Booking (BKNG) 10-Q 9 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	May 02, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Priceline Group Inc.
Entity Central Index Key	1,075,531
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		49,142,436

UNAUDITED CONSOLIDATED BALANCE

UNAUDITED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 2,434,020	$ 2,081,075
Short-term investments	2,936,158	2,218,880
Accounts receivable, net of allowance for doubtful accounts of $27,179 and $25,565, respectively	934,254	860,115
Prepaid expenses and other current assets	683,450	241,449
Total current assets	6,987,882	5,401,519
Property and equipment, net	381,197	347,017
Intangible assets, net	1,951,999	1,993,885
Goodwill	2,402,306	2,396,906
Long-term investments	10,140,630	9,591,067
Other assets	130,238	108,579
Total assets	21,994,252	19,838,973
Current liabilities:
Accounts payable	407,575	419,108
Accrued expenses and other current liabilities	986,681	857,467
Deferred merchant bookings	879,405	614,361
Convertible debt	974,538	967,734
Total current liabilities	3,248,199	2,858,670
Deferred income taxes	497,847	822,334
Other long-term liabilities	128,564	138,767
Long-term debt	7,286,102	6,170,522
Total liabilities	11,160,712	9,990,293
Convertible debt	22,521	28,538
Stockholders' equity:
Common stock, $0.008 par value; authorized 1,000,000,000 shares, 62,495,991 and 62,379,247 shares issued, respectively	486	485
Treasury stock, 13,315,844 and 13,190,929 shares, respectively	(7,067,508)	(6,855,164)
Additional paid-in capital	5,558,194	5,482,653
Retained earnings	12,072,792	11,326,852
Accumulated other comprehensive income (loss)	247,055	(134,684)
Total stockholders' equity	10,811,019	9,820,142
Total liabilities and stockholders' equity	$ 21,994,252	$ 19,838,973

UNAUDITED CONSOLIDATED BALANCE3

UNAUDITED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 27,179	$ 25,565
Common stock, par value (in dollars per share)	$ 0.008	$ 0.008
Common stock, authorized shares (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	62,495,991	62,379,247
Treasury stock, shares (in shares)	13,315,844	13,190,929

UNAUDITED CONSOLIDATED STATEMEN

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Agency revenues	$ 1,785,313	$ 1,500,029
Merchant revenues	442,045	470,032
Advertising and other revenues	192,046	178,058
Total revenues	2,419,404	2,148,119
Cost of revenues	85,169	128,669
Gross profit	2,334,235	2,019,450
Operating expenses:
Performance advertising	980,773	779,909
Brand advertising	73,012	69,845
Sales and marketing	114,036	92,323
Personnel, including stock-based compensation of $58,948 and $66,000, respectively	351,030	308,351
General and administrative	135,547	113,045
Information technology	39,945	32,788
Depreciation and amortization	83,430	72,871
Total operating expenses	1,777,773	1,469,132
Operating income	556,462	550,318
Other income (expense):
Interest income	31,992	20,347
Interest expense	(55,717)	(46,894)
Foreign currency transactions and other	(5,127)	(12,928)
Impairment of cost-method investment	0	(50,350)
Total other expense	(28,852)	(89,825)
Earnings before income taxes	527,610	460,493
Income tax expense	71,987	86,069
Net income	$ 455,623	$ 374,424
Net income applicable to common stockholders per basic common share	$ 9.26	$ 7.54
Weighted-average number of basic common shares outstanding	49,192	49,630
Net income applicable to common stockholders per diluted common share	$ 9.11	$ 7.47
Weighted-average number of diluted common shares outstanding	50,025	50,129

UNAUDITED CONSOLIDATED STATEME5

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Allocated Share-based Compensation Expense	$ 58,948	$ 66,000

UNAUDITED CONSOLIDATED STATEME6

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income		$ 455,623	$ 374,424
Other comprehensive income, net of tax
Foreign currency translation adjustments	[1]	35,805	77,372
Unrealized (loss) gain on marketable securities	[2]	345,934	(24,459)
Comprehensive income		$ 837,362	$ 427,337
[1]	Foreign currency translation adjustments include a tax benefit of $19,733 and $61,096 for the three months ended March 31, 2017 and 2016, respectively, associated with net investment hedges (See Note 10). The remaining balance in foreign currency translation adjustments excludes income taxes as a result of the Company's intention to indefinitely reinvest the earnings of its international subsidiaries outside of the United States (See Note 9).
[2]	Net of a tax charge of $7,855 and $29,128 for the three months ended March 31, 2017 and 2016, respectively. Unrealized gain (loss) on marketable securities includes a net unrealized gain of $323,688 for the three months ended March 31, 2017, compared to a net unrealized loss of $113,152 for three months ended March 31, 2016 on the Company's investments in Ctrip.com International Ltd. ("Ctrip"), which were exempt from tax in the Netherlands.

UNAUDITED CONSOLIDATED STATEME7

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Tax (benefit) associated with gain (loss) on net investment hedges	$ (19,733)	$ (61,096)
Tax (benefit) associated with gain (loss) on marketable securities	7,855	29,128
Amount of gain (loss) on marketable securities which is non-taxable	$ 323,688	$ (113,152)

UNAUDITED CONSOLIDATED STATEME8

UNAUDITED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY - 3 months ended Mar. 31, 2017 - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2016	$ 9,820,142		$ 485	$ (6,855,164)	$ 5,482,653	$ 11,326,852	$ (134,684)
Balance (in shares) at Dec. 31, 2016			62,379	(13,191)
Increase (Decrease) in Stockholders' Equity
Net income	455,623					455,623
Foreign currency translation adjustments, net of tax benefit of $19,733	35,805	[1]					35,805
Unrealized gain on marketable securities, net of tax charge of $7,855	345,934	[2]					345,934
Reclassification adjustment for convertible debt	6,017				6,017
Exercise of stock options and vesting of restricted stock units and performance share units	1,479		$ 1		1,478
Exercise of stock options and vesting of restricted stock units and/or performance share units (in shares)			117
Repurchase of common stock	(212,344)			$ (212,344)
Repurchase of common stock (in shares)				(125)
Stock-based compensation and other stock-based payments	59,059				59,059
Conversion of debt	(1)				(1)
Balance (in shares) at Mar. 31, 2017			62,496	(13,316)
Balance at Mar. 31, 2017	10,811,019		$ 486	$ (7,067,508)	5,558,194	12,072,792	$ 247,055
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adoption of accounting standard updates	$ 299,305				$ 8,988	$ 290,317
[1]	Foreign currency translation adjustments include a tax benefit of $19,733 and $61,096 for the three months ended March 31, 2017 and 2016, respectively, associated with net investment hedges (See Note 10). The remaining balance in foreign currency translation adjustments excludes income taxes as a result of the Company's intention to indefinitely reinvest the earnings of its international subsidiaries outside of the United States (See Note 9).
[2]	Net of a tax charge of $7,855 and $29,128 for the three months ended March 31, 2017 and 2016, respectively. Unrealized gain (loss) on marketable securities includes a net unrealized gain of $323,688 for the three months ended March 31, 2017, compared to a net unrealized loss of $113,152 for three months ended March 31, 2016 on the Company's investments in Ctrip.com International Ltd. ("Ctrip"), which were exempt from tax in the Netherlands.

UNAUDITED CONSOLIDATED STATEME9

UNAUDITED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Stockholders' Equity [Abstract]
Tax (benefit) associated with gain (loss) on net investment hedges	$ (19,733)	$ (61,096)
Tax (benefit) associated with gain (loss) on marketable securities	$ 7,855	$ 29,128

UNAUDITED CONSOLIDATED STATEM10

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
OPERATING ACTIVITIES:
Net income	$ 455,623	$ 374,424
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	40,412	30,486
Amortization	43,018	42,385
Provision for uncollectible accounts, net	13,530	6,812
Deferred income tax benefit	(24,441)	(25,681)
Stock-based compensation expense and other stock-based payments	59,059	66,034
Amortization of debt issuance costs	2,067	1,837
Amortization of debt discount	17,625	17,009
Impairment of cost-method investment	0	50,350
Excess tax benefits on stock-based awards and other equity deductions	0	18,073
Changes in assets and liabilities:
Accounts receivable	(78,428)	(191,704)
Prepaid expenses and other current assets	(443,643)	(340,485)
Accounts payable, accrued expenses and other current liabilities	305,758	294,349
Other	(9,962)	869
Net cash provided by operating activities	380,618	344,758
INVESTING ACTIVITIES:
Purchase of investments	(1,498,723)	(1,051,346)
Proceeds from sale of investments	676,474	1,252,604
Additions to property and equipment	(70,559)	(53,256)
Acquisitions and other investments, net of cash acquired	(6)	(723)
Net cash (used in) provided by investing activities	(892,814)	147,279
FINANCING ACTIVITIES:
Proceeds from short-term borrowing	0	100,000
Proceeds from the issuance of long-term debt	1,051,722	2,500
Payments related to conversion of senior notes	(4)	0
Payments for repurchase of common stock	(209,797)	(241,719)
Proceeds from exercise of stock options	1,479	4,815
Net cash provided by (used in) financing activities	843,400	(134,404)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	21,737	22,296
Net increase in cash, cash equivalents and restricted cash	352,941	379,929
Cash, cash equivalents and restricted cash, beginning of period	2,082,007	1,478,071
Cash, cash equivalents and restricted cash, end of period	2,434,948	1,858,000
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid during the period for income taxes	536,192	449,314
Cash paid during the period for interest	38,496	40,119
Non-cash financing activity	$ 1,000	$ 0

BASIS OF PRESENTATION

BASIS OF PRESENTATION	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION Management of The Priceline Group 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 ("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 for interim reporting. As permitted under those rules, the Company condensed or omitted certain footnotes or other financial information that are normally required by 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, 2016 . The Unaudited Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries, including its primary brands of Booking.com, priceline.com, KAYAK, agoda.com, Rentalcars.com and OpenTable. All inter-company accounts and transactions have been eliminated in consolidation. The functional currency of the Company's foreign subsidiaries is generally the respective local currency. 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 the average exchange rates for the period. Translation gains and losses are included as a component of " Accumulated other comprehensive income (loss) " in the accompanying Unaudited Consolidated Balance Sheets. Foreign currency transaction gains and losses are included in "Foreign currency transactions and other" 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 the full year. Reclassifications: Due to the adoption of new accounting updates in the fourth quarter of 2016 related to the presentation of restricted cash and the first quarter of 2017 related to stock-based compensation, certain amounts in the Unaudited Consolidated Statement of Cash Flows for the three months ended March 31, 2016 have been reclassified to conform to the current year presentation. Restricted Cash: The following table reconciles cash, cash equivalents and restricted cash reported in the Unaudited Consolidated Balance Sheets to the total amount shown in the Unaudited Consolidated Statements of Cash Flows: March 31, December 31, As included in the Unaudited Consolidated Balance Sheets: Cash and cash equivalents $ 2,434,020 $ 2,081,075 Restricted cash included in prepaid expenses and other current assets 928 932 Total cash, cash equivalents and restricted cash as shown in the Unaudited Consolidated Statements of Cash Flows $ 2,434,948 $ 2,082,007 Recent Accounting Pronouncements Adopted Definition of a Business In January 2017, the Financial Accounting Standards Board ("FASB") issued a new accounting update to clarify the definition of a business and provide additional guidance to assist entities with evaluating whether transactions should be accounted for as asset acquisitions (or disposals) or business combinations (or disposals of a business). Under this update, an entity first determines whether substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets. If this criterion is met, the transaction should be accounted for as an asset acquisition as opposed to a business combination. This distinction is important because the accounting for an asset acquisition may differ significantly from the accounting for a business combination. This update eliminates the requirement to evaluate whether a market participant could replace missing elements (e.g., inputs or processes), narrows the definition of outputs and requires that a business include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. For public business entities, this update is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods, and is required to be applied prospectively. The Company early adopted this update in the first quarter of 2017 and the adoption did not have an impact to the Unaudited Consolidated Financial Statements. Intra-entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued new accounting guidance on income tax accounting associated with intra-entity transfers of assets other than inventory. This accounting update, which is part of the FASB's simplification initiative, is intended to reduce diversity in practice and the complexity of tax accounting, particularly for those transfers involving intellectual property. This new guidance requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. For public business entities, this update is effective for annual reporting periods beginning after December 15, 2017. Entities are required to apply this accounting update on a modified retrospective basis with a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company early adopted this update in the first quarter of 2017. The adoption resulted in a cumulative net charge to retained earnings of $4.2 million , a reduction in deferred tax liabilities of $5.7 million and reductions in current and long-term assets of $3.3 million and $6.6 million , respectively, as of January 1, 2017. Share-based Compensation In March 2016, the FASB issued new accounting guidance to improve the accounting for certain aspects of share-based payment transactions as part of its simplification initiative. The key provisions of this accounting update are: (1) recognizing current excess tax benefits in the income statement in the period the benefits are deducted on the income tax return as opposed to an adjustment to additional paid-in capital in the period the benefits are realized by reducing a current income tax liability, (2) allowing an entity-wide election to account for forfeitures related to service conditions as they occur instead of estimating the total number of awards that will be forfeited because the requisite service period will not be rendered, (3) allowing the net settlement of an equity award for employee statutory tax withholding purposes to not exceed the maximum statutory tax rate by relevant tax jurisdiction instead of withholding taxes for each employee based on a minimum statutory withholding tax rate, and (4) requiring the presentation of excess tax benefits as operating cash flows and cash payments for employee statutory tax withholding related to vested stock awards as financing cash flows in the consolidated statements of cash flows. Under this new accounting standard, all previously unrecognized equity deductions are recognized as a deferred tax asset, net of any valuation allowance, with a cumulative-effect adjustment to retained earnings as of the beginning of the year of adoption of this standard. The Company adopted this accounting update in the first quarter of 2017 and recorded a deferred tax asset of $301.4 million related to previously unrecognized U.S. equity tax deductions, with an offsetting cumulative-effect adjustment to retained earnings as of January 1, 2017. The Company elected to account for forfeitures related to service conditions as they occur; as a result, there was a cumulative net charge to retained earnings of $6.9 million (forfeiture expenses adjustment after taxes) and the recognition of a deferred tax asset of $2.1 million , with an offsetting credit to additional paid-in capital of $9.0 million . In addition, the Company elected to change the presentation of excess tax benefits in the Unaudited Consolidated Statement of Cash Flows for periods prior to January 1, 2017 to reflect these excess tax benefits in operating cash flows instead of financing cash flows, resulting in a reclassification of $18.1 million for the three months ended March 31, 2016 . "Payments for repurchase of common stock" in the Unaudited Consolidated Statements of Cash Flows includes withholding taxes paid on vested stock awards (see Note 8). Other Recent Accounting Pronouncements Premium Amortization on Purchased Callable Debt Securities In March 2017, the FASB issued a new accounting update to shorten the premium amortization period of purchased callable debt securities with non-contingent call features that are callable at fixed prices and on preset dates from their contractual maturity to the earliest call date. For public business entities, this new accounting update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. Entities are required to apply this accounting update on a modified retrospective basis with a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact to its Consolidated Financial Statements of adopting this new update. Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued a new accounting update to simplify the test for goodwill impairment by eliminating Step 2, which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill, which requires a hypothetical purchase price allocation, with the carrying amount of that reporting unit’s goodwill. Under this update, an entity would perform its quantitative annual, or interim, goodwill impairment test using the current Step 1 test and recognize an impairment charge for the excess of the carrying value of a reporting unit over its fair value. For public business entities, this update is effective for their annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests occurring after January 1, 2017. The accounting update will be applied prospectively. The Company is currently evaluating the impact to its Consolidated Financial Statements of adopting this new update. Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued new accounting guidance on the measurement of credit losses for financial assets measured at amortized cost, which includes accounts receivable and available-for-sale debt securities. For financial assets measured at amortized cost, this new guidance requires an entity to (1) estimate its lifetime expected credit losses upon recognition of the financial assets and establish an allowance to present the net amount expected to be collected, (2) recognize this allowance and changes in the allowance during subsequent periods through net income and (3) consider relevant information about past events, current conditions and reasonable and supportable forecasts in assessing the lifetime expected credit losses. For available-for-sale debt securities, this new guidance made several targeted amendments to the existing other-than-temporary impairment model, including (1) requiring disclosure of the allowance for credit losses, (2) allowing reversals of the previously recognized credit losses until the entity has the intent to sell, is more-likely-than-not required to sell the securities or the maturity of the securities, (3) limiting impairment to the difference between the amortized cost basis and fair value and (4) not allowing entities to consider the length of time that fair value has been less than amortized cost as a factor in evaluating whether a credit loss exists. This update is effective for public business entities for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Entities are required to apply this accounting update on a modified retrospective basis with a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact to its Consolidated Financial Statements of adopting this new guidance. Leases In February 2016, the FASB issued a new accounting standard intended to improve the financial reporting of lease transactions. The new accounting standard requires lessees to recognize an asset and a liability on the balance sheet for the right and obligation created by entering into a lease transaction for all leases with the exception of short-term leases. The new standard retains the dual-model concept by requiring entities to determine if a lease is an operating or financing lease and the current "bright line" percentages could be used as guidance in applying the new standard. The lessor accounting model remains largely unchanged. The new standard significantly expands qualitative and quantitative disclosures for lessees. The update is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is allowed. Entities are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company is currently evaluating the impact to its Consolidated Financial Statements of adopting this new standard. Recognition and Measurement of Financial Instruments In January 2016, the FASB issued a new accounting update which amends the guidance on the recognition and measurement of financial instruments. The update requires (1) an entity to measure equity investments (except those accounted for under the equity method or those that result in consolidation of the investee) at fair value with changes in fair value recognized in net income rather than accumulated other comprehensive income (loss), (2) allows an entity to elect to measure those equity investments that do not have a readily determinable fair value at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer, (3) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, and (4) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity’s evaluation of their other deferred tax assets. This update is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption, although allowed in certain circumstances, is not applicable to the Company. An entity would apply this update by a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. After the adoption of this new accounting guidance, in the first quarter of 2018, the Company will record in net income fair value changes in its investments in Ctrip equity securities, which could vary significantly quarter to quarter (see Note 4 for the carrying values and fair values of these equity investments). In addition, the Company intends to continue to use the cost method of accounting for equity investments without a readily determinable fair value. Revenue from Contracts with Customers In May 2014, the FASB issued a new accounting standard on the recognition of revenue from contracts with customers that was designed to create greater comparability for financial statement users across industries and jurisdictions. The core principle of this standard is that an "entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services." The new standard also requires enhanced disclosures on the nature, amount, timing and uncertainty of revenue from contracts with customers. Since May 2014, the FASB has issued several amendments to this standard, including additional guidance, and deferred the effective date for public business entities to annual and interim periods beginning after December 15, 2017. The Company will adopt this new standard in the first quarter of 2018 and expects to apply the modified retrospective transition approach, which means that revenues for 2016 and 2017 will be reported on a historical basis and revenues for 2018 will be reported on the new basis and disclosed on the historical basis. The revenue standard will change the timing of revenue recognition for travel reservation services. For example, revenue for accommodation reservation services will be recognized at check-in rather than check-out. The Company does not currently expect material impacts to its annual gross profit or net income due to this timing change, although the effects on quarterly gross profit and net income may be more significant. In addition, the adoption of the revenue standard will change the presentation of Name Your Own Price ® revenue from "gross" to "net" reporting, which will decrease revenue and cost of revenue equally, but have no impact on gross profit or net income.

