EPAM Systems (EPAM) 10-Q 8 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 31, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2019
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		54,850,289
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 777,365	$ 770,560
Accounts receivable, net of allowance of $1,882 and $1,557, respectively	343,864	297,685
Unbilled revenues	135,786	104,652
Prepaid expenses and other current assets	28,808	26,171
Total current assets	1,285,823	1,199,068
Property and equipment, net	111,175	102,646
Operating lease right-of-use assets	210,447	0
Intangible assets, net	53,821	57,065
Goodwill	179,214	166,832
Deferred tax assets	69,734	69,983
Other noncurrent assets	21,237	16,208
Total assets	1,931,451	1,611,802
Current liabilities
Accounts payable	6,043	7,444
Accrued expenses and other current liabilities	96,026	127,937
Due to employees	64,032	49,683
Deferred compensation due to employees	7,928	9,920
Taxes payable, current	50,156	67,845
Operating lease liabilities, current	48,429	0
Total current liabilities	272,614	262,829
Long-term debt	25,000	25,031
Taxes payable, noncurrent	43,650	43,685
Operating lease liabilities, noncurrent	158,137	0
Other noncurrent liabilities	9,803	17,661
Total liabilities	509,204	349,206
Commitments and contingencies (Note 12)
Stockholders’ equity
Common stock, $0.001 par value; 160,000,000 authorized; 54,799,024 and 54,099,927 shares issued, 54,779,289 and 54,080,192 shares outstanding at June 30, 2019 and December 31, 2018, respectively	55	54
Additional paid-in capital	574,619	544,700
Retained earnings	879,064	759,533
Treasury stock	(177)	(177)
Accumulated other comprehensive loss	(31,314)	(41,514)
Total stockholders’ equity	1,422,247	1,262,596
Total liabilities and stockholders’ equity	$ 1,931,451	$ 1,611,802

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Accounts receivable allowance	$ 1,882	$ 1,557
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)	54,799,024	54,099,927
Common stock, shares outstanding (in shares)	54,779,289	54,080,192

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenues	$ 551,587	$ 445,647	$ 1,072,920	$ 869,795
Operating expenses:
Cost of revenues (exclusive of depreciation and amortization)	355,915	289,175	700,604	566,809
Selling, general and administrative expenses	111,762	93,273	213,548	182,914
Depreciation and amortization expense	11,028	8,962	21,228	17,138
Income from operations	72,882	54,237	137,540	102,934
Interest and other income, net	1,190	1,052	4,266	501
Foreign exchange (loss)/gain	(3,562)	1,830	(7,046)	1,583
Income before provision for/(benefit from) income taxes	70,510	57,119	134,760	105,018
Provision for/(benefit from) income taxes	11,733	6,864	15,229	(9,655)
Net income	58,777	50,255	119,531	114,673
Foreign currency translation adjustments, net of tax	2,620	(15,834)	5,563	(12,525)
Unrealized gain/(loss) on cash-flow hedging instruments, net of tax	1,537	(2,076)	4,637	(2,007)
Comprehensive income	$ 62,934	$ 32,345	$ 129,731	$ 100,141
Net income per share:
Basic (in dollars per share)	$ 1.07	$ 0.94	$ 2.19	$ 2.15
Diluted (in dollars per share)	$ 1.02	$ 0.89	$ 2.08	$ 2.03
Shares used in calculation of net income per share:
Basic (in shares)	54,681,959	53,517,124	54,464,753	53,299,038
Diluted (in shares)	57,614,284	56,587,009	57,426,563	56,414,986

