Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net Income	$ 171	$ 137	$ 513	$ 380
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	3	1	4	2
Amortization of prior service credit	(1)	(1)	(1)	(1)
Derivatives
Unrealized gain (loss) on derivative instruments, net of tax of $—, $—, $—, and $(1)	0	0	1	(4)
Reclassification adjustments included in net income, net of tax of $1, $—, $1, and $—	0	0	0	0
Other Comprehensive Income (Loss)	2	0	4	(3)
Comprehensive Income	173	137	517	377
Comprehensive Income (Loss) Attributable to Noncontrolling Interests	(5)	1	(12)	1
Comprehensive Income Attributable to CMS Energy	178	136	529	376
Consumers Energy Company
Net Income	190	160	526	395
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1	0	1	0
Derivatives
Other Comprehensive Income (Loss)	1	0	1	0
Comprehensive Income	$ 191	$ 160	$ 527	$ 395