Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income (Loss)	$ 68	$ 84	$ 270	$ 288
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1	1	2	1
Investments
Unrealized gain (loss) on investments, net of tax	(1)		(1)
Derivative Instruments
Reclassification adjustments included in net income, net of tax				1
Other Comprehensive Income (Loss)		1	1	2
Comprehensive Income	68	85	271	290
Comprehensive Income Attributable to Noncontrolling Interest	1	1	1	1
Comprehensive Income Attributable to CMS Energy	67	84	270	289
Consumers Energy Company [Member]
Net Income (Loss)	84	109	299	330
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1	1	2	1
Investments
Unrealized gain (loss) on investments, net of tax	(2)	1	(2)	3
Reclassification adjustments included in net income, net of tax			(5)
Derivative Instruments
Other Comprehensive Income (Loss)	(1)	2	(5)	4
Comprehensive Income Attributable to CMS Energy	$ 83	$ 111	$ 294	$ 334