Area of a real estate property.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
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- Definition

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Term of lessee's operating lease not yet commenced, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Details

Name:	us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis=bkng_HeadquartersMember
Namespace Prefix:
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- Details

Name:	srt_StatementGeographicalAxis=bkng_ManchesterEnglandMember
Namespace Prefix:
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- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
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- Details

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COMMITMENTS AND CONTINGENCIES - Other Contractual Obligations (Details) ft² in Thousands, £ in Millions, $ in Millions	Dec. 31, 2020 USD ($)	Dec. 31, 2020 GBP (£)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 ft²
Headquarters \| Manchester, England \| Rentalcars.com
Other Commitments [Line Items]
Area of property subject to lease (in square feet) \| ft²				222
Term of lease not yet commenced	13 years	13 years
Headquarters \| Manchester, England \| Rentalcars.com \| Operating lease obligations
Other Commitments [Line Items]
Contractual obligation	$ 88	£ 65
Standby Letters of Credit
Other Commitments [Line Items]
Letters of credit outstanding \| $	$ 134		$ 155