Yelp (YELP) 10-K 26 Feb 21 2020 FY Annual report Financial data

Cover page

Cover page - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-35444
Entity Registrant Name	YELP INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-1854266
Entity Address, Address Line One	140 New Montgomery Street, 9th Floor
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94105
City Area Code	415
Local Phone Number	908-3801
Title of 12(b) Security	Common Stock, par value $0.000001 per share
Trading Symbol	YELP
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,415,991,469
Entity Common Stock, Shares Outstanding		74,930,522
Documents Incorporated by Reference	Portions of the registrant’s definitive Proxy Statement for the 2021 Annual Meeting of Stockholders to be filed with the U.S. Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K are incorporated by reference in Part III, Items 10-14 of this Annual Report on Form 10-K.
Entity Central Index Key	0001345016
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 595,875	$ 170,281
Short-term marketable securities	0	242,000
Accounts receivable (net of allowance for doubtful accounts of $11,559 and $7,686 at December 31, 2020 and December 31, 2019, respectively)	88,400	106,832
Prepaid expenses and other current assets	28,450	14,196
Total current assets	712,725	533,309
Long-term marketable securities	0	53,499
Property, equipment and software, net	101,718	110,949
Operating lease, right-of-use asset	168,209	197,866
Goodwill	109,261	104,589
Intangibles, net	13,521	10,082
Restricted cash	665	22,037
Other non-current assets	48,848	38,369
Total assets	1,154,947	1,070,700
Current liabilities:
Accounts payable and accrued liabilities	87,760	72,333
Operating lease liabilities — current	51,161	57,507
Deferred revenue	4,109	4,315
Total current liabilities	143,030	134,155
Operating lease liabilities — long-term	148,935	174,756
Other long-term liabilities	8,448	6,798
Total liabilities	300,413	315,709
Commitments and contingencies (Note 13)
Stockholders’ equity:
Common stock, $0.000001 par value — 200,000,000 shares authorized, 75,371,368 shares issued and 75,272,350 outstanding at December 31, 2020 and 71,185,468 shares issued and outstanding at December 31, 2019	0	0
Additional paid-in capital	1,398,248	1,259,803
Treasury stock	(2,964)	0
Accumulated other comprehensive loss	(6,807)	(11,759)
Accumulated deficit	(533,943)	(493,053)
Total stockholders’ equity	854,534	754,991
Total liabilities and stockholders’ equity	$ 1,154,947	$ 1,070,700

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowance for credit loss, current	$ 11,559	$ 7,686	$ 8,685	$ 8,602
Common stock, par value (in dollars per share)	$ 0.000001	$ 0.000001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	75,371,368	71,185,468
Common stock, shares outstanding (in shares)	75,272,350	71,185,468

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net revenue	$ 872,933	$ 1,014,194	$ 942,773
Costs and expenses:
Cost of revenue (exclusive of depreciation and amortization shown separately below)	57,186	62,410	57,872
Sales and marketing	437,060	500,386	483,309
Product development	232,561	230,440	212,319
General and administrative	130,450	136,091	120,569
Depreciation and amortization	50,609	49,356	42,807
Restructuring	3,862	0	0
Total costs and expenses	911,728	978,683	916,876
(Loss) income from operations	(38,795)	35,511	25,897
Other income, net	3,670	14,256	14,109
(Loss) income before income taxes	(35,125)	49,767	40,006
(Benefit from) provision for income taxes	(15,701)	8,886	(15,344)
Net (loss) income attributable to common stockholders	$ (19,424)	$ 40,881	$ 55,350
Net (loss) income per share attributable to common stockholders
Basic (in dollars per share)	$ (0.27)	$ 0.55	$ 0.66
Diluted (in dollars per share)	$ (0.27)	$ 0.52	$ 0.62
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders
Basic (in shares)	73,005	74,627	83,573
Diluted (in shares)	73,005	77,969	88,709

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (19,424)	$ 40,881	$ 55,350
Other comprehensive income (loss):
Foreign currency translation adjustments	4,952	(738)	(2,760)
Foreign currency adjustments to net income upon liquidation of investments in foreign entities	0	0	183
Other comprehensive income (loss)	4,952	(738)	(2,577)
Comprehensive (loss) income	$ (14,472)	$ 40,143	$ 52,773

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit)Cumulative Effect, Period of Adoption, Adjustment
Balance (in shares) at Dec. 31, 2017			83,724,916
Balance at Dec. 31, 2017	$ 1,108,697		$ 0	$ 1,038,017	$ (46)	$ (8,444)	$ 79,170
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of employee stock options (in shares)			779,871
Issuance of common stock upon exercises of employee stock options	15,581			15,581
Issuance of common stock upon vesting of RSUs (in shares)			1,946,476
Issuance of common stock upon vesting of RSUs	0
Issuance of common stock for employee stock purchase plan (in shares)			442,679
Issuance of common stock for employee stock purchase plan	14,198			14,198
Stock-based compensation (inclusive of capitalized stock-based compensation)	121,878			121,878
Shares withheld related to net share settlement of equity awards	(50,212)			(50,212)
Repurchases of common stock	(187,397)				(187,397)
Retirement of common stock (in shares)			(4,897,103)
Retirement of common stock	0				187,443		(187,443)
Foreign currency adjustments	(2,577)					(2,577)
Net (loss) income	55,350						55,350
Balance (in shares) at Dec. 31, 2018			81,996,839
Balance at Dec. 31, 2018	1,075,518		$ 0	1,139,462	0	(11,021)	(52,923)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of employee stock options (in shares)			826,124
Issuance of common stock upon exercises of employee stock options	17,488			17,488
Issuance of common stock upon vesting of RSUs (in shares)			2,018,794
Issuance of common stock upon vesting of RSUs	0
Issuance of common stock for employee stock purchase plan (in shares)			534,120
Issuance of common stock for employee stock purchase plan	14,775			14,775
Stock-based compensation (inclusive of capitalized stock-based compensation)	131,223			131,223
Shares withheld related to net share settlement of equity awards	(43,145)			(43,145)
Repurchases of common stock	(481,011)				(481,011)
Retirement of common stock (in shares)			(14,190,409)
Retirement of common stock	0				481,011		(481,011)
Foreign currency adjustments	(738)					(738)
Net (loss) income	$ 40,881						40,881
Balance (in shares) at Dec. 31, 2019	71,185,468		71,185,468
Balance at Dec. 31, 2019	$ 754,991	$ (34)	$ 0	1,259,803	0	(11,759)	(493,053)	$ (34)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Issuance of common stock upon exercises of employee stock options (in shares)	1,544,610		1,544,610
Issuance of common stock upon exercises of employee stock options	$ 13,168			13,168
Issuance of common stock upon vesting of RSUs (in shares)			2,683,900
Issuance of common stock upon vesting of RSUs	0
Issuance of common stock for employee stock purchase plan (in shares)			662,063
Issuance of common stock for employee stock purchase plan	14,214			14,214
Stock-based compensation (inclusive of capitalized stock-based compensation)	134,003			134,003
Shares withheld related to net share settlement of equity awards	(22,940)			(22,940)
Repurchases of common stock	$ (24,396)				(24,396)
Retirement of common stock (in shares)	(704,673)		(704,673)
Retirement of common stock	$ 0				21,432		(21,432)
Foreign currency adjustments	4,952					4,952
Net (loss) income	$ (19,424)						(19,424)
Balance (in shares) at Dec. 31, 2020	75,272,350		75,371,368
Balance at Dec. 31, 2020	$ 854,534		$ 0	$ 1,398,248	$ (2,964)	$ (6,807)	$ (533,943)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities
Net (loss) income	$ (19,424)	$ 40,881	$ 55,350
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	50,609	49,356	42,807
Provision for doubtful accounts	32,265	22,543	24,515
Stock-based compensation	124,574	121,512	114,386
Noncash lease cost	42,235	41,365	0
Deferred income taxes	(11,181)	(2,799)	(15,469)
Other adjustments, net	2,193	(2,997)	(722)
Changes in operating assets and liabilities:
Accounts receivable	(13,833)	(42,070)	(35,664)
Prepaid expenses and other assets	164	(1,349)	(5,192)
Operating lease liabilities	(46,283)	(41,808)	0
Accounts payable, accrued liabilities and other liabilities	15,382	20,148	(19,824)
Net cash provided by operating activities	176,701	204,782	160,187
Investing Activities
Sales and maturities of marketable securities — available-for-sale	290,395	0	0
Purchases of marketable securities — held-to-maturity	(87,438)	(541,451)	(751,237)
Maturities of marketable securities — held-to-maturity	93,200	674,097	613,700
Sale of investment prior to maturity	0	0	17,895
Purchases of other investments	(10,000)	0	0
Release of escrow deposit	0	28,750	0
Purchases of property, equipment and software	(32,002)	(37,522)	(44,972)
Purchase of intangible asset	(6,129)	0	0
Other investing activities	333	461	245
Net cash provided by (used in) investing activities	248,359	124,335	(164,369)
Financing Activities
Proceeds from issuance of common stock for employee stock-based plans	27,382	32,263	29,779
Taxes paid related to the net share settlement of equity awards	(23,605)	(42,771)	(50,144)
Repurchases of common stock	(24,396)	(481,011)	(187,382)
Other financing activities	(433)	0	0
Net cash used in financing activities	(21,052)	(491,519)	(207,747)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	214	(115)	360
Change in cash, cash equivalents and restricted cash	404,222	(162,517)	(211,569)
Cash, cash equivalents and restricted cash — Beginning of period	192,318	354,835	566,404
Cash, cash equivalents and restricted cash — End of period	596,540	192,318	354,835
Supplemental Disclosures of Other Cash Flow Information
Cash paid for income taxes, net	214	6,912	29,159
Supplemental Disclosures of Noncash Investing and Financing Activities
Purchases of property, equipment and software recorded in accounts payable and accrued liabilities	1,155	1,490	4,440
Tax liability related to net share settlement of equity awards included in accounts payable and accrued liabilities	45	912	971
Operating lease right-of-use assets obtained in exchange for new operating lease liabilities	13,549	6,325	0
Repurchases of common stock recorded in accrued liabilities	$ 1,689	$ 0	$ 0

