EPAM Systems (EPAM) 10-Q 7 May 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	001-35418
Entity Registrant Name	EPAM SYSTEMS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	22-3536104
Entity Address, Street Name	41 University Drive
Entity Address, Suite No.	Suite 202
Entity Address, City or Town	Newtown
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	18940
City Area Code	267
Local Phone Number	759-9000
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	EPAM
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Central Index Key	0001352010
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		55,639,436
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 916,253	$ 936,552
Trade receivables and contract assets, net of allowance of $5,356 and $2,920, respectively	542,698	497,716
Prepaid and other current assets	48,786	39,943
Total current assets	1,507,737	1,474,211
Property and equipment, net	164,671	165,259
Operating lease right-of-use assets	243,671	238,991
Intangible assets, net	58,676	56,258
Goodwill	198,534	195,043
Deferred tax assets	79,044	75,013
Other noncurrent assets	59,548	39,433
Total assets	2,311,881	2,244,208
Current liabilities
Accounts payable	5,232	7,831
Accrued compensation and benefits expenses	250,560	230,035
Accrued expenses and other current liabilities	66,434	82,476
Income taxes payable, current	6,987	9,064
Operating lease liabilities, current	60,108	57,542
Total current liabilities	389,321	386,948
Long-term debt	25,046	25,074
Income taxes payable, noncurrent	45,847	45,878
Operating lease liabilities, noncurrent	189,312	180,848
Other noncurrent liabilities	14,873	9,315
Total liabilities	664,399	648,063
Commitments and contingencies (Note 12)
Stockholders’ equity
Common stock, $0.001 par value; 160,000,000 authorized; 55,608,835 and 55,207,446 shares issued, 55,589,100 and 55,187,711 shares outstanding at March 31, 2020 and December 31, 2019, respectively	56	55
Additional paid-in capital	610,579	607,051
Retained earnings	1,106,285	1,020,590
Treasury stock	(177)	(177)
Accumulated other comprehensive loss	(69,261)	(31,374)
Total stockholders’ equity	1,647,482	1,596,145
Total liabilities and stockholders’ equity	$ 2,311,881	$ 2,244,208

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets
Trade receivables and contract assets allowance	$ 5,356	$ 2,920
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	160,000,000	160,000,000
Common stock, shares issued (in shares)	55,608,835	55,207,446
Common stock, shares outstanding (in shares)	55,589,100	55,187,711

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 651,359	$ 521,333
Operating expenses:
Cost of revenues (exclusive of depreciation and amortization)	423,802	344,689
Selling, general and administrative expenses	125,108	101,786
Depreciation and amortization expense	14,940	10,200
Income from operations	87,509	64,658
Interest and other income, net	2,386	3,076
Foreign exchange gain/(loss)	6,524	(3,484)
Income before provision for income taxes	96,419	64,250
Provision for income taxes	10,854	3,496
Net income	85,565	60,754
Foreign currency translation adjustments, net of tax	(28,519)	2,943
Unrealized (loss)/gain on cash-flow hedging instruments, net of tax	(9,368)	3,100
Comprehensive income	$ 47,678	$ 66,797
Net income per share:
Basic (in dollars per share)	$ 1.55	$ 1.12
Diluted (in dollars per share)	$ 1.47	$ 1.06
Shares used in calculation of net income per share:
Basic (in shares)	55,286,747	54,245,133
Diluted (in shares)	58,142,570	57,236,427

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY Statement - USD ($) $ in Thousands	Total	Restricted Stock Units	Common Stock	Common StockRestricted Stock Units	Additional Paid-in Capital	Additional Paid-in CapitalRestricted Stock Units	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Balance, beginning of period (in shares) at Dec. 31, 2018			54,080,192
Balance, beginning of period at Dec. 31, 2018	$ 1,262,596		$ 54		$ 544,700		$ 759,533		$ (41,514)
Treasury stock, beginning of period (in shares) at Dec. 31, 2018								19,735
Treasury stock, beginning period at Dec. 31, 2018								$ (177)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures [Abstract]
Stock units vested (in shares)				242,414
Stock units withheld for employee taxes		$ (13,483)				$ (13,483)
Stock units withheld for employee taxes (in shares)				(81,562)
Proceeds from stock options exercises	11,890				11,890
Proceeds from stock options exercises (in shares)			323,464
Stock-based compensation expense	10,425				10,425
Foreign currency translation adjustments, net of tax	2,943								2,943
Change in unrealized gains and losses on cash flow hedges, net of tax	3,100								3,100
Net income	60,754						60,754
Balance, end of period (in shares) at Mar. 31, 2019			54,564,508
Balance, end of period at Mar. 31, 2019	$ 1,338,225		$ 54		553,532		820,287		(35,471)
Treasury stock, end of period (in shares) at Mar. 31, 2019								19,735
Treasury stock, end of period at Mar. 31, 2019								$ (177)
Balance, beginning of period (in shares) at Dec. 31, 2019	55,187,711		55,187,711
Balance, beginning of period at Dec. 31, 2019	$ 1,596,145		$ 55		607,051		1,020,590		(31,374)
Treasury stock, beginning of period (in shares) at Dec. 31, 2019								19,735
Treasury stock, beginning period at Dec. 31, 2019								$ (177)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures [Abstract]
Stock units vested (in shares)				273,904
Stock units withheld for employee taxes		$ (15,822)				$ (15,822)
Stock units withheld for employee taxes (in shares)				(89,990)
Proceeds from stock options exercises	7,141		$ 1		7,140
Proceeds from stock options exercises (in shares)			217,475
Stock-based compensation expense	12,210				12,210
Foreign currency translation adjustments, net of tax	(28,519)								(28,519)
Change in unrealized gains and losses on cash flow hedges, net of tax	(9,368)								(9,368)
Cumulative effect of adoption of ASU | ASU 2016-13	130						130
Net income	$ 85,565						85,565
Balance, end of period (in shares) at Mar. 31, 2020	55,589,100		55,589,100
Balance, end of period at Mar. 31, 2020	$ 1,647,482		$ 56		$ 610,579		$ 1,106,285		$ (69,261)
Treasury stock, end of period (in shares) at Mar. 31, 2020								19,735
Treasury stock, end of period at Mar. 31, 2020								$ (177)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 85,565	$ 60,754
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	14,940	10,200
Operating lease right-of-use assets amortization expense	16,816	12,187
Bad debt expense	2,719	(133)
Deferred taxes	8,288	846
Stock-based compensation expense	11,881	21,856
Other	5,893	520
Changes in assets and liabilities:
Trade receivables and contract assets	(51,423)	(48,343)
Prepaid and other assets	(9,746)	401
Accounts payable	(2,407)	(2,488)
Accrued expenses and other liabilities	5,437	(22,360)
Operating lease liabilities	(15,646)	(13,175)
Income taxes payable	(9,062)	(20,467)
Net cash provided by/(used in) operating activities	63,255	(202)
Cash flows from investing activities:
Purchases of property and equipment	(29,075)	(13,424)
Acquisition of business, net of cash acquired (Note 2)	(10,339)	0
Payments for cost method investments	(20,000)	(5,000)
Other investing activities, net	(71)	(136)
Net cash used in investing activities	(59,485)	(18,560)
Cash flows from financing activities:
Proceeds from stock option exercises	6,850	11,402
Payments of withholding taxes related to net share settlements of restricted stock units	(1,018)	(1,208)
Payment of contingent consideration for previously acquired business	(7,869)	0
Other financing activities, net	(9)	(13)
Net cash (used in)/provided by financing activities	(2,046)	10,181
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(22,009)	548
Net decrease in cash, cash equivalents and restricted cash	(20,285)	(8,033)
Cash, cash equivalents and restricted cash, beginning of period	937,688	771,711
Cash, cash equivalents and restricted cash, end of period	$ 917,403	$ 763,678

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOW (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Cash and cash equivalents	$ 916,253	$ 936,552
Total restricted cash		1,136
Total cash, cash equivalents, restricted cash and restricted cash equivalents	917,403	937,688
Other noncurrent assets
Restricted cash	$ 1,150	$ 1,136

BUSINESS AND SUMMARY OF SIGNIFI

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES EPAM Systems, Inc. (the “Company” or “EPAM”) is a leading global provider of digital platform engineering and software development services to customers located around the world, primarily in North America, Europe, Asia and Australia. The Company’s industry expertise includes financial services, travel and consumer, software and hi-tech, business information and media, life sciences and healthcare, as well as other emerging industries. The Company is incorporated in Delaware with headquarters in Newtown, Pennsylvania. Basis of Presentation — The accompanying unaudited condensed consolidated financial statements of EPAM have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP” or “U.S. GAAP”) and Article 10 of Regulation S-X under the Securities Exchange Act of 1934, as amended. The unaudited condensed consolidated financial statements include the financial statements of EPAM Systems, Inc. and its subsidiaries with all intercompany balances and transactions eliminated. These unaudited condensed consolidated financial statements and accompanying notes should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto for the year ended December 31, 2019 included in its Annual Report on Form 10-K. The preparation of these condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in these condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates, and such differences may be material to the condensed consolidated financial statements. Operating results for the interim periods are not necessarily indicative of results that may be expected to occur for the entire year. In management’s opinion, all adjustments considered necessary for a fair presentation of the accompanying unaudited condensed consolidated financial statements have been included, and all adjustments are of a normal and recurring nature. As previously disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, certain amounts recorded in the prior-period consolidated statement of cash flows presented have been reclassified to conform to the current-period financial statement presentation. These reclassifications had no effect on previously reported results of operations. Adoption of New Accounting Standards Unless otherwise discussed below, the adoption of new accounting standards did not have a material impact on the Company’s consolidated financial position, results of operations, changes in stockholders’ equity and cash flows. Measurement of Credit Losses on Financial Instruments — In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments in this update changed how companies measure and recognize credit impairment for many financial assets. The new credit loss model requires companies to immediately recognize an estimate of credit losses expected to occur over the remaining life of the financial assets (including trade receivables) that are in the scope of the update. The update also made amendments to the current impairment model for held-to-maturity and available-for-sale debt securities and certain guarantees. The Company adopted Topic 326, effective January 1, 2020, using a modified-retrospective approach through a cumulative effect adjustment to retained earnings as of the beginning of the period of adoption. As a result of the adoption of Topic 326, the Company recorded an immaterial reduction to its allowance for doubtful accounts for trade receivables and contract assets . Pending Accounting Standards From time to time, new accounting pronouncements are issued by the FASB or other standards-setting bodies that the Company will adopt according to the various timetables the FASB specifies. Unless otherwise discussed below, the Company believes the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position, results of operations and cash flows upon adoption.

