Other Financial Information - Other Noncurrent Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred Credits and Other Liabilities [Abstract]
Unrecognized tax benefits	$ 448	$ 454
Deferred revenue	108	108
Operating	76	89
Other	53	61
Total other noncurrent liabilities	$ 685	$ 712