Income Taxes (Principal Components Of Deferred Income Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Deferred income tax assets
Tax loss and credit carryforwards	$ 385	$ 332
Net regulatory tax liability	318	349
Reserves and accruals	35	32
Total deferred income tax assets	738	713
Valuation allowance	(2)	(2)
Total deferred income tax assets, net of valuation allowance	736	711
Deferred income tax liabilities
Plant, property, and equipment	(2,515)	(2,395)
Employee benefits	(433)	(399)
Gas inventory	(53)	(22)
Securitized costs	(39)	(46)
Other	(103)	(59)
Total deferred income tax liabilities	(3,143)	(2,921)
Total net deferred income tax liabilities	(2,407)	(2,210)
Consumers Energy Company
Deferred income tax assets
Tax loss and credit carryforwards	145	134
Net regulatory tax liability	318	349
Reserves and accruals	28	24
Total deferred income tax assets, net of valuation allowance	491	507
Deferred income tax liabilities
Plant, property, and equipment	(2,458)	(2,341)
Employee benefits	(423)	(388)
Gas inventory	(53)	(22)
Securitized costs	(39)	(46)
Other	(103)	(50)
Total deferred income tax liabilities	(3,076)	(2,847)
Total net deferred income tax liabilities	$ (2,585)	$ (2,340)