Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net Income	$ 183	$ 210	$ 696	$ 590
Retirement Benefits Liability
Net loss arising during the period, net of tax	0	(5)	0	(5)
Settlement arising during the period, net of tax	0	1	0	1
Amortization of net actuarial loss, net of tax	1	1	5	3
Amortization of prior service credit	0	0	(1)	(1)
Derivatives
Unrealized gain (loss) on derivative instruments, net of tax of $—, $—, $—, and $(1)	0	(1)	1	(5)
Reclassification adjustments included in net income, net of tax of $—, $—, $1, and $—	0	1	0	1
Other Comprehensive Income (Loss)	1	(3)	5	(6)
Comprehensive Income	184	207	701	584
Comprehensive Loss Attributable to Noncontrolling Interests	(6)	(8)	(18)	(7)
Comprehensive Income Attributable to CMS Energy	190	215	719	591
Consumers Energy Company
Net Income	186	230	712	625
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1	1	2	1
Derivatives
Other Comprehensive Income (Loss)	1	1	2	1
Comprehensive Income	$ 187	$ 231	$ 714	$ 626