Retirement Benefits and Trusteed Assets (OPEB - Accumulated Postretirement Obligations in Excess of Plan Assets) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Accumulated postretirement benefit obligation	$ 530	$ 628
Fair value of plan assets	296	326
Accumulated postretirement benefit obligation in excess of plan assets	234	302
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Accumulated postretirement benefit obligation	501	592
Fair value of plan assets	276	302
Accumulated postretirement benefit obligation in excess of plan assets	$ 225	$ 290