Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net loss arising during the period TAX	$ (3)	$ (1)	$ (4)
Prior service credit adjustment TAX	0	0	3
Amortization of net actuarial loss TAX	(1)	(1)	(1)
Amortization of prior service credit TAX	0	(1)	0
Unrealized loss on derivative instruments TAX	1	0
Unrealized loss on derivative instruments TAX			0
Reclassification adjustments included in net income TAX	0
Reclassification adjustments included in net income TAX		0	0
Consumers Energy Company
Net loss arising during the period TAX	(3)	2	(1)
Amortization of net actuarial loss TAX	0	0	0
Unrealized gain on investments TAX	0	0	1
Reclassification adjustments included in net income TAX	$ 0	$ 0	$ (6)