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY Statement - USD ($) $ in Thousands	Total	Common Stock	Common StockRestricted Stock Units (RSUs)	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Balance, beginning of period (in shares) at Dec. 31, 2017		52,983,685
Balance, beginning of period at Dec. 31, 2017	$ 974,947	$ 53		$ 473,874	$ 518,820		$ (17,623)
Treasury stock, beginning of period (in shares) at Dec. 31, 2017						19,735
Treasury stock, beginning period at Dec. 31, 2017						$ (177)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures [Abstract]
Stock units vested (in shares)			186,327
Stock units withheld for employee taxes	(6,986)			(6,986)
Stock units withheld for employee taxes (in shares)			(61,950)
Proceeds from stock options exercises	7,649			7,649
Proceeds from stock options exercises (in shares)		198,936
Stock-based compensation expense	11,485			11,485
Foreign currency translation adjustments, net of tax	3,309						3,309
Change in unrealized gains and loss on cash-flow hedges, net of tax	69						69
Cumulative effect of the adoption of ASU | ASU 2014-09	457				457
Net income	64,418				64,418
Balance, end of period (in shares) at Mar. 31, 2018		53,306,998
Balance, end of period at Mar. 31, 2018	1,055,348	$ 53		486,022	583,695		(14,245)
Treasury stock, end of period (in shares) at Mar. 31, 2018						19,735
Treasury stock, end of period at Mar. 31, 2018						$ (177)
Balance, beginning of period (in shares) at Dec. 31, 2017		52,983,685
Balance, beginning of period at Dec. 31, 2017	974,947	$ 53		473,874	518,820		(17,623)
Treasury stock, beginning of period (in shares) at Dec. 31, 2017						19,735
Treasury stock, beginning period at Dec. 31, 2017						$ (177)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures [Abstract]
Net income	114,673
Balance, end of period (in shares) at Jun. 30, 2018		53,685,267
Balance, end of period at Jun. 30, 2018	1,112,803	$ 54		511,131	633,950		(32,155)
Treasury stock, end of period (in shares) at Jun. 30, 2018						19,735
Treasury stock, end of period at Jun. 30, 2018						$ (177)
Balance, beginning of period (in shares) at Mar. 31, 2018		53,306,998
Balance, beginning of period at Mar. 31, 2018	1,055,348	$ 53		486,022	583,695		(14,245)
Treasury stock, beginning of period (in shares) at Mar. 31, 2018						19,735
Treasury stock, beginning period at Mar. 31, 2018						$ (177)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures [Abstract]
Stock units vested (in shares)			12,348
Stock units withheld for employee taxes	(224)			(224)
Stock units withheld for employee taxes (in shares)			(1,942)
Proceeds from stock options exercises	14,648	$ 1		14,647
Proceeds from stock options exercises (in shares)		367,863
Stock-based compensation expense	10,686			10,686
Foreign currency translation adjustments, net of tax	(15,834)						(15,834)
Change in unrealized gains and loss on cash-flow hedges, net of tax	(2,076)						(2,076)
Net income	50,255				50,255
Balance, end of period (in shares) at Jun. 30, 2018		53,685,267
Balance, end of period at Jun. 30, 2018	$ 1,112,803	$ 54		511,131	633,950		(32,155)
Treasury stock, end of period (in shares) at Jun. 30, 2018						19,735
Treasury stock, end of period at Jun. 30, 2018						$ (177)
Balance, beginning of period (in shares) at Dec. 31, 2018	54,080,192	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 loss 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, 2018	54,080,192	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]
Net income	$ 119,531
Balance, end of period (in shares) at Jun. 30, 2019	54,779,289	54,779,289
Balance, end of period at Jun. 30, 2019	$ 1,422,247	$ 55		574,619	879,064		(31,314)
Treasury stock, end of period (in shares) at Jun. 30, 2019						19,735
Treasury stock, end of period at Jun. 30, 2019						$ (177)
Balance, beginning of period (in shares) at Mar. 31, 2019		54,564,508
Balance, beginning of period at Mar. 31, 2019	1,338,225	$ 54		553,532	820,287		(35,471)
Treasury stock, beginning of period (in shares) at Mar. 31, 2019						19,735
Treasury stock, beginning period at Mar. 31, 2019						$ (177)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures [Abstract]
Stock units vested (in shares)			11,757
Stock units withheld for employee taxes	(363)			(363)
Stock units withheld for employee taxes (in shares)			(2,084)
Proceeds from stock options exercises	10,584	$ 1		10,583
Proceeds from stock options exercises (in shares)		205,108
Stock-based compensation expense	10,867			10,867
Foreign currency translation adjustments, net of tax	2,620						2,620
Change in unrealized gains and loss on cash-flow hedges, net of tax	1,537						1,537
Net income	$ 58,777				58,777
Balance, end of period (in shares) at Jun. 30, 2019	54,779,289	54,779,289
Balance, end of period at Jun. 30, 2019	$ 1,422,247	$ 55		$ 574,619	$ 879,064		$ (31,314)
Treasury stock, end of period (in shares) at Jun. 30, 2019						19,735
Treasury stock, end of period at Jun. 30, 2019						$ (177)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 119,531	$ 114,673
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	21,228	17,138
Operating lease right-of-use assets amortization expense	25,732	0
Bad debt expense	167	1,529
Deferred taxes	(1,193)	(27,581)
Stock-based compensation expense	37,553	31,406
Other	3,938	(2,099)
Changes in assets and liabilities:
Accounts receivable	(44,582)	(15,051)
Unbilled revenues	(30,750)	(35,334)
Prepaid expenses and other assets	1,690	(4,495)
Accounts payable	(2,069)	1,008
Accrued expenses and other liabilities	(34,420)	(15,861)
Operating lease liabilities	(25,705)	0
Due to employees	(4,781)	1,351
Taxes payable	(22,512)	105
Net cash provided by operating activities	43,827	66,789
Cash flows from investing activities:
Purchases of property and equipment	(25,025)	(19,303)
Acquisition of businesses, net of cash acquired (Note 2)	(16,240)	(50,264)
Other investing activities, net	(6,180)	1,253
Net cash used in investing activities	(47,445)	(68,314)
Cash flows from financing activities:
Proceeds from stock option exercises	22,415	22,368
Payments of withholding taxes related to net share settlements of restricted stock units	(13,084)	(6,696)
Repayment of debt	(6)	(3,478)
Acquisition of businesses, contingent consideration	(1,104)	0
Other financing activities, net	(13)	(603)
Net cash provided by financing activities	8,208	11,591
Effect of exchange rate changes on cash, cash equivalents and restricted cash	2,248	(7,645)
Net increase in cash, cash equivalents and restricted cash	6,838	2,421
Cash, cash equivalents and restricted cash, beginning of period	771,711	582,855
Cash, cash equivalents and restricted cash, end of period	$ 778,549	$ 585,276