STOCK-BASED EMPLOYEE COMPENSATI

STOCK-BASED EMPLOYEE COMPENSATION	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED EMPLOYEE COMPENSATION	STOCK-BASED EMPLOYEE COMPENSATION Stock-based compensation expense included in personnel expenses in the Unaudited Consolidated Statements of Operations was approximately $58.9 million and $66.0 million for the three months ended March 31, 2017 and 2016 , respectively. Stock-based compensation is recognized in the financial statements based upon fair value. Fair value is recognized as expense on a straight-line basis over the employee's requisite service period. The fair value of performance share units and restricted stock units is determined based on the number of units granted and the quoted price of the Company's common stock as of the grant date. Stock-based compensation related to performance share units reflects the estimated probable outcome at the end of the performance period. The fair value of employee stock options assumed in acquisitions was determined using the Black-Scholes model and the market value of the Company's common stock at the respective acquisition dates. Restricted Stock Units and Performance Share Units The following table summarizes the activity of restricted stock units and performance share units ("share-based awards") during the three months ended March 31, 2017 : Share-Based Awards Shares Weighted-Average Grant Date Fair Value Unvested at December 31, 2016 515,606 $ 1,287.88 Granted 155,095 $ 1,735.10 Vested (112,791 ) $ 1,325.40 Performance Share Units Adjustment (445 ) $ 1,291.76 Forfeited (7,103 ) $ 1,301.58 Unvested at March 31, 2017 550,362 $ 1,406.29 As of March 31, 2017 , there was $534.7 million of total future compensation cost related to unvested share-based awards to be recognized over a weighted-average period of 2.3 years. During the three months ended March 31, 2017 , the Company made broad-based grants of 81,202 restricted stock units that generally vest after three years, subject to certain exceptions for terminations other than for "cause," for "good reason" or on account of death or disability. These share-based awards had a total grant date fair value of $140.9 million based on a weighted-average grant date fair value per share of $1,735.10 . In addition, during the three months ended March 31, 2017 , the Company granted 73,893 performance share units to executives and certain other employees. The performance share units had a total grant date fair value of $128.2 million based upon a weighted-average grant date fair value per share of $1,735.10 . The performance share units are payable in shares of the Company's common stock upon vesting. Subject to certain exceptions for terminations other than for "cause," for "good reason" or on account of death or disability, recipients of these performance share units generally must continue their service through the requisite service period in order to receive any shares. Stock-based compensation related to performance share units reflects the estimated probable outcome at the end of the performance period. The actual number of shares to be issued on the vesting date will be determined upon completion of the performance period, which ends December 31, 2019 , assuming there is no accelerated vesting for, among other things, a termination of employment under certain circumstances. As of March 31, 2017 , the estimated number of probable shares to be issued is a total of 73,893 shares, net of performance share units forfeited and vested since the grant date. If the maximum performance thresholds are met at the end of the performance period, a maximum number of 147,786 total shares could be issued. If the minimum performance thresholds are not met, 60,636 shares would be issued at the end of the performance period. 2016 Performance Share Units During the year ended December 31, 2016 , the Company granted 85,735 performance share units with a grant date fair value of $111.7 million , based on a weighted-average grant date fair value per share of $1,302.25 . The actual number of shares to be issued will be determined upon completion of the performance period which generally ends December 31, 2018 . At March 31, 2017 , there were 75,421 unvested 2016 performance share units outstanding, net of performance share units that were forfeited or vested since the grant date. As of March 31, 2017 , the number of shares estimated to be issued pursuant to these performance share units at the end of the performance period is a total of 117,795 shares. If the maximum thresholds are met at the end of the performance period, a maximum of 170,125 total shares could be issued pursuant to these performance share units. If the minimum performance thresholds are not met, 45,779 shares would be issued at the end of the performance period. 2015 Performance Share Units During the year ended December 31, 2015 , the Company granted 107,623 performance share units with a grant date fair value of $133.2 million , based on a weighted-average grant date fair value per share of $1,237.53 . The actual number of shares to be issued will be determined upon completion of the performance period which generally ends December 31, 2017 . At March 31, 2017 , there were 74,914 unvested 2015 performance share units outstanding, net of performance share units that were forfeited or vested since the grant date. As of March 31, 2017 , the number of shares estimated to be issued pursuant to these performance share units at the end of the performance period is a total of 128,379 shares. If the maximum thresholds are met at the end of the performance period, a maximum of 185,316 total shares could be issued pursuant to these performance share units. If the minimum performance thresholds are not met, 43,832 shares would be issued at the end of the performance period. Stock Options All outstanding employee stock options were assumed in acquisitions. The following table summarizes the activity for stock options during the three months ended March 31, 2017 : Employee Stock Options Number of Shares Weighted-Average Aggregate Intrinsic Value (in thousands) Weighted-Average Remaining Contractual Term Balance, December 31, 2016 48,983 $ 372.07 $ 53,587 4.4 Exercised (3,992 ) $ 368.68 Forfeited (610 ) $ 894.15 Balance, March 31, 2017 44,381 $ 365.20 $ 62,789 4.2 Vested and exercisable as of March 31, 2017 43,125 $ 354.23 $ 61,485 4.1 Vested and exercisable as of March 31, 2017 and expected to vest thereafter, net of estimated forfeitures 44,381 $ 365.20 $ 62,789 4.2 The aggregate intrinsic value of employee stock options that were exercised during the three months ended March 31, 2017 and 2016 was $5.4 million and $12.7 million , respectively. During the three months ended March 31, 2017 and 2016 , stock options vested for 539 and 5,367 shares of common stock with an acquisition-date fair value of $0.3 million and $3.5 million , respectively. For the three months ended March 31, 2017 and 2016 , the Company recorded stock-based compensation expense related to employee stock options of $0.3 million and $2.9 million , respectively. As of March 31, 2017 , there was $0.7 million of total future compensation costs related to unvested employee stock options to be recognized over a weighted-average period of 0.7 years.

NET INCOME PER SHARE

NET INCOME PER SHARE	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
NET INCOME PER SHARE	NET INCOME PER SHARE The Company computes basic net income per share by dividing net income applicable to common shareholders by the weighted-average number of common shares outstanding during the period. Diluted net income per share is based upon the weighted-average number of common and common equivalent shares outstanding during the period. 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 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. The convertible notes are included in the calculation of diluted net income per share if their inclusion is dilutive under the treasury stock method. A reconciliation of the weighted-average number of shares outstanding used in calculating diluted earnings per share is as follows (in thousands): Three Months Ended 2017 2016 Weighted-average number of basic common shares outstanding 49,192 49,630 Weighted-average dilutive stock options, restricted stock units and performance share units 227 275 Assumed conversion of Convertible Senior Notes 606 224 Weighted-average number of diluted common and common equivalent shares outstanding 50,025 50,129 Anti-dilutive potential common shares 2,256 2,665 Anti-dilutive potential common shares for the three months ended March 31, 2017 include approximately 1.7 million shares that could be issued under the Company's outstanding convertible notes. Under the treasury stock method, the convertible notes will generally have an anti-dilutive impact on net income per share if the conversion prices for the convertible notes exceed the Company's average stock price.

INVESTMENTS

INVESTMENTS	3 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
INVESTMENTS	INVESTMENTS Short-term and Long-term Investments in Available-for-sale Securities The following table summarizes, by major security type, the Company's investments as of March 31, 2017 (in thousands): Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term investments: International government securities $ 517,398 $ 1,254 $ (187 ) $ 518,465 U.S. government securities 580,630 17 (427 ) 580,220 Corporate debt securities 1,831,179 1,482 (1,166 ) 1,831,495 Commercial paper 5,978 — — 5,978 Total short-term investments $ 2,935,185 $ 2,753 $ (1,780 ) $ 2,936,158 Long-term investments: International government securities $ 450,445 $ 1,894 $ (788 ) $ 451,551 U.S. government securities 828,777 286 (6,744 ) 822,319 Corporate debt securities 6,387,523 10,334 (37,658 ) 6,360,199 U.S. government agency securities 4,971 — (25 ) 4,946 Ctrip convertible debt securities 1,275,000 171,425 (8,050 ) 1,438,375 Ctrip equity securities 655,311 407,929 — 1,063,240 Total long-term investments $ 9,602,027 $ 591,868 $ (53,265 ) $ 10,140,630 The Company's investment policy seeks to preserve capital and maintain sufficient liquidity to meet operational and other needs of the business. As of March 31, 2017 , the weighted-average life of the Company’s fixed income investment portfolio, excluding the Company's investment in Ctrip convertible debt securities, was approximately 2.0 years with an average credit quality of A+/A1/A+. The Company invests in international government securities with high credit quality. As of March 31, 2017 , investments in international government securities principally included debt securities issued by the governments of the Netherlands, Belgium, France, Germany and Austria. On May 26, 2015 and August 7, 2014, the Company invested $250 million and $500 million , respectively, in five -year senior convertible notes issued at par by Ctrip. On December 11, 2015, the Company invested $500 million in a Ctrip ten -year senior convertible note issued at par value, which included a put option allowing the Company to require a prepayment in cash from Ctrip at the end of the sixth year of the note. On September 12, 2016, the Company invested $25 million in a Ctrip six -year senior convertible note issued at par value, which included a put option allowing the Company to require prepayment in cash from Ctrip at the end of the third year of the note. The conversion feature associated with this September 2016 Ctrip convertible note met the definition of an embedded derivative (see Note 5 ). As of March 31, 2017 , the Company had also invested $655.3 million of its international cash in Ctrip American Depositary Shares ("ADSs"). The convertible debt and equity securities of Ctrip have been marked-to-market in accordance with the accounting guidance for available-for-sale securities. In connection with the Company's investments in Ctrip's convertible notes, Ctrip granted the Company the right to appoint an observer to its board of directors and permission to acquire its shares (through the acquisition of Ctrip ADSs in the open market) so that combined with ADSs issuable upon conversion of the August 2014, May 2015 and September 2016 convertible notes, the Company could hold up to an aggregate of approximately 15% of Ctrip's outstanding equity. As of March 31, 2017 , the Company did not have significant influence over Ctrip. The following table summarizes, by major security type, the Company's investments as of December 31, 2016 (in thousands): Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term investments: International government securities $ 249,552 $ 221 $ (89 ) $ 249,684 U.S. government securities 456,971 57 (140 ) 456,888 Corporate debt securities 1,510,119 1,119 (928 ) 1,510,310 Commercial paper 1,998 — — 1,998 Total short-term investments $ 2,218,640 $ 1,397 $ (1,157 ) $ 2,218,880 Long-term investments: International government securities $ 655,857 $ 4,110 $ (623 ) $ 659,344 U.S. government securities 773,718 337 (7,463 ) 766,592 Corporate debt securities 6,042,271 9,973 (50,455 ) 6,001,789 U.S. government agency securities 4,979 — (27 ) 4,952 Ctrip convertible debt securities 1,275,000 65,800 (47,712 ) 1,293,088 Ctrip equity securities 655,311 213,233 (3,242 ) 865,302 Total long-term investments $ 9,407,136 $ 293,453 $ (109,522 ) $ 9,591,067 The Company has classified its investments as available-for-sale securities. These securities are carried at estimated fair value with the aggregate unrealized gains and losses related to these investments, net of taxes, reflected as a part of " Accumulated other comprehensive income (loss) " in the Unaudited Consolidated Balance Sheets. Classification as short-term or long-term investment is based upon the maturity of the debt securities. The Company recognized net realized gains of $0.2 million for the three months ended March 31, 2017 compared to net realized losses of $2.9 million for the three months ended March 31, 2016 , related to investments. As of March 31, 2017 , the Company does not consider any of its investments to be other-than-temporarily impaired. Cost-method Investments The Company held investments in equity securities of private companies, companies typically at an early stage of development, of approximately $7.6 million at both March 31, 2017 and December 31, 2016 . The investments are accounted for under the cost method and included in "Other assets" in the Company's Unaudited Consolidated Balance Sheets. There have been no identified events or changes in circumstances to indicate a potential impairment with the Company's cost-method investments as of March 31, 2017 . In March 2016, the Company recognized an impairment of approximately $50 million , which was not tax deductible, related to its investment in Hotel Urbano.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Financial assets and liabilities carried at fair value as of March 31, 2017 are classified in the tables below in the categories described below (in thousands): Level 1 Level 2 Total ASSETS: Cash equivalents: Money market funds $ 1,249,091 $ — $ 1,249,091 International government securities — 35,052 35,052 U.S. government securities — 159,956 159,956 Corporate debt securities — 10,243 10,243 Time deposits 4,724 — 4,724 Short-term investments: International government securities — 518,465 518,465 U.S. government securities — 580,220 580,220 Corporate debt securities — 1,831,495 1,831,495 Commercial paper — 5,978 5,978 Long-term investments: International government securities — 451,551 451,551 U.S. government securities — 822,319 822,319 Corporate debt securities — 6,360,199 6,360,199 U.S. government agency securities — 4,946 4,946 Ctrip convertible debt securities — 1,438,375 1,438,375 Ctrip equity securities 1,063,240 — 1,063,240 Derivatives: Currency exchange derivatives — 558 558 Total assets at fair value $ 2,317,055 $ 12,219,357 $ 14,536,412 Level 1 Level 2 Total LIABILITIES: Currency exchange derivatives $ — $ 593 $ 593 Financial assets and liabilities carried at fair value as of December 31, 2016 are classified in the tables below in the categories described below (in thousands): Level 1 Level 2 Total ASSETS: Cash equivalents: Money market funds $ 977,468 $ — $ 977,468 International government securities — 30,266 30,266 U.S. government securities — 176,140 176,140 Corporate debt securities — 9,273 9,273 Commercial paper — 1,998 1,998 Time deposits 49,160 — 49,160 Short-term investments: International government securities — 249,684 249,684 U.S. government securities — 456,888 456,888 Corporate debt securities — 1,510,310 1,510,310 Commercial paper — 1,998 1,998 Long-term investments: International government securities — 659,344 659,344 U.S. government securities — 766,592 766,592 Corporate debt securities — 6,001,789 6,001,789 U.S. government agency securities — 4,952 4,952 Ctrip convertible debt securities — 1,293,088 1,293,088 Ctrip equity securities 865,302 — 865,302 Derivatives: Currency exchange derivatives — 756 756 Total assets at fair value $ 1,891,930 $ 11,163,078 $ 13,055,008 Level 1 Level 2 Total LIABILITIES: Currency exchange derivatives $ — $ 1,015 $ 1,015 There are three levels of inputs to measure fair value. The definition of each input is described below: Level 1 : Quoted prices in active markets that are accessible by the Company at the measurement date for identical assets and liabilities. Level 2 : Inputs that are observable, either directly or indirectly. Such prices may be based upon quoted prices for identical or comparable securities in active markets or inputs not quoted on active markets, but corroborated by market data. Level 3 : Unobservable inputs are used when little or no market data is available. Investments in corporate debt securities, U.S. and international government securities, commercial paper, government agency securities and convertible debt securities are considered "Level 2 " valuations because the Company has access to quoted prices, but does not have visibility to the volume and frequency of trading for all of these investments. For the Company's investments, 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. The Company's derivative instruments are valued using pricing models. Pricing models take into account the contract terms as well as multiple inputs where applicable, such as interest rate yield curves, option volatility and currency rates. Derivatives are considered "Level 2 " fair value measurements. The Company's derivative instruments are typically short-term in nature. As of March 31, 2017 and December 31, 2016 , the Company's cash consisted of bank deposits. Other financial assets and liabilities, including restricted cash, accounts receivable, accounts payable, accrued expenses and deferred merchant bookings are carried at cost which approximates their fair value because of the short-term nature of these items. At both March 31, 2017 and December 31, 2016 , the Company held investments in equity securities of private companies of $7.6 million and these investments are accounted for under the cost method of accounting (see Note 4 ). See Note 4 for information on the carrying value of available-for-sale investments, Note 7 for the estimated fair value of the Company's outstanding Senior Notes and Note 11 for the Company's contingent liabilities associated with business acquisitions. In the normal course of business, the Company is exposed to the impact of foreign currency fluctuations. The Company limits these risks by following established risk management policies and procedures, including the use of derivatives. The Company does not use derivatives for trading or speculative purposes. All derivative instruments are recognized in the Unaudited Consolidated Balance Sheets at fair value. Gains and losses resulting from changes in the fair value of derivative instruments that are not designated as hedging instruments for accounting purposes are recognized in the Unaudited Consolidated Statements of Operations in the period that the changes occur. Changes in the fair value of derivatives designated as net investment hedges are recorded as currency translation adjustments to offset a portion of the currency translation adjustment from Euro-denominated net assets held by certain subsidiaries and are recognized in the Unaudited Consolidated Balance Sheets in " Accumulated other comprehensive income (loss) ." Derivatives Not Designated as Hedging Instruments — The Company is exposed to adverse movements in currency exchange rates as the operating results of its international operations are translated from local currency into U.S. Dollars upon consolidation. The Company enters into average-rate derivative contracts to hedge translation risk from short-term foreign exchange rate fluctuations for the Euro, British Pound Sterling and certain other currencies versus the U.S. Dollar. As of March 31, 2017 and December 31, 2016 , there were no outstanding derivative contracts related to foreign currency translation risk. Foreign exchange losses of $1.1 million and $3.6 million for the three months ended March 31, 2017 and 2016 , respectively, are recorded related to these derivatives in "Foreign currency transactions and other" in the Unaudited Consolidated Statements of Operations. The Company also enters into foreign currency forward contracts to hedge its exposure to the impact of movements in currency exchange rates on its transactional balances denominated in currencies other than the functional currency. Foreign exchange derivatives outstanding as of March 31, 2017 associated with foreign currency transaction risks resulted in a net liability of $0.1 million , with a liability in the amount of $0.6 million recorded in "Accrued expenses and other current liabilities" and an asset in the amount of $0.5 million recorded in "Prepaid expenses and other current assets" in the Unaudited Consolidated Balance Sheet. Foreign exchange derivatives outstanding as of December 31, 2016 associated with foreign exchange transactions resulted in a net liability of $0.3 million , with a liability in the amount of $1.0 million recorded in "Accrued expenses and other current liabilities" and an asset in the amount of $0.7 million recorded in "Prepaid expenses and other current assets" in the Unaudited Consolidated Balance Sheet. Derivatives associated with these transaction risks resulted in foreign exchange gains of $6.8 million and $12.4 million for the three months ended March 31, 2017 and 2016 , respectively. These mark-to-market adjustments on the derivative contracts, offset by the effect of changes in currency exchange rates on transactions denominated in currencies other than the functional currency, resulted in net losses of $5.9 million and $4.4 million for the three months ended March 31, 2017 and 2016 , respectively. The net impacts related to these derivatives are recorded in "Foreign currency transactions and other" in the Unaudited Consolidated Statements of Operations. The settlement of derivative contracts not designated as hedging instruments resulted in net cash inflows of $2.7 million and $22.3 million for the three months ended March 31, 2017 and 2016 , respectively, and are reported within " Net cash provided by operating activities " in the Unaudited Consolidated Statements of Cash Flows. Embedded Derivative — In September 2016, the Company invested $25 million in a Ctrip convertible note (see Note 4 ). The Company determined that the conversion option for this note met the definition of an embedded derivative. At March 31, 2017 and December 31, 2016 , the embedded derivative had an estimated fair value of $3.2 million and $1.8 million , respectively, and is reported in the balance sheet with its host contract in long-term investments. The embedded derivative is bifurcated for measurement purposes only and the mark-to-market for the three months ended March 31, 2017 was a $1.4 million gain, which is included in "Foreign currency transactions and other" in the Company's Unaudited Consolidated Statement of Operations.

