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Area of a real estate property.

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COMMITMENTS AND CONTINGENCIES (Details) ft² in Thousands, ₺ in Millions, € in Millions, £ in Millions, $ in Millions	1 Months Ended			3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended
	Jan. 31, 2019 USD ($)	Jan. 31, 2019 EUR (€)	Dec. 31, 2015 EUR (€)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2016 EUR (€)	Dec. 31, 2018 USD ($) ft²	Sep. 30, 2019 USD ($)	Sep. 30, 2019 TRY (₺)	Dec. 31, 2018 USD ($) ft²	Dec. 31, 2018 EUR (€)	Sep. 30, 2019 EUR (€)	Dec. 31, 2018 GBP (£) ft²
Commitments and Contingencies
French digital services tax rate								3.00%	3.00%
Payment for contingent consideration liability					$ 37
Booking.com \| Headquarters
Commitments and Contingencies
Contractual obligation				$ 135		€ 270		$ 135				€ 124
Acquisition of land use rights \| €						€ 43
Booking.com \| Headquarters \| Ground Lease
Commitments and Contingencies
Contractual obligation				79				79				€ 72
Series of individually immaterial business acquisitions \| Level 3
Commitments and Contingencies
Contingent consideration liability							$ 28			$ 28
French Tax Audit
Commitments and Contingencies
Assessed taxes including interest and penalties \| €			€ 356
Payment required to appeal a litigation matter	$ 403	€ 356
Taxes Owed For Prior Periods
Commitments and Contingencies
Charge for estimated probable tax owed for prior periods, including applicable interest and penalties				10			$ 46
Loss contingency accrual				65				65
Estimated reasonably possible loss in excess of amount accrued				25				25
Wage-related taxes owed for prior periods, including interest
Commitments and Contingencies
Charge for estimated probable tax owed for prior periods, including applicable interest and penalties								61
Italian Tax Audit
Commitments and Contingencies
Assessed taxes including interest and penalties										$ 52	€ 48
Turkish Tax Audit
Commitments and Contingencies
Assessed taxes including interest and penalties								96	₺ 544
French Digital Services Tax [Member]
Commitments and Contingencies
French digital service tax accrual				$ 29				$ 29
Manchester, England \| Rentalcars.com \| Headquarters
Commitments and Contingencies
Area of real estate property \| ft²							222			222			222
Term of lease for office space in Manchester UK for Rentalcars.com							13 years			13 years			13 years
Manchester, England \| Rentalcars.com \| Headquarters \| Operating Lease Obligations
Commitments and Contingencies
Contractual obligation							$ 80			$ 80			£ 65