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOW (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Cash and cash equivalents	$ 777,365	$ 770,560
Total restricted cash	1,184	1,151
Total cash, cash equivalents, restricted cash and restricted cash equivalents	778,549	771,711
Prepaid and other current assets
Restricted cash	14	14
Other noncurrent assets
Restricted cash	$ 1,170	$ 1,137

BUSINESS AND SUMMARY OF SIGNIFI

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 2019
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, PA. 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 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, 2018 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. Adoption of New Accounting Standards Unless otherwise discussed below, the adoption of new accounting standards did not have an impact on the Company’s consolidated financial position, results of operations, changes in stockholders’ equity and cash flows. Leases — In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-02, Leases (“Topic 842”). The standard supersedes previously existing lease guidance (“Topic 840”) and requires entities to recognize all leases, with the exception of leases with a term of twelve months or less, on the balance sheet as right-of-use assets (“RoU Assets”) and lease liabilities. The guidance also changes disclosure requirements with a focus on providing information that will enable users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The Company adopted Topic 842, effective January 1, 2019, using the optional transition approach, which allows the Company to apply the provisions of the standard at the effective date without adjusting the comparable periods and carry forward disclosures under previously existing guidance for those periods presented within the Company’s financial statements. The Company determines if an arrangement is a lease or contains a lease at inception. The Company performs an assessment and classifies the lease as either an operating lease or a financing lease at the lease commencement date with a right-of-use asset and a lease liability recognized in the statement of financial position under both classifications. The Company does not have finance leases that are material to the Company’s condensed consolidated financial statements. Lease liabilities are initially measured at the present value of lease payments not yet paid. The present value is determined by applying the readily determinable rate implicit in the lease or, if not available, the incremental borrowing rate of the lessee. The Company determines the incremental borrowing rate of the lessee on a lease-by-lease basis by developing an estimated centralized U.S. dollar borrowing rate for a fully collateralized obligation with a term similar to the lease term, and adjusts the rate to reflect the incremental risk associated with the currency in which the lease is denominated. Lease agreements of the Company may include options to extend or terminate the lease and the Company includes such options in the lease term when it is reasonably certain that the Company will exercise that option. RoU Assets are recognized based on the initial measurement of the lease liabilities plus initial direct costs less lease incentives and, according to the guidance for long-lived assets, RoU Assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Lease expense for operating leases is recognized on a straight-line basis over the lease term. The Company elected a practical expedient to account for lease and non-lease components together as a single lease component. The Company also elected the short-term lease recognition exemption for all classes of lease assets with an original term of twelve months or less. As part of the transition, the Company elected a package of practical expedients allowing it to carry forward historical accounting for any expired or existing contracts that are or contain lease contracts, including classification of such contracts and initial direct costs associated with them. The adoption of Topic 842 on January 1, 2019 resulted in the recognition of RoU Assets for operating leases of $177,597 and operating lease liabilities of $173,863 . The adoption of Topic 842 did not have an impact on the condensed consolidated statement of income and comprehensive income, condensed consolidated statement of changes in stockholders’ equity or the condensed consolidated statement of cash flows. See Note 6 “Leases” in the condensed consolidated interim financial statements for additional information regarding leases. 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. Measurement of Credit Losses on Financial Instruments — Effective January 1, 2020, the Company will be required to adopt the amended guidance of FASB ASC Topic 326, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , (with early adoption permitted effective January 1, 2019.) The amendments in this update change how companies measure and recognize credit impairment for many financial assets. The new expected credit loss model will require 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. Entities are required to adopt the standard using a modified-retrospective approach through a cumulative effect adjustment to retained earnings as of the beginning of the period of adoption. The Company has not yet completed its assessment of the impact of the new guidance on its consolidated financial statements and will adopt the standard on January 1, 2020.