ACQUISITION

ACQUISITION	3 Months Ended
	Mar. 31, 2020
Business Combinations [Abstract]
ACQUISITION	ACQUISITION 2020 Acquisition — During the three months ended March 31, 2020, the Company completed one acquisition with a purchase price of $14,663 including contingent consideration with a fair value of $4,042 . The Company committed to making earnout payments with a maximum amount payable of $16,582 subject to attainment of specified performance targets in the first and second calendar years after the acquisition date. This acquisition increased EPAM’s software and service capabilities in financial services as well as added $6,300 of intangible assets, consisting mainly of customer relationships. Revenues generated by this acquisition totaled $1,043 during the three months ended March 31, 2020

GOODWILL

GOODWILL	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL	GOODWILL Goodwill by reportable segment was as follows: North America Europe Russia Total Balance as of January 1, 2020 $ 113,426 $ 80,873 $ 744 $ 195,043 Other 2019 acquisitions purchase accounting adjustments 210 (42 ) 20 188 2020 Acquisition 6,818 — — 6,818 Effect of net foreign currency exchange rate changes (373 ) (3,078 ) (64 ) (3,515 ) Balance as of March 31, 2020 $ 120,081 $ 77,753 $ 700 $ 198,534 There were no accumulated impairment losses in the North America or Europe reportable segments as of March 31, 2020 or December 31, 2019 . The Russia segment had accumulated goodwill impairment losses of $2,241 as of March 31, 2020 and December 31, 2019 .

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Company carries certain assets and liabilities at fair value on a recurring basis on its consolidated balance sheets. The following tables present the fair values of the Company’s financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2020 and December 31, 2019: As of March 31, 2020 Balance Level 1 Level 2 Level 3 Foreign exchange derivative assets $ 55 $ — $ 55 $ — Total assets measured at fair value on a recurring basis $ 55 $ — $ 55 $ — Foreign exchange derivative liabilities $ 10,475 $ — $ 10,475 $ — Contingent consideration 5,705 — — 5,705 Total liabilities measured at fair value on a recurring basis $ 16,180 $ — $ 10,475 $ 5,705 As of December 31, 2019 Balance Level 1 Level 2 Level 3 Foreign exchange derivative assets $ 1,910 $ — $ 1,910 $ — Total assets measured at fair value on a recurring basis $ 1,910 $ — $ 1,910 $ — Foreign exchange derivative liabilities $ 243 $ — $ 243 $ — Contingent consideration 10,495 — — 10,495 Total liabilities measured at fair value on a recurring basis $ 10,738 $ — $ 243 $ 10,495 The foreign exchange derivatives are valued using pricing models and discounted cash flow methodologies based on observable foreign exchange data at the measurement date. See Note 5 “Derivative Financial Instruments” in the condensed consolidated interim financial statements for additional information regarding derivative financial instruments. The fair value of the contingent consideration was determined using a probability-weighted expected return method and is based on the expected future payments to be made to the sellers of the acquired businesses in accordance with the provisions outlined in the respective purchase agreements. Although there is significant judgment involved, the Company believes its estimates and assumptions are reasonable. In determining fair value, the Company considered a variety of factors, including future performance of the acquired business using financial projections developed by the Company and market risk assumptions that were derived for revenue growth and earnings before interest and taxes. The Company estimated future payments using the earnout formula and performance targets specified in the purchase agreement and adjusted those estimates to reflect the probability of their achievement. Those weighted-average estimated future payments were then discounted to present value using a rate based on the weighted-average cost of capital of guideline companies. The discount rate used to determine the fair value of contingent consideration for the 2020 Acquisition was 17.5% . Changes in financial projections, market risk assumptions, discount rates or probability assumptions related to achieving the various earnout criteria would result in a change in the fair value of the recorded contingent liabilities. Such changes, if any, are recorded within Interest and other income, net in the Company’s consolidated statement of income and comprehensive income. A reconciliation of the beginning and ending balances of Level 3 acquisition-related contingent consideration using significant unobservable inputs for the three months ended March 31, 2020 is as follows: Amount Contingent consideration liabilities as of January 1, 2020 $ 10,495 Payment of contingent consideration for previously acquired business (7,869 ) Acquisition date fair value of contingent consideration — 2020 Acquisition (Note 2) 4,042 Changes in fair value of contingent consideration included in Interest and other income, net (438 ) Effect of net foreign currency exchange rate changes (525 ) Contingent consideration liabilities as of March 31, 2020 $ 5,705 Financial Assets and Liabilities Not Measured at Fair Value on a Recurring Basis Estimates of fair value of financial instruments not carried at fair value on a recurring basis on the Company’s consolidated balance sheets are generally subjective in nature, and are determined as of a specific point in time based on the characteristics of the financial instruments and relevant market information. The generally short maturities of certain assets and liabilities result in a number of assets and liabilities for which fair value equals or closely approximates the amount recorded on the Company’s consolidated balance sheets. The following tables present the estimated fair values of the Company’s financial assets and liabilities not measured at fair value on a recurring basis as of the dates indicated: Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 March 31, 2020 Financial Assets: Cash equivalents: Money market funds $ 334,194 $ 334,194 $ 334,194 $ — $ — Time deposits 2 2 — 2 — Total cash equivalents $ 334,196 $ 334,196 $ 334,194 $ 2 $ — Restricted cash $ 1,150 $ 1,150 $ 1,150 $ — $ — Employee loans $ 2,159 $ 2,159 $ — $ — $ 2,159 Financial Liabilities: Borrowings under the 2017 Credit Facility $ 25,011 $ 25,011 $ — $ 25,011 $ — Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 December 31, 2019 Financial Assets: Cash equivalents: Money market funds $ 407,817 $ 407,817 $ 407,817 $ — $ — Time deposits 10,002 10,002 — 10,002 — Total cash equivalents $ 417,819 $ 417,819 $ 407,817 $ 10,002 $ — Restricted cash $ 1,136 $ 1,136 $ 1,136 $ — $ — Employee loans $ 2,434 $ 2,434 $ — $ — $ 2,434 Financial Liabilities: Borrowings under the 2017 Credit Facility $ 25,017 $ 25,017 $ — $ 25,017 $ —

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	DERIVATIVE FINANCIAL INSTRUMENTS In the normal course of business, the Company uses derivative financial instruments to manage the risk of fluctuations in foreign currency exchange rates. The Company has a hedging program whereby it enters into a series of foreign exchange forward contracts with durations of twelve months or less that are designated as cash flow hedges of forecasted Russian ruble, Polish zloty and Indian rupee transactions. As of March 31, 2020 , all of the Company’s foreign exchange forward contracts were designated as hedges and there is no financial collateral (including cash collateral) required to be posted by the Company related to the foreign exchange forward contracts. The fair value of derivative instruments on the Company’s consolidated balance sheets as of March 31, 2020 and December 31, 2019 were as follows: As of March 31, 2020 As of December 31, 2019 Balance Sheet Classification Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives Foreign exchange forward contracts - Designated as hedging instruments Prepaid expenses and other current assets $ 55 $ 1,910 Accrued expenses and other current liabilities $ 10,475 $ 243 The Company records changes in the fair value of its cash flow hedges in accumulated other comprehensive loss in the consolidated balance sheets until the forecasted transaction occurs. When the forecasted transaction occurs, the Company reclassifies the related gain or loss on the cash flow hedge to cost of revenues (exclusive of depreciation and amortization). In the event the underlying forecasted transaction does not occur, or it becomes probable that it will not occur, the Company reclassifies the gain or loss on the related cash flow hedge into income. If the Company does not elect hedge accounting, or the contract does not qualify for hedge accounting treatment, the changes in fair value from period to period are recorded in income. The changes in the fair value of foreign currency derivative instruments in our unaudited condensed consolidated statements of income and comprehensive income for the three months ended March 31, 2020 and 2019 were as follows: Three Months Ended 2020 2019 Foreign exchange forward contracts - Designated as hedging instruments: Net (loss)/gain in fair value recognized in accumulated other comprehensive loss $ (12,087 ) $ 3,999 Net loss reclassified from accumulated other comprehensive loss into cost of revenues (exclusive of depreciation and amortization) $ (660 ) $ (452 )

LEASES

LEASES	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
LEASES	LEASES The Company leases office space, corporate apartments, office equipment, and vehicles. Many of the Company’s leases contain variable payments including changes in base rent and charges for common area maintenance or other miscellaneous expenses. Due to this variability, the cash flows associated with these variable payments are not included in the minimum lease payments used in determining the right-of-use assets and associated lease liabilities and are recognized in the period in which the obligation for such payments is incurred. The Company’s leases have remaining lease terms ranging from 0.1 years to 11.1 years . Certain lease agreements, mainly for office space, include options to extend or terminate the lease before the expiration date. The Company considers such options when determining the lease term when it is reasonably certain that the Company will exercise that option. The Company leases and subleases a portion of its office space to third parties. Lease income and sublease income were immaterial for the three months ended March 31, 2020 and 2019. During the three months ended March 31, 2020 and 2019, the components of lease expense were as follows: Three Months Ended March 31, Income Statement Classification 2020 2019 Operating lease cost Selling, general and administrative expenses $ 18,863 $ 13,719 Variable lease cost Selling, general and administrative expenses 2,635 2,097 Short-term lease cost Selling, general and administrative expenses 540 898 Total lease cost $ 22,038 $ 16,714 Supplemental cash flow information related to leases for the three months ended March 31, 2020 and 2019 was as follows: Three Months Ended Three Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows used for operating leases $ 16,891 $ 14,696 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 31,252 $ 12,825 Non-cash net increase/(decrease) due to lease modifications: Operating lease right-of-use assets $ 4,584 $ (5,174 ) Operating lease liabilities $ 4,573 $ (5,106 ) Weighted average remaining lease term and discount rate as of March 31, 2020 and 2019 were as follows: As of March 31, 2020 As of March 31, 2019 Weighted average remaining lease term, in years: Operating leases 6.0 5.9 Weighted average discount rate: Operating leases 3.3 % 4.0 % As of March 31, 2020 , operating lease liabilities will mature as follows: Year ending December 31, Lease Payments 2020 (excluding three months ended March 31, 2020) $ 50,933 2021 59,351 2022 42,665 2023 31,190 2024 26,870 Thereafter 62,988 Total lease payments 273,997 Less: imputed interest (24,577 ) Total $ 249,420 As of March 31, 2020 , the Company had committed to payments of $13,727 related to operating lease agreements that had not yet commenced. These operating leases will commence during various dates during 2020 with lease terms ranging from 2.0 to 10.9 years . The Company did not have any material finance lease agreements that had not yet commenced.