INTANGIBLE ASSETS AND GOODWILL

INTANGIBLE ASSETS AND GOODWILL	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS AND GOODWILL	INTANGIBLE ASSETS AND GOODWILL The Company's intangible assets at March 31, 2017 and December 31, 2016 consisted of the following (in thousands): March 31, 2017 December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Amortization Weighted Supply and distribution agreements $ 812,361 $ (287,948 ) $ 524,413 $ 809,287 $ (270,813 ) $ 538,474 3 - 20 years 16 years Technology 112,451 (85,670 ) 26,781 112,141 (80,549 ) 31,592 1 - 5 years 5 years Patents 1,623 (1,608 ) 15 1,623 (1,598 ) 25 15 years 15 years Internet domain names 40,047 (26,394 ) 13,653 39,495 (25,089 ) 14,406 2 - 20 years 8 years Trade names 1,667,686 (282,322 ) 1,385,364 1,667,221 (261,412 ) 1,405,809 4-20 years 20 years Non-compete agreements 21,900 (20,127 ) 1,773 21,900 (18,321 ) 3,579 3-4 years 3 years Total intangible assets $ 2,656,068 $ (704,069 ) $ 1,951,999 $ 2,651,667 $ (657,782 ) $ 1,993,885 Intangible assets are amortized on a straight-line basis. Intangible asset amortization expense was approximately $43.0 million and $42.4 million for the three months ended March 31, 2017 and 2016 , respectively. The amortization expense for intangible assets for the remainder of 2017 , the annual expense for the next five years, and the expense thereafter is expected to be as follows (in thousands): Remainder of 2017 $ 119,143 2018 141,951 2019 130,759 2020 123,903 2021 119,095 2022 117,966 Thereafter 1,199,182 $ 1,951,999 The change in goodwill for the three months ended March 31, 2017 consists of the following (in thousands): Balance at December 31, 2016 $ 2,396,906 Currency translation adjustments 5,400 Balance at March 31, 2017 $ 2,402,306 A substantial portion of the intangibles and goodwill relates to the acquisition of OpenTable in July 2014 and KAYAK in May 2013. There have been no events or changes in circumstances to indicate a potential impairment to goodwill or intangible assets as of March 31, 2017 .

DEBT

DEBT	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
DEBT	DEBT Short-term Borrowing On March 31, 2016, the Company utilized a credit line in an amount of $100.0 million associated with the purchase of marketable debt securities. This borrowing was repaid on April 1, 2016. Revolving Credit Facility In June 2015, the Company entered into a $2.0 billion five -year unsecured revolving credit facility with a group of lenders. Borrowings under the revolving credit facility will bear interest, at the Company’s option, at a rate per annum equal to either (i) the adjusted LIBOR for the interest period in effect for such borrowing plus an applicable margin ranging from 0.875% to 1.50% ; or (ii) the greatest of (a) Bank of America, N.A.'s prime lending rate, (b) the federal funds rate plus 0.50% , and (c) an adjusted LIBOR for an interest period of one month plus 1.00% , plus an applicable margin ranging from 0.00% to 0.50% . Undrawn balances available under the revolving credit facility are subject to commitment fees at the applicable rate ranging from 0.085% to 0.20% . The revolving credit facility provides for the issuance of up to $70.0 million of letters of credit as well as borrowings of up to $50.0 million on same-day notice, referred to as swingline loans. Borrowings under the revolving credit facility may be made in U.S. Dollars, Euros, British Pounds Sterling and any other foreign currency agreed to by the lenders. The proceeds of loans made under the facility would be used for working capital and general corporate purposes, which could include acquisitions, share repurchases or debt repayments. There were no borrowings outstanding and approximately $3.9 million and $3.8 million of letters of credit issued under the facility as of March 31, 2017 and December 31, 2016 , respectively. Outstanding Debt Outstanding debt as of March 31, 2017 consisted of the following (in thousands): March 31, 2017 Outstanding Principal Amount Unamortized Debt Discount and Debt Issuance Cost Carrying Value Short-term debt: 1.0% Convertible Senior Notes due March 2018 $ 999,997 $ (25,459 ) $ 974,538 Long-term debt: 0.35% Convertible Senior Notes due June 2020 $ 1,000,000 $ (83,969 ) $ 916,031 0.9% Convertible Senior Notes due September 2021 1,000,000 (99,325 ) 900,675 0.8% (€1 Billion) Senior Notes due March 2022 1,069,550 (7,133 ) 1,062,417 2.15% (€750 Million) Senior Notes due November 2022 802,163 (5,144 ) 797,019 2.375% (€1 Billion) Senior Notes due September 2024 1,069,550 (12,577 ) 1,056,973 3.65% Senior Notes due March 2025 500,000 (3,618 ) 496,382 3.6% Senior Notes due June 2026 1,000,000 (7,425 ) 992,575 1.8% (€1 Billion) Senior Notes due March 2027 1,069,550 (5,520 ) 1,064,030 Total long-term debt $ 7,510,813 $ (224,711 ) $ 7,286,102 Outstanding debt as of December 31, 2016 consisted of the following (in thousands): December 31, 2016 Outstanding Principal Amount Unamortized Debt Discount and Debt Issuance Cost Carrying Value Short-term debt: 1.0% Convertible Senior Notes due March 2018 $ 1,000,000 $ (32,266 ) $ 967,734 Long-term debt: 0.35% Convertible Senior Notes due June 2020 $ 1,000,000 $ (90,251 ) $ 909,749 0.9% Convertible Senior Notes due September 2021 1,000,000 (104,592 ) 895,408 2.15% (€750 Million) Senior Notes due November 2022 791,063 (5,336 ) 785,727 2.375% (€1 Billion) Senior Notes due September 2024 1,054,750 (12,861 ) 1,041,889 3.65% Senior Notes due March 2025 500,000 (3,727 ) 496,273 3.6% Senior Notes due June 2026 1,000,000 (7,619 ) 992,381 1.8% (€1 Billion) Senior Notes due March 2027 1,054,750 (5,655 ) 1,049,095 Total long-term debt $ 6,400,563 $ (230,041 ) $ 6,170,522 Based upon the closing price of the Company's common stock for the prescribed measurement periods during the three months ended March 31, 2017 and December 31, 2016 , the contingent conversion threshold on the 2018 Notes (as defined below) was exceeded. Therefore, the 2018 Notes were convertible at the option of the holders, and, accordingly, the Company reported the carrying value of the 2018 Notes as a current liability in the Company's Unaudited Consolidated Balance Sheet as of March 31, 2017 and December 31, 2016 . Since these notes are convertible at the option of the holders and the principal amount is required to be paid in cash, the Company reclassified the unamortized debt discount for the 2018 Notes in the amount of $22.5 million and $28.5 million before tax as of March 31, 2017 and December 31, 2016 , respectively, from additional paid-in-capital to convertible debt in the mezzanine section in the Company's Unaudited Consolidated Balance Sheet. The determination of whether or not the 2018 Notes are convertible is performed on a quarterly basis. Consequently, the 2018 Notes may or may not be convertible in future quarters. The contingent conversion thresholds on the 2020 Notes (as defined below) and the 2021 Notes (as defined below) were not exceeded at March 31, 2017 or December 31, 2016 , and therefore these notes were reported as a non-current liability in the Unaudited Consolidated Balance Sheets. Fair Value of Debt As of March 31, 2017 and December 31, 2016 , the estimated fair value of the outstanding Senior Notes was approximately $10.1 billion and $8.4 billion , respectively, and was considered a "Level 2 " fair value measurement (see Note 5 ). Fair value was estimated based upon actual trades at the end of the reporting period or the most recent trade available as well as the Company's stock price at the end of the reporting period. A substantial portion of the market value of the Company's debt in excess of the outstanding principal amount relates to the conversion premium on the Convertible Senior Notes. Convertible Debt If the note holders exercise their option to convert, the Company delivers cash to repay the principal amount of the notes and delivers shares of common stock or cash, at its option, to satisfy the conversion value in excess of the principal amount. In cases where holders decide to convert prior to the maturity date, the Company charges the proportionate amount of remaining debt issuance costs to interest expense. Description of Senior Convertible Notes In August 2014, the Company issued in a private placement $1.0 billion aggregate principal amount of Convertible Senior Notes due September 15, 2021, with an interest rate of 0.9% (the "2021 Notes"). The Company paid $11.0 million in debt issuance costs during the year ended December 31, 2014 related to this offering. The 2021 Notes are convertible, subject to certain conditions, into the Company's common stock at a conversion price of approximately $2,055.50 per share. The 2021 Notes are convertible, at the option of the holder, prior to September 15, 2021, upon the occurrence of specific events, including but not limited to a change in control, or if the closing sales price of the Company's common stock for at least 20 trading days in the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is more than 150% of the conversion price in effect for the notes on the last trading day of the immediately preceding quarter. In the event that all or substantially all of the Company's common stock is acquired on or prior to the maturity of the 2021 Notes in a transaction in which the consideration paid to holders of the Company's common stock consists of all or substantially all cash, the Company would be required to make additional payments in the form of additional shares of common stock to the holders of the 2021 Notes in an aggregate value ranging from $0 to approximately $375 million depending upon the date of the transaction and the then current stock price of the Company. As of June 15, 2021, holders will have the right to convert all or any portion of the 2021 Notes. The 2021 Notes may not be redeemed by the Company prior to maturity. The holders may require the Company to repurchase the 2021 Notes for cash in certain circumstances. Interest on the 2021 Notes is payable on March 15 and September 15 of each year. In May 2013, the Company issued in a private placement $1.0 billion aggregate principal amount of Convertible Senior Notes due June 15, 2020, with an interest rate of 0.35% (the "2020 Notes"). The 2020 Notes were issued with an initial discount of $20.0 million . The Company paid $1.0 million in debt issuance costs during the year ended December 31, 2013 related to this offering. The 2020 Notes are convertible, subject to certain conditions, into the Company's common stock at a conversion price of approximately $1,315.10 per share. The 2020 Notes are convertible, at the option of the holder, prior to June 15, 2020, upon the occurrence of specific events, including but not limited to a change in control, or if the closing sales price of the Company's common stock for at least 20 trading days in the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is more than 150% of the conversion price in effect for the notes on the last trading day of the immediately preceding quarter. In the event that all or substantially all of the Company's common stock is acquired on or prior to the maturity of the 2020 Notes in a transaction in which the consideration paid to holders of the Company's common stock consists of all or substantially all cash, the Company would be required to make additional payments in the form of additional shares of common stock to the holders of the 2020 Notes in an aggregate value ranging from $0 to approximately $397 million depending upon the date of the transaction and the then current stock price of the Company. As of March 15, 2020, holders will have the right to convert all or any portion of the 2020 Notes. The 2020 Notes may not be redeemed by the Company prior to maturity. The holders may require the Company to repurchase the 2020 Notes for cash in certain circumstances. Interest on the 2020 Notes is payable on June 15 and December 15 of each year. In March 2012, the Company issued in a private placement $1.0 billion aggregate principal amount of Convertible Senior Notes due March 15, 2018, with an interest rate of 1.0% (the "2018 Notes"). The Company paid $20.9 million in debt issuance costs during the year ended December 31, 2012 related to this offering. The 2018 Notes are convertible, subject to certain conditions, into the Company's common stock at a conversion price of approximately $944.61 per share. The 2018 Notes are convertible, at the option of the holder, prior to March 15, 2018, upon the occurrence of specific events, including but not limited to a change in control, or if the closing sales price of the Company's common stock for at least 20 trading days in the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is more than 150% of the conversion price in effect for the notes on the last trading day of the immediately preceding quarter. In the event that all or substantially all of the Company's common stock is acquired on or prior to the maturity of the 2018 Notes in a transaction in which the consideration paid to holders of the Company's common stock consists of all or substantially all cash, the Company would be required to make additional payments in the form of additional shares of common stock to the holders of the 2018 Notes in aggregate value ranging from $0 to approximately $344 million depending upon the date of the transaction and the then current stock price of the Company. As of December 15, 2017, holders will have the right to convert all or any portion of the 2018 Notes. The 2018 Notes may not be redeemed by the Company prior to maturity. The holders may require the Company to repurchase the 2018 Notes for cash in certain circumstances. Interest on the 2018 Notes is payable on March 15 and September 15 of each year. Cash-settled convertible debt, such as the Company's Convertible Senior Notes, is separated into debt and equity components at issuance and each component is assigned a value. The value assigned to the debt component is the estimated fair value, as of the issuance date, of a similar bond without the conversion feature. The difference between the bond cash proceeds and this estimated fair value, representing the value assigned to the equity component, is recorded as a debt discount. Debt discount is amortized using the effective interest rate method over the period from the origination date through the stated maturity date. The Company estimated the straight debt borrowing rates at debt origination to be 3.50% for the 2018 Notes, 3.13% for the 2020 Notes and 3.18% for the 2021 Notes. The yield to maturity was estimated at an at-market coupon priced at par. Debt discount after tax of $82.5 million ( $142.9 million before tax) less financing costs associated with the equity component of convertible debt of $1.6 million after tax was recorded in additional paid-in capital related to the 2021 Notes at December 31, 2014. Debt discount after tax of $92.4 million ( $154.3 million before tax) less financing costs associated with the equity component of convertible debt of $0.1 million after tax was recorded in additional paid-in capital related to the 2020 Notes at June 30, 2013. Debt discount after tax of $80.9 million ( $135.2 million before tax) less financing costs associated with the equity component of convertible debt of $2.8 million after tax was recorded in additional paid-in capital related to the 2018 Notes at March 31, 2012. For the three months ended March 31, 2017 and 2016 , the Company recognized interest expense of $24.0 million and $23.4 million , respectively, related to convertible notes, which was comprised of $5.6 million for each period related to the contractual coupon interest, $17.2 million and $16.7 million , respectively, related to the amortization of debt discount, and $1.2 million and $1.1 million , respectively, related to the amortization of debt issuance costs. For the three months ended March 31, 2017 and 2016 , included in the amortization of debt discount mentioned above was $0.7 million of original issuance discount for each period related to the 2020 Notes. The remaining period for amortization of debt discount and debt issuance costs is the period until the stated maturity date for the respective debt. The weighted-average effective interest rates for the three months ended March 31, 2017 and 2016 was 3.4% and 3.5% , respectively, related to convertible notes. Other Long-term Debt In March 2017, the Company issued Senior Notes due March 10, 2022, with an interest rate of 0.8% (the "March 2022 Notes") for an aggregate principal amount of 1.0 billion Euros. The March 2022 Notes were issued with an initial discount of 2.1 million Euros. In addition, the Company paid $4.0 million in debt issuance costs during the three months ended March 31, 2017. Interest on the March 2022 Notes is payable annually on March 10, beginning March 10, 2018. Subject to certain limited exceptions, all payments of interest and principal for the March 2022 Notes will be made in Euros. In May 2016, the Company issued Senior Notes due June 1, 2026, with an interest rate of 3.6% (the "2026 Notes") for an aggregate principal amount of $1.0 billion . The 2026 Notes were issued with an initial discount of $1.9 million . In addition, the Company paid $6.2 million in debt issuance costs during the year ended December 31, 2016. Interest on the 2026 Notes is payable semi-annually on June 1 and December 1. In November 2015, the Company issued Senior Notes due November 25, 2022, with an interest rate of 2.15% (the "November 2022 Notes") for an aggregate principal amount of 750 million Euros. The November 2022 Notes were issued with an initial discount of 2.2 million Euros. In addition, the Company paid $3.7 million in debt issuance costs during the year ended December 31, 2015. Interest on the November 2022 Notes is payable annually on November 25. Subject to certain limited exceptions, all payments of interest and principal, including payments made upon any redemption of the November 2022 Notes will be made in Euros. In March 2015, the Company issued Senior Notes due March 15, 2025, with an interest rate of 3.65% (the "2025 Notes") for an aggregate principal amount of $500 million . The 2025 Notes were issued with an initial discount of $1.3 million . In addition, the Company paid $3.2 million in debt issuance costs during the year ended December 31, 2015. Interest on the 2025 Notes is payable semi-annually on March 15 and September 15. In March 2015, the Company issued Senior Notes due March 3, 2027, with an interest rate of 1.8% (the "2027 Notes") for an aggregate principal amount of 1.0 billion Euros. The 2027 Notes were issued with an initial discount of 0.3 million Euros. In addition, the Company paid $6.3 million in debt issuance costs during the year ended December 31, 2015. Interest on the 2027 Notes is payable annually on March 3. Subject to certain limited exceptions, all payments of interest and principal for the 2027 Notes will be made in Euros. In September 2014, the Company issued Senior Notes due September 23, 2024, with an interest rate of 2.375% (the "2024 Notes") for an aggregate principal amount of 1.0 billion Euros. The 2024 Notes were issued with an initial discount of 9.4 million Euros. In addition, the Company paid $6.5 million in debt issuance costs during the year ended December 31, 2014. Interest on the 2024 Notes is payable annually on September 23. Subject to certain limited exceptions, all payments of interest and principal for the 2024 Notes will be made in Euros. The aggregate principal value of the March 2022 Notes, November 2022 Notes, 2024 Notes and 2027 Notes and accrued interest thereon are designated as a hedge of the Company's net investment in certain Euro functional currency subsidiaries. The foreign currency transaction gains or losses on these liabilities are measured based upon changes in spot rates and are recorded in " Accumulated other comprehensive income (loss) " in the Unaudited Consolidated Balance Sheets. The Euro-denominated net assets of these subsidiaries are translated into U.S. Dollars at each balance sheet date, with effects of foreign currency changes also reported in " Accumulated other comprehensive income (loss) "in the Unaudited Consolidated Balance Sheets. Since the notional amount of the recorded Euro-denominated debt and related interest are not greater than the notional amount of the Company's net investment, the Company does not expect to incur any ineffectiveness on this hedge. Debt discount is amortized using the effective interest rate method over the period from the origination date through the stated maturity date. The Company estimated the effective interest rates at debt origination to be 0.84% for the March 2022 Notes, 2.20% for the November 2022 Notes, 2.48% for the 2024 Notes, 3.68% for the 2025 Notes, 3.62% for the 2026 Notes and 1.80% for the 2027 Notes. For the three months ended March 31, 2017 and 2016 , the Company recognized interest expense of $30.6 million and $21.4 million , respectively, related to other long-term debt, which was comprised of $29.5 million and $20.5 million , respectively, for the contractual coupon interest, $0.4 million for each period related to the amortization of debt discount and $0.7 million and $0.5 million , respectively, related to the amortization of debt issuance costs. The remaining period for amortization of debt discount and debt issuance costs is the period until the stated maturity dates for the respective debt. In March 2016, the Company received a ten -year loan from the State of Connecticut in the amount of $2.5 million with an interest rate of 1% in connection with the construction of office space in Connecticut. In the first quarter of 2017, $1.0 million of the loan was forgiven as a result of meeting certain employment and salary conditions. The remaining balance of the loan will be forgiven in 2019 if certain employment and salary conditions are met. As of March 31, 2017 and December 31, 2016 , the loan in the amount of $1.5 million and $2.5 million , respectively, is reported in " Other long-term liabilities " in the Unaudited Consolidated Balance Sheet.

