Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net Income	$ 93	$ 125	$ 292	$ 289
Retirement Benefits Liability
Amortization of net actuarial loss	1	1	1	1
Amortization of prior service credit, net of tax		(1)		(1)
Investments
Unrealized gain (loss) on investments, net of tax			1
Other Comprehensive Income	1		2
Comprehensive Income	94	125	294	289
Comprehensive Income Attributable to Noncontrolling Interest	1	1	1	1
Comprehensive Income Attributable to CMS Energy	93	124	293	288
Consumers Energy Company [Member]
Net Income	104	132	315	304
Retirement Benefits Liability
Amortization of net actuarial loss	1		1
Investments
Unrealized gain (loss) on investments, net of tax		2	2	5
Reclassification adjustments included in net income, net of tax			(8)
Other Comprehensive Income	1	2	(5)	5
Comprehensive Income Attributable to CMS Energy	$ 105	$ 134	$ 310	$ 309