BASIS OF PRESENTATION (Policies)	6 Months Ended
Jun. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Management of Booking Holdings Inc. (the "Company") is responsible for the Unaudited Consolidated Financial Statements included in this document. The Unaudited Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") and include all normal and recurring adjustments that management of the Company considers necessary for a fair presentation of its financial position and operating results. The Company prepared the Unaudited Consolidated Financial Statements following the requirements of the Securities and Exchange Commission ("SEC") for interim reporting. As permitted under those rules, the Company condensed or omitted certain footnotes or other financial information that are normally required by U.S. GAAP for annual financial statements. These statements should be read in combination with the Consolidated Financial Statements in the Company's Annual Report on Form 10-K for the year ended December 31, 2021. The Unaudited Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries, including acquired businesses from the dates of acquisition. All intercompany accounts and transactions have been eliminated in consolidation. The functional currency of the Company's subsidiaries is generally the respective local currency. For international operations, assets and liabilities are translated into U.S. Dollars at the rate of exchange existing at the balance sheet date. Income statement amounts are translated at monthly average exchange rates applicable for the period. Translation gains and losses are included as a component of "Accumulated other comprehensive loss" in the accompanying Consolidated Balance Sheets. Foreign currency transaction gains and losses are included in "Other income (expense), net" in the Unaudited Consolidated Statements of Operations. Revenues, expenses, assets and liabilities can vary during each quarter of the year. Therefore, the results and trends in these interim financial statements may not be the same as those for any subsequent quarter or the full year.
Reclassification	Reclassification Certain amounts from prior periods have been reclassified to conform to the current period presentation.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting for Convertible Instruments and Contracts in an Entity's Own Equity On January 1, 2022, the Company adopted the new accounting standards update relating to convertible instruments and contracts in an entity's own equity. Compared to legacy U.S. GAAP, the accounting standards update reduces the number of accounting models for convertible debt instruments, requires fewer embedded conversion features to be separately recognized from the host contract, and amends certain guidance to reduce form-over-substance-based accounting conclusions. Under the updated guidance, upon the initial recognition of convertible debt, the Company presents the entire amount attributable to the debt as a liability. The initial carrying amount of the convertible debt liability is reduced by any direct and incremental issuance costs paid to third parties that are associated with the convertible debt issuance. No amount attributable to the debt is initially recognized within equity unless the instrument is issued at a substantial premium. In calculating diluted earnings per share, the accounting standards update also requires the use of the if-converted method for the Company's convertible debt. The Company adopted the accounting standards update on a modified retrospective basis applied to the 0.75% convertible senior notes due May 2025 (see Note 9) resulting in an increase of $30 million to "Retained earnings" as of January 1, 2022. The significant corresponding balance sheet changes as of that date were an increase of $86 million to "Long-term debt" and decreases of $96 million to "Additional paid-in capital" and $21 million to "Deferred income taxes". For the Company’s convertible debt, interest expense for the periods beginning after January 1, 2022 is reflected in the financial statements using interest rates that are closer to the coupon interest rate of the debt rather than the higher imputed interest expense that resulted from the separation of conversion features required by legacy U.S. GAAP. See Note 4 for additional information on net income per share calculations. Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions In June 2022, the Financial Accounting Standards Board issued an accounting standards update with guidance on the fair value measurement of equity securities subject to contractual sale restrictions. The update clarifies that a contractual restriction on the sale of an equity security is not considered part of the unit of account of the equity security and, therefore, is not considered in measuring fair value. The update also clarifies that an entity cannot, as a separate unit of account, recognize and measure a contractual sale restriction. The update also requires certain additional disclosures for equity securities subject to contractual sale restrictions. The amendments in this update are effective for the Company from January 1, 2024. Early adoption is permitted for both interim and annual financial statements that have not yet been issued or made available for issuance. The Company is currently evaluating the impact of adopting the accounting standards update.
Earnings Per Share	The Company computes basic net income (loss) per share by dividing net income (loss) applicable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net income (loss) per share is based upon the weighted-average number of common and common equivalent shares outstanding during the period. Only dilutive common equivalent shares that decrease the net income per share or increase the net loss per share are included in the computation of diluted net income (loss) per share. Common equivalent shares related to stock options, restricted stock units, and performance share units are calculated using the treasury stock method. Performance share units are included in the weighted-average common equivalent shares based on the number of shares that would be issued if the end of the reporting period were the end of the performance period, if the result would be dilutive. The Company's convertible senior notes have net share settlement features requiring the Company upon conversion to settle the principal amount of the debt for cash and the conversion premium for cash or shares of the Company's common stock, at the Company's option. If the conversion prices for the convertible senior notes exceed the Company's average stock price for the period, the convertible senior notes generally have no impact on diluted net income/loss per share. For periods prior to January 1, 2022, the treasury stock method was used for convertible senior notes in the calculation of diluted net income per share. Following the adoption of the accounting standards update on January 1, 2022 (see Note 1), the if-converted method is used for all periods after that date.
Fair Value Measurement	Investments See Note 5 for additional information related to the Company's investments. The valuation of the Company's investment in debt securities is considered a "Level 2" valuation because the Company has access to quoted prices for identical or comparable securities, but does not have visibility into the volume and frequency of trading for this investment. A market approach is used for recurring fair value measurements and the valuation techniques use inputs that are observable, or can be corroborated by observable data, in an active marketplace. Investments in private companies measured using Level 3 inputs The Company's investments measured using Level 3 inputs primarily consist of investments in privately-held companies that are classified as equity securities without readily determinable fair values. Fair values of privately held securities are estimated using a variety of valuation methodologies, including both market and income approaches. The Company uses valuation techniques appropriate for the type of investment and the information available about the investee as of the valuation date to determine fair value. Recent financing transactions in the investee, such as new investments in preferred stock, are generally considered the best indication of the enterprise value and therefore used as a basis to estimate fair value. However, based on a number of factors, such as the proximity in timing to the valuation date or the volume or other terms of these financing transactions, the Company may also use other valuation techniques to supplement this data, including the income approach. When a recent financing transaction occurs and represents fair value, the Company also uses the calibration process, as appropriate, when estimating fair value on subsequent measurement dates. Calibration is the process of using observed transactions in the investee company's own instruments to ensure that the valuation techniques that will be employed to value the investee company investment on subsequent measurement dates begin with assumptions that are consistent with the original observed transaction as well as any more recent observed transactions in the instruments issued by the investee company.
Income Tax	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.