TREASURY STOCK

TREASURY STOCK	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
TREASURY STOCK	TREASURY STOCK In the first quarter of 2016, the Company's Board of Directors authorized a program to repurchase up to $3.0 billion of the Company's common stock. In the three months ended March 31, 2017 , the Company repurchased 80,027 shares of its common stock in the open market for an aggregate cost of $135.0 million , which included stock repurchases in March 2017 of 5,600 shares for an aggregate cost of $10.0 million that were settled in April 2017. In the first quarter of 2017, the Company's Board of Directors authorized a program to repurchase up to $2.0 billion of the Company's common stock, in addition to amounts previously authorized. As of March 31, 2017 , the Company had a remaining authorization of $4.0 billion to purchase its common stock. The Company may make additional repurchases of shares under its stock repurchase programs, depending on prevailing market conditions, alternate uses of capital and other factors. Whether and when to initiate and/or complete any purchase of common stock and the amount of common stock purchased will be determined at the Company's discretion. The Board of Directors has given the Company the general authorization to repurchase shares of its common stock to satisfy employee withholding tax obligations related to stock-based compensation. The Company repurchased 44,888 shares and 90,401 shares at an aggregate cost of $77.3 million and $117.2 million in the three months ended March 31, 2017 and 2016 , respectively, to satisfy employee withholding taxes related to stock-based compensation. For the three months ended March 31, 2017 and 2016 , the Company remitted $69.8 million and $99.5 million of such employee withholding taxes, respectively, to the tax authorities, with the remainder remitted subsequently. The new accounting standard for stock-based compensation (see Note 1) requires us to report the cash remitted to the tax authorities as a financing activity in the Unaudited Statements of Cash Flows for all periods presented. Prior to the adoption of this standard, the Company reported the aggregate cost of the shares withheld for taxes as a financing activity and the associated unremitted withholding taxes as an operating activity on the cash flow statements. As of March 31, 2017 , there were 13,315,844 shares of the Company's common stock held in treasury.

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2017
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 rate for the three months ended March 31, 2017 was 13.6% compared to 18.7% for the three months ended March 31, 2016 . The 2017 effective tax rate differs from the U.S. federal statutory tax rate of 35% , primarily as a result of lower international tax rates and current year excess tax benefits in an amount of $9.9 million recognized from the vesting of equity awards pursuant to the adoption of an accounting update effective January 2017 (see Note 1), partially offset by certain non-deductible expenses. The 2016 effective tax rate differs from the U.S. federal statutory tax rate of 35% , primarily as a result of lower international tax rates, partially offset by the tax rate impact of a non-deductible impairment of a cost-method investment of approximately $50 million in the first quarter of 2016 (see Note 4). The Company's effective tax rate was lower for the three months ended March 31, 2017 , compared to the three months ended March 31, 2016 , primarily as a result of an increased proportion of the Company's income being taxed at lower international tax rates due to the growth of the Company's international businesses and current year excess tax benefits recognized from vesting of equity awards. In addition, the non-deductible impairment of a cost-method investment was recognized in the first quarter of 2016, which contributed to a higher effective tax rate compared to the three months ended March 31, 2017. During the three months ended March 31, 2017 and 2016 , a substantial majority of the Company's income was generated in the Netherlands. According to Dutch corporate income tax law, income generated from qualifying innovative activities is taxed at a rate of 5% ("Innovation Box Tax") rather than the Dutch statutory rate of 25% . A portion of Booking.com's earnings during the three months ended March 31, 2017 and 2016 qualifies for Innovation Box Tax treatment, which had a significant beneficial impact on the Company's effective tax rate for those periods.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME	3 Months Ended
	Mar. 31, 2017
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME	ACCUMULATED OTHER COMPREHENSIVE INCOME The table below provides the balances for each classification of accumulated other comprehensive income (loss) as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Foreign currency translation adjustments, net of tax (1) $ (275,442 ) $ (311,247 ) Net unrealized gain on marketable securities, net of tax (2) 522,497 176,563 Accumulated other comprehensive income (loss) $ 247,055 $ (134,684 ) (1) Foreign currency translation adjustments, net of tax, include net losses from fair value adjustments of $35.0 million after tax ( $52.6 million before tax) associated with settled derivatives that previously had been designated as net investment hedges at both March 31, 2017 and December 31, 2016 . Foreign currency translation adjustments, net of tax, include foreign currency transaction gains of $149.9 million after tax ( $258.0 million before tax) and $182.6 million after tax ( $310.4 million before tax) associated with the Company's March 2022 Notes, November 2022 Notes, 2024 Notes and 2027 Notes at March 31, 2017 and December 31, 2016 , respectively. The March 2022 Notes, November 2022 Notes, 2024 Notes and 2027 Notes are Euro-denominated debt and are designated as hedges of certain of the Company's Euro-denominated net assets (see Note 7 ). The remaining balance in foreign currency translation adjustments excludes income taxes as a result of the Company's intention to indefinitely reinvest the earnings of its international subsidiaries outside of the United States. (2) The unrealized gains before tax at March 31, 2017 and December 31, 2016 were $539.7 million and $185.9 million , respectively, of which unrealized gains of $472.2 million and $148.5 million , respectively, were exempt from tax in the Netherlands and unrealized gains of $67.5 million and $37.4 million , respectively, were taxable.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Competition Reviews The online travel industry has become the subject of investigations by various national competition authorities ("NCAs"), particularly in Europe. The Company is or has been involved in investigations predominantly related to whether Booking.com's contractual parity arrangements with accommodation providers, sometimes also referred to as "most favored nation" or "MFN" provisions, are anti-competitive because they require accommodation providers to provide Booking.com with room rates that are at least as low as those offered to other online travel companies ("OTCs") or through the accommodation provider's website. Some investigations relate to other issues such as reservation and cancellation clauses, commission payments and pricing behavior. For instance, in September 2016 the Swiss Price Surveillance Office initiated a market observation exercise with respect to the market position and the level of commissions of Booking.com in Switzerland. In Europe, investigations into Booking.com's price parity provisions were initiated in 2013 and 2014 by NCAs in France, Germany, Italy, Austria, Sweden, Ireland and Switzerland. A number of other NCAs have also looked at these issues. On April 21, 2015, the French, Italian and Swedish NCAs, working in close cooperation with the European Commission, announced that they had accepted "commitments" offered by Booking.com to resolve and close the investigations in France, Italy and Sweden. Under the commitments, Booking.com replaced its existing price parity agreements with accommodation providers with "narrow" price parity agreements. Under a "narrow" price parity agreement, subject to certain exceptions, an accommodation provider is still required to offer the same or better rates on Booking.com as it offers to a consumer directly online, but it is no longer required to offer the same or better rates on Booking.com as it offers to other OTCs. The commitments also allow an accommodation provider to, among other things, offer different terms and conditions (e.g., free WiFi) and availability to consumers that book with online travel companies that offer lower rates of commission or other benefits, offer lower rates to consumers that book through offline channels and continue to discount through, among other things, accommodation loyalty programs, as long as those rates are not published or marketed online. The commitments apply to accommodations in France, Italy and Sweden and were effective on July 1, 2015. The foregoing description is a summary only and is qualified in its entirety by reference to the commitments published by the NCAs on April 21, 2015. On July 1, 2015, Booking.com voluntarily implemented the commitments given to the French, Italian and Swedish NCAs throughout the European Economic Area and Switzerland. Nearly all NCAs in the European Economic Area have now closed their investigations following Booking.com's implementation of the commitments in their jurisdictions. Booking.com has also recently agreed with the NCAs in Australia, New Zealand and Georgia to implement the "narrow" price parity clause in these countries. However, the Australian NCA indicated in February 2017 that it is reassessing "narrow" price parity clauses between online travel agencies and accommodation providers. The Turkish NCA recently imposed fines on Booking.com following an investigation into Booking.com's "wide" parity clauses. Booking.com is in ongoing discussions with various NCAs in other countries regarding their concerns. The Company is currently unable to predict the long-term impact the implementation of these commitments will have on Booking.com's business, on investigations by other countries, or on industry practice more generally. On December 23, 2015, the German NCA issued a final decision prohibiting Booking.com's "narrow" price parity agreements with accommodations in Germany. The German NCA did not issue a fine, but has reserved its position regarding an order for disgorgement of profits. Booking.com is appealing the German NCA's decision. An Italian hotel association has appealed the Italian NCA's decision to accept the commitments by Booking.com. A working group of 10 European NCAs (France, Germany, Belgium, Hungary, Ireland, Italy, the Netherlands, Czech Republic, the United Kingdom and Sweden) was established by the European Commission in December 2015 to monitor the effects of the narrow price parity clause in Europe. This working group (the "ECN Working Group") issued questionnaires during 2016 to online travel agencies, including Booking.com and Expedia, meta-search sites and hotels about the narrow price parity clause. On April 6, 2017, the ECN Working Group published the results of this monitoring exercise. The report indicates that the introduction of the narrow price parity clause generally improved conditions for competition. Although neither the European Commission nor any of the participating NCAs has opened a new investigation following the publication of the report, the ECN Working Group decided to keep the sector under review and re-assess the competitive situation in due course. Separately, the French NCA, which conducted its own review of the effects of the narrow price parity clause, issued a report on February 9, 2017 stating that it has not ruled out the possibility of issuing an opinion at its own initiative if a change in competition requires it, and that it would continue to contribute actively to the ECN Working Group process. The Company is unable to predict how these appeals and the remaining investigations in other countries will ultimately be resolved, or whether further action in Europe will be taken as a result of the ECN Working Group's ongoing review. Possible outcomes include requiring Booking.com to amend or remove its rate parity clause from its contracts with accommodation providers in those jurisdictions and/or the imposition of fines. The Company is unable to predict the impact these possible outcomes might have on its business. In August 2015, French legislation known as the "Macron Law" became effective. Among other things, the Macron Law makes price parity agreements illegal, including the "narrow" price parity agreements agreed to by the French NCA in April 2015. Legislation in Austria prohibiting "narrow" price parity agreements (including the narrow parity clause) became effective on December 31, 2016. Similar legislation was approved by the Italian Senate on May 3, 2017, and will return to the Italian Chamber of Deputies for final approval. A motion to prohibit the narrow price parity clause is currently being discussed in the Swiss Parliament. It is not yet clear how the Macron Law and the Austrian legislation or the proposed Italian and Swiss legislation may affect the Company's business in the long term in France, Austria, Italy and Switzerland, respectively. Competition-related investigations, legislation or issues could also give rise to private litigation. For example, Booking.com is involved in private litigation in Sweden related to its "narrow" price parity provisions. We are unable to predict how this litigation will be resolved, or whether it will impact Booking.com's business in Sweden. Litigation Related to Travel Transaction Taxes The Company and certain third-party OTCs are currently involved in approximately thirty lawsuits, including certified and putative class actions, brought by or against U.S. states, cities and counties over issues involving the payment of travel transaction taxes (e.g., hotel occupancy taxes, excise taxes, sales taxes, etc.) related to the priceline.com business. Generally, the complaints allege, among other things, that the OTCs violated each jurisdiction's respective relevant travel transaction tax ordinance with respect to the charge and remittance of amounts to cover taxes under each law. The Company believes that the laws at issue generally do not apply to the services it provides, namely the facilitation of travel reservations, and, therefore, that it does not owe the taxes that are claimed to be owed. However, the Company has been involved in this type of litigation for many years, and state and local jurisdictions where these issues have not been resolved could assert that the Company is subject to travel transaction taxes and could seek to collect such taxes, retroactively and/or prospectively. From time to time, the Company has found it expedient to settle claims pending in these matters without conceding that the claims at issue are meritorious or that the claimed taxes are in fact due to be paid. The Company may also settle current or future travel transaction tax claims. On August 5, 2016, the tax appeal court of the State of Hawaii ruled that online travel companies, including the Company, owe General Excise Tax (GET) on the gross amounts collected from consumers on rental car reservations. The tax appeal court rejected the online travel companies' arguments that GET applies only to amounts retained by online travel companies and does not include amounts paid to rental car company suppliers. The online travel companies argued that GET should not apply to gross amounts charged to consumers for rental car reservations pursuant to the 2015 decision of the Hawaii Supreme Court in Travelocity.com, L.P., et al. v. Director of Taxation that GET applies to amounts retained by online travel companies for hotel reservations and not for gross amounts charged to consumers. The Company intends to appeal the tax appeal court decision to the Hawaii appellate courts. In order to appeal the decision, the Company must pay $13 million , which is the amount of the judgment entered on April 25, 2017. Litigation is subject to uncertainty and there could be adverse developments in these pending or future cases and proceedings. An unfavorable outcome or settlement of pending litigation may encourage the commencement of additional litigation, audit proceedings or other regulatory inquiries and also could result in substantial liabilities for past and/or future bookings, including, among other things, interest, penalties, punitive damages and/or attorneys’ fees and costs. An adverse outcome in one or more of these unresolved proceedings could have an adverse effect on the Company's results of operations or cash flows in any given operating period. However, the Company believes that even if the Company were to suffer adverse determinations in the near term in more of the pending proceedings than currently anticipated, given results to date it would not have a material impact on its liquidity or financial condition. As a result of the travel transaction tax litigation generally and other attempts by U.S. jurisdictions to levy similar taxes, the Company has established an accrual (including estimated interest and penalties) for the potential resolution of issues related to travel transaction taxes in the amount of approximately $27 million at both March 31, 2017 and December 31, 2016 . The Company's legal expenses for these matters are expensed as incurred and are not reflected in the amount accrued. The actual cost may be less or greater, potentially significantly, than the liabilities recorded. An estimate for a reasonably possible loss or range of loss in excess of the amount accrued cannot be reasonably made. Patent Infringement On February 9, 2015, International Business Machines Corporation ("IBM") filed a complaint in the U.S. District Court for the District of Delaware against The Priceline Group Inc. and its subsidiaries KAYAK Software Corporation, OpenTable, Inc. and priceline.com LLC (the "Subject Companies"). In the complaint, IBM alleges that the Subject Companies have infringed and continue to willfully infringe certain IBM patents that IBM claims relate to the presentation of applications and advertising in an interactive service, preserving state information in online transactions and single sign-on processes in a computing environment and seeks unspecified damages (including a request that the amount of compensatory damages be trebled), injunctive relief and costs and reasonable attorneys’ fees. The Subject Companies believe the claims to be without merit and are contesting them. The Subject Companies asked the court to dismiss the case due to lack of patentable subject matter in the asserted patents, and on March 30, 2016 that motion was denied without prejudice to refiling later in the case. Concurrently with the litigation, the Subject Companies filed two Inter Partes Review ("IPR") petitions and four Covered Business Method ("CBM") petitions for the patents-in-suit with the U.S. Patent and Trademark Office (the "PTAB"). The PTAB denied one of the IPR petitions and granted one of the IPR petitions, and denied the four CBM petitions. Expert discovery has concluded and the parties have fully briefed and held oral argument on summary judgment motions. There is a mediation in the case scheduled for May 23, 2017 before the Magistrate Judge. Trial in the District Court is scheduled for August 2017. The Company does not believe a loss contingency is probable and reasonably estimable and therefore has not recorded a liability for this matter. French Tax Matter French tax authorities conducted an audit of Booking.com of the years 2003 through 2012. They are asserting that Booking.com has a permanent establishment in France and are seeking to recover what they claim are unpaid income taxes and value-added taxes. In December 2015, the French tax authorities issued Booking.com assessments for approximately 356 million Euros, the majority of which would represent penalties and interest. The Company believes that Booking.com has been, and continues to be, in compliance with French tax law, and the Company intends to contest the assessments. If the Company is unable to resolve the matter with the French authorities, it would expect to challenge the assessments in the French courts. In order to contest the assessments in court, the Company may be required to pay, upfront, the full amount or a significant part of any such assessments, though any such payment would not constitute an admission by it that it owes the taxes. At the end of 2016, French authorities announced their intention to also audit the tax years 2013 to 2015, which could result in additional assessments. Turkish Matter From time to time the Company has been subject to legal proceedings and claims regarding whether it is subject to local registration requirements, such as requirements to register as a travel agent. In March 2017, in connection with a lawsuit begun in 2015 by the Association of Turkish Travel Agencies claiming that Booking.com is required to meet certain registration requirements in Turkey, a Turkish court unexpectedly ordered Booking.com to suspend offering Turkish hotels and accommodations to Turkish residents. Although Booking.com is appealing the order and believes it to be without basis, this order has had, and is likely to continue to have, a negative impact on the Company's growth and results of operations. Other The Company accrues for certain legal contingencies where it is probable that a loss has been incurred and the amount can be reasonably estimated. Such accrued amounts are not material to the Company's consolidated balance sheets and provisions recorded have not been material to the Company's consolidated results of operations or cash flows. An estimate for a reasonably possible loss or range of loss in excess of the amount accrued cannot be reasonably made. From time to time, the Company has been, and expects to continue to be, subject to legal proceedings and claims in the ordinary course of business, including claims of alleged infringement of third-party intellectual property rights. Such claims, even if not meritorious, could result in the expenditure of significant financial and managerial resources, divert management's attention from the Company's business objectives and adversely affect the Company's business, results of operations, financial condition and cash flows. Contingent Consideration for Business Acquisitions As of March 31, 2017 and December 31, 2016 , the Company recognized a liability of approximately $9 million for each period for estimated contingent payments, which was considered a "Level 3" fair value measurement (see Note 5). The estimated acquisition-date contingent liability is based upon the probability-weighted average payments for specific performance factors from the acquisition date through the performance period which ends at March 31, 2019. The range of undiscounted outcomes for the estimated contingent payments is approximately $0 to $90 million . Building Construction In September 2016, the Company signed a turnkey agreement to construct an office building in the Netherlands, which will be the future headquarters of the Booking.com business. The turnkey agreement provided for payments by Booking.com of approximately 270 million Euros and consists of two components, land use rights and the building to be constructed. Upon signing this agreement, Booking.com paid approximately 48 million Euros to the developer, which included approximately 43 million Euros for the acquired land use rights and approximately 5 million Euros for the building construction. The land use rights are included in "Other assets" and the building construction-in-progress is included in "Property and equipment, net" in the Unaudited Consolidated Balance Sheets at March 31, 2017 and December 31, 2016 . The land use rights asset and required future lease payments to the Municipality in Amsterdam of approximately 60 million Euros are recognized as rent expense on a straight-line basis over the remaining 49 -year term of the lease and are recorded in general and administrative expense in the statements of operations. Booking.com expects to pay approximately 34 million Euros related to the building construction later in 2017, with the remainder of payments being paid periodically beginning in 2018 until the expected completion of the building in late 2020. The Company expects all future payments to be made from its international cash. Acquisition of Momondo Group On February 7, 2017, the Company signed a definitive agreement to acquire the Momondo Group, which operates the travel meta-search websites Momondo and Cheapflights. The Company will use approximately $550 million of its international cash to fund this acquisition. The transaction is expected to close later in the year, subject to regulatory approval.

