Other Income and Other Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other income
Fee income	$ 0	$ 0	$ 6
All other	2	6	2
Total other income	2	6	8
Other expense
Donations	(13)	(31)	(23)
Civic and political expenditures	(6)	(27)	(21)
Loss on reacquired and extinguished debt	(16)	(18)	(18)
Unrealized investment loss	0	0	(5)
All other	(13)	0	(8)
Total other expense	(48)	(76)	(75)
Consumers Energy Company
Other income
Fee income	0	0	6
All other	2	3	2
Total other income	2	17	8
Available-for-sale Securities, Gross Realized Gains	0	14	0
Other expense
Donations	(13)	(31)	(23)
Civic and political expenditures	(6)	(27)	(21)
Unrealized investment loss	0	0	(4)
All other	(11)	0	(7)
Total other expense	$ (30)	$ (58)	$ (55)