Goodwill and Intangible Assets, Net - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Goodwill [Line Items]
Impairment of goodwill					$ 0	$ 297	$ 0
Accumulated goodwill impairment loss	$ 3,600		$ 3,600		3,600	3,600
Amortization of intangible assets					57	59	88
Trade Names
Goodwill [Line Items]
Impairment of indefinite-lived intangible assets					147	129
Trivago
Goodwill [Line Items]
Impairment of goodwill						297
Accumulated goodwill impairment loss	537		537		537	537
Trivago | Trade Names
Goodwill [Line Items]
Impairment of indefinite-lived intangible assets		$ 33		$ 15		15	$ 81
B2C
Goodwill [Line Items]
Impairment of goodwill						0
Accumulated goodwill impairment loss	3,000		3,000		3,000	3,000
B2C | Trade Names
Goodwill [Line Items]
Impairment of indefinite-lived intangible assets	114		114			114
B2B
Goodwill [Line Items]
Impairment of goodwill						0
Accumulated goodwill impairment loss	$ 14		$ 14		$ 14	$ 14