ACQUISITIONS

ACQUISITIONS	6 Months Ended
	Jun. 30, 2019
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS Continuum — On March 15, 2018 , the Company acquired all of the outstanding equity of Continuum Innovation LLC together with its subsidiaries (“Continuum”) to enhance the Company’s consulting capabilities as well as its digital and service design practices. Continuum, headquartered in Boston with offices located in Milan, Seoul, and Shanghai, focuses on four practices including strategy, physical and digital design, technology and its Made Real Lab. The acquisition of Continuum added approximately 125 design consultants to the Company’s headcount. In connection with the Continuum acquisition, the Company paid $52,515 of cash and committed to making a cash earnout payment with a maximum amount payable of $3,135 , subject to attainment of specified performance targets in the 12 months after the acquisition date. Think — On November 1, 2018 , the Company acquired all of the equity interests of Think Limited (“Think”), a digital transformation agency headquartered in London, UK. This acquisition was intended to strengthen EPAM’s digital and organizational consulting capabilities in the UK and Western European markets and enhance the Company’s global product and design offerings. In connection with the Think acquisition, the Company paid $26,254 of cash and committed to making a cash earnout payment with a maximum amount payable of $8,156 , subject to attainment of specified performance targets in the 12 months after the acquisition date. test IO — On April 30, 2019 , the Company acquired 100% of the equity interests of a crowdtesting company, test IO GmbH, and its subsidiary (“test IO”). In connection with the test IO acquisition, the Company paid $17,204 of cash. The following table summarizes the estimated fair values of the assets acquired and liabilities assumed as of the date of acquisition and updated for any changes as of June 30, 2019 for each respective acquisition: Continuum Think test IO As of March 15, 2018 As of November 1, 2018 As of April 30, 2019 Cash and cash equivalents $ 2,251 $ 2,344 $ 968 Accounts receivable 6,676 2,259 727 Unbilled revenues 2,463 284 — Prepaid expenses and other current assets 936 609 96 Goodwill 26,617 22,482 11,883 Intangible assets 14,450 6,882 6,364 Property and equipment and other noncurrent assets 8,902 642 154 Total assets acquired $ 62,295 $ 35,502 $ 20,192 Accounts payable, accrued expenses and other current liabilities $ 2,745 $ 2,205 $ 1,251 Due to employees 1,001 13 7 Long-term debt 3,220 — — Other noncurrent liabilities 490 1,040 1,730 Total liabilities assumed $ 7,456 $ 3,258 $ 2,988 Net assets acquired $ 54,839 $ 32,244 $ 17,204 During 2018, the Company adjusted initially recognized intangible assets acquired with Continuum and their useful lives as well as recognized an additional intangible asset in the form of a favorable lease, removed a noncurrent liability associated with an initially recognized unfavorable lease and revised the initial fair value of contingent consideration. The Company also finalized a working capital adjustment that resulted in cash collection in the amount of $76 reducing the original amount of the net assets acquired. These adjustments resulted in a corresponding decrease to the originally recognized value of acquired goodwill. During the first quarter of 2019, the Company finalized the fair value of the assets acquired and liabilities assumed in the acquisition of Continuum and no additional adjustments were recorded. For the acquisitions of Think and test IO, estimated fair values of the assets acquired and liabilities assumed remain provisional and based on the information that was available as of the acquisition dates. The Company expects to complete the purchase price allocations as soon as practicable but no later than one year from the acquisition dates. During the six months ended June 30, 2019, there were no adjustments recorded related to the estimated fair values of the assets acquired and liabilities assumed at the date of the acquisition of Think. As of June 30, 2019 , the following table presents the estimated fair values and useful lives of intangible assets acquired from Continuum, Think and test IO: Continuum Think test IO Weighted Average Useful Life (in years) Amount Weighted Average Useful Life (in years) Amount Weighted Average Useful Life (in years) Amount Customer relationships 6.5 $ 5,800 7 $ 6,117 3 $ 2,121 Favorable lease 11.2 5,500 — — — — Software — — — — 5 4,243 Contract royalties 8 1,900 — — — — Trade names 5 1,250 5 765 — — Total $ 14,450 $ 6,882 $ 6,364 In connection with the adoption of Topic 842, effective January 1, 2019, the Company reclassified the favorable lease intangible asset to Operating lease right-of-use assets. The goodwill recognized as a result of the acquisitions is attributable primarily to strategic and synergistic opportunities related to the consulting and design businesses, the assembled workforces acquired and other factors. The goodwill acquired as a result of the Continuum acquisition is expected to be deductible for income tax purposes while the goodwill acquired as a result of the Think and test IO acquisitions is not expected to be deductible for income tax purposes. Revenues generated by test IO, acquired on April 30, 2019, totaled $914 during both the three and six months ended June 30, 2019 . Pro forma results of operations have not been presented because the effect of the acquisitions on the Company’s condensed consolidated financial statements was not material individually or in the aggregate.