ORGANIZATION AND DESCRIPTION OF

ORGANIZATION AND DESCRIPTION OF BUSINESS	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION AND DESCRIPTION OF BUSINESS	ORGANIZATION AND DESCRIPTION OF BUSINESS Yelp Inc. was incorporated in Delaware on September 3, 2004. Except where specifically noted or the context otherwise requires, the use of terms such as the “Company” and “Yelp” in these Notes to Consolidated Financial Statements refers to Yelp Inc. and its subsidiaries. Yelp is a trusted local resource for consumers and a partner in success for businesses of all sizes. Consumers trust Yelp for its extensive ratings and reviews of businesses across a broad range of categories, while businesses advertise on Yelp to reach its large audience of generally affluent, purchase-oriented consumers. The Company consisted of Yelp Inc. and five wholly owned entities as of December 31, 2020: Yelp UK Ltd was incorporated on December 1, 2008; Darwin Social Marketing Inc. (formerly Yelp Canada Inc.) was incorporated on February 24, 2009; Yelp Ireland Limited was incorporated on May 31, 2010; Yelp Ireland Holding Company Limited was incorporated on June 16, 2010; and Yelp GmbH (formerly Qype GmbH) was acquired on October 23, 2012. Turnstyle Analytics Inc., which was acquired on April 3, 2017, was combined with Darwin Social Marketing Inc. on January 1, 2019. The financial results of these subsidiaries are included within the consolidated financial statements of the Company presented herein. Basis of Presentation —The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). All intercompany balances and transactions have been eliminated upon consolidation. Certain Significant Risks and Uncertainties —The Company operates in a dynamic industry and, accordingly, may be affected by a variety of factors. For example, the Company’s management believes that changes in any of the following areas could have a significant negative impact on the Company in terms of its future financial position, results of operations or cash flows: the duration and magnitude of the impact of the COVID-19 pandemic on the Company and the U.S. economy generally; the Company's ability to maintain and expand its advertiser base; the success of the Company's strategy; qualified employees and key personnel; levels of user engagement on the Company's platform; industry competition; reliance on search engines and the placement and prominence in results rankings; the quality and reliability of reviews; real or perceived security breaches and the Company's ability to maintain uninterrupted operation of its network infrastructure; protection of the Company’s brand, reputation and intellectual property; intellectual property infringement and other disputes; and changes in government regulation affecting the Company’s business, among other things.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Use of Estimates —The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of income and expenses during the reporting period. These estimates are based on information available as of the date of the consolidated financial statements; therefore, actual results could differ from management’s estimates. In early March 2020, COVID-19 was declared a global pandemic by the World Health Organization. Governments and around the world, including in the United States, have implemented extensive measures in an effort to control the spread of COVID-19, including travel restrictions, limitations on business activity, quarantines and shelter-in-place orders. Due to the COVID-19 pandemic and the uncertainty of the extent of the impacts, many of the estimates and assumptions required increased judgment and carry a higher degree of variability and volatility than they did prior to the pandemic. As events continue to evolve and additional information becomes available, these estimates may materially change in future periods. Foreign Currency Translation —The consolidated financial statements of the Company’s foreign subsidiaries are measured using the local currency as the functional currency. Assets and liabilities of foreign subsidiaries are translated at exchange rates in effect as of the balance sheet date. Revenues and expenses are translated at average exchange rates in effect during the year. Translation adjustments are recorded within accumulated other comprehensive loss, a separate component of stockholders’ equity. Cash and Cash Equivalents —The Company considers all highly liquid investments, such as treasury bills, commercial paper, certificates of deposit and money market instruments with maturities of three months or less at the time of acquisition to be cash equivalents. Cash and cash equivalents primarily consist of amounts held in interest-bearing money market funds that were readily convertible to cash. The fair value of cash and cash equivalents approximates their carrying value. Marketable Securities —The Company considers highly liquid treasury notes, U.S. agency securities, corporate debt securities, money market funds and other funds with maturities of more than three months to be marketable securities. Securities with less than one year to maturity are included in short-term marketable securities, and all other securities are classified as long-term marketable securities. The Company has a policy that generally requires its securities to be investment grade (i.e. rated ‘A+’ or higher by bond rating firms) with the objective of minimizing the potential risk of principal loss. The Company determines the classification of its marketable securities based on its investment strategy. Marketable securities are classified as held-to-maturity when the Company has the positive intent and ability to hold the securities to maturity, and it has an established history of holding investments to maturity. Held-to-maturity securities are stated at amortized cost and are periodically assessed for impairment. Amortized costs of debt securities are adjusted for amortization of premiums and accretion of discounts to maturity, and these adjustments are included in interest income. Marketable securities are classified as available-for-sale when the Company has established a practice of selling investments prior to maturity, or if the Company does not have the intent to hold securities to maturity to allow flexibility in response to liquidity needs. In the event that the Company classifies its investments as available-for-sale, it will only return to classifying investments as held-to-maturity once it has reestablished a practice and intent of holding investments to maturity. Available-for-sale securities are stated at fair value as of each balance sheet date and are periodically assessed for impairment. For the Company's available-for-sale securities, an investment is impaired if the fair value of the investment is less than its amortized cost basis. In assessing whether a credit loss exists, the Company compares the present value of cash flows expected to be collected from the security with the amortized cost basis of the security. If the present value of expected cash flows is less than the amortized cost basis of the security, an allowance for credit loss is recorded as a component of other income (expense), net. Any remaining unrealized losses are recorded to other comprehensive income (loss). The Company determines any realized gains or losses on the sale of marketable securities on a specific identification method and records such gains and losses as a component of other income (expense), net. Amortization of premiums and accretion of discounts are included in interest income. If the Company has the intent to sell an available-for-sale security in an unrealized loss position or it is more likely than not that it will be required to sell the security prior to recovery of its amortized cost basis, any previously recorded allowance is reversed and the entire difference between the amortized cost basis of the security and its fair value is recognized in the condensed consolidated statements of operations. Concentrations of Credit Risk —Financial instruments that potentially subject the Company to concentration of credit risk consist primarily of cash and cash equivalents and accounts receivable. The Company places its cash and cash equivalents with major financial institutions, which management assesses to be of high credit quality, in order to limit the exposure of each investment. Credit risk with respect to accounts receivable is dispersed due to the Company’s large number of customers. In addition, the Company’s credit risk is mitigated by the relatively short collection period. Collateral is not required for accounts receivable. Accounts Receivable, Net, and Payment Terms —The timing of revenue recognition may differ from the timing of invoicing to customers. The Company records an accounts receivable balance when revenue is recognized prior to or at the time of invoicing the customer. Payment terms and conditions vary by contract type and the service being provided. For advertising services, the Company typically invoices customers on a monthly basis, one month in arrears, with payment due either at the end of each billing period or up to 30 days after the end of the billing period. For transaction services, the Company collects its commission fee on each transaction either at the time of the transaction or up to 30 days after the end of the billing period. For subscription services, the Company typically invoices customers one month in advance, with payment due at the beginning of each billing period. Allowance for Doubtful Accounts —The Company maintains an allowance for doubtful accounts receivable. The allowance reflects the Company's best estimate of probable losses associated with the accounts receivable balance. It is based upon historical experience and loss patterns, the number of days that billings are past due, an evaluation of the potential risk of loss associated with delinquent accounts based on the credit risk of those accounts, known delinquent accounts, as well as current conditions and reasonable and supportable economic forecasts. When new information becomes available that allows the Company to more accurately estimate the allowance, it makes an adjustment, which is considered a change in accounting estimate. The carrying value of accounts receivable approximates their fair value. Deferred Contract Costs —The Company has determined that certain sales incentive compensation costs are incremental costs to obtain the related contract. These costs are capitalized in the period in which they are incurred and amortized on a straight-line basis over the expected customer life of the associated contract. The Company uses a straight-line basis as it expects the benefit of these costs to be realized uniformly over the amortization period. The amortization periods for contract costs, which extend up to 32 months, were determined based on both qualitative and quantitative factors, including product life cycle attributes and customer retention historical data. For contract costs with amortization periods of less than 12 months, the Company applies a practical expedient to expense such costs as incurred. The Company assesses deferred contract costs for impairment on a quarterly basis. Amortized contract costs are recorded within sales and marketing expense in the consolidated statements of operations. Deferred contract costs are included within other non-current assets on the Company's consolidated balance sheets (see Note 10, " Other Non-Current Assets " ). Deferred Revenue —The Company records deferred revenue when it has received consideration, or has the right to receive consideration, in advance of the transfer of the performance obligations of the contract to the customer. Property, Equipment and Software —Property, equipment and software are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which are approximately three Website and Internal-Use Software Development Costs —Costs related to website and internal-use software are primarily related to the Company’s website and mobile app, including support systems. The Company capitalizes its costs to develop software when: preliminary development efforts are successfully completed; management has authorized and committed project funding; and it is probable that the project will be completed and the software will be used as intended. Costs incurred for enhancements that are expected to result in additional material functionality are capitalized and amortized over the estimated useful life of the upgrades. Such costs are amortized on a straight-line basis over the estimated useful life of the related asset, which is generally three years. The Company capitalizes certain implementation costs incurred related to cloud computing arrangements that are service contracts. Such costs are amortized on a straight-line basis over the term of the associated hosting arrangement plus any reasonably certain renewal period. Any capitalized amounts related to such arrangements are recorded within prepaid expense and other current assets and within non-current assets on the consolidated balance sheets. Leases —The Company leases its office facilities under operating lease agreements that expire from 2021 to 2031, some of which include options to renew at the Company's sole discretion. If exercised, such options would extend the lease terms by up to ten years. Additionally, certain lease agreements contain options to terminate the leases, which require 6 to 12 months prior written notice to the landlord. The Company does not have any finance lease agreements. The Company recognizes on its consolidated balance sheets operating lease liabilities representing the present value of future lease payments, and an associated operating lease right-of-use asset for any operating lease with a term greater than one year. The Company recognizes the amortization of the right-of-use asset each month within lease expense. The Company elected to use the practical expedient for short-term leases, and therefore does not record operating lease right-of-use assets or lease liabilities associated with leases with durations of 12 months or less. When recording the present value of lease liabilities, a discount rate is required. The Company has concluded that the rates implicit in the various operating lease agreements are not readily determinable. As a result, the Company instead uses its incremental borrowing rate, which is calculated based on hypothetical borrowings to fund each respective lease over the lease term, as of the lease commencement date, assuming that borrowings are secured by the various leased properties. The incremental borrowing rates are determined based on an assessment of the Company’s implied credit rating, using ratings scales from reputable rating agencies that consider a number of qualitative and quantitative factors. Market rates are derived as of the lease commencement dates with reference to companies with the same debt rating that operate in a similar industry to the Company. The Company does not recognize its renewal options as part of its right-of-use assets and lease liabilities until it is reasonably certain that it will exercise such renewal options. The Company does not combine lease and non-lease components; its lease agreements provide specific allocations of the Company's obligations between lease and non-lease components. As a result, the Company is not required to exercise any judgment in determining such allocations. The Company has subleased certain office facilities under operating lease agreements that expire in 2025. The sublease agreements do not contain any options to renew. The Company recognizes a majority of the sublease rental income as a reduction in rent expense on a straight-line basis over the lease period, with any sublease income in excess of the original lease cost recorded to other income, net. Business Combinations —The Company accounts for acquisitions of entities that consist of inputs and processes that have the ability to contribute to the creation of outputs as business combinations. The Company allocates the purchase price of the acquisition to the tangible assets, liabilities and identifiable intangible assets acquired based on their estimated fair values. The excess of the purchase price over those fair values is recorded as goodwill. Acquisition-related expenses and integration costs are expensed as incurred. During the measurement period, the Company records adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. After the measurement period, which could be up to one year after the transaction date, subsequent adjustments are recorded to the Company’s consolidated statements of operations. Goodwill —Goodwill represents the excess of the purchase price in a business combination over the fair value of net tangible and intangible assets acquired. The carrying amount of goodwill is reviewed at least annually, or more frequently if events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. The Company has the option to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the Company determines that it is more likely than not that its fair value is less than the carrying amount, or opts not to perform a qualitative assessment, then the Company will compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. No impairment charges associated with goodwill have been recorded by the Company to date. Intangible Assets —Intangible assets include acquired intangible assets identified through business combinations, which are carried at fair value less accumulated amortization, and purchased intangible assets, which are carried at cost less accumulated amortization. Amortization is recorded over the estimated useful lives of the assets, generally two years to 12 years. The Company reviews amortizable intangible assets to be held and used for impairment whenever events or changes in circumstances indicate that the carrying value of the assets may not be recoverable. Determination of recoverability is based on the lowest level of identifiable estimated undiscounted cash flows resulting from the use of the asset and its eventual disposition. Measurement of any impairment loss is based on the excess of the carrying value of the asset over its fair value. No material impairment charges have been recorded to date. Impairment of Long-Lived Assets and Long-Lived Assets to Be Disposed of —The Company evaluates its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or fair value less costs to sell. Stock Repurchases —The Company accounts for repurchases of its common stock by recording the cost to repurchase those shares to treasury stock, a separate component of stockholders' equity. Upon retirement, the carrying amount of treasury stock is reduced with a corresponding reduction to par value of common stock, with any excess of the cost incurred to repurchase shares over their par value recorded as an adjustment to retained earnings (accumulated deficit) on the date of retirement. Assets and Liabilities Held for Sale —The Company considers an asset to be held for sale when: management approves and commits to a formal plan to actively market the asset for sale at a reasonable price in relation to its fair value; the asset is available for immediate sale in its present condition; an active program to locate a buyer and other actions required to complete the sale have been initiated; the sale of the asset is expected to be completed within one year; and it is unlikely that significant changes will be made to the plan. Upon designation as held for sale, the Company records the carrying value of the assets at the lower of its carrying value or its estimated fair value, less costs to sell. The Company ceases to record depreciation and amortization expense associated with assets upon their designation as held for sale. Revenue Recognition —The Company generates revenue from the sale of advertising products, transactions with consumers and other revenue sources, which correspond to the Company's major product lines. The Company recognizes revenue by applying the following steps: the contract with the customer is identified; the performance obligations in the contract are identified; the transaction price is determined; the transaction price is allocated to the performance obligations in the contract; and revenue is recognized when (or as) the Company satisfies these performance obligations in an amount that reflects the consideration it expects to be entitled to in exchange for those services. The Company applies the portfolio practical expedient to account for the vast majority of contracts with customers in each category of revenue. The Company does not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) contracts for which the amount of revenue it recognizes is equal to the amount which the Company has a right to invoice. Contracts with customers can include multiple performance obligations, where the transaction price is allocated to each performance obligation based on its relative standalone selling price ("SSP"). The Company determines SSP based on the prices of the promised goods or services charged when sold separately to customers, which are determined using contractually stated prices. The Company allocates revenue to each of the performance obligations included in a contract with multiple performance obligations at the inception of the contract. The various products and services comprising contracts with multiple performance obligations are typically capable of being distinguished and accounted for as separate performance obligations. For all contracts with customers, estimates and assumptions include determining variable consideration and identifying the nature and timing of satisfaction of performance obligations. The Company may accept lower consideration than the amount promised per the contract for certain revenue transactions and certain customers may receive cash based incentives, credits, or refunds, which are accounted for as variable consideration when estimating the amount of revenue to recognize. The Company estimates these amounts based on the expected amount to be provided to customers and reduce revenue. The Company believes that there will not be significant changes to our estimates of variable consideration. For contracts satisfied over time, the Company applies the invoice practical expedient to depict the value transferred to the customer and measure of progress towards completion of its obligations. The Company considers the right to receive consideration from a customer to correspond directly with the value to the customer of its performance completed to date. The Company does not consider the effects of the time value of money as substantially all of the Company’s contracts are invoiced on a monthly basis, one month in arrears. Revenue is recognized net of any taxes collected from customers, which are remitted to governmental authorities. The Company does not typically refund customers for services once it determines the performance obligations of the contract have been satisfied, but will assess any refund requests from customers and partners on a case by case basis. The Company records an allowance for potential future refunds, which is estimated based on historical trends and recorded as a reduction of net revenue. Advertising . The Company generates advertising revenue primarily through the display of advertising products on its website and mobile app. These arrangements are evidenced by either written or electronic acceptance of a contract that stipulates the types of advertising to be delivered, the timing and pricing. Performance-based advertising placements are priced on a cost-per-click basis, while impression-based advertising placements are priced on a cost per thousand impressions basis. The Company recognizes revenue from the delivery of performance-based ads and impression-based ads in the period of delivery, in each case net of customer discounts. The Company also offers businesses premium features in connection with their business listing pages pursuant to fixed monthly fees, and recognizes revenue from such offerings over the service period. The Company also generates advertising revenue through indirect sales of advertising products, such as through reseller contracts that allow partners to sell Yelp Branded Profiles to their clients and the monetization of remnant advertising inventory through third-party ad networks, and recognizes revenue in the period of delivery. Transactions . The Company generates transactions revenue primarily from revenue-sharing partner contracts. The Company's transactions platform provides consumers with the ability to complete food delivery and other transactions through third parties, primarily Grubhub, directly on Yelp. The Company earns a per-transaction commission fee pursuant to partnership contracts for acting as an agent for these transactions, which it recognizes on a net basis and includes in revenue upon completion of a transaction. Other Revenue . The Company generates other revenue through subscription services contracts, such as sales of monthly subscriptions to Yelp Reservations and Yelp Waitlist, licensing contracts for access to Yelp data, and other non-advertising, non-transaction partnerships. Subscription revenues are recognized ratably over the contract terms beginning on the commencement date of each contract, which is the date the service is made available to customers. Cost of Revenue —The Company’s cost of revenue primarily consists of credit card processing fees, website infrastructure expense, which includes website hosting costs, and salaries, benefits and stock-based compensation expense for the infrastructure teams responsible for operating the Company’s website and mobile app, and excludes depreciation and amortization expense. Cost of revenue also includes third-party advertising fulfillment costs. Research and Development —The Company incurs research and development expenses for costs it incurs in research aimed at developing, and in translating the results of such research into new products and services or significant improvements to existing products or services, whether intended for sale or for internal use. Such costs are considered research and development expense up to the point in time at which the product or service achieves technological feasibility. These expenses primarily consist of employee-related costs (including stock-based compensation) for the Company's engineers and other employees engaged in the research and development of its products and services, as well as allocated indirect overhead costs. Research and development costs were $230.1 million, $225.5 million and $205.8 million for the years ended December 31, 2020, 2019 and 2018, respectively, and are recorded to costs and expenses in the consolidated statements of operations for those periods, primarily within product development costs. Stock-Based Compensation —The Company accounts for stock-based employee compensation plans under the fair value recognition and measurement provisions, which require all stock-based payments to employees, including grants of stock options, restricted stock awards, restricted stock units ("RSUs"), performance-based restricted stock units ("PRSUs") and issuances under its 2012 Employee Stock Purchase Plan, as amended ("ESPP"), to be measured based on the grant-date fair value of the awards. The Company accounts for forfeitures as they occur. The fair value of options granted to employees is estimated on the grant date using the Black-Scholes-Merton option valuation model. This valuation model for stock-based compensation expense requires the Company to make assumptions and judgments about the variables used in the calculation, including the expected term (weighted-average period of time that the options granted are expected to be outstanding), the expected volatility in the fair market value of the Company’s common stock, a risk-free interest rate and expected dividends. No compensation cost is recorded for options that do not vest. The Company uses the simplified calculation of expected life as the contractual term for options of 10 years is longer than the Company has been publicly traded. Expected volatility is based on an average of the historical volatilities of the common stock of several entities with characteristics similar to those of the Company. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. The Company uses the straight-line method for expense attribution. The fair value of RSUs is measured using the closing price of the Company's common stock on the New York Stock Exchange on the grant date. The Company uses the straight-line method for expense attribution. No compensation cost is recorded for RSUs that do not vest. In May 2020, the Company changed its method of settling the employee tax liabilities associated with the vesting of RSUs from withholding a portion of the vested shares and covering such taxes with cash from its balance sheet ("Net Share Withholding"), to selling a portion of the vested shares to cover taxes. In November 2020, the Company reverted its method of settling these employee tax liabilities to Net Share Withholding. The Company has two types of PRSUs outstanding — awards for which the vesting is subject to both a time-based vesting schedule and either (a) a market condition or (b) the achievement of performance goals. For the awards subject to a market condition, the Company uses a Monte Carlo model to determine the fair value of the PRSUs. The Company uses the accelerated method for expense attribution. Compensation costs are recorded if the service condition is met regardless of whether the market performance condition is satisfied. No compensation cost is recorded if the service condition is not met. For the awards subject to performance goals, compensation costs are recorded when the Company concludes that it is probable that the performance conditions will be achieved. The Company performs an analysis in each reporting period to determine the probability that the performance goals will be met, and recognizes a cumulative catch-up adjustment to compensation cost for changes in its probability assessment in subsequent reporting periods, if required, until the performance period has expired. The fair value of the PRSUs is measured using the closing price of the Company's common stock on the New York Stock Exchange on the grant date. The Company uses the accelerated method for expense attribution. No compensation cost is recorded if the service condition is not met. Advertising Expenses —Advertising costs are expensed in the period in which the advertising takes place. Costs of producing advertising are expensed in the period in which production takes place. Total advertising expenses incurred were $22.2 million, $20.7 million and $38.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. Comprehensive (Loss) Income —Comprehensive (loss) income consists of net (loss) income and other comprehensive income (loss), which consists of foreign currency adjustments. Income Taxes —The Company records income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s financial statements or tax returns. In estimating future tax consequences, the Company generally considers all expected future events other than enactments or changes in the tax law or rates. In assessing the realization of deferred tax assets, the Company considers whether it is more likely than not that all or some portion of deferred tax assets will not be realized. The ultimate realization of the deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Valuation allowances are provided to reduce deferred tax assets to the amount that is more likely than not to be realized. In determining the need for a valuation allowance, the weight given to positive and negative evidence is commensurate with the extent to which the evidence may be objectively verified. The Company evaluates the ability to realize net deferred tax assets and the related valuation allowance on a quarterly basis. The Company operates in various tax jurisdictions and is subject to audit by various tax authorities. The Company provides for tax contingencies whenever it is deemed probable that a tax asset has been impaired or a tax liability has been incurred for events such as tax claims or changes in tax laws. Tax contingencies are based upon their technical merits, relative tax law and the specific facts and circumstances as of each reporting period. Changes in facts and circumstances could result in material changes to the amounts recorded for such tax contingencies. The Company recognizes a tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are then measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. Employee Benefit Plan —The Company sponsors a qualified 401(k) defined contribution plan covering eligible employees. Participants may contribute a portion of their annual compensation up to a maximum annual amount set by the Internal Revenue Service (“IRS”). Employer contributions under this plan were $6.1 million, $9.3 million and $11.9 million for the years ended December 31, 2020, 2019 and 2018, respectively. Insurance —The Company is self-insured for certain employee benefits including medical, dental and vision; however, the Company obtains third-party excess insurance coverage to l

CASH, CASH EQUIVALENTS AND REST

CASH, CASH EQUIVALENTS AND RESTRICTED CASH	12 Months Ended
	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
CASH, CASH EQUIVALENTS AND RESTRICTED CASH	CASH, CASH EQUIVALENTS AND RESTRICTED CASH Cash, cash equivalents and restricted cash as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, December 31, Cash $ 85,750 $ 43,581 Cash equivalents 510,125 126,700 Total cash and cash equivalents $ 595,875 $ 170,281 Restricted cash 665 22,037 Total cash, cash equivalents and restricted cash $ 596,540 $ 192,318 The increase in cash equivalents during the year ended December 31, 2020 was primarily driven by the Company's change in its investment strategy to preserve liquidity as a result of the COVID-19 pandemic. During the six months ended June 30, 2020, the Company sold securities for proceeds of $253.4 million and reinvested these funds along with $73.0 million from maturities and redemptions into money market funds, which are recorded as cash equivalents. See Note 5, " Marketable Securities, " for further details. As of December 31, 2019, the Company had letters of credit collateralized fully by bank deposits which totaled $22.0 million. These letters of credit primarily related to lease agreements for certain of the Company’s offices, which are required to be maintained and issued to the landlords of each facility. As the bank deposits had restrictions on their use, they were classified as restricted cash on the Company's consolidated balance sheet as of December 31, 2019. In May 2020, the Company moved approximately $21.5 million of these letters of credit under a sub-limit included in its credit agreement with Wells Fargo Bank, National Association, which it entered into on May 5, 2020 (the "Credit Agreement"). Each letter of credit is subject to renewal annually until the applicable lease expires. Following this transfer, the restrictions on the Company's use of the bank deposits previously used to collateralize its letters of credit were lifted and, as a result, such funds are no longer classified as restricted cash. See Note 13, " Commitments and Contingencies, " for further details on the Credit Agreement.

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS The Company’s investments in money market accounts are recorded as cash equivalents at fair value in the consolidated balance sheets. The accounting guidance for fair value measurements prioritizes the inputs used in measuring fair value in the following hierarchy: Level 1 —Observable inputs, such as quoted prices in active markets, Level 2 —Inputs other than quoted prices in active markets that are observable either directly or indirectly, or Level 3 —Unobservable inputs in which there are little or no market data, which require the Company to develop its own assumptions. This hierarchy requires the Company to use observable market data, when available, to minimize the use of unobservable inputs when determining fair value. The Company’s money market funds are classified within Level 1 of the fair value hierarchy because they are valued using quoted prices in active markets. The Company's certificates of deposit and, prior to their sale during the six months ended June 30, 2020, the Company’s commercial paper, corporate bonds and agency bonds are classified within Level 2 of the fair value hierarchy because they have been valued using inputs other than quoted prices in active markets that are observable directly or indirectly. See Note 5, " Marketable Securities, " for further details. The following table represents the fair value of the Company’s financial instruments, including those measured at fair value on a recurring basis, as of December 31, 2020 and 2019 as well as those held-to-maturity as of December 31, 2019 (in thousands): December 31, 2020 December 31, 2019 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash Equivalents: Money market funds $ 510,125 $ — $ — $ 510,125 $ 126,700 $ — $ — $ 126,700 Marketable Securities: Commercial paper — — — — — 130,472 — 130,472 Corporate bonds — — — — — 85,611 — 85,611 Agency bonds — — — — — 79,750 — 79,750 Other Investments: Certificates of deposit — 10,933 — 10,933 — — — — Total cash equivalents, marketable securities and other investments $ 510,125 $ 10,933 $ — $ 521,058 $ 126,700 $ 295,833 $ — $ 422,533 Other investments include $10.0 million that the Company invested into certificates of deposit with minority-owned financial institutions as a commitment to support underserved communities. The certificates of deposit are reflected in prepaid expenses and other current assets on the consolidated balance sheets as of December 31, 2020.