BASIS OF PRESENTATION (Policies)

6 Months Ended

Jun. 30, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Management of Booking Holdings Inc. (the "Company") is responsible for the Unaudited Consolidated Financial Statements included in this document. The Unaudited Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") and include all normal and recurring adjustments that management of the Company considers necessary for a fair presentation of its financial position and operating results. The Company prepared the Unaudited Consolidated Financial Statements following the requirements of the Securities and Exchange Commission ("SEC") for interim reporting. As permitted under those rules, the Company condensed or omitted certain footnotes or other financial information that are normally required by U.S. GAAP for annual financial statements. These statements should be read in combination with the Consolidated Financial Statements in the Company's Annual Report on Form 10-K for the year ended December 31, 2021.

The Unaudited Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries, including acquired businesses from the dates of acquisition. All intercompany accounts and transactions have been eliminated in consolidation. The functional currency of the Company's subsidiaries is generally the respective local currency. For international operations, assets and liabilities are translated into U.S. Dollars at the rate of exchange existing at the balance sheet date. Income statement amounts are translated at monthly average exchange rates applicable for the period. Translation gains and losses are included as a component of "Accumulated other comprehensive loss" in the accompanying Consolidated Balance Sheets. Foreign currency transaction gains and losses are included in "Other income (expense), net" in the Unaudited Consolidated Statements of Operations.

Revenues, expenses, assets and liabilities can vary during each quarter of the year. Therefore, the results and trends in these interim financial statements may not be the same as those for any subsequent quarter or the full year.

Reclassification

Certain amounts from prior periods have been reclassified to conform to the current period presentation.

Recent Accounting Pronouncements

Accounting for Convertible Instruments and Contracts in an Entity's Own Equity

On January 1, 2022, the Company adopted the new accounting standards update relating to convertible instruments and contracts in an entity's own equity. Compared to legacy U.S. GAAP, the accounting standards update reduces the number of accounting models for convertible debt instruments, requires fewer embedded conversion features to be separately recognized from the host contract, and amends certain guidance to reduce form-over-substance-based accounting conclusions. Under the updated guidance, upon the initial recognition of convertible debt, the Company presents the entire amount attributable to the debt as a liability. The initial carrying amount of the convertible debt liability is reduced by any direct and

incremental issuance costs paid to third parties that are associated with the convertible debt issuance. No amount attributable to the debt is initially recognized within equity unless the instrument is issued at a substantial premium. In calculating diluted earnings per share, the accounting standards update also requires the use of the if-converted method for the Company's convertible debt.

