Significant Accounting Policies (Schedule of Other Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity in earnings of equity method investees	$ 132	$ 102	$ 68
Income from REF entities	98	77	75
Contract services	51	19	21
Allowance for equity funds used during construction	28	23	21
Gains from trading securities	6	26	15
Other	18	21	7
Other income	333	268	207
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Contract services	51	21	20
Allowance for equity funds used during construction	19	18	18
Gains from trading securities	6	26	15
Other	7	12	8
Other income	$ 83	$ 77	$ 61