Leases Leases (Details Textuals) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($) agreement	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Lessee, Lease, Description [Line Items]
Term of finance lease contract	20 years	20 years
Finance lease contract, renewal option extension term	5 years	5 years
Percent ownership interest in Vector Pipeline	40.00%	40.00%
Depreciation expense associated with property under operating leases	$ 5	$ 13
Interest income recognized under finance leases	$ 1	$ 2
Contingent rental revenues			$ 107	$ 91	$ 101
Pipeline System Lease
Lessee, Lease, Description [Line Items]
Percent ownership interest in Vector Pipeline			40.00%
Lessor capital lease renewal terms			5 years
Number of energy services agreements | agreement			2
Minimum
Lessee, Lease, Description [Line Items]
Lease terms		2 years
Term of operating lease contracts	3 years	3 years
Maximum
Lessee, Lease, Description [Line Items]
Lease terms		40 years
Term of operating lease contracts	24 years	24 years
DTE Electric | Minimum
Lessee, Lease, Description [Line Items]
Lease terms		2 years
DTE Electric | Maximum
Lessee, Lease, Description [Line Items]
Lease terms		40 years