GOODWILL

GOODWILL	6 Months Ended
	Jun. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL	GOODWILL Goodwill by reportable segment was as follows: North America Europe Total Balance as of January 1, 2019 $ 103,542 $ 63,290 $ 166,832 test IO acquisition 3,177 8,706 11,883 Effect of net foreign currency exchange rate changes 162 337 499 Balance as of June 30, 2019 $ 106,881 $ 72,333 $ 179,214 There were no accumulated impairment losses in the North America or Europe reportable segments as of June 30, 2019 or December 31, 2018 .

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Jun. 30, 2019
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 June 30, 2019 and December 31, 2018: As of June 30, 2019 Balance Level 1 Level 2 Level 3 Foreign exchange derivative assets $ 2,689 $ — $ 2,689 $ — Total assets measured at fair value on a recurring basis $ 2,689 $ — $ 2,689 $ — Contingent consideration $ 7,720 $ — $ — $ 7,720 Total liabilities measured at fair value on a recurring basis $ 7,720 $ — $ — $ 7,720 As of December 31, 2018 Balance Level 1 Level 2 Level 3 Foreign exchange derivative assets $ 181 $ — $ 181 $ — Total assets measured at fair value on a recurring basis $ 181 $ — $ 181 $ — Foreign exchange derivative liabilities $ 3,475 $ — $ 3,475 $ — Contingent consideration 7,468 — — 7,468 Total liabilities measured at fair value on a recurring basis $ 10,943 $ — $ 3,475 $ 7,468 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 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 estimated future payments were then discounted to present value using a rate based on the weighted-average cost of capital of guideline companies. 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. In connection with the Continuum acquisition, the Company committed to making a cash earnout payment subject to attainment of specified performance targets in the 12 months after the acquisition date. As of the acquisition date, the Company recorded a $2,400 contingent consideration liability related to this earnout payment and, subsequently, reduced this liability by $900 during the third quarter of 2018 and $396 during the second quarter of 2019 due to the change in its fair value. The Company extinguished the earnout obligation during the second quarter of 2019 by paying $1,104 in cash. In connection with the Think acquisition, the Company committed to making a cash earnout payment subject to attainment of specified performance targets in the 12 months after the acquisition date. As of the acquisition date, the Company recorded a $5,990 contingent consideration liability related to this earnout payment as contingent consideration and, subsequently, increased its fair value by $1,752 during the second quarter of 2019 due to the change in its fair value. See Note 2 “Acquisitions” in the condensed consolidated interim financial statements for additional information regarding business acquisitions. A reconciliation of the beginning and ending balances of Level 3 acquisition-related contractual contingent liabilities using significant unobservable inputs for the six months ended June 30, 2019 is as follows: Amount Contingent consideration liabilities as of January 1, 2019 $ 7,468 Payment of contingent consideration (1,104 ) Changes in fair value of contingent consideration included in Interest and other income, net 1,356 Contingent consideration liabilities as of June 30, 2019 $ 7,720 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 June 30, 2019 Financial Assets: Cash and cash equivalents $ 777,365 $ 777,365 $ 777,365 $ — $ — Restricted cash $ 1,184 $ 1,184 $ 1,184 $ — $ — Employee loans $ 2,884 $ 2,884 $ — $ — $ 2,884 Financial Liabilities: Borrowings under the 2017 Credit Facility $ 25,017 $ 25,017 $ — $ 25,017 $ — Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 December 31, 2018 Financial Assets: Cash and cash equivalents $ 770,560 $ 770,560 $ 770,560 $ — $ — Restricted cash $ 1,151 $ 1,151 $ 1,151 $ — $ — Employee loans $ 3,525 $ 3,525 $ — $ — $ 3,525 Financial Liabilities: Borrowings under the 2017 Credit Facility $ 25,020 $ 25,020 $ — $ 25,020 $ —

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	6 Months Ended
	Jun. 30, 2019
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 June 30, 2019 , 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 June 30, 2019 and December 31, 2018 were as follows: As of June 30, 2019 As of December 31, 2018 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 $ 2,689 $ 181 Accrued expenses and other current liabilities $ — $ 3,475 The Company records changes in the fair value of its cash flow hedges in accumulated other comprehensive loss in the consolidated balance sheet 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 and six months ended June 30, 2019 and 2018 were as follows: Three Months Ended Six Months Ended 2019 2018 2019 2018 Foreign exchange forward contracts - Designated as hedging instruments: Change in fair value recognized in accumulated other comprehensive loss $ 1,984 $ (2,696 ) $ 5,983 $ (2,606 ) Net gain/(loss) reclassified from accumulated other comprehensive loss into cost of revenues (exclusive of depreciation and amortization) $ 342 $ (937 ) $ (110 ) $ (937 ) Foreign exchange forward contracts - Not designated as hedging instruments: Net gain recognized in foreign exchange (loss)/gain $ — $ — $ — $ 44

