Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net Income	$ 241	$ 199
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1
Investments
Unrealized gain (loss) on investments, net of tax	(1)	1
Other Comprehensive Income (Loss)		1
Comprehensive Income	241	200
Consumers Energy Company [Member]
Net Income	242	211
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1
Investments
Unrealized gain (loss) on investments, net of tax	(1)	2
Reclassification adjustments included in net income		(8)
Other Comprehensive Income (Loss)		(6)
Comprehensive Income	$ 242	$ 205