Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Net Income	$ 202us-gaap_ProfitLoss	$ 204us-gaap_ProfitLoss
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1
Derivative Instruments
Reclassification adjustments included in net income, net of tax		1
Other Comprehensive Income (Loss)	1	1
Comprehensive Income	203us-gaap_ComprehensiveIncomeNetOfTax	205us-gaap_ComprehensiveIncomeNetOfTax
Consumers Energy Company [Member]
Net Income	215	221
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1
Investments
Unrealized gain (loss) on investments, net of tax		2
Reclassification adjustments included in net income, net of tax	(5)
Derivative Instruments
Other Comprehensive Income (Loss)	(4)	2
Comprehensive Income	$ 211	$ 223

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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