Leases (Other Information) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Cash paid for amounts included in the measurement of these liabilities:
Operating cash flows from finance leases	$ 1
Operating cash flows from operating leases	10
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 11
Weighted Average Remaining Lease Term
Operating leases	9 years 1 month 6 days
Finance leases	2 years 8 months 12 days
Weighted Average Discount Rate
Operating leases	3.80%
Finance leases	3.00%
DTE Electric
Cash paid for amounts included in the measurement of these liabilities:
Operating cash flows from finance leases	$ 1
Operating cash flows from operating leases	3
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 0
Weighted Average Remaining Lease Term
Operating leases	10 years 4 months 24 days
Finance leases	2 years 8 months 12 days
Weighted Average Discount Rate
Operating leases	3.60%
Finance leases	3.00%