BASIS OF PRESENTATION (Policies

BASIS OF PRESENTATION (Policies)	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Adopted Definition of a Business In January 2017, the Financial Accounting Standards Board ("FASB") issued a new accounting update to clarify the definition of a business and provide additional guidance to assist entities with evaluating whether transactions should be accounted for as asset acquisitions (or disposals) or business combinations (or disposals of a business). Under this update, an entity first determines whether substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets. If this criterion is met, the transaction should be accounted for as an asset acquisition as opposed to a business combination. This distinction is important because the accounting for an asset acquisition may differ significantly from the accounting for a business combination. This update eliminates the requirement to evaluate whether a market participant could replace missing elements (e.g., inputs or processes), narrows the definition of outputs and requires that a business include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. For public business entities, this update is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods, and is required to be applied prospectively. The Company early adopted this update in the first quarter of 2017 and the adoption did not have an impact to the Unaudited Consolidated Financial Statements. Intra-entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued new accounting guidance on income tax accounting associated with intra-entity transfers of assets other than inventory. This accounting update, which is part of the FASB's simplification initiative, is intended to reduce diversity in practice and the complexity of tax accounting, particularly for those transfers involving intellectual property. This new guidance requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. For public business entities, this update is effective for annual reporting periods beginning after December 15, 2017. Entities are required to apply this accounting update on a modified retrospective basis with a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company early adopted this update in the first quarter of 2017. The adoption resulted in a cumulative net charge to retained earnings of $4.2 million , a reduction in deferred tax liabilities of $5.7 million and reductions in current and long-term assets of $3.3 million and $6.6 million , respectively, as of January 1, 2017. Share-based Compensation In March 2016, the FASB issued new accounting guidance to improve the accounting for certain aspects of share-based payment transactions as part of its simplification initiative. The key provisions of this accounting update are: (1) recognizing current excess tax benefits in the income statement in the period the benefits are deducted on the income tax return as opposed to an adjustment to additional paid-in capital in the period the benefits are realized by reducing a current income tax liability, (2) allowing an entity-wide election to account for forfeitures related to service conditions as they occur instead of estimating the total number of awards that will be forfeited because the requisite service period will not be rendered, (3) allowing the net settlement of an equity award for employee statutory tax withholding purposes to not exceed the maximum statutory tax rate by relevant tax jurisdiction instead of withholding taxes for each employee based on a minimum statutory withholding tax rate, and (4) requiring the presentation of excess tax benefits as operating cash flows and cash payments for employee statutory tax withholding related to vested stock awards as financing cash flows in the consolidated statements of cash flows. Under this new accounting standard, all previously unrecognized equity deductions are recognized as a deferred tax asset, net of any valuation allowance, with a cumulative-effect adjustment to retained earnings as of the beginning of the year of adoption of this standard. The Company adopted this accounting update in the first quarter of 2017 and recorded a deferred tax asset of $301.4 million related to previously unrecognized U.S. equity tax deductions, with an offsetting cumulative-effect adjustment to retained earnings as of January 1, 2017. The Company elected to account for forfeitures related to service conditions as they occur; as a result, there was a cumulative net charge to retained earnings of $6.9 million (forfeiture expenses adjustment after taxes) and the recognition of a deferred tax asset of $2.1 million , with an offsetting credit to additional paid-in capital of $9.0 million . In addition, the Company elected to change the presentation of excess tax benefits in the Unaudited Consolidated Statement of Cash Flows for periods prior to January 1, 2017 to reflect these excess tax benefits in operating cash flows instead of financing cash flows, resulting in a reclassification of $18.1 million for the three months ended March 31, 2016 . "Payments for repurchase of common stock" in the Unaudited Consolidated Statements of Cash Flows includes withholding taxes paid on vested stock awards (see Note 8). Other Recent Accounting Pronouncements Premium Amortization on Purchased Callable Debt Securities In March 2017, the FASB issued a new accounting update to shorten the premium amortization period of purchased callable debt securities with non-contingent call features that are callable at fixed prices and on preset dates from their contractual maturity to the earliest call date. For public business entities, this new accounting update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. Entities are required to apply this accounting update on a modified retrospective basis with a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact to its Consolidated Financial Statements of adopting this new update. Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued a new accounting update to simplify the test for goodwill impairment by eliminating Step 2, which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill, which requires a hypothetical purchase price allocation, with the carrying amount of that reporting unit’s goodwill. Under this update, an entity would perform its quantitative annual, or interim, goodwill impairment test using the current Step 1 test and recognize an impairment charge for the excess of the carrying value of a reporting unit over its fair value. For public business entities, this update is effective for their annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests occurring after January 1, 2017. The accounting update will be applied prospectively. The Company is currently evaluating the impact to its Consolidated Financial Statements of adopting this new update. Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued new accounting guidance on the measurement of credit losses for financial assets measured at amortized cost, which includes accounts receivable and available-for-sale debt securities. For financial assets measured at amortized cost, this new guidance requires an entity to (1) estimate its lifetime expected credit losses upon recognition of the financial assets and establish an allowance to present the net amount expected to be collected, (2) recognize this allowance and changes in the allowance during subsequent periods through net income and (3) consider relevant information about past events, current conditions and reasonable and supportable forecasts in assessing the lifetime expected credit losses. For available-for-sale debt securities, this new guidance made several targeted amendments to the existing other-than-temporary impairment model, including (1) requiring disclosure of the allowance for credit losses, (2) allowing reversals of the previously recognized credit losses until the entity has the intent to sell, is more-likely-than-not required to sell the securities or the maturity of the securities, (3) limiting impairment to the difference between the amortized cost basis and fair value and (4) not allowing entities to consider the length of time that fair value has been less than amortized cost as a factor in evaluating whether a credit loss exists. This update is effective for public business entities for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Entities are required to apply this accounting update on a modified retrospective basis with a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact to its Consolidated Financial Statements of adopting this new guidance. Leases In February 2016, the FASB issued a new accounting standard intended to improve the financial reporting of lease transactions. The new accounting standard requires lessees to recognize an asset and a liability on the balance sheet for the right and obligation created by entering into a lease transaction for all leases with the exception of short-term leases. The new standard retains the dual-model concept by requiring entities to determine if a lease is an operating or financing lease and the current "bright line" percentages could be used as guidance in applying the new standard. The lessor accounting model remains largely unchanged. The new standard significantly expands qualitative and quantitative disclosures for lessees. The update is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is allowed. Entities are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company is currently evaluating the impact to its Consolidated Financial Statements of adopting this new standard. Recognition and Measurement of Financial Instruments In January 2016, the FASB issued a new accounting update which amends the guidance on the recognition and measurement of financial instruments. The update requires (1) an entity to measure equity investments (except those accounted for under the equity method or those that result in consolidation of the investee) at fair value with changes in fair value recognized in net income rather than accumulated other comprehensive income (loss), (2) allows an entity to elect to measure those equity investments that do not have a readily determinable fair value at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer, (3) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, and (4) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity’s evaluation of their other deferred tax assets. This update is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption, although allowed in certain circumstances, is not applicable to the Company. An entity would apply this update by a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. After the adoption of this new accounting guidance, in the first quarter of 2018, the Company will record in net income fair value changes in its investments in Ctrip equity securities, which could vary significantly quarter to quarter (see Note 4 for the carrying values and fair values of these equity investments). In addition, the Company intends to continue to use the cost method of accounting for equity investments without a readily determinable fair value. Revenue from Contracts with Customers In May 2014, the FASB issued a new accounting standard on the recognition of revenue from contracts with customers that was designed to create greater comparability for financial statement users across industries and jurisdictions. The core principle of this standard is that an "entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services." The new standard also requires enhanced disclosures on the nature, amount, timing and uncertainty of revenue from contracts with customers. Since May 2014, the FASB has issued several amendments to this standard, including additional guidance, and deferred the effective date for public business entities to annual and interim periods beginning after December 15, 2017. The Company will adopt this new standard in the first quarter of 2018 and expects to apply the modified retrospective transition approach, which means that revenues for 2016 and 2017 will be reported on a historical basis and revenues for 2018 will be reported on the new basis and disclosed on the historical basis. The revenue standard will change the timing of revenue recognition for travel reservation services. For example, revenue for accommodation reservation services will be recognized at check-in rather than check-out. The Company does not currently expect material impacts to its annual gross profit or net income due to this timing change, although the effects on quarterly gross profit and net income may be more significant. In addition, the adoption of the revenue standard will change the presentation of Name Your Own Price ® revenue from "gross" to "net" reporting, which will decrease revenue and cost of revenue equally, but have no impact on gross profit or net income.

