-Fueled Electric Generation [Member] Consumers Energy Company [Member] site	Sep. 30, 2014 Gas-Fueled Electric Generation [Member] Consumers Energy Company [Member] site	Sep. 30, 2014 Electric Utility [Member] Consumers Energy Company [Member]	Sep. 30, 2014 Gas Utility [Member] Consumers Energy Company [Member]	Mar. 31, 2014 Gas Cost Recover (GCR) [Member] Consumers Energy Company [Member]	Sep. 30, 2014 Gas Cost Recover (GCR) [Member] Consumers Energy Company [Member]	Sep. 30, 2014 Power Supply Cost Recover (PSCR) [Member] Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Income tax benefits, to be returned to customers									$ 209	$ 260
Tax benefit, distribution to customers, term									5 years	12 years
Reduction of income tax expense			30
Accrued Power Supply	109		109									62	47
Over (under) recovery requested											(84)
Energy optimization incentive requested for exceeding savings targets					18
Requested recovery				11
Long-term debt	$ 8,042	$ 7,101	$ 5,230		$ 4,579	$ 378
Number of units planned to be retired							7	3