Retirement Benefits and Trusteed Assets (OPEB - Postretirement Cost Inclusions) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 17	$ 27	$ 30
Interest cost	65	48	46
Expected return on plan assets	(111)	(126)	(129)
Amortization of:
Net actuarial loss	10	4	13
Prior service credit	(19)	(19)	(19)
Net pension/other postretirement cost (credit)	(38)	(66)	(59)
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	13	20	23
Interest cost	49	37	35
Expected return on plan assets	(73)	(85)	(86)
Amortization of:
Net actuarial loss	1	5	11
Prior service credit	(14)	(14)	(14)
Net pension/other postretirement cost (credit)	$ (24)	$ (37)	$ (31)