BASIS OF PRESENTATION (Tables)

BASIS OF PRESENTATION (Tables)	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Restricted Cash and Cash Equivalents [Table Text Block]	Restricted Cash: The following table reconciles cash, cash equivalents and restricted cash reported in the Unaudited Consolidated Balance Sheets to the total amount shown in the Unaudited Consolidated Statements of Cash Flows: March 31, December 31, As included in the Unaudited Consolidated Balance Sheets: Cash and cash equivalents $ 2,434,020 $ 2,081,075 Restricted cash included in prepaid expenses and other current assets 928 932 Total cash, cash equivalents and restricted cash as shown in the Unaudited Consolidated Statements of Cash Flows $ 2,434,948 $ 2,082,007

STOCK-BASED EMPLOYEE COMPENSA24

STOCK-BASED EMPLOYEE COMPENSATION (Tables)	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Activity of unvested restricted stock units and performance share units	Restricted Stock Units and Performance Share Units The following table summarizes the activity of restricted stock units and performance share units ("share-based awards") during the three months ended March 31, 2017 : Share-Based Awards Shares Weighted-Average Grant Date Fair Value Unvested at December 31, 2016 515,606 $ 1,287.88 Granted 155,095 $ 1,735.10 Vested (112,791 ) $ 1,325.40 Performance Share Units Adjustment (445 ) $ 1,291.76 Forfeited (7,103 ) $ 1,301.58 Unvested at March 31, 2017 550,362 $ 1,406.29
Schedule of share-based compensation, stock options, activity	Stock Options All outstanding employee stock options were assumed in acquisitions. The following table summarizes the activity for stock options during the three months ended March 31, 2017 : Employee Stock Options Number of Shares Weighted-Average Aggregate Intrinsic Value (in thousands) Weighted-Average Remaining Contractual Term Balance, December 31, 2016 48,983 $ 372.07 $ 53,587 4.4 Exercised (3,992 ) $ 368.68 Forfeited (610 ) $ 894.15 Balance, March 31, 2017 44,381 $ 365.20 $ 62,789 4.2 Vested and exercisable as of March 31, 2017 43,125 $ 354.23 $ 61,485 4.1 Vested and exercisable as of March 31, 2017 and expected to vest thereafter, net of estimated forfeitures 44,381 $ 365.20 $ 62,789 4.2

NET INCOME PER SHARE (Tables)

NET INCOME PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Reconciliation of the weighted average number of shares outstanding used in calculating diluted earnings per share	A reconciliation of the weighted-average number of shares outstanding used in calculating diluted earnings per share is as follows (in thousands): Three Months Ended 2017 2016 Weighted-average number of basic common shares outstanding 49,192 49,630 Weighted-average dilutive stock options, restricted stock units and performance share units 227 275 Assumed conversion of Convertible Senior Notes 606 224 Weighted-average number of diluted common and common equivalent shares outstanding 50,025 50,129 Anti-dilutive potential common shares 2,256 2,665

INVESTMENTS (Tables)

INVESTMENTS (Tables)	3 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investments	The following table summarizes, by major security type, the Company's investments as of December 31, 2016 (in thousands): Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term investments: International government securities $ 249,552 $ 221 $ (89 ) $ 249,684 U.S. government securities 456,971 57 (140 ) 456,888 Corporate debt securities 1,510,119 1,119 (928 ) 1,510,310 Commercial paper 1,998 — — 1,998 Total short-term investments $ 2,218,640 $ 1,397 $ (1,157 ) $ 2,218,880 Long-term investments: International government securities $ 655,857 $ 4,110 $ (623 ) $ 659,344 U.S. government securities 773,718 337 (7,463 ) 766,592 Corporate debt securities 6,042,271 9,973 (50,455 ) 6,001,789 U.S. government agency securities 4,979 — (27 ) 4,952 Ctrip convertible debt securities 1,275,000 65,800 (47,712 ) 1,293,088 Ctrip equity securities 655,311 213,233 (3,242 ) 865,302 Total long-term investments $ 9,407,136 $ 293,453 $ (109,522 ) $ 9,591,067 The following table summarizes, by major security type, the Company's investments as of March 31, 2017 (in thousands): Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term investments: International government securities $ 517,398 $ 1,254 $ (187 ) $ 518,465 U.S. government securities 580,630 17 (427 ) 580,220 Corporate debt securities 1,831,179 1,482 (1,166 ) 1,831,495 Commercial paper 5,978 — — 5,978 Total short-term investments $ 2,935,185 $ 2,753 $ (1,780 ) $ 2,936,158 Long-term investments: International government securities $ 450,445 $ 1,894 $ (788 ) $ 451,551 U.S. government securities 828,777 286 (6,744 ) 822,319 Corporate debt securities 6,387,523 10,334 (37,658 ) 6,360,199 U.S. government agency securities 4,971 — (25 ) 4,946 Ctrip convertible debt securities 1,275,000 171,425 (8,050 ) 1,438,375 Ctrip equity securities 655,311 407,929 — 1,063,240 Total long-term investments $ 9,602,027 $ 591,868 $ (53,265 ) $ 10,140,630

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Financial instruments carried at fair value	Financial assets and liabilities carried at fair value as of March 31, 2017 are classified in the tables below in the categories described below (in thousands): Level 1 Level 2 Total ASSETS: Cash equivalents: Money market funds $ 1,249,091 $ — $ 1,249,091 International government securities — 35,052 35,052 U.S. government securities — 159,956 159,956 Corporate debt securities — 10,243 10,243 Time deposits 4,724 — 4,724 Short-term investments: International government securities — 518,465 518,465 U.S. government securities — 580,220 580,220 Corporate debt securities — 1,831,495 1,831,495 Commercial paper — 5,978 5,978 Long-term investments: International government securities — 451,551 451,551 U.S. government securities — 822,319 822,319 Corporate debt securities — 6,360,199 6,360,199 U.S. government agency securities — 4,946 4,946 Ctrip convertible debt securities — 1,438,375 1,438,375 Ctrip equity securities 1,063,240 — 1,063,240 Derivatives: Currency exchange derivatives — 558 558 Total assets at fair value $ 2,317,055 $ 12,219,357 $ 14,536,412 Level 1 Level 2 Total LIABILITIES: Currency exchange derivatives $ — $ 593 $ 593 Financial assets and liabilities carried at fair value as of December 31, 2016 are classified in the tables below in the categories described below (in thousands): Level 1 Level 2 Total ASSETS: Cash equivalents: Money market funds $ 977,468 $ — $ 977,468 International government securities — 30,266 30,266 U.S. government securities — 176,140 176,140 Corporate debt securities — 9,273 9,273 Commercial paper — 1,998 1,998 Time deposits 49,160 — 49,160 Short-term investments: International government securities — 249,684 249,684 U.S. government securities — 456,888 456,888 Corporate debt securities — 1,510,310 1,510,310 Commercial paper — 1,998 1,998 Long-term investments: International government securities — 659,344 659,344 U.S. government securities — 766,592 766,592 Corporate debt securities — 6,001,789 6,001,789 U.S. government agency securities — 4,952 4,952 Ctrip convertible debt securities — 1,293,088 1,293,088 Ctrip equity securities 865,302 — 865,302 Derivatives: Currency exchange derivatives — 756 756 Total assets at fair value $ 1,891,930 $ 11,163,078 $ 13,055,008 Level 1 Level 2 Total LIABILITIES: Currency exchange derivatives $ — $ 1,015 $ 1,015

INTANGIBLE ASSETS AND GOODWILL

INTANGIBLE ASSETS AND GOODWILL (Tables)	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets	The Company's intangible assets at March 31, 2017 and December 31, 2016 consisted of the following (in thousands): March 31, 2017 December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Amortization Weighted Supply and distribution agreements $ 812,361 $ (287,948 ) $ 524,413 $ 809,287 $ (270,813 ) $ 538,474 3 - 20 years 16 years Technology 112,451 (85,670 ) 26,781 112,141 (80,549 ) 31,592 1 - 5 years 5 years Patents 1,623 (1,608 ) 15 1,623 (1,598 ) 25 15 years 15 years Internet domain names 40,047 (26,394 ) 13,653 39,495 (25,089 ) 14,406 2 - 20 years 8 years Trade names 1,667,686 (282,322 ) 1,385,364 1,667,221 (261,412 ) 1,405,809 4-20 years 20 years Non-compete agreements 21,900 (20,127 ) 1,773 21,900 (18,321 ) 3,579 3-4 years 3 years Total intangible assets $ 2,656,068 $ (704,069 ) $ 1,951,999 $ 2,651,667 $ (657,782 ) $ 1,993,885
Annual estimated amortization expense for intangible assets for the remainder of 2017, the next five years and thereafter	The amortization expense for intangible assets for the remainder of 2017 , the annual expense for the next five years, and the expense thereafter is expected to be as follows (in thousands): Remainder of 2017 $ 119,143 2018 141,951 2019 130,759 2020 123,903 2021 119,095 2022 117,966 Thereafter 1,199,182 $ 1,951,999
Goodwill	The change in goodwill for the three months ended March 31, 2017 consists of the following (in thousands): Balance at December 31, 2016 $ 2,396,906 Currency translation adjustments 5,400 Balance at March 31, 2017 $ 2,402,306

DEBT (Tables)

DEBT (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Schedule of Debt [Table Text Block]	Outstanding Debt Outstanding debt as of March 31, 2017 consisted of the following (in thousands): March 31, 2017 Outstanding Principal Amount Unamortized Debt Discount and Debt Issuance Cost Carrying Value Short-term debt: 1.0% Convertible Senior Notes due March 2018 $ 999,997 $ (25,459 ) $ 974,538 Long-term debt: 0.35% Convertible Senior Notes due June 2020 $ 1,000,000 $ (83,969 ) $ 916,031 0.9% Convertible Senior Notes due September 2021 1,000,000 (99,325 ) 900,675 0.8% (€1 Billion) Senior Notes due March 2022 1,069,550 (7,133 ) 1,062,417 2.15% (€750 Million) Senior Notes due November 2022 802,163 (5,144 ) 797,019 2.375% (€1 Billion) Senior Notes due September 2024 1,069,550 (12,577 ) 1,056,973 3.65% Senior Notes due March 2025 500,000 (3,618 ) 496,382 3.6% Senior Notes due June 2026 1,000,000 (7,425 ) 992,575 1.8% (€1 Billion) Senior Notes due March 2027 1,069,550 (5,520 ) 1,064,030 Total long-term debt $ 7,510,813 $ (224,711 ) $ 7,286,102 Outstanding debt as of December 31, 2016 consisted of the following (in thousands): December 31, 2016 Outstanding Principal Amount Unamortized Debt Discount and Debt Issuance Cost Carrying Value Short-term debt: 1.0% Convertible Senior Notes due March 2018 $ 1,000,000 $ (32,266 ) $ 967,734 Long-term debt: 0.35% Convertible Senior Notes due June 2020 $ 1,000,000 $ (90,251 ) $ 909,749 0.9% Convertible Senior Notes due September 2021 1,000,000 (104,592 ) 895,408 2.15% (€750 Million) Senior Notes due November 2022 791,063 (5,336 ) 785,727 2.375% (€1 Billion) Senior Notes due September 2024 1,054,750 (12,861 ) 1,041,889 3.65% Senior Notes due March 2025 500,000 (3,727 ) 496,273 3.6% Senior Notes due June 2026 1,000,000 (7,619 ) 992,381 1.8% (€1 Billion) Senior Notes due March 2027 1,054,750 (5,655 ) 1,049,095 Total long-term debt $ 6,400,563 $ (230,041 ) $ 6,170,522

ACCUMULATED OTHER COMPREHENSI30

ACCUMULATED OTHER COMPREHENSIVE INCOME (Tables)	3 Months Ended
	Mar. 31, 2017
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Balances for each classification of accumulated other comprehensive income	The table below provides the balances for each classification of accumulated other comprehensive income (loss) as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Foreign currency translation adjustments, net of tax (1) $ (275,442 ) $ (311,247 ) Net unrealized gain on marketable securities, net of tax (2) 522,497 176,563 Accumulated other comprehensive income (loss) $ 247,055 $ (134,684 ) (1) Foreign currency translation adjustments, net of tax, include net losses from fair value adjustments of $35.0 million after tax ( $52.6 million before tax) associated with settled derivatives that previously had been designated as net investment hedges at both March 31, 2017 and December 31, 2016 . Foreign currency translation adjustments, net of tax, include foreign currency transaction gains of $149.9 million after tax ( $258.0 million before tax) and $182.6 million after tax ( $310.4 million before tax) associated with the Company's March 2022 Notes, November 2022 Notes, 2024 Notes and 2027 Notes at March 31, 2017 and December 31, 2016 , respectively. The March 2022 Notes, November 2022 Notes, 2024 Notes and 2027 Notes are Euro-denominated debt and are designated as hedges of certain of the Company's Euro-denominated net assets (see Note 7 ). The remaining balance in foreign currency translation adjustments excludes income taxes as a result of the Company's intention to indefinitely reinvest the earnings of its international subsidiaries outside of the United States. (2) The unrealized gains before tax at March 31, 2017 and December 31, 2016 were $539.7 million and $185.9 million , respectively, of which unrealized gains of $472.2 million and $148.5 million , respectively, were exempt from tax in the Netherlands and unrealized gains of $67.5 million and $37.4 million , respectively, were taxable.

BASIS OF PRESENTATION Basis of

BASIS OF PRESENTATION Basis of Presentation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Jan. 01, 2017	Dec. 31, 2016
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 299,305
Cash and cash equivalents	2,434,020			$ 2,081,075
Excess tax benefits on stock-based awards and other equity deductions	0	$ 18,073
Retained Earnings
Cumulative Effect of New Accounting Principle in Period of Adoption	290,317
Additional Paid-In Capital
Cumulative Effect of New Accounting Principle in Period of Adoption	8,988
Accounting Standards Update 2016-18 [Member]
Restricted cash included in prepaid expenses and other current assets	928			932
Total cash, cash equivalents and restricted cash as shown in the Unaudited Consolidated Statements of Cash Flows	$ 2,434,948			$ 2,082,007
Accounting Standards Update 2016-16 [Member] | Retained Earnings
Cumulative Effect of New Accounting Principle in Period of Adoption			$ (4,200)
Accounting Standards Update 2016-16 [Member] | Other Noncurrent Assets [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption			6,600
Accounting Standards Update 2016-16 [Member] | Other Current Assets [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption			3,300
Accounting Standards Update 2016-16 [Member] | Deferred Income Taxes [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption			(5,700)
Accounting Standards Update 2016-09, Unrecognized Equity Deductions component [Member] | Accounting Standards Update 2016-09 [Member] | Retained Earnings
Cumulative Effect of New Accounting Principle in Period of Adoption			301,400
Accounting Standards Update 2016-09, Unrecognized Equity Deductions component [Member] | Accounting Standards Update 2016-09 [Member] | Deferred Income Taxes [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption			(301,400)
Accounting Standards Update 2016-09, Forfeiture Rate Component [Member] | Accounting Standards Update 2016-09 [Member] | Retained Earnings
Cumulative Effect of New Accounting Principle in Period of Adoption			(6,900)
Accounting Standards Update 2016-09, Forfeiture Rate Component [Member] | Accounting Standards Update 2016-09 [Member] | Additional Paid-In Capital
Cumulative Effect of New Accounting Principle in Period of Adoption			9,000
Accounting Standards Update 2016-09, Forfeiture Rate Component [Member] | Accounting Standards Update 2016-09 [Member] | Deferred Income Taxes [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption			$ (2,100)

STOCK-BASED EMPLOYEE COMPENSA32

STOCK-BASED EMPLOYEE COMPENSATION (Stock-based Employee Compensation) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation expense	$ 58,948	$ 66,000

STOCK-BASED EMPLOYEE COMPENSA33

STOCK-BASED EMPLOYEE COMPENSATION (Restricted Stock Units and Performance Share Units) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock Units and Performance Share Units [Member]
Share-Based Awards - Shares
Unvested at December 31, 2016	515,606
Granted (in shares)	155,095
Vested (in shares)	(112,791)
Performance Share Units Adjustment (in shares)	(445)
Forfeited (in shares)	(7,103)
Unvested at March 31, 2017	550,362	515,606
Share-Based Awards - Weighted Average Grant Date Fair Value
Unvested at December 31, 2016	$ 1,287.88
Granted (in dollars per share)	1,735.10
Vested (in dollars per share)	1,325.40
Performance Share Units Adjustment (in dollars per share)	1,291.76
Forfeited (in shares)	1,301.58
Unvested at March 31, 2017	$ 1,406.29	$ 1,287.88
Total unrecognized estimated compensation expense, unvested share-based awards	$ 534.7
Total future compensation cost related to unvested share-based awards, expected period of recognition	2 years 3 months
Restricted Stock Units (RSUs) [Member]
Share-Based Awards - Shares
Granted (in shares)	81,202
Share-Based Awards - Weighted Average Grant Date Fair Value
Granted (in dollars per share)	$ 1,735.10
Vesting period (in years)	3 years
Grant date fair value	$ 140.9
Performance Share Units 2017 Grants [Member]
Share-Based Awards - Shares
Granted (in shares)	73,893
Share-Based Awards - Weighted Average Grant Date Fair Value
Granted (in dollars per share)	$ 1,735.10
Grant date fair value	$ 128.2
Estimated number of probable shares to be issued (in shares)	73,893
Maximum shares that could be issued (in shares)	147,786
Minimum shares that could be issued (in shares)	60,636
Performance Share Units 2016 Grants [Member]
Share-Based Awards - Shares
Granted (in shares)		85,735
Unvested at March 31, 2017	75,421
Share-Based Awards - Weighted Average Grant Date Fair Value
Granted (in dollars per share)		$ 1,302.25
Grant date fair value		$ 111.7
Estimated number of probable shares to be issued (in shares)	117,795
Maximum shares that could be issued (in shares)	170,125
Minimum shares that could be issued (in shares)	45,779
Performance Share Units 2015 Grants [Member]
Share-Based Awards - Shares
Granted (in shares)			107,623
Unvested at March 31, 2017	74,914
Share-Based Awards - Weighted Average Grant Date Fair Value
Granted (in dollars per share)			$ 1,237.53
Grant date fair value			$ 133.2
Estimated number of probable shares to be issued (in shares)	128,379
Maximum shares that could be issued (in shares)	185,316
Minimum shares that could be issued (in shares)	43,832

