Significant Accounting Policies (Other Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity earnings of equity method investees	$ 41	$ 30	$ 73	$ 59
Income from REF entities	21	29	45	52
Contract services	7	6	15	13
Allowance for equity funds used during construction	6	7	13	13
Gains from rabbi trust securities	2	22	4	22
Other	6	7	9	7
Total other income	83	101	159	166
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Contract services	7	6	15	13
Allowance for equity funds used during construction	6	6	12	12
Gains from rabbi trust securities	2	22	4	22
Other	4	3	7	3
Total other income	$ 19	$ 37	$ 38	$ 50