Leases (Other Information) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Cash paid for amounts included in the measurement of these liabilities:
Operating cash flows from finance leases	$ 4
Operating cash flows from operating leases	30
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 37
Weighted Average Remaining Lease Term
Operating leases	9 years 8 months 12 days
Finance leases	2 years 3 months 18 days
Weighted Average Discount Rate
Operating leases	3.70%
Finance leases	3.10%
DTE Electric
Cash paid for amounts included in the measurement of these liabilities:
Operating cash flows from finance leases	$ 4
Operating cash flows from operating leases	11
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 2
Weighted Average Remaining Lease Term
Operating leases	10 years 7 months 6 days
Finance leases	2 years 3 months 18 days
Weighted Average Discount Rate
Operating leases	3.70%
Finance leases	3.10%