INCOME TAXES (Notes)	9 Months Ended
INCOME TAXES (Notes)	Sep. 30, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Income tax expense consists of U.S. and international income taxes, determined using an estimate of the Company's annual effective tax rate, which is based upon the applicable tax rates and tax laws of the countries in which the income is generated. A deferred tax liability is recognized for all taxable temporary differences, and a deferred tax asset is recognized for all deductible temporary differences and operating loss and tax credit carryforwards. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The Company considers many factors when assessing the likelihood of future realization of the deferred tax assets, including its recent cumulative earnings experience by taxing jurisdiction, expectations of future income, tax planning strategies, the carryforward periods available for tax reporting purposes and other relevant factors. The Company's effective tax rates for the three and nine months ended September 30, 2020 were 4.1% and 30.4%, respectively, compared to 17.5% and 18.6% for the three and nine months ended September 30, 2019, respectively. The Company's 2020 effective tax rates differ from the U.S. federal statutory tax rate of 21%, primarily due to the non-deductible goodwill impairment charges related to OpenTable and KAYAK, the valuation allowance recorded against the deferred tax assets generated from the impairment of certain long-term investments and an increase in unrecognized tax benefits, partially offset by the benefit of the Netherlands Innovation Box Tax (discussed below). The Company's 2019 effective tax rates differ from the U.S. federal statutory tax rate of 21%, primarily due to the benefit of the Netherlands Innovation Box Tax, partially offset by the effect of higher international tax rates. The Company's effective tax rate for the three months ended September 30, 2020 was lower than the three months ended September 30, 2019, primarily due to certain lower non-deductible expenses, partially offset by discrete U.S. tax charges related to unrealized gains on equity securities and the non-deductible goodwill impairment charge related to OpenTable and KAYAK. The Company's effective tax rate for the nine months ended September 30, 2020 was higher than the nine months ended September 30, 2019, primarily due to the non-deductible goodwill impairment charges related to OpenTable and KAYAK, discrete U.S. tax charges related to unrealized gains on equity securities, an increase in unrecognized tax benefits and the valuation allowance recorded against the deferred tax asset generated from the impairment of certain long-term investments, partially offset by certain non-deductible expenses. During the three and nine months ended September 30, 2020 and September 30, 2019, a majority of the Company's income was reported in the Netherlands, where Booking.com is based. According to Dutch corporate income tax law, income generated from qualifying innovative activities is taxed at a rate of 7% ("Innovation Box Tax") rather than the Dutch statutory rate of 25%. A portion of Booking.com's earnings during the three and nine months ended September 30, 2020 and September 30, 2019 qualified for Innovation Box Tax treatment, which had a beneficial impact on the Company's effective tax rate for these periods. The aggregate amount of unrecognized tax benefits for all matters at September 30, 2020 and December 31, 2019 was $82 million and $56 million, respectively. The unrecognized tax benefits, if recognized, would impact the effective tax rate. As of September 30, 2020 and December 31, 2019, total gross interest and penalties accrued was $30 million and $10 million respectively. The majority of these unrecognized tax benefits are included in "Other long-term liabilities" and “Other assets, net” in the Consolidated Balance Sheets. The increase in unrecognized tax benefits is principally related to Booking.com’s French tax disputes (see Note 13).

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.