Other Financial Information (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 108	$ 106
Contract assets	29	34
Other	9	47
Total other current assets	238	297
Fulfillment Costs
Prepaid Expense and Other Assets, Current [Abstract]
Contract costs	48	63
Acquisition Costs
Prepaid Expense and Other Assets, Current [Abstract]
Contract costs	$ 44	$ 47