Other Financial Information - Other Current Assets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 50	$ 40
Contract acquisition costs	43	47
Contract fulfillment costs	31	28
Receivable In Like-Kind Exchange	56	0
Other	7	7
Total other current assets	187	122
Other	$ 670	$ 685