Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income	$ 186	$ 148	$ 475	$ 418
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1	2	2	4
Amortization of prior service credit, net of tax		(1)	(1)	(1)
Investments
Unrealized gain (loss) on investments	1	(2)	1	(3)
Other Comprehensive Income (Loss)	2	(1)	2
Comprehensive Income	188	147	477	418
Comprehensive Income Attributable to Noncontrolling Interest			1	1
Comprehensive Income Attributable to CMS Energy	188	147	476	417
Consumers Energy Company [Member]
Net income	195	160	499	459
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax		1		3
Investments
Unrealized gain (loss) on investments	(2)		3	(2)
Reclassification adjustments included in net income, net of tax				(5)
Other Comprehensive Income (Loss)	(2)	1	3	(4)
Comprehensive Income Attributable to CMS Energy	$ 193	$ 161	$ 502	$ 455