Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Prepaid merchant bookings	$ 493	$ 365
Deferred merchant bookings	11,392	7,723
Deferred revenue	177	164
Deferred Merchant Bookings
Disaggregation of Revenue [Line Items]
Deferred merchant bookings	10,500	6,900
Deferred merchant bookings recognized during period	3,900
Revenue recognized during period	555
Deferred Loyalty Rewards
Disaggregation of Revenue [Line Items]
Deferred merchant bookings	875	871
Revenue recognized during period	198
Deferred Revenue
Disaggregation of Revenue [Line Items]
Revenue recognized during period	76
Deferred revenue	$ 177	$ 164