Leases Assets subject to contracts accounted for as operating leases (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment, Gross		$ 18,354	$ 18,187
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		(6,851)	(6,832)
Property, Plant and Equipment, Net		11,963	$ 12,442
Property Subject to Operating Lease [Member]
Property, Plant and Equipment, Gross		2,561
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		(770)
Property, Plant and Equipment, Net	[1]	$ 1,791

[1] Our assets subject to contracts that are accounted for as operating leases primarily consist of our power plants subject to tolling contracts.