Retirement Benefits and Trusteed Assets (OPEB - Accumulated Postretirement Obligations in Excess of Plan Assets) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Accumulated postretirement benefit obligation	$ 628	$ 625
Fair value of plan assets	326	338
Accumulated postretirement benefit obligation in excess of plan assets	302	287
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Accumulated postretirement benefit obligation	592	591
Fair value of plan assets	302	316
Accumulated postretirement benefit obligation in excess of plan assets	$ 290	$ 275