Property, Plant and Equipment (Table of Property and Equipment, net) (Parenthetical) (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Other property and equipment, net	[1]	$ 957	$ 1,035
CDM [Member]
Property Plant And Equipment [Line Items]
Other property and equipment, net		$ 102	$ 80

[1] $102 million and $80 million related to CDM in 2020 and 2019, respectively