MARKETABLE SECURITIES

MARKETABLE SECURITIES	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
MARKETABLE SECURITIES	MARKETABLE SECURITIES In March 2020, the Company changed its investment strategy in response to uncertainties resulting from the COVID-19 pandemic to allow for more flexibility in preserving liquidity, which led to the transfer of $300.2 million of amortized cost of its investment portfolio from a held-to-maturity classification to available-for-sale. As a result of this transfer, the Company reversed the allowance for credit loss that had been previously recorded upon adoption of ASU 2016-13 and measured the securities at fair value as of the transfer date by recording an immaterial allowance for credit loss to other income, net and the remaining adjustment as an immaterial unrealized loss recorded to other comprehensive income. Following this transfer, during the six months ended June 30, 2020, the Company liquidated its investment portfolio, which consisted of available-for-sale short- and long-term marketable securities, for proceeds of $253.4 million. The Company recorded an immaterial net realized gain to other income, net and reinvested the proceeds from the sales, along with $73.0 million from maturities and redemptions of marketable securities, into money market funds. The amortized cost, gross unrealized gains and losses, and fair value of securities held-to-maturity as of December 31, 2019 were as follows (in thousands): December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term marketable securities: Commercial paper $ 130,464 $ 17 $ (9) $ 130,472 Corporate bonds 85,396 225 (10) 85,611 Agency bonds 26,140 90 — 26,230 Total short-term marketable securities 242,000 332 (19) 242,313 Long-term marketable securities: Agency bonds 53,499 21 — 53,520 Total long-term marketable securities 53,499 21 — 53,520 Total marketable securities $ 295,499 $ 353 $ (19) $ 295,833 The Company did not have any securities that were in an unrealized loss position as of December 31, 2020. The following tables present gross unrealized losses and fair values for those securities that were in an unrealized loss position as of December 31, 2019, aggregated by investment category and the length of time that the individual securities have been in a continuous loss position (in thousands): December 31, 2019 Less Than 12 Months 12 Months or Greater Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Commercial paper $ 63,639 $ (9) $ — $ — $ 63,639 $ (9) Corporate bonds 20,979 (10) — — 20,979 (10) Total $ 84,618 $ (19) $ — $ — $ 84,618 $ (19) Prior to the adoption of ASU 2016-13 in 2020, the Company periodically reviewed its investment portfolio for other-than-temporary impairment. The Company considered such factors as the duration, severity and reason for the decline in value, and the potential recovery period. The Company also considered whether it was more likely than not that it would be required to sell the securities before the recovery of their amortized cost basis, and whether the amortized cost basis could not be recovered as a result of credit losses. During the years ended December 31, 2019 and 2018, the Company did not recognize any other-than-temporary impairment loss.

PREPAID EXPENSES AND OTHER CURR

PREPAID EXPENSES AND OTHER CURRENT ASSETS	12 Months Ended
	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid Expenses and Other Current Assets	PREPAID EXPENSES AND OTHER CURRENT ASSETS Prepaid expenses and other current assets as of December 31, 2020 and December 31, 2019 consisted of the following (in thousands): December 31, December 31, Prepaid expenses $ 10,438 $ 10,188 Certificates of deposit 10,930 — Other current assets 7,082 4,008 Total prepaid expenses and other current assets $ 28,450 $ 14,196 As of December 31, 2020, certificates of deposit consisted primarily of $10.0 million in investments with minority-owned financial institutions made in November 2020. Other current assets primarily consists of deferred costs related to unsettled share repurchases and income tax receivables.

PROPERTY, EQUIPMENT AND SOFTWAR

PROPERTY, EQUIPMENT AND SOFTWARE, NET	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
PROPERTY, EQUIPMENT AND SOFTWARE, NET	PROPERTY, EQUIPMENT AND SOFTWARE, NET The Company capitalized $32.4 million, $33.9 million and $26.9 million in website and internal-use software costs during the years ended December 31, 2020, 2019 and 2018, respectively, which are included in property, equipment and software, net on the consolidated balance sheets. Amortization expense related to capitalized website and internal-use software was $27.1 million, $24.2 million and $19.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. The Company wrote off $1.5 million and $1.6 million of capitalized website and internal-use software costs in the years ended December 31, 2020 and 2019, respectively, and wrote off an immaterial amount in the year ended December 31, 2018. Property, equipment and software, net as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, December 31, Capitalized website and internal-use software development costs $ 171,831 $ 140,886 Leasehold improvements 88,687 86,089 Computer equipment 46,581 43,626 Furniture and fixtures 18,339 18,403 Telecommunication 4,951 5,154 Software 1,717 1,687 Total 332,106 295,845 Less accumulated depreciation (230,388) (184,896) Property, equipment and software, net $ 101,718 $ 110,949 Depreciation expense for the years ended December 31, 2020, 2019 and 2018 was approximately $48.0 million, $46.1 million and $39.3 million, respectively.

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS The Company’s goodwill is the result of its acquisitions of other businesses, and represents the excess of purchase consideration over the fair value of assets acquired and liabilities assumed. The Company performed its annual goodwill impairment analysis on August 31, 2020 and concluded that goodwill was not impaired, as the fair value of the reporting unit exceeded its carrying value. The changes in the carrying amounts of goodwill during the years ended December 31, 2020 and 2019, were as follows (in thousands): 2020 2019 Balance, beginning of period $ 104,589 $ 105,620 Effect of currency translation 4,672 (1,031) Balance, end of period $ 109,261 $ 104,589 Intangible assets as of December 31, 2020 and 2019 consisted of the following (dollars in thousands): December 31, 2020 Gross Accumulated Net Weighted Business relationships $ 9,918 $ (3,814) $ 6,104 7.8 years Developed technology 7,709 (6,238) 1,471 1.2 years Licensing agreements 6,129 (215) 5,914 9.2 years Content 4,078 (4,078) — 0.0 years Domain and data licenses 2,869 (2,837) 32 2.2 years Trademarks 877 (877) — 0.0 years User relationships 146 (146) — 0.0 years Total $ 31,726 $ (18,205) $ 13,521 December 31, 2019 Gross Accumulated Net Weighted Business relationships $ 9,918 $ (2,841) $ 7,077 8.6 years Developed technology 7,832 (4,959) 2,873 2.2 years Content 3,814 (3,814) — 0.0 years Domain and data licenses 2,869 (2,748) 121 1.7 years Trademarks 877 (872) 5 0.2 years User relationships 146 (140) 6 0.2 years Total $ 25,456 $ (15,374) $ 10,082 During the year ended December 31, 2020, the Company recorded an intangible asset of $6.1 million related to a licensing agreement that was entered into with a third party. The Company accounted for this transaction as an asset acquisition of an intangible asset and will amortize the licensing agreement on a straight-line basis over its estimated useful life of 9.5 years. Amortization expense for the years ended December 31, 2020, 2019 and 2018 was $2.6 million, $3.3 million and $3.5 million, respectively. The Company recorded an immaterial impairment charge related to developed technology during the three months ended March 31, 2020. No changes to the useful lives of any intangible assets were made. As of December 31, 2020, the estimated future amortization of intangible assets for (i) each of the succeeding five years and (ii) thereafter was as follows (in thousands): Year Ending December 31, Amount 2021 $ 2,848 2022 1,676 2023 1,359 2024 1,353 2025 1,353 Thereafter 4,932 Total $ 13,521

LEASES

LEASES	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
LEASES	LEASES The components of lease cost, net for the years ended December 31, 2020 and 2019 were as follows (in thousands): December 31, 2020 December 31, 2019 Operating lease cost $ 55,214 $ 54,451 Short-term lease cost (12 months or less) 1,288 1,287 Sublease income (7,826) (4,759) Total lease cost, net $ 48,676 $ 50,979 The Company's leases and subleases do not include any variable lease payments, residual value guarantees, related-party leases, or restrictions or covenants that would limit or prevent the Company from exercising its right to obtain substantially all of the economic benefits from use of the respective assets during the lease term. The Company will continue to disclose comparative reporting periods prior to January 1, 2019 under ASC 840. During the year ended December 31, 2018, the Company recognized rent expense, net of sublease rental income, on a straight-line basis over the lease period. Rent expense, net was $51.2 million for the year ended December 31, 2018, and sublease rental income for the year was $2.2 million. Supplemental cash flow information related to leases for the years ended December 31, 2020 and 2019 was as follows (in thousands): December 31, 2020 December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 58,515 $ 56,672 As of December 31, 2020, maturities of lease liabilities for (i) each of the succeeding five years and (ii) thereafter were as follows (in thousands): Year Ending December 31, Operating 2021 $ 52,465 2022 47,134 2023 44,207 2024 41,519 2025 22,419 Thereafter 24,422 Total minimum lease payments 232,166 Less imputed interest (32,070) Present value of lease liabilities $ 200,096 As of December 31, 2020 and 2019, the weighted-average remaining lease term and weighted-average discount rate were as follows: December 31, 2020 December 31, 2019 Weighted-average remaining lease term (years) — operating leases 5.1 5.5 Weighted-average discount rate — operating leases 6.0 % 6.1 % In October 2020, the Company entered into a lease agreement for an office facility in Toronto, Canada for which the lease term is expected to commence in 2021 and expire in 2031. The Company expects to classify this as an operating lease and, as of December 31, 2020, expected to recognize operating lease cost of approximately $9.4 million over the life of the lease.

OTHER NON-CURRENT ASSETS

OTHER NON-CURRENT ASSETS	12 Months Ended
	Dec. 31, 2020
Other Assets, Noncurrent Disclosure [Abstract]
OTHER NON-CURRENT ASSETS	OTHER NON-CURRENT ASSETS Other non-current assets as of December 31, 2020 and 2019 consisted of the following (in thousands): 2020 2019 Deferred tax assets $ 31,163 $ 20,054 Deferred contract costs 14,522 15,138 Other non-current assets 3,163 3,177 Total other non-current assets $ 48,848 $ 38,369 Deferred contract costs as of December 31, 2020 and 2019, and changes in deferred contract costs during the years ended December 31, 2020 and 2019, were as follows (in thousands): 2020 2019 Balance, beginning of period $ 15,138 $ 12,345 Add: costs deferred on new contracts 15,328 14,998 Less: amortization recorded in sales and marketing expenses (15,944) (12,205) Balance, end of period $ 14,522 $ 15,138 Due to the impact of the COVID-19 pandemic, the Company concluded that the useful lives of deferred contract costs had a range of up to 26 months as of March 31, 2020, down from 32 months as of December 31, 2019. As a result, additional amortized commission expense of $3.4 million was recorded in sales and marketing expenses during the three months ended March 31, 2020. Following an observed improvement in customer retention and a reduction in customer delinquencies in the three months ended September 30, 2020, the Company's updated expected customer life calculation as of September 30, 2020 indicated that the useful lives of deferred contract costs had returned to a range of up to 32 months, reflecting the expected lives observed before the COVID-19 pandemic. As of December 31, 2020, the Company concluded that there were no changes in the estimated customer life for any component of the deferred contract costs balances from September 30, 2020.

CONTRACT BALANCES

CONTRACT BALANCES	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
CONTRACT BALANCES	CONTRACT BALANCES The changes in the allowance for doubtful accounts during the years ended December 31, 2020, 2019 and 2018, were as follows (in thousands): Year Ended December 31, 2020 2019 2018 Balance, beginning of period $ 7,686 $ 8,685 $ 8,602 Add: provision for doubtful accounts 32,265 22,543 24,515 Less: write-offs, net of recoveries (28,392) (23,542) (24,432) Balance, end of period $ 11,559 $ 7,686 $ 8,685 The net increase in the allowance for doubtful accounts in the year ended December 31, 2020 was primarily related to an anticipated increase in customer delinquencies due to the COVID-19 pandemic. In calculating the allowance for doubtful accounts as of December 31, 2020, the Company considered expectations of probable credit losses associated with the COVID-19 pandemic based on observed trends to date in cancellations, observed changes to date in the credit risk of specific customers, the impact of anticipated closures and bankruptcies using forecasted economic indicators in addition to historical experience and loss patterns during periods of macroeconomic uncertainty. Contract liabilities consist of deferred revenue, which is recorded on the consolidated balance sheets when the Company has received consideration, or has the right to receive consideration, in advance of transferring the performance obligations under the contract to the customer. Changes in deferred revenue during the years ended December 31, 2020 and 2019 were as follows (in thousands): Year Ended December 31, 2020 2019 Balance, beginning of period $ 4,315 $ 3,843 Less: recognition of deferred revenue from beginning balance (3,869) (3,744) Add: net increase in current period contract liabilities 3,663 4,216 Balance, end of period $ 4,109 $ 4,315 The majority of the deferred revenue balance as of December 31, 2020 is expected to be recognized as revenue in the subsequent three-month period ending March 31, 2021. No other contract assets or liabilities are recorded on the Company's consolidated balance sheets as of December 31, 2020 and 2019.

