Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

GOODWILL, INTANGIBLE ASSETS AND OTHER LONG-LIVED ASSETS - Goodwill (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Goodwill
Impairment of goodwill	$ 0		$ 0		$ 0	$ 489
Cumulative impairment charges	$ 2,000				$ 2,000		$ 2,000
OpenTable And KAYAK
Goodwill
Impairment of goodwill		$ 573		$ 489