The Company adopted the accounting standards update on a modified retrospective basis applied to the 0.75% convertible senior notes due May 2025 (see Note 9) resulting in an increase of $30 million to "Retained earnings" as of January 1, 2022. The significant corresponding balance sheet changes as of that date were an increase of $86 million to "Long-term debt" and decreases of $96 million to "Additional paid-in capital" and $21 million to "Deferred income taxes". For the Company’s convertible debt, interest expense for the periods beginning after January 1, 2022 is reflected in the financial statements using interest rates that are closer to the coupon interest rate of the debt rather than the higher imputed interest expense that resulted from the separation of conversion features required by legacy U.S. GAAP. See Note 4 for additional information on net income per share calculations.

Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions

In June 2022, the Financial Accounting Standards Board issued an accounting standards update with guidance on the fair value measurement of equity securities subject to contractual sale restrictions. The update clarifies that a contractual restriction on the sale of an equity security is not considered part of the unit of account of the equity security and, therefore, is not considered in measuring fair value. The update also clarifies that an entity cannot, as a separate unit of account, recognize and measure a contractual sale restriction. The update also requires certain additional disclosures for equity securities subject to contractual sale restrictions. The amendments in this update are effective for the Company from January 1, 2024. Early adoption is permitted for both interim and annual financial statements that have not yet been issued or made available for issuance. The Company is currently evaluating the impact of adopting the accounting standards update.

Earnings Per Share

The Company computes basic net income (loss) per share by dividing net income (loss) applicable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net income (loss) per share is based upon the weighted-average number of common and common equivalent shares outstanding during the period. Only dilutive common equivalent shares that decrease the net income per share or increase the net loss per share are included in the computation of diluted net income (loss) per share.

Common equivalent shares related to stock options, restricted stock units, and performance share units are calculated using the treasury stock method. Performance share units are included in the weighted-average common equivalent shares based on the number of shares that would be issued if the end of the reporting period were the end of the performance period, if the result would be dilutive.

The Company's convertible senior notes have net share settlement features requiring the Company upon conversion to settle the principal amount of the debt for cash and the conversion premium for cash or shares of the Company's common stock, at the Company's option. If the conversion prices for the convertible senior notes exceed the Company's average stock price for the period, the convertible senior notes generally have no impact on diluted net income/loss per share. For periods prior to January 1, 2022, the treasury stock method was used for convertible senior notes in the calculation of diluted net income per share. Following the adoption of the accounting standards update on January 1, 2022 (see Note 1), the if-converted method is used for all periods after that date.

Fair Value Measurement

Investments

See Note 5 for additional information related to the Company's investments.

The valuation of the Company's investment in debt securities is considered a "Level 2" valuation because the Company has access to quoted prices for identical or comparable securities, but does not have visibility into the volume and frequency of trading for this investment. A market approach is used for recurring fair value measurements and the valuation techniques use inputs that are observable, or can be corroborated by observable data, in an active marketplace.

Investments in private companies measured using Level 3 inputs

The Company's investments measured using Level 3 inputs primarily consist of investments in privately-held companies that are classified as equity securities without readily determinable fair values. Fair values of privately held securities are estimated using a variety of valuation methodologies, including both market and income approaches. The Company uses valuation techniques appropriate for the type of investment and the information available about the investee as of the valuation date to determine fair value. Recent financing transactions in the investee, such as new investments in preferred stock, are generally considered the best indication of the enterprise value and therefore used as a basis to estimate fair value. However, based on a number of factors, such as the proximity in timing to the valuation date or the volume or other terms of these financing transactions, the Company may also use other valuation techniques to supplement this data, including the income approach. When a recent financing transaction occurs and represents fair value, the Company also uses the calibration process, as appropriate, when estimating fair value on subsequent measurement dates. Calibration is the process of using observed transactions in the investee company's own instruments to ensure that the valuation techniques that will be employed to value the investee company investment on subsequent measurement dates begin with assumptions that are consistent with the original observed transaction as well as any more recent observed transactions in the instruments issued by the investee company.

Income Tax

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.