Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Prepaid merchant bookings	$ 846	$ 581
Deferred merchant bookings	9,203	5,688
Deferred revenue	178	166
Deferred Merchant Bookings
Disaggregation of Revenue [Line Items]
Deferred merchant bookings	8,400	4,900
Deferred merchant bookings recognized during period	2,500
Revenue recognized during period	393
Deferred Loyalty Rewards
Disaggregation of Revenue [Line Items]
Deferred merchant bookings	831	798
Revenue recognized during period	144
Deferred Revenue
Disaggregation of Revenue [Line Items]
Revenue recognized during period	70
Deferred revenue	$ 178	$ 166