LEASES

LEASES	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
LEASES	LEASES The Company leases office space, corporate apartments, office equipment, and vehicles. The Company leases office space in order to minimize risks associated with ownership such as fluctuations in real estate prices. The leasing of corporate apartments is used to minimize costs associated with business trips of Company personnel. 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 RoU Assets and associated lease liabilities and are recognized in the period in which the obligation for such payments is incurred. The Company subleases a portion of its office space to third parties. The Company leases office equipment for those assets requiring extensive support including maintenance, repairs and replacement of obsolete parts. The Company leases vehicles in certain locations primarily as an employee benefit. The Company’s leases have remaining lease terms ranging from 1 day to 11.9 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. During the three and six months ended June 30, 2019 , the components of lease expense were as follows: Income Statement Classification Three Months Ended Six Months Ended Operating lease cost Selling, general and administrative expenses $ 15,196 $ 28,915 Variable lease cost Selling, general and administrative expenses 1,999 4,096 Short-term lease cost Selling, general and administrative expenses 1,006 1,904 Sublease income Interest and other income, net (477 ) (932 ) Total lease cost $ 17,724 $ 33,983 Supplemental cash flow information related to leases was as follows: Three Months Ended Six Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows used for operating leases $ 14,105 $ 28,801 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 40,722 $ 53,547 Non-cash net increase due to lease modifications: Operating lease right-of-use assets $ 8,324 $ 3,150 Operating lease liabilities $ 8,358 $ 3,252 Weighted average remaining lease term and discount rate as of June 30, 2019 is as follows: As of Weighted average remaining lease term, in years: Operating leases 6.2 Weighted average discount rate: Operating leases 3.6 % As of June 30, 2019 , operating lease liabilities will mature as follows: Year ending December 31, Lease Payments 2019 (excluding six months ended June 30, 2019) $ 29,047 2020 49,610 2021 41,267 2022 26,122 2023 19,659 Thereafter 64,305 Total lease payments 230,010 Less: imputed interest (23,444 ) Total $ 206,566 There were no lease agreements that contained material restrictive covenants or material residual value guarantees as of June 30, 2019 . There were no lease agreements signed with related parties as of June 30, 2019 . As of June 30, 2019, the Company had committed to payments of $65,266 related to operating lease agreements that had not yet commenced. These operating leases will commence during various dates during 2019 through 2020 with lease terms ranging from 1.0 to 11.6 years . The Company did not have any material finance lease agreements that had not yet commenced.

LONG-TERM DEBT

LONG-TERM DEBT	6 Months Ended
	Jun. 30, 2019
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 credit facility 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 June 30, 2019 , 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 June 30, 2019 , 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 3.4 % 3.5 % Irrevocable standby letters of credit $ 379 $ 382 Available borrowing capacity $ 274,621 $ 274,618 Current maximum borrowing capacity $ 300,000 $ 300,000

