Other Income and Other Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Income and Expenses [Line Items]
Donations	$ (3)	$ (13)	$ (31)
Civic and political expenditures	(6)	(6)	(27)
Loss on reacquired and extinguished debt	0	(16)	(18)
All other	(4)	(13)	0
Total other expense	(13)	(48)	(76)
Consumers Energy Company
Other Income and Expenses [Line Items]
Gain on CMS Energy common stock			14
Donations	(3)	(13)	(31)
Civic and political expenditures	(6)	(6)	(27)
All other	(4)	(11)	0
Total other expense	$ (13)	$ (30)	$ (58)