LONG-TERM DEBT

LONG-TERM DEBT	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT Revolving Line of Credit — On May 24, 2017, the Company entered into an unsecured credit facility (the “2017 Credit Facility”), as may be amended from time to time, with PNC Bank, National Association; PNC Capital Markets LLC; Citibank N.A.; Wells Fargo Bank, National Association; Fifth Third Bank and Santander Bank, N.A. (collectively the “Lenders”). The 2017 Credit Facility provides for a borrowing capacity of $300,000 , with potential to increase the borrowing capacity up to $400,000 if certain conditions are met. The 2017 Credit Facility matures on May 24, 2022 . Borrowings under the 2017 Credit Facility may be denominated in U.S. dollars or up to a maximum of $100,000 equivalent in British pounds sterling, Canadian dollars, euros or Swiss francs and other currencies as may be approved by the administrative agent and the Lenders. Borrowings under the 2017 Credit Facility bear interest at either a base rate or Euro-rate plus a margin based on the Company’s leverage ratio. The base rate is equal to the highest of (a) the Overnight Bank Funding Rate, plus 0.5% , (b) the Prime Rate, and (c) the Daily LIBOR Rate, plus 1.0% . As of March 31, 2020 , the Company’s outstanding borrowings are subject to a LIBOR-based interest rate which resets regularly at issuance, based on lending terms. The 2017 Credit Facility includes customary business and financial covenants that may restrict the Company’s ability to make or pay dividends (other than certain intercompany dividends) if a potential or an actual event of default has occurred or would be triggered. As of March 31, 2020 , the Company was in compliance with all covenants contained in the 2017 Credit Facility. The following table presents the outstanding debt and borrowing capacity of the Company under the 2017 Credit Facility: As of As of Outstanding debt $ 25,000 $ 25,000 Interest rate 1.9 % 2.8 % Irrevocable standby letters of credit $ 298 $ 303 Available borrowing capacity $ 274,702 $ 274,697 Current maximum borrowing capacity $ 300,000 $ 300,000

REVENUES

REVENUES	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
REVENUES	REVENUES Disaggregation of Revenues The following tables present the disaggregation of the Company’s revenues by customer location, including a reconciliation of the disaggregated revenues with the reportable segments (Note 13 “Segment Information”) for the periods indicated: Three Months Ended March 31, 2020 Reportable Segments North America Europe Russia Consolidated Revenues Customer Locations North America $ 377,784 $ 10,419 $ 1,627 $ 389,830 Europe 10,332 212,722 3 223,057 CIS 2,554 12 22,294 24,860 APAC 432 13,180 — 13,612 Revenues $ 391,102 $ 236,333 $ 23,924 $ 651,359 Three Months Ended March 31, 2019 Reportable Segments North America Europe Russia Consolidated Revenues Customer Locations North America $ 303,745 $ 12,891 $ 16 $ 316,652 Europe 4,747 168,620 141 173,508 CIS 1,739 13 16,422 18,174 APAC 458 12,541 — 12,999 Revenues $ 310,689 $ 194,065 $ 16,579 $ 521,333 The following tables present the disaggregation of the Company’s revenues by industry vertical, including a reconciliation of the disaggregated revenues with the reportable segments (Note 13 “Segment Information”) for the periods indicated: Three Months Ended March 31, 2020 Reportable Segments North America Europe Russia Consolidated Revenues Industry Verticals Business Information & Media $ 80,220 $ 58,146 $ 360 $ 138,726 Financial Services 47,868 67,594 16,181 131,643 Software & Hi-Tech 101,737 18,146 1,966 121,849 Travel & Consumer 54,724 61,067 3,739 119,530 Life Sciences & Healthcare 61,611 7,619 9 69,239 Emerging Verticals 44,942 23,761 1,669 70,372 Revenues $ 391,102 $ 236,333 $ 23,924 $ 651,359 Three Months Ended March 31, 2019 Reportable Segments North America Europe Russia Consolidated Revenues Industry Verticals Business Information & Media $ 62,361 $ 32,531 $ 140 $ 95,032 Financial Services 38,394 61,835 13,032 113,261 Software & Hi-Tech 79,121 20,370 440 99,931 Travel & Consumer 47,000 55,202 2,124 104,326 Life Sciences & Healthcare 50,156 4,556 62 54,774 Emerging Verticals 33,657 19,571 781 54,009 Revenues $ 310,689 $ 194,065 $ 16,579 $ 521,333 The following tables present the disaggregation of the Company’s revenues by contract type including a reconciliation of the disaggregated revenues with the Company’s reportable segments (Note 13 “Segment Information”) for the periods indicated: Three Months Ended March 31, 2020 Reportable Segments North America Europe Russia Consolidated Revenues Contract Types Time-and-material $ 357,263 $ 190,320 $ 13,596 $ 561,179 Fixed-price 31,855 45,255 8,821 85,931 Licensing 1,770 162 1,458 3,390 Other revenues 214 596 49 859 Revenues $ 391,102 $ 236,333 $ 23,924 $ 651,359 Three Months Ended March 31, 2019 Reportable Segments North America Europe Russia Consolidated Revenues Contract Types Time-and-material $ 284,725 $ 168,213 $ 11,272 $ 464,210 Fixed-price 24,740 25,246 5,287 55,273 Licensing 836 398 6 1,240 Other revenues 388 208 14 610 Revenues $ 310,689 $ 194,065 $ 16,579 $ 521,333 Timing of Revenue Recognition The following tables present the timing of revenue recognition for the periods indicated: Three Months Ended March 31, 2020 Reportable Segments North America Europe Russia Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 1,292 $ 162 $ 1,456 $ 2,910 Transferred over time 389,810 236,171 22,468 648,449 Revenues $ 391,102 $ 236,333 $ 23,924 $ 651,359 Three Months Ended March 31, 2019 Reportable Segments North America Europe Russia Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 404 $ 47 $ — $ 451 Transferred over time 310,285 194,018 16,579 520,882 Revenues $ 310,689 $ 194,065 $ 16,579 $ 521,333 During the three months ended March 31, 2020 the Company recognized $5,814 of revenues from performance obligations satisfied in previous periods compared to $1,704 during the three months ended March 31, 2019. The following table includes the estimated revenues expected to be recognized in the future related to performance obligations that are partially or fully unsatisfied as of March 31, 2020 . The Company applies a practical expedient and does not disclose the value of unsatisfied performance obligations for contracts that (i) have an original expected duration of one year or less and (ii) contracts for which it recognizes revenues at the amount to which it has the right to invoice for services provided: Less than 1 year 1 Year 2 Years 3 Years Total Contract Type Fixed-price $ 14,332 $ 1,443 $ — $ — $ 15,775 The Company applies a practical expedient and does not disclose the amount of the transaction price allocated to the remaining performance obligations nor provide an explanation of when the Company expects to recognize that amount as revenue for certain variable consideration. Contract Balances The following table provides information on the classification of contract assets and liabilities in the condensed consolidated balance sheets: As of As of Contract assets included in Trade receivables and contract assets $ 16,176 $ 14,320 Contract liabilities included in Accrued expenses and other current liabilities $ 11,370 $ 9,132 Contract assets have not materially changed from December 31, 2019. Contract liabilities comprise amounts collected from the Company’s customers for revenues not yet earned. Such amounts are anticipated to be recorded as revenues when services are performed in subsequent periods. Contract liabilities have not materially changed from December 31, 2019. During the three months ended March 31, 2020 , the Company recognized $6,537 of revenues that were included in Accrued expenses and other current liabilities at December 31, 2019. During the three months ended March 31, 2019, the Company recognized $3,051

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION The following table summarizes the components of stock-based compensation expense recognized in the Company’s condensed consolidated statements of income and comprehensive income for the periods indicated: Three Months Ended 2020 2019 Cost of revenues (exclusive of depreciation and amortization) $ 3,984 $ 12,781 Selling, general and administrative expenses 7,897 9,075 Total $ 11,881 $ 21,856 Stock Options Stock option activity under the Company’s plans is set forth below: Number of Options Weighted Average Exercise Price Aggregate Intrinsic Value Weighted Average Remaining Contractual Term (in years) Options outstanding at January 1, 2020 3,322,930 $ 50.85 Options granted 144,724 $ 175.22 Options exercised (217,475 ) $ 32.84 Options forfeited/cancelled (7,489 ) $ 121.05 Options outstanding at March 31, 2020 3,242,690 $ 57.45 $ 415,750 4.8 Options vested and exercisable at March 31, 2020 2,856,545 $ 45.67 $ 399,900 4.3 Options expected to vest at March 31, 2020 352,278 $ 143.52 $ 14,845 8.8 As of March 31, 2020 , $18,416 of total remaining unrecognized stock-based compensation cost related to unvested stock options, net of estimated forfeitures, is expected to be recognized over the weighted-average remaining requisite service period of 3.1 years . Restricted Stock and Restricted Stock Units Service-Based Awards The table below summarizes activity related to the Company’s equity-classified and liability-classified service-based awards for the three months ended March 31, 2020 : Equity-Classified Restricted Stock Equity-Classified Equity-Settled Restricted Stock Units Liability-Classified Cash-Settled Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested service-based awards outstanding at January 1, 2020 9,791 $ 162.96 758,785 $ 122.48 242,288 $ 105.40 Awards granted — $ — 235,231 $ 178.79 56,061 $ 181.59 Awards vested — $ — (273,904 ) $ 104.26 (111,966 ) $ 90.08 Awards forfeited/cancelled — $ — (11,838 ) $ 128.62 (1,365 ) $ 111.01 Unvested service-based awards outstanding at March 31, 2020 9,791 $ 162.96 708,274 $ 148.13 185,018 $ 137.72 As of March 31, 2020 , $1,276 of total remaining unrecognized stock-based compensation cost related to service-based equity-classified restricted stock is expected to be recognized over the weighted-average remaining requisite service period of 2.4 years . As of March 31, 2020 , $89,043 of total remaining unrecognized stock-based compensation cost related to service-based equity-classified restricted stock units (“RSUs”), net of estimated forfeitures, is expected to be recognized over the weighted-average remaining requisite service period of 3.0 years . During the first quarter of 2020, 11,927 equity-classified RSUs were granted in connection with a 2020 acquisition of a business. See Note 2 “Acquisitions” in the condensed consolidated interim financial statements for additional information regarding business acquisitions. During the first quarter of 2020, in connection with a 2019 acquisition of a business, the Company formally issued 5,793 equity-classified RSUs. As of March 31, 2020 , $28,651 of total remaining unrecognized stock-based compensation cost related to service-based liability-classified cash-settled RSUs, net of estimated forfeitures, is expected to be recognized over the weighted-average remaining requisite service period of 2.6 years . During the first quarter of 2020, 6,054 liability-classified cash-settled RSUs were granted in connection with an acquisition of a business. See Note 2 “Acquisitions” in the condensed consolidated interim financial statements for additional information regarding business acquisitions. The liability associated with the service-based liability-classified RSUs as of March 31, 2020 and December 31, 2019 , was $8,253 and $21,902 , respectively, and was classified as Accrued compensation and benefits expenses in the condensed consolidated balance sheets. Performance-Based Awards The table below summarizes activity related to the Company’s equity-classified performance-based awards for the three months ended March 31, 2020 : Equity-Classified Equity-Classified Equity-Settled Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested performance-based awards outstanding at January 1, 2020 9,393 $ 165.87 — $ — Awards granted — $ — 24,836 $ 177.81 Unvested performance-based awards outstanding at March 31, 2020 9,393 $ 165.87 24,836 $ 177.81 As of March 31, 2020 , $934 of total remaining unrecognized stock-based compensation cost related to performance-based restricted stock is expected to be recognized over the weighted-average remaining requisite service period of 3.4 years . During the first quarter of 2020, in connection with a 2019 acquisition of a business, the Company formally issued 24,836 performance-based equity-classified RSUs. As of March 31, 2020 , $2,526 of total remaining unrecognized stock-based compensation cost related to performance-based equity-classified RSUs is expected to be recognized over the weighted-average remaining requisite service period of 3.0 years . During the first quarter of 2020, the Company agreed to issue equity-classified RSUs at future dates worth up to $2,171 in connection with an acquisition of a business. The number of awards to be issued is subject to attainment of specified performance targets in the 2 years after the acquisition date as well as the Company’s stock price at the time of formal issuance. The awards require continued service and vest over 3 years from the date of acquisition.

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES In determining its interim provision for income taxes, the Company uses an estimated annual effective tax rate, which is based on expected annual profit before tax, statutory tax rates and tax planning opportunities available in the various jurisdictions in which the Company operates. Certain significant or unusual items are separately recognized in the quarter in which they occur and can be a source of variability in the effective tax rates from quarter to quarter. The Company’s worldwide effective tax rates for the three months ended March 31, 2020 and 2019 were 11.3% and 5.4% , respectively. The Company’s effective tax rates benefited from excess tax benefits recorded upon vesting or exercise of stock-based awards of $11,697 and $11,513 during the three months ended March 31, 2020 and 2019 , respectively.