ACCOUNTS PAYABLE AND ACCRUED LI

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
ACCOUNTS PAYABLE AND ACCRUED LIABILITIES	ACCOUNTS PAYABLE AND ACCRUED LIABILITIES Accounts payable and accrued liabilities as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, December 31, Accounts payable $ 8,853 $ 6,002 Employee-related liabilities 57,684 41,488 Accrued sales and marketing expenses 2,137 2,982 Taxes payable 975 3,695 Accrued cost of revenue 8,269 7,208 Other accrued liabilities 9,842 10,958 Total accounts payable and accrued liabilities $ 87,760 $ 72,333 The net increase in accounts payable and accrued liabilities during the year ended December 31, 2020 was primarily driven by an increase in employee-related liabilities, which comprised a $15.0 million deferral of employer social security taxes related to the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) to be paid in 2021.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal Proceedings —In January 2018, a putative class action lawsuit alleging violations of the federal securities laws was filed in the U.S. District Court for the Northern District of California, naming as defendants the Company and certain of its officers. The complaint, which the plaintiff amended on June 25, 2018, alleges violations of the Securities Exchange Act of 1934, as amended, by the Company and its officers for allegedly making materially false and misleading statements regarding its business and operations on February 9, 2017. The plaintiff seeks unspecified monetary damages and other relief. On August 2, 2018, the Company and the other defendants filed a motion to dismiss the amended complaint, which the court granted in part and denied in part on November 27, 2018. On October 22, 2019, the Court approved a stipulation to certify a class in this action. The case remains pending. Due to the preliminary nature of this lawsuit, the Company is unable to reasonably estimate either the probability of incurring a loss or an estimated range of such loss, if any, from the lawsuit. The Company is subject to other legal proceedings arising in the ordinary course of business. Although the results of litigation and claims cannot be predicted with certainty, the Company currently does not believe that the final outcome of any of these other matters will have a material adverse effect on the Company’s business, financial position, results of operations or cash flows. Indemnification Agreements —In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to customers, vendors, lessors, business partners and other parties with respect to certain matters, including, but not limited to, losses arising out of the breach of such agreements, services to be provided by the Company or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with directors and certain officers and employees that require the Company to, among other things, indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. While the outcome of claims cannot be predicted with certainty, the Company does not believe that the outcome of any claims under the indemnification arrangements will have a material effect on the Company’s financial position, results of operations or cash flows. Revolving Credit Facility —In May 2020, the Company entered into a Credit Agreement with Wells Fargo Bank, National Association, which provides for a three-year, $75.0 million senior unsecured revolving credit facility including a letter of credit sub-limit of $25.0 million. The commitments under the Credit Agreement expire on May 5, 2023. Interest on any borrowings under the revolving credit facility will accrue at either LIBOR plus 1.25% or at an alternative base rate plus 0.25%, at the Company's election. Interest is payable monthly in arrears for base rate loans and at the end of the applicable interest period (or, if the interest period extends over three months, at the end of each three-month interval during the interest period) for LIBOR loans. The Company is also required to pay an annual commitment fee that accrues at 0.25% per annum on the unused portion of the aggregate commitments under the revolving credit facility, payable quarterly in arrears. Debt issuance-related costs were $0.4 million and will be amortized to interest expense on a straight-line basis over the life of the Credit Agreement. The Company is required to pay a fee that accrues at 0.70% per annum on the undrawn portion of any letter of credit, payable quarterly in arrears. In May 2020, the Company moved letters of credit in an aggregate amount of approximately $21.5 million under the letter of credit sub-limit, which reduced the amount it can borrow under the revolving credit facility. Approximately $53.5 million remained available under the revolving credit facility as of December 31, 2020. The Company was in compliance with all covenants associated with the credit facility and there were no loans outstanding under the Credit Agreement as of December 31, 2020. See " Liquidity and Capital Resources, " included under Part II, Item 7 in this Annual Report for additional information on the covenants included in the Credit Agreement.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS’ EQUITY The following table presents the number of shares authorized and issued and outstanding as of the dates indicated: December 31, 2020 December 31, 2019 Shares Shares Shares Shares Stockholders’ equity: Common stock, $0.000001 par value 200,000,000 75,371,368 200,000,000 71,185,468 Undesignated preferred stock 10,000,000 — 10,000,000 — Stock Repurchase Program In July 2017, the Company’s board of directors approved a stock repurchase program under which the Company was authorized to repurchase up to $200.0 million of its outstanding common stock. The Company's board of directors authorized the Company to repurchase up to an additional $250.0 million of its outstanding common stock in each of November 2018, February 2019 and January 2020, bringing the total amount of authorized repurchases to $950.0 million as of December 31, 2020, $244.6 million of which remained available as of December 31, 2020. The Company may purchase shares at management’s discretion in the open market, in privately negotiated transactions, in transactions structured through investment banking institutions, or a combination of the foregoing. Pursuant to the restructuring plan announced on April 9, 2020 (the "Restructuring Plan"), the Company suspended share repurchases under the stock repurchase program. The Company resumed share repurchases during the three months ended December 31, 2020. See " Note 19, " Restructuring, " for further details on the Restructuring Plan. During the year ended December 31, 2020, the Company repurchased on the open market 803,691 shares for an aggregate purchase price of $24.4 million, of which 704,673 shares were retired. As of December 31, 2020, the Company had a treasury stock balance of 99,018 shares, which were excluded from its outstanding share count as of such date and subsequently retired in January 2021. During the year ended December 31, 2019, the Company repurchased on the open market and subsequently retired 14,190,409 shares for aggregate purchase price of $481.0 million. Common Stock Reserved for Future Issuance As of December 31, 2020, the Company had reserved shares of common stock for future issuances in connection with the following: Number of Shares Stock options outstanding 4,622,828 RSUs outstanding 9,757,787 Available for future equity award grants 5,333,200 Available for future ESPP offerings 880,067 Total reserved for future issuance 20,593,882 Equity Incentive Plans The Company has outstanding awards under three equity incentive plans: the Amended and Restated 2005 Equity Incentive Plan (the “2005 Plan”); the 2011 Equity Incentive Plan (the “2011 Plan”); and the 2012 Equity Incentive Plan, as amended (the “2012 Plan”). In July 2011, the Company adopted the 2011 Plan, terminated the 2005 Plan and provided that no further stock awards were to be granted under the 2005 Plan. All outstanding stock awards under the 2005 Plan continue to be governed by their existing terms. Upon the effectiveness of the underwriting agreement in connection with the Company’s initial public offering (“IPO”), the Company terminated the 2011 Plan and all shares that were reserved under the 2011 Plan but not issued were assumed by the 2012 Plan. No further awards will be granted pursuant to the 2011 Plan. All outstanding stock awards under the 2011 Plan continue to be governed by their existing terms. Under the 2012 Plan, the Company has the ability to issue incentive stock options, non-statutory stock options, stock appreciation rights, RSUs, restricted stock awards, performance units and performance shares. Additionally, the 2012 Plan provides for the grant of performance cash awards to employees, directors and consultants. Stock Options Stock options granted under the 2012 Plan are granted at a price per share not less than the fair value of a share of the Company’s common stock on the grant date. Options granted to date generally vest over a three four For the years ended December 31, 2020, 2019 and 2018, the weighted-average assumptions used for the Black-Scholes-Merton option valuation model were as follows: Year Ended December 31, 2020 2019 2018 Dividend yield — — — Annual risk-free rate 0.5 % 2.5 % 2.2 % Expected volatility 45.9 % 48.3 % 42.0 % Expected term (years) 5.7 6.0 6.0 A summary of stock option activity for the year ended December 31, 2020 is as follows: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2019 6,210,385 $ 25.10 4.3 $ 75,805 Granted 158,050 31.21 Exercised (1,544,610) 8.53 Canceled (200,997) 47.24 Outstanding at December 31, 2020 4,622,828 $ 29.89 4.7 $ 30,451 Options vested and exercisable at December 31, 2020 4,022,236 $ 28.90 4.2 $ 30,071 Aggregate intrinsic value represents the difference between the closing price of the Company’s common stock as quoted on the New York Stock Exchange on a given date and the exercise price of outstanding, in-the-money options. The total intrinsic value of options exercised was approximately $33.8 million, $12.0 million and $18.9 million for the years ended December 31, 2020, 2019 and 2018, respectively. The weighted-average grant date fair value of options granted was $10.01, $17.64 and $18.89 per share for the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020, total unrecognized compensation costs related to unvested stock options was approximately $9.0 million, which the Company expects to recognize over a weighted-average time period of 2.0 years. RSUs RSUs generally vest over a four-year period, on one of three schedules: (a) 25% vesting at the end of one year and the remaining vesting quarterly or annually thereafter; (b) 10% vesting over the first year, 20% vesting over the second year, 30% vesting over the third year and 40% vesting over the fourth year; or (c) ratably on a quarterly basis. RSUs also include PRSUs, which are subject to both a time-based vesting schedule and either (a) a market condition or (b) the achievement of performance goals. For PRSUs subject to a market condition, the Company recognizes expense from the date of grant. For PRSUs subject to performance goals, the Company recognizes expense when it is probable that the performance condition will be achieved. The shares underlying each PRSU award subject to a market condition will be eligible to vest only if the average closing price of the Company's common stock equals or exceeds $45.3125 over any 60-day trading period during the four years following the grant date of February 7, 2019. If this market condition is met, the shares underlying each PRSU award will vest quarterly over four years from the grant date (the "Time-Based Vesting Schedule"). Any shares subject to the PRSUs that have met the Time-Based Vesting Schedule at the time the market condition is achieved will fully vest as of such date; thereafter, any remaining nonvested shares subject to the PRSUs will continue vesting solely according to the Time-Based Vesting Schedule, subject to the applicable employee's continued service as of each such vesting date. For PRSUs subject to performance goals, a percentage of the target number of shares, ranging from zero to 200%, will become eligible to vest based on the Company's level of achievement of certain financial targets, subject to a four-year, quarterly vesting schedule ("2020 Time-Based Vesting Schedule"). The shares subject to performance goals become eligible to vest once the achievement against the financial targets is known, which will be no later than March 15, 2021. On the quarterly vest date immediately following such determination, the eligible shares, if any, will vest to the extent that the employee has met the 2020 Time-Based Vesting Schedule as of such date. Thereafter, the eligible shares will continue to vest in accordance with the 2020 Time-Based Vesting Schedule, subject to the applicable employee's continued service as of each such vesting date. The Company performed an analysis as of December 31, 2020 to assess the probability of achievement of the PRSU financial targets and, as a result, recorded compensation costs in the year ended December 31, 2020 for the PRSUs that it expected to vest. As the PRSU activity during the year ended December 31, 2020 was not material, it is presented together with the RSU activity in the table below. A summary of RSU and PRSU activity for the year ended December 31, 2020 is as follows: Number of Shares Weighted- Average Grant Date Fair Value Nonvested at December 31, 2019 7,625,584 $ 36.51 Granted 7,412,006 26.04 Vested (1) (3,370,406) 35.59 Canceled (1,909,397) 34.80 Nonvested at December 31, 2020 9,757,787 $ 29.22 (1) Includes 686,506 shares that vested but were not issued due to net share settlement for payment of employee taxes. The aggregate fair value as of the vest date of RSUs that vested during the years ended December 31, 2020, 2019 and 2018 was $95.0 million, $112.4 million and $131.1 million, respectively. As of December 31, 2020, the Company had approximately $262.9 million of unrecognized stock-based compensation expense related to RSUs, which it expects to recognize over the remaining weighted-average vesting period of approximately 2.8 years. Employee Stock Purchase Plan The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations, during designated offering periods. At the end of each offering period, employees are able to purchase shares at 85% of the fair market value of the Company’s common stock on the last day of the offering period, based on the closing sales price of the Company's common stock as quoted on the New York Stock Exchange on such date. During the years ended December 31, 2020, 2019 and 2018, employees purchased 662,063, 534,120 and 442,679 shares, respectively, at a weighted-average purchase price per share of $21.47, $27.66 and $32.07, respectively. The Company recognized stock-based compensation expense related to the ESPP of $2.5 million, $2.6 million and $2.6 million in the years ended December 31, 2020, 2019 and 2018, respectively. Stock-Based Compensation The following table summarizes the effects of stock-based compensation expense related to stock-based awards in the consolidated statements of operations during the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 Cost of revenue $ 3,784 $ 4,535 $ 4,572 Sales and marketing 29,670 30,668 30,779 Product development 67,622 63,433 56,882 General and administrative 23,498 22,876 22,153 Total stock-based compensation recorded to income before incomes taxes 124,574 121,512 114,386 Benefit from income taxes (31,920) (31,565) (30,237) Total stock-based compensation recorded to net income $ 92,654 $ 89,947 $ 84,149 During the years ended December 31, 2020, 2019 and 2018, the Company capitalized $9.4 million, $9.8 million and $7.8 million, respectively, of stock-based compensation expense as website and internal-use software costs.

OTHER INCOME, NET

OTHER INCOME, NET	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
OTHER INCOME, NET	OTHER INCOME, NET Other income, net for the years ended December 31, 2020, 2019 and 2018 consisted of the following (in thousands): Year Ended December 31, 2020 2019 2018 Interest income, net $ 2,273 $ 13,328 $ 13,804 Transaction gain (loss) on foreign exchange 20 27 (70) Other non-operating income, net 1,377 901 375 Other income, net $ 3,670 $ 14,256 $ 14,109

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The following table presents domestic and foreign components of (loss) income before income taxes for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 United States $ (28,878) $ 55,292 $ 44,856 Foreign (6,247) (5,525) (4,850) Total (loss) income before income taxes $ (35,125) $ 49,767 $ 40,006 The income tax (benefit) provision is composed of the following (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ (4,823) $ 8,598 $ (819) State (434) 2,570 384 Foreign 737 517 560 Total current tax $ (4,520) $ 11,685 $ 125 Deferred: Federal $ (10,456) $ (2,916) $ (10,032) State (731) 59 (6,491) Foreign 6 58 1,054 Total deferred tax (11,181) (2,799) (15,469) Total (benefit from) provision for income taxes $ (15,701) $ 8,886 $ (15,344) The following table presents a reconciliation of the statutory federal rate and the Company’s effective tax rate for the periods presented: Year Ended December 31, 2020 2019 2018 Income tax at federal statutory rate 21.00 % 21.00 % 21.00 % State tax, net of federal tax effect 2.87 2.83 3.24 Foreign income tax rate differential 1.04 (0.56) (0.54) Stock-based compensation (6.42) 3.46 (16.80) Income tax credits 39.52 (26.94) (35.83) Change in valuation allowance (15.64) 10.40 (25.08) Change in uncertain tax positions (0.36) 0.56 4.48 Employee fringe benefits (2.27) 5.97 7.28 Other non-deductible expenses (1.85) 1.42 2.73 Deferred adjustments 1.37 0.37 2.24 Net operating loss carryback - CARES Act 5.64 — — Other (0.20) (0.65) (1.07) Effective tax rate 44.70 % 17.86 % (38.35) % Deferred Tax Balances Deferred income taxes reflect the net tax effects of temporary differences between carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The following table presents the significant components of the Company’s deferred tax assets and liabilities for the periods presented (in thousands): As of December 31, 2020 2019 Deferred tax assets: Reserves and others $ 5,246 $ 6,547 Stock-based compensation 20,388 19,950 Net operating loss carryforward 5,509 4,628 Tax credit carryforward 40,513 23,642 Operating lease liabilities 49,229 60,206 Gross deferred tax assets 120,885 114,973 Valuation allowance (28,941) (23,447) Total deferred tax assets 91,944 91,526 Deferred tax liabilities: Depreciation and amortization (15,551) (16,359) Deferred contract costs (3,735) (3,869) Operating lease right-of-use assets (41,495) (51,244) Total deferred tax liabilities (60,781) (71,472) Net deferred tax assets $ 31,163 $ 20,054 As of December 31, 2020, the Company had federal and state net operating loss carryforwards of approximately $12.9 million and $40.9 million, respectively, expiring beginning in 2035 and 2025, respectively. As of the balance sheet date, the Company's wholly owned subsidiaries, Yelp GmbH (Germany) and Darwin Social Marketing Inc. (Canada), had net operating loss carryforwards of $1.8 million and non-capital loss carryforwards of $0.3 million, respectively. The losses in Germany have an indefinite carryforward period; the losses in Canada will begin to expire in 2037 if unused. The Company had federal research credit carryforwards of approximately $37.9 million (gross) that begin to expire in 2031, if unused, and California research credit carryforwards of approximately $57.6 million (gross) that do not expire. Utilization of net operating loss carryforwards and credits may be subject to a substantial annual limitation due to the ownership change limitations provided by the Internal Revenue Code of 1986, as amended, and similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before utilization. The Company does not expect any previous ownership changes, as defined under Section 382 and 383 of the Internal Revenue Code, to result in a limitation that will materially reduce the total amount of net operating loss carryforwards and credits that can be utilized. Further, foreign loss carryforwards may be subject to limitations under the applicable laws of the taxing jurisdictions due to ownership change limitations. As of December 31, 2020, the Company had accumulated undistributed earnings generated by its foreign subsidiaries of approximately $6.2 million. The Company continues to assert that all its foreign earnings are to be permanently reinvested and expects future U.S. cash generation to be sufficient to meet future U.S. cash needs. As such, the Company has not recognized a deferred tax liability related to unremitted foreign earnings. Impacts of Recent Tax Legislation On March 27, 2020, the CARES Act was signed into law. The CARES Act includes, among other items, provisions relating to refundable payroll tax credits, deferral of the employer portion of certain payroll taxes, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The CARES Act allows losses incurred in 2018, 2019 and 2020 to be carried back to each of the five preceding tax years and to offset 100% of regular taxable income. Additionally, the CARES Act accelerates the Company’s ability to receive refunds of alternative minimum tax credits generated in prior tax years. The Company recognized a benefit in the current year as a result of the ability to carry back its 2020 losses to 2017 as permitted under the CARES Act. Deferred Tax Valuation Allowance As more fully described in “Income Taxes” in Note 2, " Summary of Significant Accounting Policies ," the Company maintains valuation allowances against deferred tax balances where appropriate and considers all positive and negative evidence that the Company would have future taxable income sufficient to realize the benefit of its deferred tax assets. Valuation allowances of $28.9 million and $23.4 million primarily related to California state tax credits were recorded against the Company's net deferred tax asset balances as of December 31, 2020 and 2019, respectively. Since the Company mainly conducts research and development activities in California but earns a substantial portion of its U.S. income in other states, the Company could not assert, at the required more-likely-than-not level of certainty, that it will generate future taxable California income sufficient to realize the benefit of these deferred tax assets. Accordingly, the Company maintained a valuation allowance against specific state credits. Unrecognized Tax Benefits A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): Year Ended December 31, 2020 2019 2018 Balance at the beginning of the year $ 40,718 $ 33,107 $ 18,215 (Decrease) increase based on tax positions related to the prior year (453) (611) 3,654 Increase based on tax positions related to the current year 7,942 9,995 11,485 Decrease from tax authorities' settlements — (1,773) — Lapse of statute of limitations — — (247) Balance at the end of the year $ 48,207 $ 40,718 $ 33,107 As of December 31, 2020, the Company had $27.6 million of unrecognized tax benefits that, if recognized, would affect the effective tax rate. The Company’s policy is to record interest and penalties related to unrecognized tax benefits as income tax expense. During each of the years ended December 31, 2020, 2019 and 2018, the Company recorded an immaterial amount of interest and penalties. In addition, the Company is subject to the continuous examination of its income tax returns by the IRS and other tax authorities. The Company’s federal and state income tax returns for fiscal years subsequent to 2003 remain open to

NET (LOSS) INCOME PER SHARE

NET (LOSS) INCOME PER SHARE	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
NET (LOSS) INCOME PER SHARE	NET (LOSS) INCOME PER SHARE Basic net (loss) income per share is computed using the weighted-average number of outstanding shares of common stock during the period. Diluted net (loss) income per share is computed using the weighted-average number of outstanding shares of common stock and, when dilutive, potential shares of common stock outstanding during the period. Potential common shares consist of the incremental shares of common stock issuable upon the exercise of stock options, shares issuable upon the vesting of RSUs (including PRSUs), and, to a lesser extent, purchase rights related to the ESPP. The following tables present the calculation of basic and diluted net (loss) income per share for the periods presented (in thousands, except per share data): Year Ended December 31, 2020 2019 2018 Basic net (loss) income per share: Net (loss) income $ (19,424) $ 40,881 $ 55,350 Shares used in computation: Weighted-average common shares outstanding 73,005 74,627 83,573 Basic net (loss) income per share attributable to common stockholders: $ (0.27) $ 0.55 $ 0.66 Year Ended December 31, 2020 2019 2018 Diluted net (loss) income per share: Net (loss) income $ (19,424) $ 40,881 $ 55,350 Shares used in computation: Weighted-average common shares outstanding 73,005 74,627 83,573 Stock options — 2,367 2,984 Restricted stock units — 973 2,137 Employee stock purchase program — 2 15 Number of shares used in diluted calculation 73,005 77,969 88,709 Diluted net (loss) income per share attributable to common stockholders $ (0.27) $ 0.52 $ 0.62 The following stock-based instruments were excluded from the calculation of diluted net (loss) income per share because their effect would have been anti-dilutive for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 Stock options 4,623 2,580 2,030 Restricted stock units 9,758 2,020 373 ESPP 62 — —

INFORMATION ABOUT REVENUE AND G

INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS	INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS The Company considers operating segments to be components of the Company for which separate financial information is available and evaluated regularly by the Company’s chief operating decision maker in deciding how to allocate resources and in assessing performance. The chief operating decision maker for the Company is the chief executive officer. The chief executive officer reviews financial information presented on a consolidated basis, accompanied by information about revenue by product line and geographic region for purposes of allocating resources and evaluating financial performance. The Company has determined that it has a single operating and reporting segment. When the Company communicates results externally, it disaggregates net revenue into major product lines and primary geographical markets, which is based on the billing address of the customer. The disaggregation of revenue by major product lines is based on the type of service provided and also aligns with the timing of revenue recognition for each. To reflect the Company's strategic focus on creating differentiated experiences for its Services categories and Restaurants, Retail & Other categories, the Company has further disaggregated advertising revenue for the year ended December 31, 2020, 2019 and 2018 to reflect these two high-level category groupings. The Services categories consist of the following businesses: home, local, auto, professional, pets, events, real estate and financial services. The Restaurants, Retail & Other categories consist of the following businesses: restaurants, shopping, beauty & fitness, health and other. Net Revenue The following table presents the Company’s net revenue by major product line (and by category for advertising revenue) for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 Net revenue by product: Advertising revenue by category: Services $ 515,019 $ 512,729 $ 457,531 Restaurants, Retail & Other 321,096 464,196 449,956 Advertising 836,115 976,925 907,487 Transactions 15,017 12,436 13,694 Other revenue 21,801 24,833 21,592 Total net revenue $ 872,933 $ 1,014,194 $ 942,773 During the years ended December 31, 2020, 2019 and 2018, no individual customer accounted for 10% or more of consolidated net revenue. As a result of the COVID-19 pandemic, the Company considered whether there was any impact to the manner in which revenue is recognized, in particular with respect to the collectability criteria for recognizing revenue from contracts with customers. The Company did not change the manner in which it recognizes revenue as a result of that assessment. During the year ended December 31, 2020, the Company offered a number of relief incentives totaling $22.6 million to advertising and other revenue customers most impacted by the COVID-19 pandemic. These incentives were primarily in the form of waived advertising fees and waived subscription fees. The Company accounted for these incentives as price concessions and reduced net revenue recognized in the year ended December 31, 2020 accordingly. During the year ended December 31, 2020, the Company also paused certain advertising campaigns that were scheduled to run from April to May 2020 and offered certain free advertising products during those months with a total value of $14.5 million. All paused advertising campaigns that were not cancelled by customers resumed by the end of May 2020. The following table presents the Company’s net revenue by major geographic region for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 United States $ 863,300 $ 1,000,245 $ 929,569 All other countries 9,633 13,949 13,204 Total net revenue $ 872,933 $ 1,014,194 $ 942,773 Long-Lived Assets The following table presents the Company’s long-lived assets by major geographic region for the periods presented (in thousands): As of December 31, 2020 2019 United States $ 97,548 $ 109,849 All other countries 4,170 1,100 Total long-lived assets $ 101,718 $ 110,949

