Stockholders' Deficit - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of Options
Options outstanding at beginning of period (in shares)	2.2
Granted (in shares)	0.0
Exercised (in shares)	0.2
Cancelled (in shares)	0.0
Options outstanding at end of period (in shares)	2.0	2.2
Options exercisable (in shares)	1.8
Options expected to vest (in shares)	0.2
Weighted Average Exercise Price (per share)
Options outstanding at beginning of period (in USD per share)	$ 32,890,000
Granted (in USD per share)	74,160,000
Exercised (in USD per share)	26,260,000
Cancelled (in USD per share)	41,130,000
Options outstanding at end of period (in USD per share)	33,590,000	$ 32,890,000
Options exercisable at end of period (in usd per share)	34,190,000
Options expected to vest (in USD per share)	$ 28,960,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding, Weighted Average Remaining Contract Term (Years)	5 years 3 months 18 days	6 years 2 months 12 days
Options exercisable, Weighted Average Remaining Contractual Term (Years)	5 years 1 month 6 days
Options expected to vest, Weighted Average Remaining Contract Term (years)	7 years 3 months 18 days
Options outstanding at beginning of period, Aggregate Intrinsic Value	$ 20
Exercised, Aggregate Intrinsic Value	7	$ 6	$ 15
Options outstanding at end of period, Aggregate Intrinsic Value	68	$ 20
Options exercisable, Aggregate Intrinsic Value	59
Options expected to vest, Aggregate Intrinsic Value	$ 8