REVENUE - Impact of COVID-19 (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
(Increase) reduction in revenue for refunds paid or estimated to be payable due to the Impact of COVID-19	$ (21)	$ 42

Amount of reduction (increase) to revenue for refunds paid or estimated to be payable to travelers to provide free cancellation for certain non-refundable reservations without a corresponding estimated expected recovery from the travel service provider.

No definition available.

Name:	bkng_ContractWithCustomerReductionIncreaseToRevenueForRefundsPaidOrEstimatedToBePayableToTravelers
Namespace Prefix:	bkng_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration