Leases (Other Information) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Cash paid for amounts included in the measurement of these liabilities:
Operating cash flows from finance leases	$ 3
Operating cash flows from operating leases	19
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 22
Weighted Average Remaining Lease Term
Operating leases	9 years 10 months 24 days
Finance leases	2 years 6 months
Weighted Average Discount Rate
Operating leases	3.80%
Finance leases	3.10%
DTE Electric
Cash paid for amounts included in the measurement of these liabilities:
Operating cash flows from finance leases	$ 3
Operating cash flows from operating leases	7
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 1
Weighted Average Remaining Lease Term
Operating leases	10 years 4 months 24 days
Finance leases	2 years 6 months
Weighted Average Discount Rate
Operating leases	3.70%
Finance leases	3.10%