Significant Accounting Policies (Schedule of Other Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity in earnings of equity method investees	$ 102	$ 68	$ 66
Income from REF entities	77	75	83
Gains from trading securities	26	15	1
Allowance for equity funds used during construction	23	21	21
Contract services	19	21	27
Other	21	7	11
Other income	268	207	209
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity in earnings of equity method investees	1	2	2
Gains from trading securities	26	15	1
Allowance for equity funds used during construction	18	18	20
Contract services	21	20	27
Other	11	6	10
Other income	$ 77	$ 61	$ 60