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Basic earnings per share is computed by dividing net income available to common shareholders by the weighted-average number of shares of common stock outstanding during the period. For purposes of computing basic earnings per share, any nonvested shares of restricted stock that have been issued by the Company and are contingently returnable to the Company are excluded from the weighted-average number of shares of common stock outstanding during the period. Diluted earnings per share is computed by dividing net income available to common shareholders by the weighted-average number of shares of common stock outstanding during the period increased to include the number of additional shares of common stock that would have been outstanding if the potentially dilutive securities had been issued. Potentially dilutive securities include outstanding stock options, unvested restricted stock and unvested equity-settled RSUs. The dilutive effect of potentially dilutive securities is reflected in diluted earnings per share by application of the treasury stock method. The following table sets forth the computation of basic and diluted earnings per share of common stock as follows: Three Months Ended 2020 2019 Numerator for basic and diluted earnings per share: Net income $ 85,565 $ 60,754 Numerator for basic and diluted earnings per share $ 85,565 $ 60,754 Denominator: Weighted average common shares for basic earnings per share 55,286,747 54,245,133 Net effect of dilutive stock options, restricted stock units and restricted stock awards 2,855,823 2,991,294 Weighted average common shares for diluted earnings per share 58,142,570 57,236,427 Net income per share: Basic $ 1.55 $ 1.12 Diluted $ 1.47 $ 1.06 The number of shares underlying equity-based awards that were excluded from the calculation of diluted earnings per share as their effect would be anti-dilutive was 9,118 and 26,203 during the three months ended March 31, 2020 and 2019, respectively.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Indemnification Obligations — In the normal course of business, the Company is a party to a variety of agreements under which it may be obligated to indemnify the other party for certain matters. These obligations typically arise in contracts where the Company customarily agrees to hold the other party harmless against losses arising from a breach of representations or covenants for certain matters, infringement of third party intellectual property rights, data privacy violations, and certain tortious conduct in the course of providing services. The duration of these indemnifications varies, and in certain cases, is indefinite. The Company is unable to reasonably estimate the maximum potential amount of future payments under these or similar agreements due to the unique facts and circumstances of each agreement and the fact that certain indemnifications provide for no limitation to the maximum potential future payments under the indemnification. Management is not aware of any such matters that would have a material effect on the condensed consolidated financial statements of the Company. Litigation — From time to time, the Company is involved in litigation, claims or other contingencies arising in the ordinary course of business. The Company accrues a liability when a loss is considered probable and the amount can be reasonably estimated. When a material loss contingency is reasonably possible but not probable, the Company does not record a liability, but instead discloses the nature and the amount of the claim, and an estimate of the loss or range of loss, if such an estimate can be made. Legal fees are expensed as incurred. In the opinion of management, the outcome of any existing claims and legal or regulatory proceedings, if decided adversely, is not expected to have a material effect on the Company’s business, financial condition, results of operations or cash flows. Building Acquisition Commitments — During the year ended December 31, 2019, the Company entered into an agreement to purchase office space in Ukraine intended to support the global delivery center in that country. The agreement is subject to completion of construction and other ordinary closing conditions. As of March 31, 2020, the Company has committed to making future payments totaling approximately $36,900 including VAT to the sellers upon transfer of the building.

SEGMENTS INFORMATION

SEGMENTS INFORMATION	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION The Company determines its business segments and reports segment information in accordance with how the Company’s chief operating decision maker (“CODM”) organizes the segments to evaluate performance, allocate resources and make business decisions. Segment results are based on the segment’s revenues and operating profit, where segment operating profit is defined as income from operations before unallocated costs. Expenses included in segment operating profit consist principally of direct selling and delivery costs as well as an allocation of certain shared services expenses. Certain corporate expenses are not allocated to specific segments as these expenses are not controllable at the segment level. Such expenses include certain types of professional fees, non-corporate taxes, compensation to non-employee directors and certain other general and administrative expenses, including compensation of specific groups of non-production employees. In addition, the Company does not allocate amortization of intangible assets acquired through business combinations, goodwill and other asset impairment charges, stock-based compensation expenses, acquisition-related costs and certain other one-time charges. These unallocated amounts are combined with total segment operating profit to arrive at consolidated income from operations as reported below in the reconciliation of segment operating profit to consolidated income before provision for income taxes. Additionally, management has determined that it is not practical to allocate identifiable assets by segment since such assets are used interchangeably among the segments. The Company manages its business primarily based on the managerial responsibility for its client base and market. As managerial responsibility for a particular customer relationship generally correlates with the customer’s geographic location, there is a high degree of similarity between customer locations and the geographic boundaries of the Company’s reportable segments. In some cases, managerial responsibility for a particular customer is assigned to a management team in another region and is usually based on the strength of the relationship between customer executives and particular members of EPAM’s senior management team. In such cases, the customer’s activity would be reported through the management team’s reportable segment. During the fourth quarter of 2019, the Company changed its management reporting of segment revenue to exclude other income. Prior year amounts presented below have been changed to conform to the new presentation. Revenues from external customers and operating profit, before unallocated expenses, by reportable segments for the three months ended March 31, 2020 and 2019 , were as follows: Three Months Ended 2020 2019 Segment revenues: North America $ 391,102 $ 310,689 Europe 236,333 194,065 Russia 23,924 16,579 Total segment revenues $ 651,359 $ 521,333 Segment operating profit: North America $ 78,927 $ 64,457 Europe 31,779 31,785 Russia 519 589 Total segment operating profit $ 111,225 $ 96,831 Intersegment transactions were excluded from the above on the basis that they are neither included in the measure of a segment’s profit and loss results, nor considered by the CODM during the review of segment results. There were no customers that accounted for more than 10% of total segment revenues during the three months ended March 31, 2020 and 2019 . Reconciliation of segment operating profit to consolidated income before provision for income taxes is presented below: Three Months Ended 2020 2019 Total segment operating profit: $ 111,225 $ 96,831 Unallocated amounts: Stock-based compensation expense (11,881 ) (21,856 ) Amortization of intangibles assets (3,135 ) (2,138 ) Other acquisition-related expenses (468 ) (511 ) Other unallocated costs (8,232 ) (7,668 ) Income from operations 87,509 64,658 Interest and other income, net 2,386 3,076 Foreign exchange gain/(loss) 6,524 (3,484 ) Income before provision for income taxes $ 96,419 $ 64,250 Geographic Area Information Long-lived assets include property and equipment, net of accumulated depreciation and amortization, and management has determined that it is not practical to allocate these assets by segment since such assets are used interchangeably among the segments. Physical locations and values of the Company’s long-lived assets are presented below: As of As of Belarus $ 74,766 $ 75,984 Ukraine 27,384 24,652 United States 17,845 15,637 Russia 13,414 17,980 India 6,874 7,443 Poland 4,988 5,029 Hungary 4,887 5,201 China 2,806 3,036 Other 11,707 10,297 Total $ 164,671 $ 165,259 The table below presents information about the Company’s revenues by customer location for the three months ended March 31, 2020 and 2019 : Three Months Ended 2020 2019 United States $ 370,089 $ 299,680 United Kingdom 92,132 65,739 Switzerland 47,222 36,233 Netherlands 25,909 20,616 Russia 21,961 15,892 Germany 20,193 19,154 Canada 17,920 16,972 Other locations 55,933 47,047 Total $ 651,359 $ 521,333

BUSINESS AND SUMMARY OF SIGNI_2

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Nature of Operations	EPAM Systems, Inc. (the “Company” or “EPAM”) is a leading global provider of digital platform engineering and software development services to customers located around the world, primarily in North America, Europe, Asia and Australia. The Company’s industry expertise includes financial services, travel and consumer, software and hi-tech, business information and media, life sciences and healthcare, as well as other emerging industries. The Company is incorporated in Delaware with headquarters in Newtown, Pennsylvania.
Basis of Presentation	Basis of Presentation — The accompanying unaudited condensed consolidated financial statements of EPAM have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP” or “U.S. GAAP”) and Article 10 of Regulation S-X under the Securities Exchange Act of 1934, as amended. The unaudited condensed consolidated financial statements include the financial statements of EPAM Systems, Inc. and its subsidiaries with all intercompany balances and transactions eliminated. These unaudited condensed consolidated financial statements and accompanying notes should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto for the year ended December 31, 2019
Use of Estimates	The preparation of these condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in these condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates, and such differences may be material to the condensed consolidated financial statements. Operating results for the interim periods are not necessarily indicative of results that may be expected to occur for the entire year. In management’s opinion, all adjustments considered necessary for a fair presentation of the accompanying unaudited condensed consolidated financial statements have been included, and all adjustments are of a normal and recurring nature.
Reclassifications	As previously disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, certain amounts recorded in the prior-period consolidated statement of cash flows presented have been reclassified to conform to the current-period financial statement presentation. These reclassifications had no effect on previously reported results of operations.
Adoption of New Accounting Standards	Adoption of New Accounting Standards Unless otherwise discussed below, the adoption of new accounting standards did not have a material impact on the Company’s consolidated financial position, results of operations, changes in stockholders’ equity and cash flows. Measurement of Credit Losses on Financial Instruments — In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments in this update changed how companies measure and recognize credit impairment for many financial assets. The new credit loss model requires companies to immediately recognize an estimate of credit losses expected to occur over the remaining life of the financial assets (including trade receivables) that are in the scope of the update. The update also made amendments to the current impairment model for held-to-maturity and available-for-sale debt securities and certain guarantees. The Company adopted Topic 326, effective January 1, 2020, using a modified-retrospective approach through a cumulative effect adjustment to retained earnings as of the beginning of the period of adoption. As a result of the adoption of Topic 326, the Company recorded an immaterial reduction to its allowance for doubtful accounts for trade receivables and contract assets . Pending Accounting Standards From time to time, new accounting pronouncements are issued by the FASB or other standards-setting bodies that the Company will adopt according to the various timetables the FASB specifies. Unless otherwise discussed below, the Company believes the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position, results of operations and cash flows upon adoption.

FAIR VALUE MEASUREMENTS (Polici

FAIR VALUE MEASUREMENTS (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Fair Value of Financial Instruments	The foreign exchange derivatives are valued using pricing models and discounted cash flow methodologies based on observable foreign exchange data at the measurement date. See Note 5 “Derivative Financial Instruments” in the condensed consolidated interim financial statements for additional information regarding derivative financial instruments. The fair value of the contingent consideration was determined using a probability-weighted expected return method and is based on the expected future payments to be made to the sellers of the acquired businesses in accordance with the provisions outlined in the respective purchase agreements. Although there is significant judgment involved, the Company believes its estimates and assumptions are reasonable. In determining fair value, the Company considered a variety of factors, including future performance of the acquired business using financial projections developed by the Company and market risk assumptions that were derived for revenue growth and earnings before interest and taxes. The Company estimated future payments using the earnout formula and performance targets specified in the purchase agreement and adjusted those estimates to reflect the probability of their achievement. Those weighted-average estimated future payments were then discounted to present value using a rate based on the weighted-average cost of capital of guideline companies. The discount rate used to determine the fair value of contingent consideration for the 2020 Acquisition was 17.5% . Changes in financial projections, market risk assumptions, discount rates or probability assumptions related to achieving the various earnout criteria would result in a change in the fair value of the recorded contingent liabilities. Such changes, if any, are recorded within Interest and other income, net in the Company’s consolidated statement of income and comprehensive income.