STOCK-BASED EMPLOYEE COMPENSA34

STOCK-BASED EMPLOYEE COMPENSATION (Stock Options) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Vested and exercisable as of March 31, 2017 and expected to vest thereafter, net of estimated forfeitures
Allocated Share-based Compensation Expense	$ 58,948	$ 66,000
Employee Stock Option [Member]
Number of Shares
Beginning balance (in shares)	48,983
Exercised (in shares)	(3,992)
Forfeited (in shares)	(610)
Ending balance (in shares)	44,381		48,983
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 372.07
Exercised (in dollars per share)	368.68
Forfeited (in dollars per share)	894.15
Ending balance (in dollars per share)	$ 365.20		$ 372.07
Aggregate Intrinsic Value	$ 62,789		$ 53,587
Weighted Average Remaining Contractual Term	4 years 2 months		4 years 5 months
Vested and exercisable as of March 31, 2017
Number of Shares	43,125
Weighted Average Exercise Price (in dollars per share)	$ 354.23
Aggregate Intrinsic Value	$ 61,485
Weighted Average Remaining Contractual Term, Exercisable	4 years 1 month
Vested and exercisable as of March 31, 2017 and expected to vest thereafter, net of estimated forfeitures
Number of Shares	44,381
Weighted Average Exercise Price (in dollars per share)	$ 365.20
Aggregate Intrinsic Value	$ 62,789
Weighted Average Remaining Contractual Term	4 years 2 months
Stock options exercised, total intrinsic value	$ 5,400	$ 12,700
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares	539	5,367
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	$ 300	$ 3,500
Allocated Share-based Compensation Expense	300	$ 2,900
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options	$ 700
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	8 months

NET INCOME PER SHARE (Details)

NET INCOME PER SHARE (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Weighted-average number of basic common shares outstanding	49,192	49,630
Weighted-average dilutive stock options, restricted stock units and performance share units	227	275
Assumed conversion of convertible debt (in shares)	606	224
Weighted average number of diluted common and common equivalent shares outstanding (in shares)	50,025	50,129
Unvested Stock Awards Outstanding and Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potential common shares	2,256	2,665
Convertible Debt [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive potential common shares	1,700

INVESTMENTS (Details)

INVESTMENTS (Details) - USD ($) $ in Thousands	Sep. 12, 2016	Dec. 11, 2015	May 26, 2015	Aug. 07, 2014	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Investments
Weighted maturity of investments					2 years
Marketable Securities, Realized Gain (Loss)					$ 200	$ (2,900)
Cost Method Investments					7,600		$ 7,600
Cost-method Investments, Other than Temporary Impairment					0	50,350
Ctrip.com International, Ltd. [Member]
Investments
Debt Investment, Term	6 years	10 years	5 years	5 years
Maximum Ownership Percentage in Ctrip			15.00%
Hotel Urbano [Member]
Investments
Cost-method Investments, Other than Temporary Impairment						$ 50,350
Short-term Investments [Member]
Investments
Cost					2,935,185		2,218,640
Gross Unrealized Gains					2,753		1,397
Gross Unrealized Losses					(1,780)		(1,157)
Fair Value					2,936,158		2,218,880
Short-term Investments [Member] | International government securities
Investments
Cost					517,398		249,552
Gross Unrealized Gains					1,254		221
Gross Unrealized Losses					(187)		(89)
Fair Value					518,465		249,684
Short-term Investments [Member] | U.S. government securities
Investments
Cost					580,630		456,971
Gross Unrealized Gains					17		57
Gross Unrealized Losses					(427)		(140)
Fair Value					580,220		456,888
Short-term Investments [Member] | Corporate debt securities
Investments
Cost					1,831,179		1,510,119
Gross Unrealized Gains					1,482		1,119
Gross Unrealized Losses					(1,166)		(928)
Fair Value					1,831,495		1,510,310
Short-term Investments [Member] | Commercial paper
Investments
Cost					5,978		1,998
Gross Unrealized Gains					0		0
Gross Unrealized Losses					0		0
Fair Value					5,978		1,998
Long-term Investments [Member]
Investments
Cost					9,602,027		9,407,136
Gross Unrealized Gains					591,868		293,453
Gross Unrealized Losses					(53,265)		(109,522)
Fair Value					10,140,630		9,591,067
Long-term Investments [Member] | International government securities
Investments
Cost					450,445		655,857
Gross Unrealized Gains					1,894		4,110
Gross Unrealized Losses					(788)		(623)
Fair Value					451,551		659,344
Long-term Investments [Member] | U.S. government securities
Investments
Cost					828,777		773,718
Gross Unrealized Gains					286		337
Gross Unrealized Losses					(6,744)		(7,463)
Fair Value					822,319		766,592
Long-term Investments [Member] | Corporate debt securities
Investments
Cost					6,387,523		6,042,271
Gross Unrealized Gains					10,334		9,973
Gross Unrealized Losses					(37,658)		(50,455)
Fair Value					6,360,199		6,001,789
Long-term Investments [Member] | U.S. government agency securities
Investments
Cost					4,971		4,979
Gross Unrealized Gains					0		0
Gross Unrealized Losses					(25)		(27)
Fair Value					4,946		4,952
Long-term Investments [Member] | Ctrip convertible debt securities | Ctrip.com International, Ltd. [Member]
Investments
Cost	$ 25,000	$ 500,000	$ 250,000	$ 500,000	1,275,000		1,275,000
Gross Unrealized Gains					171,425		65,800
Gross Unrealized Losses					(8,050)		(47,712)
Fair Value					1,438,375		1,293,088
Long-term Investments [Member] | Ctrip equity securities | Ctrip.com International, Ltd. [Member]
Investments
Cost					655,311		655,311
Gross Unrealized Gains					407,929		213,233
Gross Unrealized Losses					0		(3,242)
Fair Value					$ 1,063,240		$ 865,302

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - Recurring Basis [Member] - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
ASSETS:
Total assets at fair value	$ 14,536,412	$ 13,055,008
Foreign Currency Contracts [Member]
ASSETS:
Total assets at fair value	558	756
LIABILITIES:
Total liabilities at fair value	593	1,015
Money market funds | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	1,249,091	977,468
International government securities | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	35,052	30,266
International government securities | Short-term Investments [Member]
ASSETS:
Total assets at fair value	518,465	249,684
International government securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	451,551	659,344
U.S. government securities | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	159,956	176,140
U.S. government securities | Short-term Investments [Member]
ASSETS:
Total assets at fair value	580,220	456,888
U.S. government securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	822,319	766,592
Commercial paper | Cash Equivalents [Member]
ASSETS:
Total assets at fair value		1,998
Commercial paper | Short-term Investments [Member]
ASSETS:
Total assets at fair value	5,978	1,998
Time deposits | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	4,724	49,160
Corporate debt securities | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	10,243	9,273
Corporate debt securities | Short-term Investments [Member]
ASSETS:
Total assets at fair value	1,831,495	1,510,310
Corporate debt securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	6,360,199	6,001,789
U.S. government agency securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	4,946	4,952
Ctrip convertible debt securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	1,438,375	1,293,088
Ctrip equity securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	1,063,240	865,302
Level 1 [Member]
ASSETS:
Total assets at fair value	2,317,055	1,891,930
Level 1 [Member] | Foreign Currency Contracts [Member]
ASSETS:
Total assets at fair value	0	0
LIABILITIES:
Total liabilities at fair value	0	0
Level 1 [Member] | Money market funds | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	1,249,091	977,468
Level 1 [Member] | International government securities | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | International government securities | Short-term Investments [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | International government securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | U.S. government securities | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | U.S. government securities | Short-term Investments [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | U.S. government securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | Commercial paper | Cash Equivalents [Member]
ASSETS:
Total assets at fair value		0
Level 1 [Member] | Commercial paper | Short-term Investments [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | Time deposits | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	4,724	49,160
Level 1 [Member] | Corporate debt securities | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | Corporate debt securities | Short-term Investments [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | Corporate debt securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | U.S. government agency securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | Ctrip convertible debt securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	0	0
Level 1 [Member] | Ctrip equity securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	1,063,240	865,302
Level 2 [Member]
ASSETS:
Total assets at fair value	12,219,357	11,163,078
Level 2 [Member] | Foreign Currency Contracts [Member]
ASSETS:
Total assets at fair value	558	756
LIABILITIES:
Total liabilities at fair value	593	1,015
Level 2 [Member] | Money market funds | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	0	0
Level 2 [Member] | International government securities | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	35,052	30,266
Level 2 [Member] | International government securities | Short-term Investments [Member]
ASSETS:
Total assets at fair value	518,465	249,684
Level 2 [Member] | International government securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	451,551	659,344
Level 2 [Member] | U.S. government securities | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	159,956	176,140
Level 2 [Member] | U.S. government securities | Short-term Investments [Member]
ASSETS:
Total assets at fair value	580,220	456,888
Level 2 [Member] | U.S. government securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	822,319	766,592
Level 2 [Member] | Commercial paper | Cash Equivalents [Member]
ASSETS:
Total assets at fair value		1,998
Level 2 [Member] | Commercial paper | Short-term Investments [Member]
ASSETS:
Total assets at fair value	5,978	1,998
Level 2 [Member] | Time deposits | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	0	0
Level 2 [Member] | Corporate debt securities | Cash Equivalents [Member]
ASSETS:
Total assets at fair value	10,243	9,273
Level 2 [Member] | Corporate debt securities | Short-term Investments [Member]
ASSETS:
Total assets at fair value	1,831,495	1,510,310
Level 2 [Member] | Corporate debt securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	6,360,199	6,001,789
Level 2 [Member] | U.S. government agency securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	4,946	4,952
Level 2 [Member] | Ctrip convertible debt securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	1,438,375	1,293,088
Level 2 [Member] | Ctrip equity securities | Long-term Investments [Member]
ASSETS:
Total assets at fair value	$ 0	$ 0

FAIR VALUE MEASUREMENTS (Narrat

FAIR VALUE MEASUREMENTS (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Sep. 12, 2016	Dec. 11, 2015	May 26, 2015	Aug. 07, 2014
Fair Value Disclosures [Abstract]
Cost Method Investments	$ 7,600		$ 7,600
Derivatives Not Designated as Hedging Instruments
Foreign exchange gains (losses), net of derivative activity	(5,900)	$ (4,400)
Embedded Derivative, Gain on Embedded Derivative	1,400
Foreign Exchange Contracts, Translation Risk [Member]
Derivatives Not Designated as Hedging Instruments
Foreign exchange gains (losses) recorded in Foreign currency transactions and other	(1,100)	(3,600)
Foreign currency derivative instruments not designated as hedging instruments at fair value, net	0		0
Foreign Exchange Contracts, Transaction Risk [Member]
Derivatives Not Designated as Hedging Instruments
Foreign exchange gains (losses) recorded in Foreign currency transactions and other	6,800	12,400
Foreign currency derivative instruments not designated as hedging instruments at fair value, net	(100)		(300)
Foreign exchange derivative assets recorded in Prepaid expenses and other current assets	500		700
Foreign exchange derivative liabilities recorded in Accrued expenses and other current liabilities	600		1,000
Foreign Currency Contracts [Member]
Derivatives Not Designated as Hedging Instruments
Net cash inflow from settlement of derivative contracts included in operating activities	2,700	$ 22,300
Long-term Investments [Member]
Derivatives Not Designated as Hedging Instruments
Available-for-sale Securities, Amortized Cost Basis	9,602,027		9,407,136
Ctrip.com International, Ltd. [Member] | Ctrip convertible debt securities | Long-term Investments [Member]
Derivatives Not Designated as Hedging Instruments
Available-for-sale Securities, Amortized Cost Basis	1,275,000		1,275,000	$ 25,000	$ 500,000	$ 250,000	$ 500,000
Embedded Derivative, Fair Value of Embedded Derivative Asset	$ 3,200		$ 1,800

INTANGIBLE ASSETS AND GOODWIL39

INTANGIBLE ASSETS AND GOODWILL (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Finite-lived intangible assets
Gross Carrying Amount	$ 2,656,068		$ 2,651,667
Accumulated Amortization	(704,069)		(657,782)
Net Carrying Amount	1,951,999		1,993,885
Amortization	43,018	$ 42,385
Annual estimated amortization expense for intangible assets
Remainder of 2017	119,143
2,018	141,951
2,019	130,759
2,020	123,903
2,021	119,095
2,022	117,966
Thereafter	1,199,182
Total	1,951,999
Goodwill:
Balance at December 31, 2016	2,396,906
Currency translation adjustments	5,400
Balance at March 31, 2017	2,402,306
Supply and distribution agreements [Member]
Finite-lived intangible assets
Gross Carrying Amount	812,361		809,287
Accumulated Amortization	(287,948)		(270,813)
Net Carrying Amount	$ 524,413		538,474
Finite lived intangibles, weighted average useful life	16 years
Technology [Member]
Finite-lived intangible assets
Gross Carrying Amount	$ 112,451		112,141
Accumulated Amortization	(85,670)		(80,549)
Net Carrying Amount	$ 26,781		31,592
Finite lived intangibles, weighted average useful life	5 years
Patents [Member]
Finite-lived intangible assets
Gross Carrying Amount	$ 1,623		1,623
Accumulated Amortization	(1,608)		(1,598)
Net Carrying Amount	$ 15		25
Amortization period (in years)	15 years
Finite lived intangibles, weighted average useful life	15 years
Internet domain names [Member]
Finite-lived intangible assets
Gross Carrying Amount	$ 40,047		39,495
Accumulated Amortization	(26,394)		(25,089)
Net Carrying Amount	$ 13,653		14,406
Finite lived intangibles, weighted average useful life	8 years
Trade Names [Member]
Finite-lived intangible assets
Gross Carrying Amount	$ 1,667,686		1,667,221
Accumulated Amortization	(282,322)		(261,412)
Net Carrying Amount	$ 1,385,364		1,405,809
Finite lived intangibles, weighted average useful life	20 years
Noncompete Agreements [Member]
Finite-lived intangible assets
Gross Carrying Amount	$ 21,900		21,900
Accumulated Amortization	(20,127)		(18,321)
Net Carrying Amount	$ 1,773		$ 3,579
Finite lived intangibles, weighted average useful life	3 years
Minimum [Member] | Supply and distribution agreements [Member]
Finite-lived intangible assets
Amortization period (in years)	3 years
Minimum [Member] | Technology [Member]
Finite-lived intangible assets
Amortization period (in years)	1 year
Minimum [Member] | Internet domain names [Member]
Finite-lived intangible assets
Amortization period (in years)	2 years
Minimum [Member] | Trade Names [Member]
Finite-lived intangible assets
Amortization period (in years)	4 years
Minimum [Member] | Noncompete Agreements [Member]
Finite-lived intangible assets
Amortization period (in years)	3 years
Maximum [Member] | Supply and distribution agreements [Member]
Finite-lived intangible assets
Amortization period (in years)	20 years
Maximum [Member] | Technology [Member]
Finite-lived intangible assets
Amortization period (in years)	5 years
Maximum [Member] | Internet domain names [Member]
Finite-lived intangible assets
Amortization period (in years)	20 years
Maximum [Member] | Trade Names [Member]
Finite-lived intangible assets
Amortization period (in years)	20 years
Maximum [Member] | Noncompete Agreements [Member]
Finite-lived intangible assets
Amortization period (in years)	4 years

DEBT (Revolving Credit Facility

DEBT (Revolving Credit Facility) (Details) - USD ($)	Jun. 19, 2015	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Line of Credit Facility [Line Items]
Short-term Debt				$ 100,000,000
Letters of credit issued		$ 3,900,000	$ 3,800,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 2,000,000,000
Line of Credit Facility, term (in years)	5 years
Line of Credit, Current		$ 0	$ 0
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 70,000,000
Swingline Loans [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 50,000,000
Minimum [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Commitment fee rate	0.085%
Minimum [Member] | Rate 2C [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.00%
Maximum [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Commitment fee rate	0.20%
Maximum [Member] | Rate 2C [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Rate 1 [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.875%
London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] | Rate 1 [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.50%
Federal Funds Purchased [Member] | Rate 2B [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
One Month LIBOR [Member] | Rate 2C [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.00%