REVENUES

REVENUES	6 Months Ended
	Jun. 30, 2019
Revenue from Contract with Customer [Abstract]
REVENUES	REVENUES Disaggregation of Revenues The Company’s revenues are sourced from four geographic markets: North America, Europe, CIS and APAC. CIS includes revenues from customers in Belarus, Kazakhstan, Russia and Ukraine, and APAC, which stands for Asia Pacific, includes revenues from customers in East Asia, Southeast Asia and Australia. 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 June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Customer Locations North America $ 323,221 $ 11,553 $ 16 $ 334,790 $ (2 ) $ 334,788 Europe 5,233 172,099 99 177,431 (86 ) 177,345 CIS 2,005 — 23,086 25,091 — 25,091 APAC 580 13,800 — 14,380 (17 ) 14,363 Revenues $ 331,039 $ 197,452 $ 23,201 $ 551,692 $ (105 ) $ 551,587 Six Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Customer Locations North America $ 626,966 $ 24,444 $ 32 $ 651,442 $ (2 ) $ 651,440 Europe 9,980 340,866 240 351,086 (233 ) 350,853 CIS 3,744 13 39,509 43,266 (1 ) 43,265 APAC 1,038 26,352 — 27,390 (28 ) 27,362 Revenues $ 641,728 $ 391,675 $ 39,781 $ 1,073,184 $ (264 ) $ 1,072,920 Three Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Customer Locations North America $ 250,273 $ 14,177 $ 14 $ 264,464 $ (13 ) $ 264,451 Europe 3,086 146,998 — 150,084 (280 ) 149,804 CIS 2,089 28 17,294 19,411 — 19,411 APAC 1,655 10,292 72 12,019 (38 ) 11,981 Revenues $ 257,103 $ 171,495 $ 17,380 $ 445,978 $ (331 ) $ 445,647 Six Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Customer Locations North America $ 476,343 $ 27,538 $ 29 $ 503,910 $ (13 ) $ 503,897 Europe 5,826 297,478 42 303,346 (457 ) 302,889 CIS 4,092 91 37,008 41,191 — 41,191 APAC 2,038 19,731 87 21,856 (38 ) 21,818 Revenues $ 488,299 $ 344,838 $ 37,166 $ 870,303 $ (508 ) $ 869,795 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 June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Industry Verticals Financial Services $ 43,531 $ 58,966 $ 18,009 $ 120,506 $ (101 ) $ 120,405 Travel & Consumer 48,178 56,175 2,761 107,114 — 107,114 Software & Hi-Tech 85,600 19,442 478 105,520 (2 ) 105,518 Business Information & Media 62,340 35,692 104 98,136 (1 ) 98,135 Life Sciences & Healthcare 54,287 4,907 4 59,198 — 59,198 Emerging Verticals 37,103 22,270 1,845 61,218 (1 ) 61,217 Revenues $ 331,039 $ 197,452 $ 23,201 $ 551,692 $ (105 ) $ 551,587 Six Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Industry Verticals Financial Services $ 81,925 $ 120,954 $ 31,041 $ 233,920 $ (254 ) $ 233,666 Travel & Consumer 95,178 111,377 4,885 211,440 — 211,440 Software & Hi-Tech 164,721 39,812 918 205,451 (2 ) 205,449 Business Information & Media 124,701 68,228 244 193,173 (6 ) 193,167 Life Sciences & Healthcare 104,443 9,463 66 113,972 — 113,972 Emerging Verticals 70,760 41,841 2,627 115,228 (2 ) 115,226 Revenues $ 641,728 $ 391,675 $ 39,781 $ 1,073,184 $ (264 ) $ 1,072,920 Three Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Industry Verticals Financial Services $ 26,732 $ 62,496 $ 14,091 $ 103,319 $ (331 ) $ 102,988 Travel & Consumer 47,104 52,120 1,792 101,016 — 101,016 Software & Hi-Tech 64,536 19,857 624 85,017 — 85,017 Business Information & Media 59,532 18,117 — 77,649 — 77,649 Life Sciences & Healthcare 32,876 5,649 — 38,525 — 38,525 Emerging Verticals 26,323 13,256 873 40,452 — 40,452 Revenues $ 257,103 $ 171,495 $ 17,380 $ 445,978 $ (331 ) $ 445,647 Six Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Industry Verticals Financial Services $ 48,688 $ 128,314 $ 30,316 $ 207,318 $ (508 ) $ 206,810 Travel & Consumer 87,791 101,574 3,465 192,830 — 192,830 Software & Hi-Tech 125,100 40,151 1,388 166,639 — 166,639 Business Information & Media 116,869 36,987 — 153,856 — 153,856 Life Sciences & Healthcare 60,343 10,472 — 70,815 — 70,815 Emerging Verticals 49,508 27,340 1,997 78,845 — 78,845 Revenues $ 488,299 $ 344,838 $ 37,166 $ 870,303 $ (508 ) $ 869,795 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 June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Contract Types Time-and-material $ 300,326 $ 167,581 $ 12,047 $ 479,954 $ — $ 479,954 Fixed-price 29,681 29,204 10,943 69,828 — 69,828 Licensing 624 142 196 962 — 962 Other revenues 408 525 15 948 (105 ) 843 Revenues $ 331,039 $ 197,452 $ 23,201 $ 551,692 $ (105 ) $ 551,587 Six Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Contract Types Time-and-material $ 585,051 $ 335,794 $ 23,319 $ 944,164 $ — $ 944,164 Fixed-price 54,421 54,450 16,230 125,101 — 125,101 Licensing 1,460 540 202 2,202 — 2,202 Other revenues 796 891 30 1,717 (264 ) 1,453 Revenues $ 641,728 $ 391,675 $ 39,781 $ 1,073,184 $ (264 ) $ 1,072,920 Three Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Contract Types Time-and-material $ 233,747 $ 156,637 $ 9,765 $ 400,149 $ — $ 400,149 Fixed-price 22,483 14,081 7,607 44,171 — 44,171 Licensing 638 327 1 966 — 966 Other revenues 235 450 7 692 (331 ) 361 Revenues $ 257,103 $ 171,495 $ 17,380 $ 445,978 $ (331 ) $ 445,647 Six Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Contract Types Time-and-material $ 448,063 $ 316,103 $ 19,861 $ 784,027 $ — $ 784,027 Fixed-price 38,475 27,034 17,279 82,788 — 82,788 Licensing 1,300 946 11 2,257 — 2,257 Other revenues 461 755 15 1,231 (508 ) 723 Revenues $ 488,299 $ 344,838 $ 37,166 $ 870,303 $ (508 ) $ 869,795 Timing of Revenue Recognition The following tables present the timing of revenue recognition for the periods indicated: Three Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 220 $ 197 $ — $ 417 $ (105 ) $ 312 Transferred over time 330,819 197,255 23,201 551,275 — 551,275 Revenues $ 331,039 $ 197,452 $ 23,201 $ 551,692 $ (105 ) $ 551,587 Six Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 624 $ 402 $ 1 $ 1,027 $ (264 ) $ 763 Transferred over time 641,104 391,273 39,780 1,072,157 — 1,072,157 Revenues $ 641,728 $ 391,675 $ 39,781 $ 1,073,184 $ (264 ) $ 1,072,920 Three Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 294 $ 634 $ — $ 928 $ (331 ) $ 597 Transferred over time 256,809 170,861 17,380 445,050 — 445,050 Revenues $ 257,103 $ 171,495 $ 17,380 $ 445,978 $ (331 ) $ 445,647 Six Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 638 $ 1,062 $ 10 $ 1,710 $ (508 ) $ 1,202 Transferred over time 487,661 343,776 37,156 868,593 — 868,593 Revenues $ 488,299 $ 344,838 $ 37,166 $ 870,303 $ (508 ) $ 869,795 During the three and six months ended June 30, 2019 the Company recognized $7,693 and $4,119 of revenues, respectively, from performance obligations satisfied in previous periods compared to $5,452 and $6,618 during the three and six months ended June 30, 2018, respectively. 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 June 30, 2019 . 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 $ 10,534 $ 4,104 $ 217 $ — $ 14,855 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 Unbilled revenues $ 23,381 $ 13,522 Contract liabilities included in Accrued expenses and other current liabilities $ 6,321 $ 4,558 Contract liabilities included in Other noncurrent liabilities $ 3 $ 224 Contract assets included in Unbilled revenues are recorded when services have been provided but the Company does not have an unconditional right to receive consideration. The Company recognizes an impairment loss when the contract carrying amount is greater than the remaining consideration expected less the remaining costs of providing services. Contract assets have increased from December 31, 2018 primarily due to new contracts entered into in 2019 where the Company’s right to bill is contingent upon achievement of contractual milestones. 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 increased from December 31, 2018 primarily due to the seasonal nature of customer prepayments and the acquisition of test IO on April 30, 2019. During the three and six months ended June 30, 2019 , the Company recognized $610 and $3,661

