Retirement Benefits and Trusteed Assets (OPEB - Postretirement Cost Inclusions) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 30	$ 26	$ 22
Interest cost	46	56	70
Expected return on plan assets	(129)	(128)	(96)
Amortization of:
Net actuarial loss	13	16	12
Prior service credit	(19)	(19)	(9)
Net pension cost/other postretirement cost (credit)	(59)	(49)	(1)
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	23	20	16
Interest cost	35	43	53
Expected return on plan assets	(86)	(87)	(65)
Amortization of:
Net actuarial loss	11	11	5
Prior service credit	(14)	(14)	(7)
Net pension cost/other postretirement cost (credit)	$ (31)	$ (27)	$ 2