Significant Accounting Policies - Contract Balances (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Change in Contract with Customer, Liability [Roll Forward]
Contract liabilities, beginning of the period	$ 71	$ 87
Rewards earnings and gift card issuances	250	250
Redemption and breakage	(267)	(263)
Acquired contract liabilities	109	0
Other	4	0
Contract liabilities, end of the period	$ 167	$ 74