RESTRUCTURING

RESTRUCTURING	12 Months Ended
	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
RESTRUCTURING	RESTRUCTURING On April 9, 2020, the Company announced the Restructuring Plan to help manage the near-term financial impacts of the COVID-19 pandemic. In addition to reductions and deferrals in spending, the Restructuring Plan’s cost-cutting measures included workforce reductions affecting approximately 1,000 employees and furloughs affecting approximately 1,100 additional employees, as well as salary reductions and reduced-hour work weeks. On July 13, 2020, the Company announced an additional workforce reduction (separate from the Restructuring Plan) affecting approximately 60 employees. By the end of August 2020, the Company restored reduced salaries and returned many of its furloughed employees. The Company incurred $3.9 million in restructuring costs during the year ended December 31, 2020 in connection with terminations under the Restructuring Plan and additional workforce reduction, which represent expenditures for severance, payroll taxes and related benefits costs. These costs were recorded as restructuring expenses on the Company's consolidated statements of operations. Additional costs related to supporting furloughed employees incurred during the year ended December 31, 2020 were excluded from restructuring expenses and recorded in operating expenses. The Company paid substantially all the costs incurred in connection with the terminations under the Restructuring Plan and additional workforce reduction as of December 31, 2020 and does not expect to incur any material additional costs in connection with these terminations.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation—The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). All intercompany balances and transactions have been eliminated upon consolidation.
Use of Estimates	Use of Estimates —The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of income and expenses during the reporting period. These estimates are based on information available as of the date of the consolidated financial statements; therefore, actual results could differ from management’s estimates. In early March 2020, COVID-19 was declared a global pandemic by the World Health Organization. Governments and around the world, including in the United States, have implemented extensive measures in an effort to control the spread of COVID-19, including travel restrictions, limitations on business activity, quarantines and shelter-in-place orders. Due to the COVID-19 pandemic and the uncertainty of the extent of the impacts, many of the estimates and assumptions required increased judgment and carry a higher degree of variability and volatility than they did prior to the pandemic. As events continue to evolve and additional information becomes available, these estimates may materially change in future periods.
Foreign Currency Translation	Foreign Currency Translation —The consolidated financial statements of the Company’s foreign subsidiaries are measured using the local currency as the functional currency. Assets and liabilities of foreign subsidiaries are translated at exchange rates in effect as of the balance sheet date. Revenues and expenses are translated at average exchange rates in effect during the year. Translation adjustments are recorded within accumulated other comprehensive loss, a separate component of stockholders’ equity.
Cash and Cash Equivalents	Cash and Cash Equivalents —The Company considers all highly liquid investments, such as treasury bills, commercial paper, certificates of deposit and money market instruments with maturities of three months or less at the time of acquisition to be cash equivalents. Cash and cash equivalents primarily consist of amounts held in interest-bearing money market funds that were readily convertible to cash. The fair value of cash and cash equivalents approximates their carrying value.
Marketable Securities	Marketable Securities —The Company considers highly liquid treasury notes, U.S. agency securities, corporate debt securities, money market funds and other funds with maturities of more than three months to be marketable securities. Securities with less than one year to maturity are included in short-term marketable securities, and all other securities are classified as long-term marketable securities. The Company has a policy that generally requires its securities to be investment grade (i.e. rated ‘A+’ or higher by bond rating firms) with the objective of minimizing the potential risk of principal loss. The Company determines the classification of its marketable securities based on its investment strategy. Marketable securities are classified as held-to-maturity when the Company has the positive intent and ability to hold the securities to maturity, and it has an established history of holding investments to maturity. Held-to-maturity securities are stated at amortized cost and are periodically assessed for impairment. Amortized costs of debt securities are adjusted for amortization of premiums and accretion of discounts to maturity, and these adjustments are included in interest income. Marketable securities are classified as available-for-sale when the Company has established a practice of selling investments prior to maturity, or if the Company does not have the intent to hold securities to maturity to allow flexibility in response to liquidity needs. In the event that the Company classifies its investments as available-for-sale, it will only return to classifying investments as held-to-maturity once it has reestablished a practice and intent of holding investments to maturity. Available-for-sale securities are stated at fair value as of each balance sheet date and are periodically assessed for impairment. For the Company's available-for-sale securities, an investment is impaired if the fair value of the investment is less than its amortized cost basis. In assessing whether a credit loss exists, the Company compares the present value of cash flows expected to be collected from the security with the amortized cost basis of the security. If the present value of expected cash flows is less than the amortized cost basis of the security, an allowance for credit loss is recorded as a component of other income (expense), net. Any remaining unrealized losses are recorded to other comprehensive income (loss). The Company determines any realized gains or losses on the sale of marketable securities on a specific identification method and records such gains and losses as a component of other income (expense), net. Amortization of premiums and accretion of discounts are included in interest income. If the Company has the intent to sell an available-for-sale security in an unrealized loss position or it is more likely than not that it will be required to sell the security prior to recovery of its amortized cost basis, any previously recorded allowance is reversed and the entire difference between the amortized cost basis of the security and its fair value is recognized in the condensed consolidated statements of operations.
Concentrations of Credit Risk	Concentrations of Credit Risk —Financial instruments that potentially subject the Company to concentration of credit risk consist primarily of cash and cash equivalents and accounts receivable. The Company places its cash and cash equivalents with major financial institutions, which management assesses to be of high credit quality, in order to limit the exposure of each investment.
Accounts Receivable, Net and Payment Terms	Accounts Receivable, Net, and Payment Terms—The timing of revenue recognition may differ from the timing of invoicing to customers. The Company records an accounts receivable balance when revenue is recognized prior to or at the time of invoicing the customer. Payment terms and conditions vary by contract type and the service being provided. For advertising services, the Company typically invoices customers on a monthly basis, one month in arrears, with payment due either at the end of each billing period or up to 30 days after the end of the billing period. For transaction services, the Company collects its commission fee on each transaction either at the time of the transaction or up to 30 days after the end of the billing period. For subscription services, the Company typically invoices customers one month in advance, with payment due at the beginning of each billing period.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts —The Company maintains an allowance for doubtful accounts receivable. The allowance reflects the Company's best estimate of probable losses associated with the accounts receivable balance. It is based upon historical experience and loss patterns, the number of days that billings are past due, an evaluation of the potential risk of loss associated with delinquent accounts based on the credit risk of those accounts, known delinquent accounts, as well as
Deferred Contract Costs and Cost of Revenue	Deferred Contract Costs —The Company has determined that certain sales incentive compensation costs are incremental costs to obtain the related contract. These costs are capitalized in the period in which they are incurred and amortized on a straight-line basis over the expected customer life of the associated contract. The Company uses a straight-line basis as it expects the benefit of these costs to be realized uniformly over the amortization period. The amortization periods for contract costs, which extend up to 32 months, were determined based on both qualitative and quantitative factors, including product life cycle attributes and customer retention historical data. For contract costs with amortization periods of less than 12 months, the Company applies a practical expedient to expense such costs as incurred. The Company assesses deferred contract costs for impairment on a quarterly basis. Amortized contract costs are recorded within sales and marketing expense in the consolidated statements of operations. Deferred contract costs are included within other non-current assets on the Company's consolidated balance sheets (see Note 10, " Other Non-Current Assets " ). Cost of Revenue —The Company’s cost of revenue primarily consists of credit card processing fees, website infrastructure expense, which includes website hosting costs, and salaries, benefits and stock-based compensation expense for the infrastructure teams responsible for operating the Company’s website and mobile app, and excludes depreciation and amortization expense. Cost of revenue also includes third-party advertising fulfillment costs.
Deferred Revenue and Revenue Recognition	Deferred Revenue —The Company records deferred revenue when it has received consideration, or has the right to receive consideration, in advance of the transfer of the performance obligations of the contract to the customer. Revenue Recognition —The Company generates revenue from the sale of advertising products, transactions with consumers and other revenue sources, which correspond to the Company's major product lines. The Company recognizes revenue by applying the following steps: the contract with the customer is identified; the performance obligations in the contract are identified; the transaction price is determined; the transaction price is allocated to the performance obligations in the contract; and revenue is recognized when (or as) the Company satisfies these performance obligations in an amount that reflects the consideration it expects to be entitled to in exchange for those services. The Company applies the portfolio practical expedient to account for the vast majority of contracts with customers in each category of revenue. The Company does not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) contracts for which the amount of revenue it recognizes is equal to the amount which the Company has a right to invoice. Contracts with customers can include multiple performance obligations, where the transaction price is allocated to each performance obligation based on its relative standalone selling price ("SSP"). The Company determines SSP based on the prices of the promised goods or services charged when sold separately to customers, which are determined using contractually stated prices. The Company allocates revenue to each of the performance obligations included in a contract with multiple performance obligations at the inception of the contract. The various products and services comprising contracts with multiple performance obligations are typically capable of being distinguished and accounted for as separate performance obligations. For all contracts with customers, estimates and assumptions include determining variable consideration and identifying the nature and timing of satisfaction of performance obligations. The Company may accept lower consideration than the amount promised per the contract for certain revenue transactions and certain customers may receive cash based incentives, credits, or refunds, which are accounted for as variable consideration when estimating the amount of revenue to recognize. The Company estimates these amounts based on the expected amount to be provided to customers and reduce revenue. The Company believes that there will not be significant changes to our estimates of variable consideration. For contracts satisfied over time, the Company applies the invoice practical expedient to depict the value transferred to the customer and measure of progress towards completion of its obligations. The Company considers the right to receive consideration from a customer to correspond directly with the value to the customer of its performance completed to date. The Company does not consider the effects of the time value of money as substantially all of the Company’s contracts are invoiced on a monthly basis, one month in arrears. Revenue is recognized net of any taxes collected from customers, which are remitted to governmental authorities. The Company does not typically refund customers for services once it determines the performance obligations of the contract have been satisfied, but will assess any refund requests from customers and partners on a case by case basis. The Company records an allowance for potential future refunds, which is estimated based on historical trends and recorded as a reduction of net revenue. Advertising . The Company generates advertising revenue primarily through the display of advertising products on its website and mobile app. These arrangements are evidenced by either written or electronic acceptance of a contract that stipulates the types of advertising to be delivered, the timing and pricing. Performance-based advertising placements are priced on a cost-per-click basis, while impression-based advertising placements are priced on a cost per thousand impressions basis. The Company recognizes revenue from the delivery of performance-based ads and impression-based ads in the period of delivery, in each case net of customer discounts. The Company also offers businesses premium features in connection with their business listing pages pursuant to fixed monthly fees, and recognizes revenue from such offerings over the service period. The Company also generates advertising revenue through indirect sales of advertising products, such as through reseller contracts that allow partners to sell Yelp Branded Profiles to their clients and the monetization of remnant advertising inventory through third-party ad networks, and recognizes revenue in the period of delivery. Transactions . The Company generates transactions revenue primarily from revenue-sharing partner contracts. The Company's transactions platform provides consumers with the ability to complete food delivery and other transactions through third parties, primarily Grubhub, directly on Yelp. The Company earns a per-transaction commission fee pursuant to partnership contracts for acting as an agent for these transactions, which it recognizes on a net basis and includes in revenue upon completion of a transaction. Other Revenue . The Company generates other revenue through subscription services contracts, such as sales of monthly subscriptions to Yelp Reservations and Yelp Waitlist, licensing contracts for access to Yelp data, and other non-advertising, non-transaction partnerships. Subscription revenues are recognized ratably over the contract terms beginning on the commencement date of each contract, which is the date the service is made available to customers.
Property, Equipment and Software	Property, Equipment and Software —Property, equipment and software are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which are approximately three
Website and Internal-Use Software Development Costs	Website and Internal-Use Software Development Costs —Costs related to website and internal-use software are primarily related to the Company’s website and mobile app, including support systems. The Company capitalizes its costs to develop software when: preliminary development efforts are successfully completed; management has authorized and committed project funding; and it is probable that the project will be completed and the software will be used as intended. Costs incurred for enhancements that are expected to result in additional material functionality are capitalized and amortized over the estimated useful life of the upgrades. Such costs are amortized on a straight-line basis over the estimated useful life of the related asset, which is generally three years. The Company capitalizes certain implementation costs incurred related to cloud computing arrangements that are service contracts. Such costs are amortized on a straight-line basis over the term of the associated hosting arrangement plus any reasonably certain renewal period. Any capitalized amounts related to such arrangements are recorded within prepaid expense and other current assets and within non-current assets on the consolidated balance sheets.
Leases	Leases —The Company leases its office facilities under operating lease agreements that expire from 2021 to 2031, some of which include options to renew at the Company's sole discretion. If exercised, such options would extend the lease terms by up to ten years. Additionally, certain lease agreements contain options to terminate the leases, which require 6 to 12 months prior written notice to the landlord. The Company does not have any finance lease agreements. The Company recognizes on its consolidated balance sheets operating lease liabilities representing the present value of future lease payments, and an associated operating lease right-of-use asset for any operating lease with a term greater than one year. The Company recognizes the amortization of the right-of-use asset each month within lease expense. The Company elected to use the practical expedient for short-term leases, and therefore does not record operating lease right-of-use assets or lease liabilities associated with leases with durations of 12 months or less. When recording the present value of lease liabilities, a discount rate is required. The Company has concluded that the rates implicit in the various operating lease agreements are not readily determinable. As a result, the Company instead uses its incremental borrowing rate, which is calculated based on hypothetical borrowings to fund each respective lease over the lease term, as of the lease commencement date, assuming that borrowings are secured by the various leased properties. The incremental borrowing rates are determined based on an assessment of the Company’s implied credit rating, using ratings scales from reputable rating agencies that consider a number of qualitative and quantitative factors. Market rates are derived as of the lease commencement dates with reference to companies with the same debt rating that operate in a similar industry to the Company. The Company does not recognize its renewal options as part of its right-of-use assets and lease liabilities until it is reasonably certain that it will exercise such renewal options.
Business Combinations	Business Combinations —The Company accounts for acquisitions of entities that consist of inputs and processes that have the ability to contribute to the creation of outputs as business combinations. The Company allocates the purchase price of the acquisition to the tangible assets, liabilities and identifiable intangible assets acquired based on their estimated fair values. The excess of the purchase price over those fair values is recorded as goodwill. Acquisition-related expenses and integration costs are expensed as incurred. During the measurement period, the Company records adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. After the measurement period, which could be up to one year after the transaction date, subsequent adjustments are recorded to the Company’s consolidated statements of operations.
Goodwill	Goodwill—Goodwill represents the excess of the purchase price in a business combination over the fair value of net tangible and intangible assets acquired. The carrying amount of goodwill is reviewed at least annually, or more frequently if events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. The Company has the option to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the Company determines that it is more likely than not that its fair value is less than the carrying amount, or opts not to perform a qualitative assessment, then the Company will compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value.
Intangible Assets	Intangible Assets—Intangible assets include acquired intangible assets identified through business combinations, which are carried at fair value less accumulated amortization, and purchased intangible assets, which are carried at cost less accumulated amortization. Amortization is recorded over the estimated useful lives of the assets, generally two years to 12 years. The Company reviews amortizable intangible assets to be held and used for impairment whenever events or changes in circumstances indicate that the carrying value of the assets may not be recoverable. Determination of recoverability is based on the lowest level of identifiable estimated undiscounted cash flows resulting from the use of the asset and its eventual disposition. Measurement of any impairment loss is based on the excess of the carrying value of the asset over its fair value.
Impairment of Long-Lived Assets and Long-Lived Assets to be Disposed of	Impairment of Long-Lived Assets and Long-Lived Assets to Be Disposed of —The Company evaluates its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or fair value less costs to sell.
Stock Repurchases	Stock Repurchases —The Company accounts for repurchases of its common stock by recording the cost to repurchase those shares to treasury stock, a separate component of stockholders' equity. Upon retirement, the carrying amount of treasury stock is reduced with a corresponding reduction to par value of common stock, with any excess of the cost incurred to repurchase shares over their par value recorded as an adjustment to retained earnings (accumulated deficit) on the date of retirement.
Assets and Liabilities Held For Sale	Assets and Liabilities Held for Sale —The Company considers an asset to be held for sale when: management approves and commits to a formal plan to actively market the asset for sale at a reasonable price in relation to its fair value; the asset is available for immediate sale in its present condition; an active program to locate a buyer and other actions required to complete the sale have been initiated; the sale of the asset is expected to be completed within one year; and it is unlikely that significant changes will be made to the plan. Upon designation as held for sale, the Company records the carrying value of the assets at the lower of its carrying value or its estimated fair value, less costs to sell. The Company ceases to record depreciation and amortization expense associated with assets upon their designation as held for sale.
Research and Development	Research and Development—The Company incurs research and development expenses for costs it incurs in research aimed at developing, and in translating the results of such research into new products and services or significant improvements to existing products or services, whether intended for sale or for internal use. Such costs are considered research and development expense up to the point in time at which the product or service achieves technological feasibility. These expenses primarily consist of employee-related costs (including stock-based compensation) for the Company's engineers and other employees engaged in the research and development of its products and services, as well as allocated indirect overhead costs.
Stock-Based Compensation	Stock-Based Compensation —The Company accounts for stock-based employee compensation plans under the fair value recognition and measurement provisions, which require all stock-based payments to employees, including grants of stock options, restricted stock awards, restricted stock units ("RSUs"), performance-based restricted stock units ("PRSUs") and issuances under its 2012 Employee Stock Purchase Plan, as amended ("ESPP"), to be measured based on the grant-date fair value of the awards. The Company accounts for forfeitures as they occur. The fair value of options granted to employees is estimated on the grant date using the Black-Scholes-Merton option valuation model. This valuation model for stock-based compensation expense requires the Company to make assumptions and judgments about the variables used in the calculation, including the expected term (weighted-average period of time that the options granted are expected to be outstanding), the expected volatility in the fair market value of the Company’s common stock, a risk-free interest rate and expected dividends. No compensation cost is recorded for options that do not vest. The Company uses the simplified calculation of expected life as the contractual term for options of 10 years is longer than the Company has been publicly traded. Expected volatility is based on an average of the historical volatilities of the common stock of several entities with characteristics similar to those of the Company. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. The Company uses the straight-line method for expense attribution. The fair value of RSUs is measured using the closing price of the Company's common stock on the New York Stock Exchange on the grant date. The Company uses the straight-line method for expense attribution. No compensation cost is recorded for RSUs that do not vest. In May 2020, the Company changed its method of settling the employee tax liabilities associated with the vesting of RSUs from withholding a portion of the vested shares and covering such taxes with cash from its balance sheet ("Net Share Withholding"), to selling a portion of the vested shares to cover taxes. In November 2020, the Company reverted its method of settling these employee tax liabilities to Net Share Withholding. The Company has two types of PRSUs outstanding — awards for which the vesting is subject to both a time-based vesting schedule and either (a) a market condition or (b) the achievement of performance goals. For the awards subject to a market condition, the Company uses a Monte Carlo model to determine the fair value of the PRSUs. The Company uses the accelerated method for expense attribution. Compensation costs are recorded if the service condition is met regardless of whether the market performance condition is satisfied. No compensation cost is recorded if the service condition is not met. For the awards subject to performance goals, compensation costs are recorded when the Company concludes that it is probable that the performance conditions will be achieved. The Company performs an analysis in each reporting period to determine the probability that the performance goals will be met, and recognizes a cumulative catch-up adjustment to compensation cost for changes in its probability assessment in subsequent reporting periods, if required, until the performance period has expired. The fair value of the PRSUs is measured using the closing price of the Company's common stock on the New York Stock Exchange on the grant date. The Company uses the accelerated method for expense attribution. No compensation cost is recorded if the service condition is not met.
Advertising Expenses	Advertising Expenses—Advertising costs are expensed in the period in which the advertising takes place. Costs of producing advertising are expensed in the period in which production takes place.
Comprehensive (Loss) Income	Comprehensive (Loss) Income —Comprehensive (loss) income consists of net (loss) income and other comprehensive income (loss), which consists of foreign currency adjustments.
Income Taxes	Income Taxes —The Company records income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s financial statements or tax returns. In estimating future tax consequences, the Company generally considers all expected future events other than enactments or changes in the tax law or rates. In assessing the realization of deferred tax assets, the Company considers whether it is more likely than not that all or some portion of deferred tax assets will not be realized. The ultimate realization of the deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Valuation allowances are provided to reduce deferred tax assets to the amount that is more likely than not to be realized. In determining the need for a valuation allowance, the weight given to positive and negative evidence is commensurate with the extent to which the evidence may be objectively verified. The Company evaluates the ability to realize net deferred tax assets and the related valuation allowance on a quarterly basis. The Company operates in various tax jurisdictions and is subject to audit by various tax authorities. The Company provides for tax contingencies whenever it is deemed probable that a tax asset has been impaired or a tax liability has been incurred for events such as tax claims or changes in tax laws. Tax contingencies are based upon their technical merits, relative tax law and the specific facts and circumstances as of each reporting period. Changes in facts and circumstances could result in material changes to the amounts recorded for such tax contingencies. The Company recognizes a tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are then measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement.
Employee Benefit Plan	Employee Benefit Plan—The Company sponsors a qualified 401(k) defined contribution plan covering eligible employees. Participants may contribute a portion of their annual compensation up to a maximum annual amount set by the Internal Revenue Service (“IRS”).
Insurance	Insurance —The Company is self-insured for certain employee benefits including medical, dental and vision; however, the Company obtains third-party excess insurance coverage to limit its exposure to certain claims. Liabilities associated with these benefits include estimates of both claims filed and losses incurred but not yet reported. The Company utilizes valuations provided by reputable, independent third-party actuaries. The Company's self-insured liabilities are included in the consolidated balance sheets within accounts payable and accrued liabilities.
Recently Adopted Accounting Pronouncements and Recent Accounting Pronouncements Not Yet Effective	Recently Adopted Accounting Pronouncements Credit Loss Accounting —In June 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2016-13, "Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" ("ASU 2016-13"). ASU 2016-13 requires certain types of financial instruments, including trade receivables and held-to-maturity investments measured at amortized cost, to be presented as the net amount expected to be collected based on historical events, current conditions and forecast information. The Company adopted and began applying ASU 2016-13 on January 1, 2020 by recording a cumulative-effect adjustment to retained earnings. This adjustment recorded an allowance related to expected credit losses on the Company's held-to-maturity debt securities, which was subsequently reversed upon its change in investment strategy in March 2020. This allowance took into consideration the composition and credit quality of the financial instruments, their respective historical credit loss activity, and reasonable and supportable economic forecasts and conditions at the time of adoption. The adoption did not have a material impact on the Company's consolidated financial statements. Goodwill Impairment Accounting —In January 2017, the FASB issued Accounting Standards Update No. 2017-04, "Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment" ("ASU 2017-04"). ASU 2017-04 simplified the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. Under the new standard, entities perform goodwill impairment tests by comparing the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. The Company adopted ASU 2017-04 on January 1, 2020 and the adoption did not have a material impact on its consolidated financial statements. Fair Value Disclosure —In August 2018, the FASB issued Accounting Standards Update No. 2018-13, "Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement" ("ASU 2018-13"), which amended Accounting Standards Codification 820, "Fair Value Measurement." ASU 2018-13 modified the disclosure requirements for fair value measurements by removing, modifying and adding certain disclosures. The Company adopted ASU 2018-13 on January 1, 2020 and the adoption did not have a material impact on its consolidated financial statements. Cloud Computing Arrangements Accounting —In August 2018, the FASB issued Accounting Standards Update No. 2018-15, "Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract" ("ASU 2018-15"). ASU 2018-15 requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification 350-40 to determine which implementation costs to defer and which to recognize as assets. ASU 2018-15 generally aligns the guidance on recognizing implementation costs incurred in a cloud computing arrangement that is a service contract with that for implementation costs incurred to develop or obtain internal-use software, including hosting arrangements that include an internal-use software license. The Company adopted ASU 2018-15 prospectively and began applying it on January 1, 2020. The adoption did not have a material impact on the Company's financial statements. Recent Accounting Pronouncements Not Yet Effective In December 2019, the FASB issued Accounting Standards Update No. 2019-12, Income Taxes (Topic 740): “Simplifying the Accounting for Income Taxes” (“ASU 2019-12”), which simplifies the accounting for income taxes by removing certain exceptions to the general principles for recording income taxes, while also simplifying certain recognition and allocation approaches to accounting for income taxes. ASU 2019-12 will be effective for the first interim period within annual periods beginning after December 15, 2020 on a prospective basis or modified retrospective basis for certain provisions, and early adoption is permitted. The Company is currently evaluating the impact of ASU 2019-12 on its consolidated financial statements and related disclosures.