DERIVATIVE FINANCIAL INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Reporting of Cash Flow Hedges	The Company records changes in the fair value of its cash flow hedges in accumulated other comprehensive loss in the consolidated balance sheets until the forecasted transaction occurs. When the forecasted transaction occurs, the Company reclassifies the related gain or loss on the cash flow hedge to cost of revenues (exclusive of depreciation and amortization). In the event the underlying forecasted transaction does not occur, or it becomes probable that it will not occur, the Company reclassifies the gain or loss on the related cash flow hedge into income.
Reporting of Derivative Activity	If the Company does not elect hedge accounting, or the contract does not qualify for hedge accounting treatment, the changes in fair value from period to period are recorded in income.

INCOME TAXES INCOME TAXES (Poli

INCOME TAXES INCOME TAXES (Policies)	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	In determining its interim provision for income taxes, the Company uses an estimated annual effective tax rate, which is based on expected annual profit before tax, statutory tax rates and tax planning opportunities available in the various jurisdictions in which the Company operates. Certain significant or unusual items are separately recognized in the quarter in which they occur and can be a source of variability in the effective tax rates from quarter to quarter.

GOODWILL (Tables)

GOODWILL (Tables)	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill By Reportable Segment	Goodwill by reportable segment was as follows: North America Europe Russia Total Balance as of January 1, 2020 $ 113,426 $ 80,873 $ 744 $ 195,043 Other 2019 acquisitions purchase accounting adjustments 210 (42 ) 20 188 2020 Acquisition 6,818 — — 6,818 Effect of net foreign currency exchange rate changes (373 ) (3,078 ) (64 ) (3,515 ) Balance as of March 31, 2020 $ 120,081 $ 77,753 $ 700 $ 198,534

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables present the fair values of the Company’s financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2020 and December 31, 2019: As of March 31, 2020 Balance Level 1 Level 2 Level 3 Foreign exchange derivative assets $ 55 $ — $ 55 $ — Total assets measured at fair value on a recurring basis $ 55 $ — $ 55 $ — Foreign exchange derivative liabilities $ 10,475 $ — $ 10,475 $ — Contingent consideration 5,705 — — 5,705 Total liabilities measured at fair value on a recurring basis $ 16,180 $ — $ 10,475 $ 5,705 As of December 31, 2019 Balance Level 1 Level 2 Level 3 Foreign exchange derivative assets $ 1,910 $ — $ 1,910 $ — Total assets measured at fair value on a recurring basis $ 1,910 $ — $ 1,910 $ — Foreign exchange derivative liabilities $ 243 $ — $ 243 $ — Contingent consideration 10,495 — — 10,495 Total liabilities measured at fair value on a recurring basis $ 10,738 $ — $ 243 $ 10,495
Acquisition-Related Contingent Consideration Roll Forward	A reconciliation of the beginning and ending balances of Level 3 acquisition-related contingent consideration using significant unobservable inputs for the three months ended March 31, 2020 is as follows: Amount Contingent consideration liabilities as of January 1, 2020 $ 10,495 Payment of contingent consideration for previously acquired business (7,869 ) Acquisition date fair value of contingent consideration — 2020 Acquisition (Note 2) 4,042 Changes in fair value of contingent consideration included in Interest and other income, net (438 ) Effect of net foreign currency exchange rate changes (525 ) Contingent consideration liabilities as of March 31, 2020 $ 5,705
Reported Amounts and Estimated Fair Values of the Financial Assets and Liabilities	The following tables present the estimated fair values of the Company’s financial assets and liabilities not measured at fair value on a recurring basis as of the dates indicated: Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 March 31, 2020 Financial Assets: Cash equivalents: Money market funds $ 334,194 $ 334,194 $ 334,194 $ — $ — Time deposits 2 2 — 2 — Total cash equivalents $ 334,196 $ 334,196 $ 334,194 $ 2 $ — Restricted cash $ 1,150 $ 1,150 $ 1,150 $ — $ — Employee loans $ 2,159 $ 2,159 $ — $ — $ 2,159 Financial Liabilities: Borrowings under the 2017 Credit Facility $ 25,011 $ 25,011 $ — $ 25,011 $ — Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 December 31, 2019 Financial Assets: Cash equivalents: Money market funds $ 407,817 $ 407,817 $ 407,817 $ — $ — Time deposits 10,002 10,002 — 10,002 — Total cash equivalents $ 417,819 $ 417,819 $ 407,817 $ 10,002 $ — Restricted cash $ 1,136 $ 1,136 $ 1,136 $ — $ — Employee loans $ 2,434 $ 2,434 $ — $ — $ 2,434 Financial Liabilities: Borrowings under the 2017 Credit Facility $ 25,017 $ 25,017 $ — $ 25,017 $ —

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	The fair value of derivative instruments on the Company’s consolidated balance sheets as of March 31, 2020 and December 31, 2019 were as follows: As of March 31, 2020 As of December 31, 2019 Balance Sheet Classification Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives Foreign exchange forward contracts - Designated as hedging instruments Prepaid expenses and other current assets $ 55 $ 1,910 Accrued expenses and other current liabilities $ 10,475 $ 243
Changes in the Fair Value of Derivative Instruments	The changes in the fair value of foreign currency derivative instruments in our unaudited condensed consolidated statements of income and comprehensive income for the three months ended March 31, 2020 and 2019 were as follows: Three Months Ended 2020 2019 Foreign exchange forward contracts - Designated as hedging instruments: Net (loss)/gain in fair value recognized in accumulated other comprehensive loss $ (12,087 ) $ 3,999 Net loss reclassified from accumulated other comprehensive loss into cost of revenues (exclusive of depreciation and amortization) $ (660 ) $ (452 )

LEASES (Tables)

LEASES (Tables)	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Components of Lease Expenses	During the three months ended March 31, 2020 and 2019, the components of lease expense were as follows: Three Months Ended March 31, Income Statement Classification 2020 2019 Operating lease cost Selling, general and administrative expenses $ 18,863 $ 13,719 Variable lease cost Selling, general and administrative expenses 2,635 2,097 Short-term lease cost Selling, general and administrative expenses 540 898 Total lease cost $ 22,038 $ 16,714
Supplemental Cash Flow Information	Supplemental cash flow information related to leases for the three months ended March 31, 2020 and 2019 was as follows: Three Months Ended Three Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows used for operating leases $ 16,891 $ 14,696 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 31,252 $ 12,825 Non-cash net increase/(decrease) due to lease modifications: Operating lease right-of-use assets $ 4,584 $ (5,174 ) Operating lease liabilities $ 4,573 $ (5,106 )
Weighted Average Lease Terms and Discount Rates	Weighted average remaining lease term and discount rate as of March 31, 2020 and 2019 were as follows: As of March 31, 2020 As of March 31, 2019 Weighted average remaining lease term, in years: Operating leases 6.0 5.9 Weighted average discount rate: Operating leases 3.3 % 4.0 %
Maturity of Operating Lease Liabilities	As of March 31, 2020 , operating lease liabilities will mature as follows: Year ending December 31, Lease Payments 2020 (excluding three months ended March 31, 2020) $ 50,933 2021 59,351 2022 42,665 2023 31,190 2024 26,870 Thereafter 62,988 Total lease payments 273,997 Less: imputed interest (24,577 ) Total $ 249,420

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Outstanding Debt And Borrowing Capacity	The following table presents the outstanding debt and borrowing capacity of the Company under the 2017 Credit Facility: As of As of Outstanding debt $ 25,000 $ 25,000 Interest rate 1.9 % 2.8 % Irrevocable standby letters of credit $ 298 $ 303 Available borrowing capacity $ 274,702 $ 274,697 Current maximum borrowing capacity $ 300,000 $ 300,000

REVENUES (Tables)

REVENUES (Tables)	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenues	The following tables present the disaggregation of the Company’s revenues by customer location, including a reconciliation of the disaggregated revenues with the reportable segments (Note 13 “Segment Information”) for the periods indicated: Three Months Ended March 31, 2020 Reportable Segments North America Europe Russia Consolidated Revenues Customer Locations North America $ 377,784 $ 10,419 $ 1,627 $ 389,830 Europe 10,332 212,722 3 223,057 CIS 2,554 12 22,294 24,860 APAC 432 13,180 — 13,612 Revenues $ 391,102 $ 236,333 $ 23,924 $ 651,359 Three Months Ended March 31, 2019 Reportable Segments North America Europe Russia Consolidated Revenues Customer Locations North America $ 303,745 $ 12,891 $ 16 $ 316,652 Europe 4,747 168,620 141 173,508 CIS 1,739 13 16,422 18,174 APAC 458 12,541 — 12,999 Revenues $ 310,689 $ 194,065 $ 16,579 $ 521,333 The following tables present the disaggregation of the Company’s revenues by industry vertical, including a reconciliation of the disaggregated revenues with the reportable segments (Note 13 “Segment Information”) for the periods indicated: Three Months Ended March 31, 2020 Reportable Segments North America Europe Russia Consolidated Revenues Industry Verticals Business Information & Media $ 80,220 $ 58,146 $ 360 $ 138,726 Financial Services 47,868 67,594 16,181 131,643 Software & Hi-Tech 101,737 18,146 1,966 121,849 Travel & Consumer 54,724 61,067 3,739 119,530 Life Sciences & Healthcare 61,611 7,619 9 69,239 Emerging Verticals 44,942 23,761 1,669 70,372 Revenues $ 391,102 $ 236,333 $ 23,924 $ 651,359 Three Months Ended March 31, 2019 Reportable Segments North America Europe Russia Consolidated Revenues Industry Verticals Business Information & Media $ 62,361 $ 32,531 $ 140 $ 95,032 Financial Services 38,394 61,835 13,032 113,261 Software & Hi-Tech 79,121 20,370 440 99,931 Travel & Consumer 47,000 55,202 2,124 104,326 Life Sciences & Healthcare 50,156 4,556 62 54,774 Emerging Verticals 33,657 19,571 781 54,009 Revenues $ 310,689 $ 194,065 $ 16,579 $ 521,333 The following tables present the disaggregation of the Company’s revenues by contract type including a reconciliation of the disaggregated revenues with the Company’s reportable segments (Note 13 “Segment Information”) for the periods indicated: Three Months Ended March 31, 2020 Reportable Segments North America Europe Russia Consolidated Revenues Contract Types Time-and-material $ 357,263 $ 190,320 $ 13,596 $ 561,179 Fixed-price 31,855 45,255 8,821 85,931 Licensing 1,770 162 1,458 3,390 Other revenues 214 596 49 859 Revenues $ 391,102 $ 236,333 $ 23,924 $ 651,359 Three Months Ended March 31, 2019 Reportable Segments North America Europe Russia Consolidated Revenues Contract Types Time-and-material $ 284,725 $ 168,213 $ 11,272 $ 464,210 Fixed-price 24,740 25,246 5,287 55,273 Licensing 836 398 6 1,240 Other revenues 388 208 14 610 Revenues $ 310,689 $ 194,065 $ 16,579 $ 521,333 Timing of Revenue Recognition The following tables present the timing of revenue recognition for the periods indicated: Three Months Ended March 31, 2020 Reportable Segments North America Europe Russia Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 1,292 $ 162 $ 1,456 $ 2,910 Transferred over time 389,810 236,171 22,468 648,449 Revenues $ 391,102 $ 236,333 $ 23,924 $ 651,359 Three Months Ended March 31, 2019 Reportable Segments North America Europe Russia Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 404 $ 47 $ — $ 451 Transferred over time 310,285 194,018 16,579 520,882 Revenues $ 310,689 $ 194,065 $ 16,579 $ 521,333
Revenue Expected to be Recognized in Future Related to Remaining Performance Obligations	The following table includes the estimated revenues expected to be recognized in the future related to performance obligations that are partially or fully unsatisfied as of March 31, 2020 . The Company applies a practical expedient and does not disclose the value of unsatisfied performance obligations for contracts that (i) have an original expected duration of one year or less and (ii) contracts for which it recognizes revenues at the amount to which it has the right to invoice for services provided: Less than 1 year 1 Year 2 Years 3 Years Total Contract Type Fixed-price $ 14,332 $ 1,443 $ — $ — $ 15,775
Contract Balances	The following table provides information on the classification of contract assets and liabilities in the condensed consolidated balance sheets: As of As of Contract assets included in Trade receivables and contract assets $ 16,176 $ 14,320 Contract liabilities included in Accrued expenses and other current liabilities $ 11,370 $ 9,132

