Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net Income	$ 84	$ 81	$ 288	$ 225
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1	1	1	2
Investments
Unrealized gain (loss) on investments, net of tax		(3)		(3)
Derivative Instruments
Reclassification adjustments included in net income, net of tax			1
Other Comprehensive Income (Loss)	1	(2)	2	(1)
Comprehensive Income	85	79	290	224
Comprehensive Income Attributable to Noncontrolling Interest	1	1	1	1
Comprehensive Income Attributable to CMS Energy	84	78	289	223
Consumers Energy Company [Member]
Net Income	109	100	330	262
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1	1	1	2
Investments
Unrealized gain (loss) on investments, net of tax	1	(4)	3
Reclassification adjustments included in net income, net of tax				(3)
Derivative Instruments
Other Comprehensive Income (Loss)	2	(3)	4	(1)
Comprehensive Income	$ 111	$ 97	$ 334	$ 261