CASH, CASH EQUIVALENTS AND RE_2

CASH, CASH EQUIVALENTS AND RESTRICTED CASH (Tables)	12 Months Ended
	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Schedule of Cash and Cash Equivalents	Cash, cash equivalents and restricted cash as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, December 31, Cash $ 85,750 $ 43,581 Cash equivalents 510,125 126,700 Total cash and cash equivalents $ 595,875 $ 170,281 Restricted cash 665 22,037 Total cash, cash equivalents and restricted cash $ 596,540 $ 192,318
Restrictions on Cash and Cash Equivalents	Cash, cash equivalents and restricted cash as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, December 31, Cash $ 85,750 $ 43,581 Cash equivalents 510,125 126,700 Total cash and cash equivalents $ 595,875 $ 170,281 Restricted cash 665 22,037 Total cash, cash equivalents and restricted cash $ 596,540 $ 192,318

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value	The following table represents the fair value of the Company’s financial instruments, including those measured at fair value on a recurring basis, as of December 31, 2020 and 2019 as well as those held-to-maturity as of December 31, 2019 (in thousands): December 31, 2020 December 31, 2019 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash Equivalents: Money market funds $ 510,125 $ — $ — $ 510,125 $ 126,700 $ — $ — $ 126,700 Marketable Securities: Commercial paper — — — — — 130,472 — 130,472 Corporate bonds — — — — — 85,611 — 85,611 Agency bonds — — — — — 79,750 — 79,750 Other Investments: Certificates of deposit — 10,933 — 10,933 — — — — Total cash equivalents, marketable securities and other investments $ 510,125 $ 10,933 $ — $ 521,058 $ 126,700 $ 295,833 $ — $ 422,533

MARKETABLE SECURITIES (Tables)

MARKETABLE SECURITIES (Tables)	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Schedule of the Fair Value to Amortized Cost Basis of Securities Held-to-Maturity	The amortized cost, gross unrealized gains and losses, and fair value of securities held-to-maturity as of December 31, 2019 were as follows (in thousands): December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term marketable securities: Commercial paper $ 130,464 $ 17 $ (9) $ 130,472 Corporate bonds 85,396 225 (10) 85,611 Agency bonds 26,140 90 — 26,230 Total short-term marketable securities 242,000 332 (19) 242,313 Long-term marketable securities: Agency bonds 53,499 21 — 53,520 Total long-term marketable securities 53,499 21 — 53,520 Total marketable securities $ 295,499 $ 353 $ (19) $ 295,833
Schedule of Unrealized Loss on Investments	The following tables present gross unrealized losses and fair values for those securities that were in an unrealized loss position as of December 31, 2019, aggregated by investment category and the length of time that the individual securities have been in a continuous loss position (in thousands): December 31, 2019 Less Than 12 Months 12 Months or Greater Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Commercial paper $ 63,639 $ (9) $ — $ — $ 63,639 $ (9) Corporate bonds 20,979 (10) — — 20,979 (10) Total $ 84,618 $ (19) $ — $ — $ 84,618 $ (19)

PREPAID EXPENSES AND OTHER CU_2

PREPAID EXPENSES AND OTHER CURRENT ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets as of December 31, 2020 and December 31, 2019 consisted of the following (in thousands): December 31, December 31, Prepaid expenses $ 10,438 $ 10,188 Certificates of deposit 10,930 — Other current assets 7,082 4,008 Total prepaid expenses and other current assets $ 28,450 $ 14,196

PROPERTY, EQUIPMENT, AND SOFTWA

PROPERTY, EQUIPMENT, AND SOFTWARE, NET (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of Property, Equipment and Software	Property, equipment and software, net as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, December 31, Capitalized website and internal-use software development costs $ 171,831 $ 140,886 Leasehold improvements 88,687 86,089 Computer equipment 46,581 43,626 Furniture and fixtures 18,339 18,403 Telecommunication 4,951 5,154 Software 1,717 1,687 Total 332,106 295,845 Less accumulated depreciation (230,388) (184,896) Property, equipment and software, net $ 101,718 $ 110,949

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in the carrying amounts of goodwill during the years ended December 31, 2020 and 2019, were as follows (in thousands): 2020 2019 Balance, beginning of period $ 104,589 $ 105,620 Effect of currency translation 4,672 (1,031) Balance, end of period $ 109,261 $ 104,589
Schedule of Intangible Assets	Intangible assets as of December 31, 2020 and 2019 consisted of the following (dollars in thousands): December 31, 2020 Gross Accumulated Net Weighted Business relationships $ 9,918 $ (3,814) $ 6,104 7.8 years Developed technology 7,709 (6,238) 1,471 1.2 years Licensing agreements 6,129 (215) 5,914 9.2 years Content 4,078 (4,078) — 0.0 years Domain and data licenses 2,869 (2,837) 32 2.2 years Trademarks 877 (877) — 0.0 years User relationships 146 (146) — 0.0 years Total $ 31,726 $ (18,205) $ 13,521 December 31, 2019 Gross Accumulated Net Weighted Business relationships $ 9,918 $ (2,841) $ 7,077 8.6 years Developed technology 7,832 (4,959) 2,873 2.2 years Content 3,814 (3,814) — 0.0 years Domain and data licenses 2,869 (2,748) 121 1.7 years Trademarks 877 (872) 5 0.2 years User relationships 146 (140) 6 0.2 years Total $ 25,456 $ (15,374) $ 10,082
Schedule of Future Amortization Expense	As of December 31, 2020, the estimated future amortization of intangible assets for (i) each of the succeeding five years and (ii) thereafter was as follows (in thousands): Year Ending December 31, Amount 2021 $ 2,848 2022 1,676 2023 1,359 2024 1,353 2025 1,353 Thereafter 4,932 Total $ 13,521

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Lease Cost and Supplemental Cash Flow Information	The components of lease cost, net for the years ended December 31, 2020 and 2019 were as follows (in thousands): December 31, 2020 December 31, 2019 Operating lease cost $ 55,214 $ 54,451 Short-term lease cost (12 months or less) 1,288 1,287 Sublease income (7,826) (4,759) Total lease cost, net $ 48,676 $ 50,979 The Company's leases and subleases do not include any variable lease payments, residual value guarantees, related-party leases, or restrictions or covenants that would limit or prevent the Company from exercising its right to obtain substantially all of the economic benefits from use of the respective assets during the lease term. Supplemental cash flow information related to leases for the years ended December 31, 2020 and 2019 was as follows (in thousands): December 31, 2020 December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 58,515 $ 56,672
Lessee, Operating Lease, Liability, Maturity	As of December 31, 2020, maturities of lease liabilities for (i) each of the succeeding five years and (ii) thereafter were as follows (in thousands): Year Ending December 31, Operating 2021 $ 52,465 2022 47,134 2023 44,207 2024 41,519 2025 22,419 Thereafter 24,422 Total minimum lease payments 232,166 Less imputed interest (32,070) Present value of lease liabilities $ 200,096
Assets And Liabilities, Lessee Information	As of December 31, 2020 and 2019, the weighted-average remaining lease term and weighted-average discount rate were as follows: December 31, 2020 December 31, 2019 Weighted-average remaining lease term (years) — operating leases 5.1 5.5 Weighted-average discount rate — operating leases 6.0 % 6.1 %

OTHER NON-CURRENT ASSETS (Table

OTHER NON-CURRENT ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
Other Assets, Noncurrent Disclosure [Abstract]
Schedule of Other Non-current Assets	Other non-current assets as of December 31, 2020 and 2019 consisted of the following (in thousands): 2020 2019 Deferred tax assets $ 31,163 $ 20,054 Deferred contract costs 14,522 15,138 Other non-current assets 3,163 3,177 Total other non-current assets $ 48,848 $ 38,369
Capitalized Contract Cost	Deferred contract costs as of December 31, 2020 and 2019, and changes in deferred contract costs during the years ended December 31, 2020 and 2019, were as follows (in thousands): 2020 2019 Balance, beginning of period $ 15,138 $ 12,345 Add: costs deferred on new contracts 15,328 14,998 Less: amortization recorded in sales and marketing expenses (15,944) (12,205) Balance, end of period $ 14,522 $ 15,138

CONTRACT BALANCES (Tables)

CONTRACT BALANCES (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Schedule of Allowance for Doubtful Accounts Receivable	The changes in the allowance for doubtful accounts during the years ended December 31, 2020, 2019 and 2018, were as follows (in thousands): Year Ended December 31, 2020 2019 2018 Balance, beginning of period $ 7,686 $ 8,685 $ 8,602 Add: provision for doubtful accounts 32,265 22,543 24,515 Less: write-offs, net of recoveries (28,392) (23,542) (24,432) Balance, end of period $ 11,559 $ 7,686 $ 8,685
Contract with Customer, Liability	Changes in deferred revenue during the years ended December 31, 2020 and 2019 were as follows (in thousands): Year Ended December 31, 2020 2019 Balance, beginning of period $ 4,315 $ 3,843 Less: recognition of deferred revenue from beginning balance (3,869) (3,744) Add: net increase in current period contract liabilities 3,663 4,216 Balance, end of period $ 4,109 $ 4,315

ACCOUNTS PAYABLE AND ACCRUED _2

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, December 31, Accounts payable $ 8,853 $ 6,002 Employee-related liabilities 57,684 41,488 Accrued sales and marketing expenses 2,137 2,982 Taxes payable 975 3,695 Accrued cost of revenue 8,269 7,208 Other accrued liabilities 9,842 10,958 Total accounts payable and accrued liabilities $ 87,760 $ 72,333

