Retirement Benefits and Trusteed Assets (Net Other Postretirement Credit) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 15	$ 18	$ 17
Interest cost	61	62	65
Expected return on plan assets	(117)	(120)	(111)
Amortization of:
Net actuarial loss	2	6	10
Prior service credit	0	(10)	(19)
Net pension/other postretirement cost (credit)	(39)	(44)	(38)
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	11	14	13
Interest cost	46	47	49
Expected return on plan assets	(77)	(79)	(73)
Amortization of:
Net actuarial loss	(2)	1	1
Prior service credit	0	(6)	(14)
Net pension/other postretirement cost (credit)	$ (22)	$ (23)	$ (24)