Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance	$ 10	$ 10	$ 10
Additions for tax positions of prior years	0	0	0
Unrecognized tax benefits, ending balance	10	10	10
DTE Electric
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance	13	13	13
Additions for tax positions of prior years	0	0	0
Unrecognized tax benefits, ending balance	$ 13	$ 13	$ 13