Significant Accounting Policies - Contract Balances (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Change in Contract with Customer, Liability [Roll Forward]
Contract liabilities, beginning of the period	$ 71	$ 87
Rewards earnings and gift card issuances	165	175
Redemption and breakage	(180)	(182)
Acquired contract liabilities	104	0
Other	1	0
Contract liabilities, end of the period	$ 161	$ 80