Retirement Benefits and Trusteed Assets (Pension Plan - Contributions) (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contributions to qualified pension plans	$ 185	$ 231
Qualified Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contributions to qualified pension plans	175	223	$ 179
Qualified Plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contributions to qualified pension plans	$ 175	$ 185	$ 145