Significant Accounting Policies (Other Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity earnings of equity method investees	$ 30	$ 20	$ 59	$ 43
Income from REF entities	29	29	52	56
Gains from equity and fixed income securities	22	7	22	24
Allowance for equity funds used during construction	7	6	13	13
Contract services	6	6	13	14
Other	7	5	7	11
Total other income	101	73	166	161
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Gains from equity and fixed income securities	22	7	22	24
Allowance for equity funds used during construction	6	6	12	12
Contract services	6	8	13	16
Other	3	4	3	6
Total other income	$ 37	$ 25	$ 50	$ 58