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
Schedule of Stock by Class	The following table presents the number of shares authorized and issued and outstanding as of the dates indicated: December 31, 2020 December 31, 2019 Shares Shares Shares Shares Stockholders’ equity: Common stock, $0.000001 par value 200,000,000 75,371,368 200,000,000 71,185,468 Undesignated preferred stock 10,000,000 — 10,000,000 —
Schedule of Common Stock Reserved for Future Issuance	As of December 31, 2020, the Company had reserved shares of common stock for future issuances in connection with the following: Number of Shares Stock options outstanding 4,622,828 RSUs outstanding 9,757,787 Available for future equity award grants 5,333,200 Available for future ESPP offerings 880,067 Total reserved for future issuance 20,593,882
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	For the years ended December 31, 2020, 2019 and 2018, the weighted-average assumptions used for the Black-Scholes-Merton option valuation model were as follows: Year Ended December 31, 2020 2019 2018 Dividend yield — — — Annual risk-free rate 0.5 % 2.5 % 2.2 % Expected volatility 45.9 % 48.3 % 42.0 % Expected term (years) 5.7 6.0 6.0
Schedule of Stock Option Activity	A summary of stock option activity for the year ended December 31, 2020 is as follows: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2019 6,210,385 $ 25.10 4.3 $ 75,805 Granted 158,050 31.21 Exercised (1,544,610) 8.53 Canceled (200,997) 47.24 Outstanding at December 31, 2020 4,622,828 $ 29.89 4.7 $ 30,451 Options vested and exercisable at December 31, 2020 4,022,236 $ 28.90 4.2 $ 30,071
Summary of RSU Activity	A summary of RSU and PRSU activity for the year ended December 31, 2020 is as follows: Number of Shares Weighted- Average Grant Date Fair Value Nonvested at December 31, 2019 7,625,584 $ 36.51 Granted 7,412,006 26.04 Vested (1) (3,370,406) 35.59 Canceled (1,909,397) 34.80 Nonvested at December 31, 2020 9,757,787 $ 29.22
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs	The following table summarizes the effects of stock-based compensation expense related to stock-based awards in the consolidated statements of operations during the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 Cost of revenue $ 3,784 $ 4,535 $ 4,572 Sales and marketing 29,670 30,668 30,779 Product development 67,622 63,433 56,882 General and administrative 23,498 22,876 22,153 Total stock-based compensation recorded to income before incomes taxes 124,574 121,512 114,386 Benefit from income taxes (31,920) (31,565) (30,237) Total stock-based compensation recorded to net income $ 92,654 $ 89,947 $ 84,149

OTHER INCOME, NET (Tables)

OTHER INCOME, NET (Tables)	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Schedule of Other Income (Expense)	Other income, net for the years ended December 31, 2020, 2019 and 2018 consisted of the following (in thousands): Year Ended December 31, 2020 2019 2018 Interest income, net $ 2,273 $ 13,328 $ 13,804 Transaction gain (loss) on foreign exchange 20 27 (70) Other non-operating income, net 1,377 901 375 Other income, net $ 3,670 $ 14,256 $ 14,109

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Income (Loss) before Income Taxes	The following table presents domestic and foreign components of (loss) income before income taxes for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 United States $ (28,878) $ 55,292 $ 44,856 Foreign (6,247) (5,525) (4,850) Total (loss) income before income taxes $ (35,125) $ 49,767 $ 40,006
Tax Provision	The income tax (benefit) provision is composed of the following (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ (4,823) $ 8,598 $ (819) State (434) 2,570 384 Foreign 737 517 560 Total current tax $ (4,520) $ 11,685 $ 125 Deferred: Federal $ (10,456) $ (2,916) $ (10,032) State (731) 59 (6,491) Foreign 6 58 1,054 Total deferred tax (11,181) (2,799) (15,469) Total (benefit from) provision for income taxes $ (15,701) $ 8,886 $ (15,344)
Reconciliation of Effective Income Tax Rate	The following table presents a reconciliation of the statutory federal rate and the Company’s effective tax rate for the periods presented: Year Ended December 31, 2020 2019 2018 Income tax at federal statutory rate 21.00 % 21.00 % 21.00 % State tax, net of federal tax effect 2.87 2.83 3.24 Foreign income tax rate differential 1.04 (0.56) (0.54) Stock-based compensation (6.42) 3.46 (16.80) Income tax credits 39.52 (26.94) (35.83) Change in valuation allowance (15.64) 10.40 (25.08) Change in uncertain tax positions (0.36) 0.56 4.48 Employee fringe benefits (2.27) 5.97 7.28 Other non-deductible expenses (1.85) 1.42 2.73 Deferred adjustments 1.37 0.37 2.24 Net operating loss carryback - CARES Act 5.64 — — Other (0.20) (0.65) (1.07) Effective tax rate 44.70 % 17.86 % (38.35) %
Schedule of Deferred Tax Assets and Liabilities	The following table presents the significant components of the Company’s deferred tax assets and liabilities for the periods presented (in thousands): As of December 31, 2020 2019 Deferred tax assets: Reserves and others $ 5,246 $ 6,547 Stock-based compensation 20,388 19,950 Net operating loss carryforward 5,509 4,628 Tax credit carryforward 40,513 23,642 Operating lease liabilities 49,229 60,206 Gross deferred tax assets 120,885 114,973 Valuation allowance (28,941) (23,447) Total deferred tax assets 91,944 91,526 Deferred tax liabilities: Depreciation and amortization (15,551) (16,359) Deferred contract costs (3,735) (3,869) Operating lease right-of-use assets (41,495) (51,244) Total deferred tax liabilities (60,781) (71,472) Net deferred tax assets $ 31,163 $ 20,054
Schedule of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): Year Ended December 31, 2020 2019 2018 Balance at the beginning of the year $ 40,718 $ 33,107 $ 18,215 (Decrease) increase based on tax positions related to the prior year (453) (611) 3,654 Increase based on tax positions related to the current year 7,942 9,995 11,485 Decrease from tax authorities' settlements — (1,773) — Lapse of statute of limitations — — (247) Balance at the end of the year $ 48,207 $ 40,718 $ 33,107

NET (LOSS) INCOME PER SHARE (Ta

NET (LOSS) INCOME PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share	The following tables present the calculation of basic and diluted net (loss) income per share for the periods presented (in thousands, except per share data): Year Ended December 31, 2020 2019 2018 Basic net (loss) income per share: Net (loss) income $ (19,424) $ 40,881 $ 55,350 Shares used in computation: Weighted-average common shares outstanding 73,005 74,627 83,573 Basic net (loss) income per share attributable to common stockholders: $ (0.27) $ 0.55 $ 0.66 Year Ended December 31, 2020 2019 2018 Diluted net (loss) income per share: Net (loss) income $ (19,424) $ 40,881 $ 55,350 Shares used in computation: Weighted-average common shares outstanding 73,005 74,627 83,573 Stock options — 2,367 2,984 Restricted stock units — 973 2,137 Employee stock purchase program — 2 15 Number of shares used in diluted calculation 73,005 77,969 88,709 Diluted net (loss) income per share attributable to common stockholders $ (0.27) $ 0.52 $ 0.62
Schedule of Anti-dilutive Securities	The following stock-based instruments were excluded from the calculation of diluted net (loss) income per share because their effect would have been anti-dilutive for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 Stock options 4,623 2,580 2,030 Restricted stock units 9,758 2,020 373 ESPP 62 — —

INFORMATION ABOUT REVENUE AND_2

INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of Revenue by Product Line	The following table presents the Company’s net revenue by major product line (and by category for advertising revenue) for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 Net revenue by product: Advertising revenue by category: Services $ 515,019 $ 512,729 $ 457,531 Restaurants, Retail & Other 321,096 464,196 449,956 Advertising 836,115 976,925 907,487 Transactions 15,017 12,436 13,694 Other revenue 21,801 24,833 21,592 Total net revenue $ 872,933 $ 1,014,194 $ 942,773
Schedule of Net Revenue by Geographic Region	The following table presents the Company’s net revenue by major geographic region for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 United States $ 863,300 $ 1,000,245 $ 929,569 All other countries 9,633 13,949 13,204 Total net revenue $ 872,933 $ 1,014,194 $ 942,773
Schedule of Long-Lived Assets by Geographic Region	The following table presents the Company’s long-lived assets by major geographic region for the periods presented (in thousands): As of December 31, 2020 2019 United States $ 97,548 $ 109,849 All other countries 4,170 1,100 Total long-lived assets $ 101,718 $ 110,949

ORGANIZATION AND DESCRIPTION _2

ORGANIZATION AND DESCRIPTION OF BUSINESS (Details)	Dec. 31, 2020entity
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of wholly-owned entities	5

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Accounts Receivable, Net and Payment Terms) (Details)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Line Items]
Contracts invoiced in arrears, duration	1 month
Advertising
Accounting Policies [Line Items]
Contracts invoiced in arrears, duration	1 month
Payment collection after billing period, duration	30 days
Transactions
Accounting Policies [Line Items]
Payment collection after billing period, duration	30 days

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Deferred Contract Costs) (Details)	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Accounting Policies [Line Items]
Capitalized contract cost, amortization period	12 months	32 months	26 months	32 months
Maximum
Accounting Policies [Line Items]
Capitalized contract cost, amortization period	32 months

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Property, Equipment and Software) (Details)	12 Months Ended
	Dec. 31, 2020
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Capitalized website and internal-use software development costs
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Leases) (Details)	12 Months Ended
	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Renewal term	10 years
Minimum
Lessee, Lease, Description [Line Items]
Cancellation notice provision	6 months
Maximum
Lessee, Lease, Description [Line Items]
Cancellation notice provision	12 months

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Goodwill and Intangible Assets) (Details)	12 Months Ended
	Dec. 31, 2020USD ($)
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment loss	$ 0
Impairment of intangible assets	$ 0
Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	2 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	12 years

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Revenue Recognition) (Details)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Contracts invoiced in arrears, duration	1 month

SUMMARY OF SIGNIFICANT ACCOUN_9

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Research and Development) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Research and development expense	$ 230.1	$ 225.5	$ 205.8

SUMMARY OF SIGNIFICANT ACCOU_10

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Stock-Based Compensation) (Details)	Dec. 31, 2020award_type
Accounting Policies [Abstract]
Types of performing restricted stock units	2

SUMMARY OF SIGNIFICANT ACCOU_11

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Advertising Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Advertising expense	$ 22.2	$ 20.7	$ 38

SUMMARY OF SIGNIFICANT ACCOU_12

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Employee Benefit Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Employer contributions	$ 6.1	$ 9.3	$ 11.9

CASH, CASH EQUIVALENTS AND RE_3

CASH, CASH EQUIVALENTS AND RESTRICTED CASH (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Cash	$ 85,750	$ 43,581
Cash equivalents	510,125	126,700
Total cash and cash equivalents	595,875	170,281
Restricted cash	665	22,037
Total cash, cash equivalents and restricted cash	$ 596,540	$ 192,318	$ 354,835	$ 566,404

CASH, CASH EQUIVALENTS AND RE_4

CASH, CASH EQUIVALENTS AND RESTRICTED CASH (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	May 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Proceeds from sale of debt securities, available-for-sale	$ 253,400
Restricted cash		$ 665		$ 22,037
Marketable securities proceeds reinvested	$ 73,000
Letters of credit outstanding			$ 21,500

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS (Summary) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable Securities		$ 295,833
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents, marketable securities and other investments	$ 521,058	422,533
Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		130,472
Recurring | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		85,611
Recurring | Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		79,750
Recurring | Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	10,933	0
Recurring | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	510,125	126,700
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents, marketable securities and other investments	510,125	126,700
Recurring | Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		0
Recurring | Level 1 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		0
Recurring | Level 1 | Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		0
Recurring | Level 1 | Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0	0
Recurring | Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	510,125	126,700
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents, marketable securities and other investments	10,933	295,833
Recurring | Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		130,472
Recurring | Level 2 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		85,611
Recurring | Level 2 | Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		79,750
Recurring | Level 2 | Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	10,933	0
Recurring | Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	0	0
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents, marketable securities and other investments	0	0
Recurring | Level 3 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		0
Recurring | Level 3 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		0
Recurring | Level 3 | Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Marketable Securities		0
Recurring | Level 3 | Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0	0
Recurring | Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	$ 0	$ 0

FAIR VALUE OF FINANCIAL INVESTM

FAIR VALUE OF FINANCIAL INVESTMENTS (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expenses and Other Current Assets [Line Items]
Certificates of deposit	$ 10,930	$ 0
CD Invested With Minority Owned Financial Institutions
Prepaid Expenses and Other Current Assets [Line Items]
Certificates of deposit	$ 10,000

MARKETABLE SECURITIES (Narrativ

MARKETABLE SECURITIES (Narrative) (Details) - USD ($)	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Debt securities, available-for-sale, amortized cost			$ 300,200,000
Proceeds from sale of debt securities, available-for-sale	$ 253,400,000
Proceeds from maturities reinvested	$ 73,000,000
Unrealized loss position		$ 0		$ 84,618,000

MARKETABLE SECURITIES (Schedule

MARKETABLE SECURITIES (Schedule of the Fair Value to Amortized Cost Basis of Securities Held-to-Maturity) (Details) $ in Thousands	Dec. 31, 2019USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost, short term marketable securities	$ 242,000
Gross Unrealized Gains	332
Gross Unrealized Losses	(19)
Fair Value	242,313
Amortized Cost, long-term marketable securities	53,499
Gross Unrealized Gains	21
Gross Unrealized Losses	0
Fair Value	53,520
Amortized Cost	295,499
Gross Unrealized Gains	353
Gross Unrealized Losses	(19)
Fair Value	295,833
Commercial paper
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost, short term marketable securities	130,464
Gross Unrealized Gains	17
Gross Unrealized Losses	(9)
Fair Value	130,472
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost, short term marketable securities	85,396
Gross Unrealized Gains	225
Gross Unrealized Losses	(10)
Fair Value	85,611
Agency bonds
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost, short term marketable securities	26,140
Gross Unrealized Gains	90
Gross Unrealized Losses	0
Fair Value	26,230
Amortized Cost, long-term marketable securities	53,499
Gross Unrealized Gains	21
Gross Unrealized Losses	0
Fair Value	$ 53,520

MARKETABLE SECURITIES (Schedu_2

MARKETABLE SECURITIES (Schedule of Securities in an Unrealized Loss Position) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Fair Value
Less Than 12 Months		$ 84,618,000
12 Months or Greater		0
Total	$ 0	84,618,000
Unrealized Loss
Less Than 12 Months		(19,000)
12 Months or Greater		0
Total		(19,000)
Commercial paper
Fair Value
Less Than 12 Months		63,639,000
12 Months or Greater		0
Total		63,639,000
Unrealized Loss
Less Than 12 Months		(9,000)
12 Months or Greater		0
Total		(9,000)
Corporate bonds
Fair Value
Less Than 12 Months		20,979,000
12 Months or Greater		0
Total		20,979,000
Unrealized Loss
Less Than 12 Months		(10,000)
12 Months or Greater		0
Total		$ (10,000)

PREPAID EXPENSES AND OTHER CU_3

PREPAID EXPENSES AND OTHER CURRENT ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 10,438	$ 10,188
Certificates of deposit	10,930	0
Other current assets	7,082	4,008
Total prepaid expenses and other current assets	$ 28,450	$ 14,196

PREPAID EXPENSES AND OTHER CU_4

PREPAID EXPENSES AND OTHER CURRENT ASSETS (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expenses and Other Current Assets [Line Items]
Certificates of deposit	$ 10,930	$ 0
CD Invested With Minority Owned Financial Institutions
Prepaid Expenses and Other Current Assets [Line Items]
Certificates of deposit	$ 10,000

PROPERTY, EQUIPMENT AND SOFTW_2

PROPERTY, EQUIPMENT AND SOFTWARE, NET (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Capitalized website and internal-use software costs	$ 32.4	$ 33.9	$ 26.9
Amortization expense related to website and internal-use software	27.1	24.2	19
Impairment of assets	1.5	1.6
Depreciation expense	$ 48	$ 46.1	$ 39.3

PROPERTY, EQUIPMENT AND SOFTW_3

PROPERTY, EQUIPMENT AND SOFTWARE, NET - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, equipment and software	$ 332,106	$ 295,845
Less accumulated depreciation	(230,388)	(184,896)
Property, equipment and software, net	101,718	110,949
Capitalized website and internal-use software development costs
Property, Plant and Equipment [Line Items]
Property, equipment and software	171,831	140,886
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, equipment and software	88,687	86,089
Computer equipment
Property, Plant and Equipment [Line Items]
Property, equipment and software	46,581	43,626
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, equipment and software	18,339	18,403
Telecommunication
Property, Plant and Equipment [Line Items]
Property, equipment and software	4,951	5,154
Software
Property, Plant and Equipment [Line Items]
Property, equipment and software	$ 1,717	$ 1,687

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS (Schedule of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Balance, beginning of period	$ 104,589	$ 105,620
Effect of currency translation	4,672	(1,031)
Balance, end of period	$ 109,261	$ 104,589

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 31,726	$ 25,456
Accumulated Amortization	(18,205)	(15,374)
Total	13,521	10,082
Business relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	9,918	9,918
Accumulated Amortization	(3,814)	(2,841)
Total	$ 6,104	$ 7,077
Weighted Average Remaining Life (in years)	7 years 9 months 18 days	8 years 7 months 6 days
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 7,709	$ 7,832
Accumulated Amortization	(6,238)	(4,959)
Total	$ 1,471	$ 2,873
Weighted Average Remaining Life (in years)	1 year 2 months 12 days	2 years 2 months 12 days
Licensing agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 6,129
Accumulated Amortization	(215)
Total	$ 5,914
Weighted Average Remaining Life (in years)	9 years 2 months 12 days
Content
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,078	$ 3,814
Accumulated Amortization	(4,078)	(3,814)
Total	$ 0	$ 0
Weighted Average Remaining Life (in years)	0 years	0 years
Domain and data licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,869	$ 2,869
Accumulated Amortization	(2,837)	(2,748)
Total	$ 32	$ 121
Weighted Average Remaining Life (in years)	2 years 2 months 12 days	1 year 8 months 12 days
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 877	$ 877
Accumulated Amortization	(877)	(872)
Total	$ 0	$ 5
Weighted Average Remaining Life (in years)	0 years	2 months 12 days
User relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 146	$ 146
Accumulated Amortization	(146)	(140)
Total	$ 0	$ 6
Weighted Average Remaining Life (in years)	0 years	2 months 12 days

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS (Schedule of Intangible Assets) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Amortization expense		$ 2.6	$ 3.3	$ 3.5
Licensing agreements
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired		$ 6.1
Useful life	9 years 6 months

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS (Schedule of Future Amortization Expense) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2021	$ 2,848
2022	1,676
2023	1,359
2024	1,353
2025	1,353
Thereafter	4,932
Total	$ 13,521	$ 10,082

LEASES (Lease Cost) (Details)

LEASES (Lease Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease cost	$ 55,214	$ 54,451
Short-term lease cost (12 months or less)	1,288	1,287
Sublease income	(7,826)	(4,759)	$ (2,200)
Total lease cost, net	$ 48,676	$ 50,979