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Components of Stock-Based Compensation Expenses	The following table summarizes the components of stock-based compensation expense recognized in the Company’s condensed consolidated statements of income and comprehensive income for the periods indicated: Three Months Ended 2020 2019 Cost of revenues (exclusive of depreciation and amortization) $ 3,984 $ 12,781 Selling, general and administrative expenses 7,897 9,075 Total $ 11,881 $ 21,856
Stock Options Activity	Stock option activity under the Company’s plans is set forth below: Number of Options Weighted Average Exercise Price Aggregate Intrinsic Value Weighted Average Remaining Contractual Term (in years) Options outstanding at January 1, 2020 3,322,930 $ 50.85 Options granted 144,724 $ 175.22 Options exercised (217,475 ) $ 32.84 Options forfeited/cancelled (7,489 ) $ 121.05 Options outstanding at March 31, 2020 3,242,690 $ 57.45 $ 415,750 4.8 Options vested and exercisable at March 31, 2020 2,856,545 $ 45.67 $ 399,900 4.3 Options expected to vest at March 31, 2020 352,278 $ 143.52 $ 14,845 8.8
Service-based Awards Activity	The table below summarizes activity related to the Company’s equity-classified and liability-classified service-based awards for the three months ended March 31, 2020 : Equity-Classified Restricted Stock Equity-Classified Equity-Settled Restricted Stock Units Liability-Classified Cash-Settled Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested service-based awards outstanding at January 1, 2020 9,791 $ 162.96 758,785 $ 122.48 242,288 $ 105.40 Awards granted — $ — 235,231 $ 178.79 56,061 $ 181.59 Awards vested — $ — (273,904 ) $ 104.26 (111,966 ) $ 90.08 Awards forfeited/cancelled — $ — (11,838 ) $ 128.62 (1,365 ) $ 111.01 Unvested service-based awards outstanding at March 31, 2020 9,791 $ 162.96 708,274 $ 148.13 185,018 $ 137.72
Performance-based Awards Activity	The table below summarizes activity related to the Company’s equity-classified performance-based awards for the three months ended March 31, 2020 : Equity-Classified Equity-Classified Equity-Settled Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested performance-based awards outstanding at January 1, 2020 9,393 $ 165.87 — $ — Awards granted — $ — 24,836 $ 177.81 Unvested performance-based awards outstanding at March 31, 2020 9,393 $ 165.87 24,836 $ 177.81

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per share of common stock as follows: Three Months Ended 2020 2019 Numerator for basic and diluted earnings per share: Net income $ 85,565 $ 60,754 Numerator for basic and diluted earnings per share $ 85,565 $ 60,754 Denominator: Weighted average common shares for basic earnings per share 55,286,747 54,245,133 Net effect of dilutive stock options, restricted stock units and restricted stock awards 2,855,823 2,991,294 Weighted average common shares for diluted earnings per share 58,142,570 57,236,427 Net income per share: Basic $ 1.55 $ 1.12 Diluted $ 1.47 $ 1.06

SEGMENTS INFORMATION (Tables)

SEGMENTS INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Revenues from External Customers and Operating Profit, Before Unallocated Expenses	Revenues from external customers and operating profit, before unallocated expenses, by reportable segments for the three months ended March 31, 2020 and 2019 , were as follows: Three Months Ended 2020 2019 Segment revenues: North America $ 391,102 $ 310,689 Europe 236,333 194,065 Russia 23,924 16,579 Total segment revenues $ 651,359 $ 521,333 Segment operating profit: North America $ 78,927 $ 64,457 Europe 31,779 31,785 Russia 519 589 Total segment operating profit $ 111,225 $ 96,831
Reconciliation of Segment Operating Profit to Consolidated Income Before Provision for Income Taxes	Reconciliation of segment operating profit to consolidated income before provision for income taxes is presented below: Three Months Ended 2020 2019 Total segment operating profit: $ 111,225 $ 96,831 Unallocated amounts: Stock-based compensation expense (11,881 ) (21,856 ) Amortization of intangibles assets (3,135 ) (2,138 ) Other acquisition-related expenses (468 ) (511 ) Other unallocated costs (8,232 ) (7,668 ) Income from operations 87,509 64,658 Interest and other income, net 2,386 3,076 Foreign exchange gain/(loss) 6,524 (3,484 ) Income before provision for income taxes $ 96,419 $ 64,250
Physical Location and Values of Long-Lived Assets	Physical locations and values of the Company’s long-lived assets are presented below: As of As of Belarus $ 74,766 $ 75,984 Ukraine 27,384 24,652 United States 17,845 15,637 Russia 13,414 17,980 India 6,874 7,443 Poland 4,988 5,029 Hungary 4,887 5,201 China 2,806 3,036 Other 11,707 10,297 Total $ 164,671 $ 165,259
Revenues by Customer Location	The table below presents information about the Company’s revenues by customer location for the three months ended March 31, 2020 and 2019 : Three Months Ended 2020 2019 United States $ 370,089 $ 299,680 United Kingdom 92,132 65,739 Switzerland 47,222 36,233 Netherlands 25,909 20,616 Russia 21,961 15,892 Germany 20,193 19,154 Canada 17,920 16,972 Other locations 55,933 47,047 Total $ 651,359 $ 521,333

ACQUISITION (Narrative) (Detail

ACQUISITION (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)
Business Acquisition [Line Items]
Number of acquisitions	1
Revenues	$ 651,359	$ 521,333
2020 Acquisition
Business Acquisition [Line Items]
Purchase price including contingent consideration	14,663
Contingent consideration fair value	4,042
Maximum amount of earnout payable	16,582
Intangible assets	6,300
Revenues	$ 1,043

GOODWILL (Goodwill Roll Forward

GOODWILL (Goodwill Roll Forward) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Goodwill [Roll Forward]
Balance as of January 1, 2020	$ 195,043
Effect of net foreign currency exchange rate changes	(3,515)
Balance as of March 31, 2020	198,534
Other 2019 Acquisitions
Goodwill [Roll Forward]
Purchase accounting adjustments	188
2020 Acquisition
Goodwill [Roll Forward]
Acquisition	6,818
North America
Goodwill [Roll Forward]
Balance as of January 1, 2020	113,426
Effect of net foreign currency exchange rate changes	(373)
Balance as of March 31, 2020	120,081
North America | Other 2019 Acquisitions
Goodwill [Roll Forward]
Purchase accounting adjustments	210
North America | 2020 Acquisition
Goodwill [Roll Forward]
Acquisition	6,818
Europe
Goodwill [Roll Forward]
Balance as of January 1, 2020	80,873
Effect of net foreign currency exchange rate changes	(3,078)
Balance as of March 31, 2020	77,753
Europe | Other 2019 Acquisitions
Goodwill [Roll Forward]
Purchase accounting adjustments	(42)
Europe | 2020 Acquisition
Goodwill [Roll Forward]
Acquisition	0
Russia
Goodwill [Roll Forward]
Balance as of January 1, 2020	744
Effect of net foreign currency exchange rate changes	(64)
Balance as of March 31, 2020	700
Russia | Other 2019 Acquisitions
Goodwill [Roll Forward]
Purchase accounting adjustments	20
Russia | 2020 Acquisition
Goodwill [Roll Forward]
Acquisition	$ 0

GOODWILL (Goodwill Accumulated

GOODWILL (Goodwill Accumulated Impaitment Losses) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
North America
Goodwill [Line Items]
Accumulated impairment loss	$ 0	$ 0
Europe
Goodwill [Line Items]
Accumulated impairment loss	0	0
Russia
Goodwill [Line Items]
Accumulated impairment loss	$ 2,241	$ 2,241

FAIR VALUE MEASUREMENTS (Financ

FAIR VALUE MEASUREMENTS (Financial Assets and Liabilities at Fair Value on Recurring Basis) (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial Assets:
Total assets measured at fair value on a recurring basis	$ 55	$ 1,910
Financial Liabilities:
Contingent consideration	5,705	10,495
Total liabilities measured at fair value on a recurring basis	16,180	10,738
Foreign exchange contracts
Financial Assets:
Derivative assets	55	1,910
Financial Liabilities:
Derivative liabilities	10,475	243
Level 1
Financial Assets:
Total assets measured at fair value on a recurring basis	0	0
Financial Liabilities:
Contingent consideration	0	0
Total liabilities measured at fair value on a recurring basis	0	0
Level 1 | Foreign exchange contracts
Financial Assets:
Derivative assets	0	0
Financial Liabilities:
Derivative liabilities	0	0
Level 2
Financial Assets:
Total assets measured at fair value on a recurring basis	55	1,910
Financial Liabilities:
Contingent consideration	0	0
Total liabilities measured at fair value on a recurring basis	10,475	243
Level 2 | Foreign exchange contracts
Financial Assets:
Derivative assets	55	1,910
Financial Liabilities:
Derivative liabilities	10,475	243
Level 3
Financial Assets:
Total assets measured at fair value on a recurring basis	0	0
Financial Liabilities:
Contingent consideration	5,705	10,495
Total liabilities measured at fair value on a recurring basis	5,705	10,495
Level 3 | Foreign exchange contracts
Financial Assets:
Derivative assets	0	0
Financial Liabilities:
Derivative liabilities	$ 0	$ 0

FAIR VALUE MEASUREMENTS (Acquis

FAIR VALUE MEASUREMENTS (Acquisition-Related Contingent Consideration Roll Forward) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Discount Rate | 2020 Acquisition
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.175
Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration liabilities as of January 1, 2020	$ 10,495
Payment of contingent consideration for previously acquired business	(7,869)
Effect of net foreign currency exchange rate changes	(525)
Contingent consideration liabilities as of March 31, 2020	5,705
Level 3 | Interest and Other Income, Net
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in the fair value of contingent consideration	(438)
Level 3 | 2020 Acquisition
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Acquisition date fair value of contingent consideration	$ 4,042

