Significant Accounting Policies (Other Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity earnings of equity method investees	$ 37	$ 34	$ 96	$ 77
Income from REF entities	43	40	95	96
Gains from equity and fixed income securities	2	3	24	27
Contract services	7	7	20	21
Gas Storage and Pipelines post-acquisition settlement	20	0	20	0
Allowance for equity funds used during construction	6	5	19	18
Other	5	9	12	20
Total other income	120	98	286	259
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Gains from equity and fixed income securities	2	3	24	27
Contract services	7	7	20	23
Allowance for equity funds used during construction	6	5	18	17
Other	3	5	6	11
Total other income	$ 18	$ 20	$ 68	$ 78