DEBT (Outstanding Debt) (Detail

DEBT (Outstanding Debt) (Details) $ / shares in Units, $ in Thousands, € in Millions	Mar. 31, 2016USD ($)	Aug. 20, 2014USD ($)$ / shares	May 31, 2013USD ($)$ / shares	Mar. 31, 2012USD ($)$ / shares	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Mar. 31, 2017EUR (€)	Mar. 31, 2017USD ($)	Mar. 10, 2017EUR (€)	Dec. 31, 2016EUR (€)	Dec. 31, 2016USD ($)	May 23, 2016USD ($)	Nov. 25, 2015EUR (€)	Mar. 13, 2015USD ($)	Mar. 03, 2015EUR (€)	Sep. 23, 2014EUR (€)	Jun. 30, 2013USD ($)
Debt Instrument
Outstanding Principal Amount													$ 7,510,813			$ 6,400,563
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(224,711)			(230,041)
Short-term Debt	$ 100,000					$ 100,000
Total Carrying Value of Long-Term Debt													7,286,102			6,170,522
Description of Senior Notes
Convertible debt													22,521			28,538
Amortization of debt discount included in interest expense					$ 17,625	17,009
1.00% Convertible Senior Notes Due March 2018 [Member]
Debt Instrument
Short-term Debt, Gross													999,997			1,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(25,459)			(32,266)
Short-term Debt													974,538			967,734
Description of Senior Notes
Convertible debt													$ 22,521			$ 28,538
Aggregate Principal Amount				$ 1,000,000
Interest rate on Long-term Debt				1.00%								1.00%	1.00%		1.00%	1.00%
Debt financing costs paid											$ 20,900
Convertible debt conversion price (in dollars per share) | $ / shares				$ 944.61
Ratio of closing share price to conversion price as a condition for conversion of convertible 2015 Senior Notes, minimum				150.00%
Effective interest rate at debt origination or modification				3.50%
Debt discount related to convertible notes, net of tax				$ 80,900
Debt discount related to convertible notes, before tax				135,200
Debt Instrument, Convertible Carrying Amount Of The Equity Component Related To Finance Costs Net Of Tax				$ 2,800
0.35 % Convertible Senior Notes Due June 2020 [Member]
Debt Instrument
Outstanding Principal Amount													$ 1,000,000			$ 1,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(83,969)			(90,251)
Total Carrying Value of Long-Term Debt													$ 916,031			$ 909,749
Description of Senior Notes
Aggregate Principal Amount			$ 1,000,000
Interest rate on Long-term Debt			0.35%									0.35%	0.35%		0.35%	0.35%
Debt Instrument, Unamortized Discount			$ 20,000
Debt financing costs paid										$ 1,000
Convertible debt conversion price (in dollars per share) | $ / shares			$ 1,315.10
Ratio of closing share price to conversion price as a condition for conversion of convertible 2015 Senior Notes, minimum			150.00%
Effective interest rate at debt origination or modification			3.13%
Debt discount related to convertible notes, net of tax																						$ 92,400
Debt discount related to convertible notes, before tax																						154,300
Debt Instrument, Convertible Carrying Amount Of The Equity Component Related To Finance Costs Net Of Tax																						$ 100
Amortization of debt discount included in interest expense					700	700
0.9% Convertible Senior Notes Due September 2021 [Member]
Debt Instrument
Outstanding Principal Amount													$ 1,000,000			$ 1,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(99,325)			(104,592)
Total Carrying Value of Long-Term Debt													$ 900,675			$ 895,408
Description of Senior Notes
Aggregate Principal Amount		$ 1,000,000
Interest rate on Long-term Debt		0.90%										0.90%	0.90%		0.90%	0.90%
Debt financing costs paid									$ 11,000
Convertible debt conversion price (in dollars per share) | $ / shares		$ 2,055.50
Ratio of closing share price to conversion price as a condition for conversion of convertible 2015 Senior Notes, minimum		150.00%
Effective interest rate at debt origination or modification		3.18%
Debt discount related to convertible notes, net of tax									82,500
Debt discount related to convertible notes, before tax									142,900
Debt Instrument, Convertible Carrying Amount Of The Equity Component Related To Finance Costs Net Of Tax									1,600
0.8% Senior Notes Due March 2022 [Member]
Debt Instrument
Outstanding Principal Amount													$ 1,069,550
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(7,133)
Total Carrying Value of Long-Term Debt													$ 1,062,417
Description of Senior Notes
Aggregate Principal Amount | €												€ 1,000		€ 1,000
Interest rate on Long-term Debt												0.80%	0.80%	0.80%
Debt Instrument, Unamortized Discount | €														€ 2.1
Debt financing costs paid					4,000
Effective interest rate at debt origination or modification														0.84%
2.375% Senior Notes Due September 2024 [Member]
Debt Instrument
Outstanding Principal Amount													$ 1,069,550			$ 1,054,750
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(12,577)			(12,861)
Total Carrying Value of Long-Term Debt													$ 1,056,973			$ 1,041,889
Description of Senior Notes
Aggregate Principal Amount | €												€ 1,000			€ 1,000						€ 1,000
Interest rate on Long-term Debt												2.375%	2.375%		2.375%	2.375%					2.375%
Debt Instrument, Unamortized Discount | €																					€ 9.4
Debt financing costs paid									$ 6,500
Effective interest rate at debt origination or modification																					2.48%
3.65% Senior Notes Due March 2025 [Member]
Debt Instrument
Outstanding Principal Amount													$ 500,000			$ 500,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(3,618)			(3,727)
Total Carrying Value of Long-Term Debt													$ 496,382			$ 496,273
Description of Senior Notes
Aggregate Principal Amount																			$ 500,000
Interest rate on Long-term Debt												3.65%	3.65%		3.65%	3.65%			3.65%
Debt Instrument, Unamortized Discount																			$ 1,300
Debt financing costs paid								$ 3,200
Effective interest rate at debt origination or modification																			3.68%
3.6% Senior Notes Due June 2026 [Member]
Debt Instrument
Outstanding Principal Amount													$ 1,000,000			$ 1,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(7,425)			(7,619)
Total Carrying Value of Long-Term Debt													$ 992,575			$ 992,381
Description of Senior Notes
Aggregate Principal Amount																	$ 1,000,000
Interest rate on Long-term Debt												3.60%	3.60%		3.60%	3.60%	3.60%
Debt Instrument, Unamortized Discount																	$ 1,900
Debt financing costs paid							$ 6,200
Effective interest rate at debt origination or modification																	3.62%
1.8% Senior Notes Due March 2027 [Member]
Debt Instrument
Outstanding Principal Amount													$ 1,069,550			$ 1,054,750
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(5,520)			(5,655)
Total Carrying Value of Long-Term Debt													$ 1,064,030			$ 1,049,095
Description of Senior Notes
Aggregate Principal Amount | €												€ 1,000			€ 1,000					€ 1,000
Interest rate on Long-term Debt												1.80%	1.80%		1.80%	1.80%				1.80%
Debt Instrument, Unamortized Discount | €																				€ 0.3
Debt financing costs paid								6,300
Effective interest rate at debt origination or modification																				1.80%
2.15% Senior Notes Due November 2022 [Member]
Debt Instrument
Outstanding Principal Amount													$ 802,163			$ 791,063
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													(5,144)			(5,336)
Total Carrying Value of Long-Term Debt													$ 797,019			$ 785,727
Description of Senior Notes
Aggregate Principal Amount | €												€ 750			€ 750			€ 750
Interest rate on Long-term Debt												2.15%	2.15%		2.15%	2.15%		2.15%
Debt Instrument, Unamortized Discount | €																		€ 2.2
Debt financing costs paid								$ 3,700
Effective interest rate at debt origination or modification																		2.20%
Convertible Debt [Member]
Description of Senior Notes
Interest expense related to debt					24,000	23,400
Coupon Interest expense					5,600	5,600
Amortization of debt discount included in interest expense					17,200	16,700
Amortization of debt issuance costs					$ 1,200	$ 1,100
Debt, Weighted Average Interest Rate					3.40%	3.50%
Other Long-term Debt [Member]
Description of Senior Notes
Interest expense related to debt					$ 30,600	$ 21,400
Coupon Interest expense					29,500	20,500
Amortization of debt discount included in interest expense					400	400
Amortization of debt issuance costs					700	500
1% CT Loan Due March 2016 [Member]
Description of Senior Notes
Aggregate Principal Amount	$ 2,500					$ 2,500							$ 1,500
Interest rate on Long-term Debt												1.00%	1.00%
Debt Instrument, Term	10 years
Debt Instrument, Decrease, Forgiveness					$ 1,000
Minimum [Member] | 1.00% Convertible Senior Notes Due March 2018 [Member]
Description of Senior Notes
Minimum and Maximum consecutive days the closing sales price of common stock must exceed a specified percentage of conversion price to trigger conversion feature of note (in days)				20 days
Additional Payment To Debt Holder Settled In Shares Aggregate Value Of Shares				$ 0
Minimum [Member] | 0.35 % Convertible Senior Notes Due June 2020 [Member]
Description of Senior Notes
Minimum and Maximum consecutive days the closing sales price of common stock must exceed a specified percentage of conversion price to trigger conversion feature of note (in days)			20 days
Additional Payment To Debt Holder Settled In Shares Aggregate Value Of Shares			$ 0
Minimum [Member] | 0.9% Convertible Senior Notes Due September 2021 [Member]
Description of Senior Notes
Minimum and Maximum consecutive days the closing sales price of common stock must exceed a specified percentage of conversion price to trigger conversion feature of note (in days)		20 days
Additional Payment To Debt Holder Settled In Shares Aggregate Value Of Shares		$ 0
Maximum [Member] | 1.00% Convertible Senior Notes Due March 2018 [Member]
Description of Senior Notes
Minimum and Maximum consecutive days the closing sales price of common stock must exceed a specified percentage of conversion price to trigger conversion feature of note (in days)				30 days
Additional Payment To Debt Holder Settled In Shares Aggregate Value Of Shares				$ 344,000
Maximum [Member] | 0.35 % Convertible Senior Notes Due June 2020 [Member]
Description of Senior Notes
Minimum and Maximum consecutive days the closing sales price of common stock must exceed a specified percentage of conversion price to trigger conversion feature of note (in days)			30 days
Additional Payment To Debt Holder Settled In Shares Aggregate Value Of Shares			$ 397,000
Maximum [Member] | 0.9% Convertible Senior Notes Due September 2021 [Member]
Description of Senior Notes
Minimum and Maximum consecutive days the closing sales price of common stock must exceed a specified percentage of conversion price to trigger conversion feature of note (in days)		30 days
Additional Payment To Debt Holder Settled In Shares Aggregate Value Of Shares		$ 375,000
Level 2 [Member]
Description of Senior Notes
Estimated market value of outstanding debt													$ 10,100,000			$ 8,400,000

TREASURY STOCK (Details)

TREASURY STOCK (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Equity, Class of Treasury Stock [Line Items]
Treasury Stock Value Acquired, Cost Method Excluding Shares Paid Value for Tax Withholding for Share-based Compensation	$ 212,344
Remaining authorization to repurchase common stock	$ 4,000,000
Repurchase of common shares to satisfy employee withholding tax obligations related to stock-based compensation (in shares)	44,888	90,401
Repurchase of common shares to satisfy employee withholding tax obligations related to stock-based compensation	$ 77,300	$ 117,200
Payments Related to Tax Withholding for Share-based Compensation	$ 69,800	99,500
Treasury stock, shares (in shares)	13,315,844		13,190,929
Repurchase Program (Q12016) [Member]
Equity, Class of Treasury Stock [Line Items]
Treasury stock acquired repurchase authorization additional value		$ 3,000,000
Treasury Stock Shares Acquired Excluding Shares Paid for Tax Withholding for Share-based Compensation	80,027
Treasury Stock Value Acquired, Cost Method Excluding Shares Paid Value for Tax Withholding for Share-based Compensation	$ 135,000
Treasury Stock Repurchased but unsettled by period end	5,600
Treasury Stock Repurchased but unsettled by period end, amount	$ 10,000
Repurchase Program (Q12017) [Member]
Equity, Class of Treasury Stock [Line Items]
Treasury stock acquired repurchase authorization additional value	$ 2,000,000

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Percent	13.60%	18.70%
Income Tax (Benefit) arising from Excess Tax Benefits	$ (9,900)
Cost-method Investments, Other than Temporary Impairment	$ 0	$ 50,350
NETHERLANDS
Income Tax Contingency [Line Items]
Statutory federal rate	25.00%
Effective Income Tax Rate at Innovation Box Tax Rate	5.00%
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Statutory federal rate	35.00%
Hotel Urbano [Member]
Income Tax Contingency [Line Items]
Cost-method Investments, Other than Temporary Impairment		$ 50,350

ACCUMULATED OTHER COMPREHENSI44

ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' equity		$ 10,811,019	$ 9,820,142
Foreign currency translation adjustments, net of tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' equity	[1]	(275,442)	(311,247)
Net unrealized gain on marketable securities, net of tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' equity	[2]	522,497	176,563
Stockholders' equity, before tax		539,700	185,900
Stockholders' equity, before tax, taxable		67,500	37,400
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' equity		247,055	(134,684)
Net Investment Hedging [Member] | Foreign currency translation adjustments, net of tax | Euro Senior Notes [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' equity		149,900	182,600
Stockholders' equity, before tax		258,000	310,400
Net Investment Hedging [Member] | Foreign currency translation adjustments, net of tax | Foreign Exchange Forward [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' equity		(35,000)	(35,000)
Stockholders' equity, before tax		(52,600)	(52,600)
Tax and Customs Administration, Netherlands [Member] | Net unrealized gain on marketable securities, net of tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' equity, before tax, tax-exempt		$ 472,200	$ 148,500
[1]	Foreign currency translation adjustments, net of tax, include net losses from fair value adjustments of $35.0 million after tax ($52.6 million before tax) associated with settled derivatives that previously had been designated as net investment hedges at both March 31, 2017 and December 31, 2016.Foreign currency translation adjustments, net of tax, include foreign currency transaction gains of $149.9 million after tax ($258.0 million before tax) and $182.6 million after tax ($310.4 million before tax) associated with the Company's March 2022 Notes, November 2022 Notes, 2024 Notes and 2027 Notes at March 31, 2017 and December 31, 2016, respectively. The March 2022 Notes, November 2022 Notes, 2024 Notes and 2027 Notes are Euro-denominated debt and are designated as hedges of certain of the Company's Euro-denominated net assets (see Note 7). The remaining balance in foreign currency translation adjustments excludes income taxes as a result of the Company's intention to indefinitely reinvest the earnings of its international subsidiaries outside of the United States.
[2]	The unrealized gains before tax at March 31, 2017 and December 31, 2016 were $539.7 million and $185.9 million, respectively, of which unrealized gains of $472.2 million and $148.5 million, respectively, were exempt from tax in the Netherlands and unrealized gains of $67.5 million and $37.4 million, respectively, were taxable.

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) € in Millions	3 Months Ended					9 Months Ended
	Jun. 30, 2017USD ($)	Mar. 31, 2017EUR (€)country	Mar. 31, 2017USD ($)Casescountry	Sep. 30, 2016EUR (€)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017EUR (€)	Dec. 31, 2016USD ($)
Commitments and Contingencies
Pricing Parity Working Group | country		10	10
Payments to Acquire Property, Plant, and Equipment | $			$ 70,559,000		$ 53,256,000
Litigation related to travel transaction taxes [Member]
Commitments and Contingencies
Approximate number of lawsuits brought by or against states, cities and counties over issues involving the payment of travel transaction taxes (in cases) | Cases			30
Accrual for the potential resolution of issues related to travel transaction taxes (in dollars) | $			$ 27,000,000					$ 27,000,000
French Tax Audit [Member]
Commitments and Contingencies
Assessed taxes including interest and penalties | €		€ 356
Series of individually immaterial business acquisitions [Member]
Commitments and Contingencies
Contingent consideration arrangements, range of outcomes, minimum value | $			0
Contingent consideration arrangements, range of outcomes, maximum value | $			90,000,000
Booking.com [Member] | Headquarters [Member]
Commitments and Contingencies
Contractual Obligation for Building Construction | €				€ 270
Units of account				2
Payments to Acquire Productive Assets | €				€ 48
Acquisition of land use rights | €				43
Payments to Acquire Property, Plant, and Equipment | €				5
Ground Lease [Member] | Booking.com [Member] | Headquarters [Member]
Commitments and Contingencies
Contractual Obligation for Building Construction | €				€ 60
Lessee Leasing Arrangements, Operating Leases, Term of Contract				49 years
Scenario, Forecast [Member] | Momondo Group [Member]
Commitments and Contingencies
Payments to Acquire Businesses, Gross | $						$ 550,000,000
Scenario, Forecast [Member] | Booking.com [Member] | Headquarters [Member]
Commitments and Contingencies
Contractual Obligation for Building Construction | €							€ 34
Subsequent Event [Member] | Litigation related to travel transaction taxes [Member]
Commitments and Contingencies
Payment required to appeal a litigation matter | $	$ 13,000,000
Fair Value, Inputs, Level 3 [Member] | Series of individually immaterial business acquisitions [Member]
Commitments and Contingencies
Contingent consideration liability | $			$ 9,000,000					$ 9,000,000