Leases (Other Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of these liabilities:
Operating cash flows for finance leases	$ 3	$ 5
Operating cash flows for operating leases	40	40
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	18	68
Finance leases	$ 19	$ 8
Weighted Average Remaining Lease Term (Years)
Operating leases	9 years 3 months 18 days	9 years 8 months 12 days
Finance leases	7 years 7 months 6 days	9 years 1 month 6 days
Weighted Average Discount Rate
Operating leases	3.40%	3.50%
Finance leases	2.00%	3.10%
DTE Electric
Cash paid for amounts included in the measurement of these liabilities:
Operating cash flows for finance leases	$ 2	$ 5
Operating cash flows for operating leases	14	16
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	0	27
Finance leases	$ 14	$ 0
Weighted Average Remaining Lease Term (Years)
Operating leases	10 years 4 months 24 days	10 years 7 months 6 days
Finance leases	3 years 1 month 6 days	2 years
Weighted Average Discount Rate
Operating leases	3.30%	3.30%
Finance leases	1.00%	3.10%