Retirement Benefits and Trusteed Assets (Accumulated Postretirement Benefit Obligations in Excess of Plan Assets) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Accumulated postretirement benefit obligation	$ 541	$ 530
Fair value of plan assets	293	296
Accumulated postretirement benefit obligation in excess of plan assets	248	234
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Accumulated postretirement benefit obligation	510	501
Fair value of plan assets	273	276
Accumulated postretirement benefit obligation in excess of plan assets	$ 237	$ 225