Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income	$ 169	$ 172	$ 550	$ 464
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax of $- for all periods	1	0	3	1
Amortization of prior service credit	0	0	(1)	0
Investments
Unrealized gain (loss) on investments	0	1	(1)	2
Reclassification adjustments included in net income	1	0	1	0
Other Comprehensive Income	2	1	2	3
Comprehensive Income	171	173	552	467
Comprehensive Income Attributable to Noncontrolling Interests	0	0	1	1
Comprehensive Income Attributable to CMS Energy	171	173	551	466
Consumers Energy Company
Net income	180	181	574	496
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax of $- for all periods	1	0	2	1
Investments
Unrealized gain (loss) on investments	0	0	(1)	2
Reclassification adjustments included in net income	1	0	1	(8)
Other Comprehensive Income	2	0	2	(5)
Comprehensive Income	$ 182	$ 181	$ 576	$ 491