FAIR VALUE MEASUREMENTS (Estima

FAIR VALUE MEASUREMENTS (Estimated Fair Values of the Financial Assets and Liabilities not Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial Assets:
Restricted Cash		$ 1,136
Fair Value, Nonrecurring | Balance
Financial Assets:
Cash equivalents:	$ 334,196	417,819
Restricted cash	1,150	1,136
Employee loans	2,159	2,434
Fair Value, Nonrecurring | Balance | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	25,011	25,017
Fair Value, Nonrecurring | Estimated Fair Value
Financial Assets:
Cash equivalents:	334,196	417,819
Restricted cash	1,150	1,136
Employee loans	2,159	2,434
Fair Value, Nonrecurring | Estimated Fair Value | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	25,011	25,017
Fair Value, Nonrecurring | Estimated Fair Value | Level 1
Financial Assets:
Cash equivalents:	334,194	407,817
Restricted cash		1,136
Restricted Cash	1,150
Employee loans	0	0
Fair Value, Nonrecurring | Estimated Fair Value | Level 1 | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	0	0
Fair Value, Nonrecurring | Estimated Fair Value | Level 2
Financial Assets:
Cash equivalents:	2	10,002
Restricted cash	0	0
Employee loans	0	0
Fair Value, Nonrecurring | Estimated Fair Value | Level 2 | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	25,011	25,017
Fair Value, Nonrecurring | Estimated Fair Value | Level 3
Financial Assets:
Cash equivalents:	0	0
Restricted cash	0	0
Employee loans	2,159	2,434
Fair Value, Nonrecurring | Estimated Fair Value | Level 3 | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	0	0
Fair Value, Nonrecurring | Money Market Funds | Balance
Financial Assets:
Cash equivalents:	334,194	407,817
Fair Value, Nonrecurring | Money Market Funds | Estimated Fair Value
Financial Assets:
Cash equivalents:	334,194	407,817
Fair Value, Nonrecurring | Money Market Funds | Estimated Fair Value | Level 1
Financial Assets:
Cash equivalents:	334,194	407,817
Fair Value, Nonrecurring | Money Market Funds | Estimated Fair Value | Level 2
Financial Assets:
Cash equivalents:	0	0
Fair Value, Nonrecurring | Money Market Funds | Estimated Fair Value | Level 3
Financial Assets:
Cash equivalents:	0	0
Fair Value, Nonrecurring | Bank Time Deposits | Balance
Financial Assets:
Cash equivalents:	2	10,002
Fair Value, Nonrecurring | Bank Time Deposits | Estimated Fair Value
Financial Assets:
Cash equivalents:	2	10,002
Fair Value, Nonrecurring | Bank Time Deposits | Estimated Fair Value | Level 1
Financial Assets:
Cash equivalents:	0	0
Fair Value, Nonrecurring | Bank Time Deposits | Estimated Fair Value | Level 2
Financial Assets:
Cash equivalents:	2	10,002
Fair Value, Nonrecurring | Bank Time Deposits | Estimated Fair Value | Level 3
Financial Assets:
Cash equivalents:	$ 0	$ 0

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS (Fair Value of Derivative Instruments) (Details) - Foreign exchange contracts - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Financial collateral (including cash collateral) required to be posted	$ 0
Designated as hedging instruments | Cash flow hedging | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	55	$ 1,910
Designated as hedging instruments | Cash flow hedging | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 10,475	$ 243

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS (Changes in the Fair Value of Derivative Instruments) (Details) - Foreign exchange contracts - Designated as hedging instruments - Cash flow hedging - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cost of revenues (exclusive of depreciation and amortization)
Derivative Instruments, Gain (Loss) [Line Items]
Net loss reclassified	$ (660)	$ (452)
Accumulated other comprehensive loss
Derivative Instruments, Gain (Loss) [Line Items]
Net (loss)/gain in fair value	$ (12,087)	$ 3,999

LEASES (Narrative) (Details)

LEASES (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Lessee, Lease, Description [Line Items]
Commitments related to operating lease agreements that have not yet commenced	$ 13,727
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 month 6 days
Lease term of lease agreements that have not yet commenced	1 year 11 months 29 days
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	11 years 1 month 6 days
Lease term of lease agreements that have not yet commenced	10 years 10 months 24 days

LEASES (Components of Lease Exp

LEASES (Components of Lease Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lease, Cost [Line Items]
Total lease cost	$ 22,038	$ 16,714
Selling, general and administrative expenses
Lease, Cost [Line Items]
Operating lease cost	18,863	13,719
Variable lease cost	2,635	2,097
Short-term lease cost	$ 540	$ 898

LEASES (Supplemental Cash Flow

LEASES (Supplemental Cash Flow Information) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used for operating leases	$ 16,891	$ 14,696
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	31,252	12,825
Non-cash net increase/(decrease) due to lease modifications:
Operating lease right-of-use assets	4,584	(5,174)
Operating lease liabilities	$ 4,573	$ (5,106)

LEASES (Weighted Average Lease

LEASES (Weighted Average Lease Terms and Discount Rates) (Details)	Mar. 31, 2020	Dec. 31, 2019
Weighted average remaining lease term, in years:
Operating leases	6 years	5 years 10 months 24 days
Weighted average discount rate:
Operating leases	3.30%	4.00%

LEASES (Maturity of Operating L

LEASES (Maturity of Operating Lease Liabilities) (Details) $ in Thousands	Mar. 31, 2020USD ($)
Leases [Abstract]
2020 (excluding three months ended March 31, 2020)	$ 50,933
2021	59,351
2022	42,665
2023	31,190
2024	26,870
Thereafter	62,988
Total lease payments	273,997
Less: imputed interest	(24,577)
Total	$ 249,420

LONG-TERM DEBT (Details)

LONG-TERM DEBT (Details) - Credit Facility 2017 - USD ($) $ in Thousands	May 24, 2017	Mar. 31, 2020	Dec. 31, 2019
Revolving credit facility
Debt Instrument [Line Items]
Maturity date	May 24, 2022
Revolving credit facility | Overnight Bank Funding Rate
Debt Instrument [Line Items]
Variable interest rate spread	0.50%
Revolving credit facility | Daily LIBOR Rate
Debt Instrument [Line Items]
Variable interest rate spread	1.00%
Revolving credit facility | U.S. dollars
Debt Instrument [Line Items]
Line of credit, current borrowing capacity	$ 300,000
Line of credit, maximum borrowing capacity	400,000
Outstanding debt		$ 25,000	$ 25,000
Interest rate		1.90%	2.80%
Available borrowing capacity		$ 274,702	$ 274,697
Revolving credit facility | U.S. dollars | Maximum
Debt Instrument [Line Items]
Line of credit, current borrowing capacity		300,000	300,000
Revolving credit facility | Other currencies, excluding U.S. dollars
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity	$ 100,000
Standby letters of credit
Debt Instrument [Line Items]
Irrevocable standby letters of credit		$ 298	$ 303

REVENUES (Disaggregation of Rev

REVENUES (Disaggregation of Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 651,359	$ 521,333
Transferred at a point of time
Disaggregation of Revenue [Line Items]
Revenues	2,910	451
Transferred over time
Disaggregation of Revenue [Line Items]
Revenues	648,449	520,882
Time-and-material
Disaggregation of Revenue [Line Items]
Revenues	561,179	464,210
Fixed-price
Disaggregation of Revenue [Line Items]
Revenues	85,931	55,273
Licensing
Disaggregation of Revenue [Line Items]
Revenues	3,390	1,240
Other revenues
Disaggregation of Revenue [Line Items]
Revenues	859	610
Business Information & Media
Disaggregation of Revenue [Line Items]
Revenues	138,726	95,032
Financial Services
Disaggregation of Revenue [Line Items]
Revenues	131,643	113,261
Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Revenues	121,849	99,931
Travel & Consumer
Disaggregation of Revenue [Line Items]
Revenues	119,530	104,326
Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Revenues	69,239	54,774
Emerging Verticals
Disaggregation of Revenue [Line Items]
Revenues	70,372	54,009
North America
Disaggregation of Revenue [Line Items]
Revenues	389,830	316,652
Europe
Disaggregation of Revenue [Line Items]
Revenues	223,057	173,508
CIS
Disaggregation of Revenue [Line Items]
Revenues	24,860	18,174
APAC
Disaggregation of Revenue [Line Items]
Revenues	13,612	12,999
North America
Disaggregation of Revenue [Line Items]
Revenues	391,102	310,689
North America | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Revenues	1,292	404
North America | Transferred over time
Disaggregation of Revenue [Line Items]
Revenues	389,810	310,285
North America | Time-and-material
Disaggregation of Revenue [Line Items]
Revenues	357,263	284,725
North America | Fixed-price
Disaggregation of Revenue [Line Items]
Revenues	31,855	24,740
North America | Licensing
Disaggregation of Revenue [Line Items]
Revenues	1,770	836
North America | Other revenues
Disaggregation of Revenue [Line Items]
Revenues	214	388
North America | Business Information & Media
Disaggregation of Revenue [Line Items]
Revenues	80,220	62,361
North America | Financial Services
Disaggregation of Revenue [Line Items]
Revenues	47,868	38,394
North America | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Revenues	101,737	79,121
North America | Travel & Consumer
Disaggregation of Revenue [Line Items]
Revenues	54,724	47,000
North America | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Revenues	61,611	50,156
North America | Emerging Verticals
Disaggregation of Revenue [Line Items]
Revenues	44,942	33,657
North America | North America
Disaggregation of Revenue [Line Items]
Revenues	377,784	303,745
North America | Europe
Disaggregation of Revenue [Line Items]
Revenues	10,332	4,747
North America | CIS
Disaggregation of Revenue [Line Items]
Revenues	2,554	1,739
North America | APAC
Disaggregation of Revenue [Line Items]
Revenues	432	458
Europe
Disaggregation of Revenue [Line Items]
Revenues	236,333	194,065
Europe | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Revenues	162	47
Europe | Transferred over time
Disaggregation of Revenue [Line Items]
Revenues	236,171	194,018
Europe | Time-and-material
Disaggregation of Revenue [Line Items]
Revenues	190,320	168,213
Europe | Fixed-price
Disaggregation of Revenue [Line Items]
Revenues	45,255	25,246
Europe | Licensing
Disaggregation of Revenue [Line Items]
Revenues	162	398
Europe | Other revenues
Disaggregation of Revenue [Line Items]
Revenues	596	208
Europe | Business Information & Media
Disaggregation of Revenue [Line Items]
Revenues	58,146	32,531
Europe | Financial Services
Disaggregation of Revenue [Line Items]
Revenues	67,594	61,835
Europe | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Revenues	18,146	20,370
Europe | Travel & Consumer
Disaggregation of Revenue [Line Items]
Revenues	61,067	55,202
Europe | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Revenues	7,619	4,556
Europe | Emerging Verticals
Disaggregation of Revenue [Line Items]
Revenues	23,761	19,571
Europe | North America
Disaggregation of Revenue [Line Items]
Revenues	10,419	12,891
Europe | Europe
Disaggregation of Revenue [Line Items]
Revenues	212,722	168,620
Europe | CIS
Disaggregation of Revenue [Line Items]
Revenues	12	13
Europe | APAC
Disaggregation of Revenue [Line Items]
Revenues	13,180	12,541
Russia
Disaggregation of Revenue [Line Items]
Revenues	23,924	16,579
Russia | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Revenues	1,456	0
Russia | Transferred over time
Disaggregation of Revenue [Line Items]
Revenues	22,468	16,579
Russia | Time-and-material
Disaggregation of Revenue [Line Items]
Revenues	13,596	11,272
Russia | Fixed-price
Disaggregation of Revenue [Line Items]
Revenues	8,821	5,287
Russia | Licensing
Disaggregation of Revenue [Line Items]
Revenues	1,458	6
Russia | Other revenues
Disaggregation of Revenue [Line Items]
Revenues	49	14
Russia | Business Information & Media
Disaggregation of Revenue [Line Items]
Revenues	360	140
Russia | Financial Services
Disaggregation of Revenue [Line Items]
Revenues	16,181	13,032
Russia | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Revenues	1,966	440
Russia | Travel & Consumer
Disaggregation of Revenue [Line Items]
Revenues	3,739	2,124
Russia | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Revenues	9	62
Russia | Emerging Verticals
Disaggregation of Revenue [Line Items]
Revenues	1,669	781
Russia | North America
Disaggregation of Revenue [Line Items]
Revenues	1,627	16
Russia | Europe
Disaggregation of Revenue [Line Items]
Revenues	3	141
Russia | CIS
Disaggregation of Revenue [Line Items]
Revenues	22,294	16,422
Russia | APAC
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0

