Leases Lease Assets & Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Capital Leased Assets [Line Items]
Property, plant and equipment, at cost	$ 8,409	$ 8,145
Accumulated depreciation	(1,480)	(1,300)
Property, Plant and Equipment, Net	6,929	$ 6,845
Finance Lease, Liability, Current	3
Finance Lease, Liability, Noncurrent	10
Finance Lease, Liability	$ 13
Finance Lease, Weighted Average Discount Rate, Percent	5.88%
Finance Lease, Weighted Average Remaining Lease Term	5 years
Leases, Operating [Abstract]
Operating Lease, Right-of-Use Asset	$ 121
Operating Lease, Liability, Current	12
Operating Lease, Liability, Noncurrent	108
Operating Lease, Liability	$ 120
Operating Lease, Weighted Average Remaining Lease Term	13 years
Operating Lease, Weighted Average Discount Rate, Percent	4.83%
Energy Equipment
Capital Leased Assets [Line Items]
Property, plant and equipment, at cost	$ 25
Accumulated depreciation	(14)
Property, Plant and Equipment, Net	$ 11