Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Summary of Significant Accounting Policies
Period to amortize assets recognized related to costs to obtain subscriber contract	1 year
Contract cost capitalized during the period	$ 21	$ 28
Amortization expense related to the programs	41	$ 37
Total costs capitalized	$ 278		$ 298