REVENUES (Revenue Expected to b

REVENUES (Revenue Expected to be Recognized in Future Related to Remaining Performance Obligations) (Details) - Fixed-price $ in Thousands	Mar. 31, 2020USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenue related to partially or fully unsatisfied performance obligations	$ 15,775
Less than 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenue related to partially or fully unsatisfied performance obligations	14,332
1 Year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenue related to partially or fully unsatisfied performance obligations	1,443
2 Years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenue related to partially or fully unsatisfied performance obligations	0
3 Years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenue related to partially or fully unsatisfied performance obligations	$ 0

REVENUES (Contract Balances) (D

REVENUES (Contract Balances) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Change in Contract with Customer, Liability [Abstract]
Revenue recognized	$ 6,537
Revenues from performance obligations satisfied in previous period	5,814	$ 1,704
Trade receivables and contract assets
Change in Contract with Customer, Liability [Abstract]
Contract assets	16,176		$ 14,320
Accrued expenses and other current liabilities
Change in Contract with Customer, Liability [Abstract]
Contract liabilties	$ 11,370		$ 9,132

STOCK-BASED COMPENSATION (Compo

STOCK-BASED COMPENSATION (Components of Stock-Based Compensation Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 11,881	$ 21,856
Cost of revenues (exclusive of depreciation and amortization)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	3,984	12,781
Selling, general and administrative expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 7,897	$ 9,075

STOCK-BASED COMPENSATION (Stock

STOCK-BASED COMPENSATION (Stock Options Activity) (Details) - Employee Stock Option $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)$ / sharesshares
Number of Options
Options outstanding at January 1, 2020 | shares	3,322,930
Options granted | shares	144,724
Options exercised | shares	(217,475)
Options forfeited/cancelled | shares	(7,489)
Options outstanding at March 31, 2020 | shares	3,242,690
Options vested and exercisable at March 31, 2020 | shares	2,856,545
Options expected to vest at March 31, 2020 | shares	352,278
Weighted Average Exercise Price
Options outstanding at January 1, 2020 | $ / shares	$ 50.85
Options granted | $ / shares	175.22
Options exercised | $ / shares	32.84
Options forfeited/cancelled | $ / shares	121.05
Options outstanding at March 31, 2020 | $ / shares	57.45
Options vested and exercisable at March 31, 2020 | $ / shares	45.67
Options expected to vest at March 31, 2020 | $ / shares	$ 143.52
Aggregate Intrinsic Value
Options outstanding at March 31, 2020 | $	$ 415,750
Options vested and exercisable at March 31, 2020 | $	399,900
Options expected to vest at March 31, 2020 | $	$ 14,845
Weighted Average Remaining Contractual Term (in years)
Options outstanding at March 31, 2020	4 years 9 months 18 days
Options vested and exercisable at March 31, 2020	4 years 3 months 18 days
Options expected to vest at March 31, 2020	8 years 9 months 18 days

STOCK-BASED COMPENSATION (Sto_2

STOCK-BASED COMPENSATION (Stock Option Additional Information) (Details) - Employee Stock Option $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 18,416
Weighted-average remaining requisite service period	3 years 1 month 6 days

STOCK-BASED COMPENSATION (Restr

STOCK-BASED COMPENSATION (Restricted Stock and Restricted Stock Units Activity) (Details)	3 Months Ended
	Mar. 31, 2020$ / sharesshares
Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock
Number of Shares
Unvested awards outstanding at January 1, 2020	9,791
Awards granted	0
Awards vested	0
Awards forfeited/cancelled	0
Unvested awards outstanding at March 31, 2020	9,791
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2020 | $ / shares	$ 162.96
Awards granted | $ / shares	0
Awards vested | $ / shares	0
Awards forfeited/cancelled | $ / shares	0
Unvested awards outstanding at March 31, 2020 | $ / shares	$ 162.96
Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2020	758,785
Awards granted	235,231
Awards vested	(273,904)
Awards forfeited/cancelled	(11,838)
Unvested awards outstanding at March 31, 2020	708,274
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2020 | $ / shares	$ 122.48
Awards granted | $ / shares	178.79
Awards vested | $ / shares	104.26
Awards forfeited/cancelled | $ / shares	128.62
Unvested awards outstanding at March 31, 2020 | $ / shares	$ 148.13
Service Period | Liability Classified Award | Cash-Settled Award | Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2020	242,288
Awards granted	56,061
Awards vested	(111,966)
Awards forfeited/cancelled	(1,365)
Unvested awards outstanding at March 31, 2020	185,018
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2020 | $ / shares	$ 105.40
Awards granted | $ / shares	181.59
Awards vested | $ / shares	90.08
Awards forfeited/cancelled | $ / shares	111.01
Unvested awards outstanding at March 31, 2020 | $ / shares	$ 137.72
Performance Target | Equity Classified Award | Equity-Settled Award | Restricted Stock
Number of Shares
Unvested awards outstanding at January 1, 2020	9,393
Awards granted	0
Unvested awards outstanding at March 31, 2020	9,393
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2020 | $ / shares	$ 165.87
Awards granted | $ / shares	0
Unvested awards outstanding at March 31, 2020 | $ / shares	$ 165.87
Performance Target | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2020	0
Awards granted	24,836
Unvested awards outstanding at March 31, 2020	24,836
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2020 | $ / shares	$ 0
Awards granted | $ / shares	177.81
Unvested awards outstanding at March 31, 2020 | $ / shares	$ 177.81
2020 Acquisition | Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Number of Shares
Awards granted	11,927
2020 Acquisition | Service Period | Liability Classified Award | Cash-Settled Award | Restricted Stock Units
Number of Shares
Awards granted	6,054
2019 Acquisitions | Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Number of Shares
Awards granted	5,793
2019 Acquisitions | Performance Target | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Number of Shares
Awards granted	24,836

STOCK-BASED COMPENSATION (Res_2

STOCK-BASED COMPENSATION (Restricted Stock and Restricted Stock Units Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 1,276
Weighted-average remaining requisite service period	2 years 4 months 24 days
Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 89,043
Weighted-average remaining requisite service period	3 years
Service Period | Liability Classified Award | Cash-Settled Award | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 28,651
Weighted-average remaining requisite service period	2 years 7 months 6 days
Performance Target | Equity Classified Award | Equity-Settled Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 934
Weighted-average remaining requisite service period	3 years 4 months 24 days
Performance Target | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 2,526
Weighted-average remaining requisite service period	3 years
Accrued compensation and benefits expenses | Service Period | Liability Classified Award | Cash-Settled Award | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Liability associated with RSUs	$ 8,253	$ 21,902
2020 Acquisition | Performance Target | Equity Classified Award | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award value	$ 2,171
Estimated future operating results, period	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Effective tax rate	11.30%	5.40%
Excess tax benefit	$ 11,697	$ 11,513

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator for basic and diluted earnings per share:
Net income	$ 85,565	$ 60,754
Numerator for basic and diluted earnings per share	$ 85,565	$ 60,754
Denominator:
Weighted average common shares for basic earnings per share	55,286,747	54,245,133
Net effect of dilutive stock options, restricted stock units and restricted stock awards	2,855,823	2,991,294
Weighted average common shares for diluted earnings per share	58,142,570	57,236,427
Net income per share:
Basic (in dollars per share)	$ 1.55	$ 1.12
Diluted (in dollars per share)	$ 1.47	$ 1.06
Anti-dilutive options not included in the calculation (in shares)	9,118	26,203

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Building Acquisition Commitments) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Office Space Purchase Commitment | Ukraine
Other Commitments [Line Items]
Total commitment amount	$ 36,900

SEGMENTS INFORMATION (Revenues

SEGMENTS INFORMATION (Revenues from External Customers and Operating Profit Before Unallocated Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 651,359	$ 521,333
Segment operating profit	87,509	64,658
North America
Segment Reporting Information [Line Items]
Revenues	391,102	310,689
Segment operating profit	78,927	64,457
Europe
Segment Reporting Information [Line Items]
Revenues	236,333	194,065
Segment operating profit	31,779	31,785
Russia
Segment Reporting Information [Line Items]
Revenues	23,924	16,579
Segment operating profit	519	589
Operating Segments
Segment Reporting Information [Line Items]
Segment operating profit	$ 111,225	$ 96,831

SEGMENTS INFORMATION (Major Cus

SEGMENTS INFORMATION (Major Customers) (Details)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue, Segment Benchmark [Member] | Customer Concentration Risk | Operating Segments
Revenue, Major Customer [Line Items]
Number of customers	0	0

SEGMENTS INFORMATION (Reconcili

SEGMENTS INFORMATION (Reconciliation of Segment Operating Profit to Consolidated Income Before Provision for Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment operating profit	$ 87,509	$ 64,658
Stock-based compensation expense	11,881	21,856
Interest and other income, net	2,386	3,076
Foreign exchange gain/(loss)	6,524	(3,484)
Income before provision for income taxes	96,419	64,250
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment operating profit	111,225	96,831
Unallocated Amounts
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Stock-based compensation expense	(11,881)	(21,856)
Amortization of intangibles assets	(3,135)	(2,138)
Other acquisition-related expenses	(468)	(511)
Other unallocated costs	$ (8,232)	$ (7,668)

SEGMENTS INFORMATION (Physical

SEGMENTS INFORMATION (Physical Location and Values of Long-Lived Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 164,671	$ 165,259
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	74,766	75,984
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	27,384	24,652
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	17,845	15,637
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	13,414	17,980
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	6,874	7,443
Poland
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	4,988	5,029
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	4,887	5,201
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,806	3,036
Other
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 11,707	$ 10,297

SEGMENTS INFORMATION (Revenue_2

SEGMENTS INFORMATION (Revenues by Customer Location) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 651,359	$ 521,333
United States
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	370,089	299,680
United Kingdom
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	92,132	65,739
Switzerland
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	47,222	36,233
Netherlands
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	25,909	20,616
Russia
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	21,961	15,892
Germany
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	20,193	19,154
Canada
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	17,920	16,972
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 55,933	$ 47,047