Significant Accounting Policies - Contract Balances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Change in Contract with Customer, Liability [Roll Forward]
Contract liabilities, beginning of period	$ 71	$ 87
Rewards earnings and gift card issuances	357	340
Redemption and breakage	(363)	(356)
Acquired contract liabilities	109	0
Other	(25)	0
Contract liabilities, end of period	$ 149	$ 71