Other Financial Data - Schedule of Other Current Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Financial Data [Abstract]
Costs to fulfill contracts with customers	$ 339	$ 335
Taxes receivable	95	88
Prepaid expenses	111	97
Other	79	82
Total	$ 624	602
Receivables from divested business		$ 4