Segment Information - Revenue by Business Model and Service Type (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Revenue	$ 2,209	$ 2,609
Lodging
Segment Reporting Information [Line Items]
Revenue	1,518	1,687
Air
Segment Reporting Information [Line Items]
Revenue	109	248
Advertising and media
Segment Reporting Information [Line Items]
Revenue	203	265
Other
Segment Reporting Information [Line Items]
Revenue	379	409
Sales Channel, Through Intermediary \| Merchant
Segment Reporting Information [Line Items]
Revenue	1,340	1,435
Sales Channel, Through Intermediary \| Agency
Segment Reporting Information [Line Items]
Revenue	562	842
Sales Channel, Through Intermediary \| Advertising, media and other
Segment Reporting Information [Line Items]
Revenue	$ 307	$ 332

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration