Supplementary Financial Information - Other Long-Term Assets (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Capitalized Computer Software, Net	$ 147	$ 150
Deferred Costs, Noncurrent	76	84
Product Software, Net	50	40
Other Assets, Miscellaneous, Noncurrent	111	113
Other long-term assets	$ 384	$ 387