Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Disaggregation of Revenue [Line Items]
Prepaid merchant bookings	$ 457	$ 319
Deferred merchant bookings	12,915	8,517
Deferred revenue	176	164
Deferred Merchant Bookings
Disaggregation of Revenue [Line Items]
Deferred merchant bookings	11,900	7,600
Deferred merchant bookings recognized during period	4,300
Revenue recognized during period	574
Deferred Loyalty Rewards
Disaggregation of Revenue [Line Items]
Deferred merchant bookings	985	937
Revenue recognized during period	190
Deferred Revenue
Disaggregation of Revenue [Line Items]
Revenue recognized during period	75
Deferred revenue	$ 176	$ 164