LEASES (Narrative) (Details)

LEASES (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Lease expense				$ 51,200
Sublease Income		$ 7,826	$ 4,759	$ 2,200
Lease cost		$ 48,676	$ 50,979
Canada
Lessee, Lease, Description [Line Items]
Lease cost	$ 9,400

LEASES (Supplemental Cash Flow

LEASES (Supplemental Cash Flow Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 58,515	$ 56,672

LEASES (Operating Lease Maturit

LEASES (Operating Lease Maturities) (Details) $ in Thousands	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 52,465
2022	47,134
2023	44,207
2024	41,519
2025	22,419
Thereafter	24,422
Total minimum lease payments	232,166
Less imputed interest	(32,070)
Present value of lease liabilities	$ 200,096

LEASES (Additional Information)

LEASES (Additional Information) (Details)	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Weighted-average remaining lease term (years) — operating leases	5 years 1 month 6 days	5 years 6 months
Weighted-average discount rate — operating leases	6.00%	6.10%

OTHER NON-CURRENT ASSETS (Detai

OTHER NON-CURRENT ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Assets, Noncurrent Disclosure [Abstract]
Deferred tax assets	$ 31,163	$ 20,054
Deferred contract costs	14,522	15,138	$ 12,345
Other non-current assets	3,163	3,177
Total other non-current assets	$ 48,848	$ 38,369

OTHER NON-CURRENT ASSETS (Chang

OTHER NON-CURRENT ASSETS (Changes in Deferred Contract Costs) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Changes In Capitalized Contract Costs [Roll Forward]
Balance, beginning of period	$ 15,138	$ 15,138	$ 12,345
Add: costs deferred on new contracts		15,328	14,998
Less: amortization recorded in sales and marketing expenses	$ (3,400)	(15,944)	(12,205)
Balance, end of period		$ 14,522	$ 15,138

OTHER NON-CURRENT ASSETS (Narra

OTHER NON-CURRENT ASSETS (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2020
Other Assets, Noncurrent Disclosure [Abstract]
Capitalized contract cost, amortization period	26 months	12 months	32 months	32 months
Amortization expense	$ 3,400	$ 15,944	$ 12,205

CONTRACT BALANCES (Schedule of

CONTRACT BALANCES (Schedule of Changes in Allowance for Doubtful Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts:
Balance, beginning of period	$ 7,686	$ 8,685	$ 8,602
Add: provision for doubtful accounts	32,265	22,543	24,515
Less: write-offs, net of recoveries	(28,392)	(23,542)	(24,432)
Balance, end of period	$ 11,559	$ 7,686	$ 8,685

CONTRACT BALANCES (Changes in D

CONTRACT BALANCES (Changes in Deferred Revenue) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Change in Contract with Customer, Liability [Roll Forward]
Balance, beginning of period	$ 4,315	$ 3,843
Less: recognition of deferred revenue from beginning balance	(3,869)	(3,744)
Add: net increase in current period contract liabilities	3,663	4,216
Balance, end of period	$ 4,109	$ 4,315

CONTRACT BALANCES (Narrative) (

CONTRACT BALANCES (Narrative) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Deferred revenue	$ 4,109,000	$ 4,315,000	$ 3,843,000
Contract asset	0	0
Contract liability	$ 0	$ 0

ACCOUNTS PAYABLE AND ACCRUED _3

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accounts payable	$ 8,853	$ 6,002
Employee-related liabilities	57,684	41,488
Accrued sales and marketing expenses	2,137	2,982
Taxes payable	975	3,695
Accrued cost of revenue	8,269	7,208
Other accrued liabilities	9,842	10,958
Total accounts payable and accrued liabilities	$ 87,760	$ 72,333

ACCOUNTS PAYABLE AND ACCRUED _4

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES (Narrative) (Details) $ in Millions	Dec. 31, 2020USD ($)
Payables and Accruals [Abstract]
Deferred income tax liabilities, employer taxes	$ 15

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) - USD ($)	1 Months Ended
	May 31, 2020	Dec. 31, 2020
Line of Credit Facility [Line Items]
Letters of credit outstanding	$ 21,500,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility term	3 years
Line of credit facility, maximum borrowing capacity	$ 75,000,000
Commitment fee percentage	0.25%
Debt issuance costs		$ 400,000
Remaining borrowing capacity		53,500,000
Long-term line of credit		$ 0
Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread	1.25%
Revolving Credit Facility | Base Rate
Line of Credit Facility [Line Items]
Basis spread	0.25%
Letter of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 25,000,000
Unused capacity, commitment fee percentage	0.70%
Credit Agreement Sublimit
Line of Credit Facility [Line Items]
Letters of credit outstanding	$ 21,500,000

STOCKHOLDERS' EQUITY (Schedule

STOCKHOLDERS' EQUITY (Schedule of Stock by Class) (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Common Stock, Shares Authorized (in shares)	200,000,000	200,000,000
Common Stock, Shares Issued (in shares)	75,371,368	71,185,468
Undesignated Preferred Stock, Shares Authorized (in shares)	10,000,000	10,000,000
Undesignated Preferred Stock, Shares Issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.000001	$ 0.000001

STOCKHOLDERS' EQUITY (Award Com

STOCKHOLDERS' EQUITY (Award Compensation Narrative) (Details)	12 Months Ended
	Dec. 31, 2020USD ($)planschedule$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Jan. 31, 2020USD ($)	Feb. 28, 2019USD ($)	Nov. 30, 2018USD ($)	Jul. 31, 2017USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchases of common stock	$ 24,396,000	$ 481,011,000	$ 187,382,000
Treasury stock, shares retired (in shares) | shares	704,673
Treasury shares (in shares) | shares	99,018
Number of equity incentive plans | plan	3
Stock-based compensation	$ 124,574,000	121,512,000	114,386,000
Capitalized stock-based compensation	$ 9,400,000	9,800,000	7,800,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of vesting schedules | schedule	3
Exercisable period	10 years
Intrinsic value of options exercised	$ 33,800,000	$ 12,000,000	$ 18,900,000
Weighted average grant date fair value (in dollars per share) | $ / shares	$ 10.01	$ 17.64	$ 18.89
Unrecognized compensation costs	$ 9,000,000
Unrecognized compensation costs, period for recognition	2 years
Stock Options | End of year one
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	25.00%
Stock Options | First year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	10.00%
Stock Options | Second year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	20.00%
Stock Options | Third year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	30.00%
Stock Options | Fourth year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	40.00%
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Number of vesting schedules | schedule	3
Unrecognized compensation costs	$ 262,900,000
Unrecognized compensation costs, period for recognition	2 years 9 months 18 days
Aggregate fair value of vested RSUs	$ 95,000,000	$ 112,400,000	$ 131,100,000
Restricted stock units | End of year one
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	25.00%
Restricted stock units | First year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	10.00%
Restricted stock units | Second year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	20.00%
Restricted stock units | Third year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	30.00%
Restricted stock units | Fourth year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	40.00%
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Trigger price for vesting (usd per share) | $ / shares	$ 45.3125
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Subscription rate of eligible compensation	15.00%
Purchase price, percentage of fair market value	85.00%
Number of shares purchased (in shares) | shares	662,063	534,120	442,679
Weighted-average purchase price (in dollars per share) | $ / shares	$ 21.47	$ 27.66	$ 32.07
Stock-based compensation	$ 2,500,000	$ 2,600,000	$ 2,600,000
July 31, 2017 Share Repurchase Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, authorized amount	$ 950,000,000			$ 250,000,000	$ 250,000,000	$ 250,000,000	$ 200,000,000
Repurchase and retirement of common stock (in shares) | shares	803,691	14,190,409
Repurchases of common stock	$ 24,400,000	$ 481,000,000
July 2017 Share Repurchase Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining authorized repurchase amount	$ 244,600,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target vesting range	0.00%
Minimum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target vesting range	200.00%
Maximum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years

STOCKHOLDERS' EQUITY (Schedul_2

STOCKHOLDERS' EQUITY (Schedule of Shares Reserved for Issuance) (Details)	Dec. 31, 2020shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance (in shares)	20,593,882
Stock options outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance (in shares)	4,622,828
RSUs outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance (in shares)	9,757,787
Available for future equity award grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance (in shares)	5,333,200
Available for future ESPP offerings
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance (in shares)	880,067

STOCKHOLDERS' EQUITY (Schedul_3

STOCKHOLDERS' EQUITY (Schedule of Fair Value Assumptions) (Details) - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Annual risk-free rate	0.50%	2.50%	2.20%
Expected volatility	45.90%	48.30%	42.00%
Expected term (years)	5 years 8 months 12 days	6 years	6 years

STOCKHOLDERS' EQUITY (Schedul_4

STOCKHOLDERS' EQUITY (Schedule of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Outstanding, beginning balance (in shares)	6,210,385
Granted (in shares)	158,050
Exercised (in shares)	(1,544,610)
Canceled (in shares)	(200,997)
Outstanding, ending balance (in shares)	4,622,828	6,210,385
Options vested and exercisable (in shares)	4,022,236
Weighted- Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 25.10
Granted (in dollars per share)	31.21
Exercised (in dollars per share)	8.53
Canceled (in dollars per share)	47.24
Outstanding, ending balance (in dollars per share)	29.89	$ 25.10
Options vested and exercisable (in dollars per share)	$ 28.90
Weighted- Average Remaining Contractual Term
Outstanding, Weighted-Average Remaining Contractual Term (in years)	4 years 8 months 12 days	4 years 3 months 18 days
Options vested and exercisable, Weighted-Average Remaining Contractual Term (in years)	4 years 2 months 12 days
Aggregate Intrinsic Value
Outstanding, Aggregate Intrinsic Value	$ 30,451	$ 75,805
Options vested and exercisable, Aggregate Intrinsic Value	$ 30,071

STOCKHOLDERS' EQUITY (Schedul_5

STOCKHOLDERS' EQUITY (Schedule of Restricted Stock Units Activity) (Details) - Restricted stock units	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Number of Shares
Nonvested, beginning balance (in shares)	7,625,584
Granted (in shares)	7,412,006
Vested (in shares)	(3,370,406)
Canceled (in shares)	(1,909,397)
Nonvested, ending balance (in shares)	9,757,787
Weighted- Average Grant Date Fair Value
Nonvested, beginning balance (in dollars per share) | $ / shares	$ 36.51
Granted (in dollars per share) | $ / shares	26.04
Vested (in dollars per share) | $ / shares	35.59
Canceled (in dollars per share) | $ / shares	34.80
Nonvested, ending balance (in dollars per share) | $ / shares	$ 29.22
Shares vested but not issued due to net share settlement for payment of employee taxes (in shares)	686,506

STOCKHOLDERS' EQUITY (Schedul_6

STOCKHOLDERS' EQUITY (Schedule of Stock-Based Compensation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation recorded to income before incomes taxes	$ 124,574	$ 121,512	$ 114,386
Benefit from income taxes	(31,920)	(31,565)	(30,237)
Total stock-based compensation recorded to net income	92,654	89,947	84,149
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation recorded to income before incomes taxes	3,784	4,535	4,572
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation recorded to income before incomes taxes	29,670	30,668	30,779
Product development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation recorded to income before incomes taxes	67,622	63,433	56,882
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation recorded to income before incomes taxes	$ 23,498	$ 22,876	$ 22,153

OTHER INCOME, NET (Details)

OTHER INCOME, NET (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Income and Expenses [Abstract]
Interest income, net	$ 2,273	$ 13,328	$ 13,804
Transaction gain (loss) on foreign exchange	20	27	(70)
Other non-operating income, net	1,377	901	375
Other income, net	$ 3,670	$ 14,256	$ 14,109

INCOME TAXES (Schedule of Incom

INCOME TAXES (Schedule of Income (Loss) before Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
United States	$ (28,878)	$ 55,292	$ 44,856
Foreign	(6,247)	(5,525)	(4,850)
(Loss) income before income taxes	$ (35,125)	$ 49,767	$ 40,006

INCOME TAXES (Schedule of Inc_2

INCOME TAXES (Schedule of Income Tax Provision) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ (4,823)	$ 8,598	$ (819)
State	(434)	2,570	384
Foreign	737	517	560
Total current tax	(4,520)	11,685	125
Deferred:
Federal	(10,456)	(2,916)	(10,032)
State	(731)	59	(6,491)
Foreign	6	58	1,054
Total deferred tax	(11,181)	(2,799)	(15,469)
Total (benefit from) provision for income taxes	$ (15,701)	$ 8,886	$ (15,344)

INCOME TAXES (Reconciliation of

INCOME TAXES (Reconciliation of the Effective Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax at federal statutory rate	21.00%	21.00%	21.00%
State tax, net of federal tax effect	2.87%	2.83%	3.24%
Foreign income tax rate differential	1.04%	(0.56%)	(0.54%)
Stock-based compensation	(6.42%)	3.46%	(16.80%)
Income tax credits	39.52%	(26.94%)	(35.83%)
Change in valuation allowance	(15.64%)	10.40%	(25.08%)
Change in uncertain tax positions	(0.36%)	0.56%	4.48%
Employee fringe benefits	(2.27%)	5.97%	7.28%
Other non-deductible expenses	(1.85%)	1.42%	2.73%
Deferred adjustments	1.37%	0.37%	2.24%
Net operating loss carryback - CARES Act	5.64%	0.00%	0.00%
Other	(0.20%)	(0.65%)	(1.07%)
Effective tax rate	44.70%	17.86%	(38.35%)

INCOME TAXES (Schedule of Defer

INCOME TAXES (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Reserves and others	$ 5,246	$ 6,547
Stock-based compensation	20,388	19,950
Net operating loss carryforward	5,509	4,628
Tax credit carryforward	40,513	23,642
Operating lease liabilities	49,229	60,206
Gross deferred tax assets	120,885	114,973
Valuation allowance	(28,941)	(23,447)
Total deferred tax assets	91,944	91,526
Deferred tax liabilities:
Depreciation and amortization	(15,551)	(16,359)
Deferred contract costs	(3,735)	(3,869)
Operating lease right-of-use assets	(41,495)	(51,244)
Total deferred tax liabilities	(60,781)	(71,472)
Net deferred tax assets	$ 31,163	$ 20,054

INCOME TAXES (Narrative) (Detai

INCOME TAXES (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Line Items]
Undistributed earnings of foreign subsidiaries	$ 6,200
Valuation allowance	28,941	$ 23,447
Unrecognized tax benefits that would impact effective tax rate	27,600
Decrease in unrecognized tax benefits is reasonably possible	6,300
Domestic
Income Taxes [Line Items]
Net operating loss carryforwards	12,900
Domestic | Research
Income Taxes [Line Items]
Credit carryforwards	37,900
State
Income Taxes [Line Items]
Net operating loss carryforwards	40,900
State | Research
Income Taxes [Line Items]
Credit carryforwards	57,600
Germany
Income Taxes [Line Items]
Net operating loss carryforwards	1,800
Canada
Income Taxes [Line Items]
Net operating loss carryforwards	$ 300

INCOME TAXES (Reconciliation _2

INCOME TAXES (Reconciliation of Unrecognized Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	$ 40,718	$ 33,107	$ 18,215
(Decrease) increase based on tax positions related to the prior year	(453)	(611)
(Decrease) increase based on tax positions related to the prior year			3,654
Increase based on tax positions related to the current year	7,942	9,995	11,485
Decrease from tax authorities' settlements	0	(1,773)	0
Lapse of statute of limitations	0	0	(247)
Balance at the end of the year	$ 48,207	$ 40,718	$ 33,107

NET (LOSS) INCOME PER SHARE (Sc

NET (LOSS) INCOME PER SHARE (Schedule of Basic and Diluted Net Loss Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic net (loss) income per share:
Net (loss) income	$ (19,424)	$ 40,881	$ 55,350
Shares used in computation:
Weighted-average common shares outstanding (in shares)	73,005	74,627	83,573
Basic net (loss) income per share attributable to common stockholders (in dollars per share)	$ (0.27)	$ 0.55	$ 0.66
Diluted net (loss) income per share:
Net (loss) income	$ (19,424)	$ 40,881	$ 55,350
Shares used in computation:
Weighted-average common shares outstanding (in shares)	73,005	74,627	83,573
Number of shares used in diluted calculation (in shares)	73,005	77,969	88,709
Diluted net (loss) income per share attributable to common stockholders (in dollars per share)	$ (0.27)	$ 0.52	$ 0.62
Stock options
Shares used in computation:
Incremental common shares (in shares)	0	2,367	2,984
Restricted stock units
Shares used in computation:
Incremental common shares (in shares)	0	973	2,137
Employee stock purchase program
Shares used in computation:
Incremental common shares (in shares)	0	2	15

NET (LOSS) INCOME PER SHARE (_2

NET (LOSS) INCOME PER SHARE (Schedule of Anti-Dilutive Employee Stock Awards) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive awards (in shares)	4,623	2,580	2,030
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive awards (in shares)	9,758	2,020	373
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive awards (in shares)	62	0	0

INFORMATION ABOUT REVENUE AND_3

INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS (Net Revenue) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	$ 872,933	$ 1,014,194	$ 942,773
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	863,300	1,000,245	929,569
All other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	9,633	13,949	13,204
Advertising
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	836,115	976,925	907,487
Services
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	515,019	512,729	457,531
Restaurants, Retail & Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	321,096	464,196	449,956
Transactions
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	15,017	12,436	13,694
Other revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net revenue	$ 21,801	$ 24,833	$ 21,592

INFORMATION ABOUT REVENUE AND_4

INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Income Statement [Abstract]
Customer incentives	$ 22.6
Free advertising for customers	$ 14.5

INFORMATION ABOUT REVENUE AND_5

INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS (Long-Lived Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	$ 101,718	$ 110,949
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	97,548	109,849
All other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	$ 4,170	$ 1,100

RESTRUCTURING (Details)

RESTRUCTURING (Details) $ in Millions	Jul. 13, 2020employee	Apr. 09, 2020employee	Dec. 31, 2020USD ($)
Restructuring and Related Activities [Abstract]
Number of positions eliminated	60	1,000
Number of positions furloughed		1,100
Restructuring incurred cost | $			$ 3.9