Significant Accounting Policies (Schedule of Other Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Other Nonoperating Income, by Component [Line Items]
Income from REF entities	$ 139	$ 130	$ 98
Equity in earnings of equity method investees	132	111	132
Gains from rabbi trust securities	28	37	6
Contract services	28	29	51
Allowance for equity funds used during construction	25	24	28
Gas Storage and Pipelines post-acquisition settlement	20	0	0
Other	16	19	18
Other income	388	350	333
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Gains from rabbi trust securities	28	37	6
Contract services	28	32	51
Allowance for equity funds used during construction	23	22	19
Other	8	16	7
Other income	$ 87	$ 107	$ 83