Income Taxes - Components of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Provision for accrued expenses	$ 47	$ 42
Deferred loyalty rewards	217	204
Net operating loss and tax credit carryforwards	130	314
Property and equipment	25	23
Capitalized research and development	391	325
Operating lease liabilities	118	130
Long-term investments	108	168
Other	59	79
Total deferred tax assets	1,095	1,285
Less valuation allowance	(176)	(244)
Net deferred tax assets	919	1,041
Deferred tax liabilities:
Goodwill and intangible assets	(308)	(345)
Anticipatory foreign tax credits	(17)	(16)
Operating lease ROU assets	(115)	(127)
Other	(2)	0
Total deferred tax liabilities	(442)	(488)
Net deferred tax assets	$ 477	$ 553