Retirement Benefits and Trusteed Assets (OPEB - Benefits related to Qualified and Nonqualified Pension Plans Expected to be paid in the Next Ten Years) (Details) - Other postretirement benefit plan $ in Millions	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
2019	$ 88
2020	92
2021	96
2022	100
2023	102
2024-2028	532
Total	1,010
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
2019	66
2020	70
2021	73
2022	75
2023	77
2024-2028	402
Total	$ 763