Leases (Finance Leases Reported on Consolidated Statements of Financial Position) (Details) $ in Millions	Mar. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Right-of-use assets, within Property, plant, and equipment, net	$ 10
Current lease liabilities, within Current Liabilities — Other	4
DTE Electric
Lessee, Lease, Description [Line Items]
Right-of-use assets, within Property, plant, and equipment, net	10
Current lease liabilities, within Current Liabilities — Other	$ 4