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2019
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 Six Months Ended 2019 2018 2019 2018 Cost of revenues (exclusive of depreciation and amortization) $ 7,480 $ 7,054 $ 20,261 $ 15,343 Selling, general and administrative expenses 8,217 7,756 17,292 16,063 Total $ 15,697 $ 14,810 $ 37,553 $ 31,406 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, 2019 4,082,944 $ 44.54 Options granted 131,849 $ 169.13 Options modified 17,871 $ 163.55 Options exercised (528,572 ) $ 42.52 Options forfeited/cancelled (2,624 ) $ 61.38 Options outstanding at June 30, 2019 3,701,468 $ 49.83 $ 456,287 5.2 Options vested and exercisable at June 30, 2019 3,232,985 $ 40.60 $ 428,366 4.7 Options expected to vest at June 30, 2019 435,976 $ 112.48 $ 26,427 8.4 As of June 30, 2019 , $15,264 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 3.0 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 six months ended June 30, 2019 . 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, 2019 793 $ 63.10 797,903 $ 92.13 302,967 $ 83.99 Awards granted — $ — 274,381 $ 169.93 48,632 $ 169.13 Awards modified — $ — 6,897 $ 170.74 668 $ 168.36 Awards vested — $ — (255,903 ) $ 86.05 (110,012 ) $ 80.34 Awards forfeited/cancelled — $ — (18,742 ) $ 103.44 (2,648 ) $ 91.52 Unvested service-based awards outstanding at June 30, 2019 793 $ 63.10 804,536 $ 121.01 239,607 $ 103.10 As of June 30, 2019 , $26 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 1.0 years . As of June 30, 2019 , $78,261 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 2.9 years . During the second quarter of 2019, 17,565 RSUs were granted in connection with the acquisition of test IO. As of June 30, 2019 , $30,785 of total remaining unrecognized stock-based compensation cost related to service-based liability-classified RSUs, net of estimated forfeitures, is expected to be recognized over the weighted-average remaining requisite service period of 2.3 years . The liability associated with the service-based liability-classified RSUs as of June 30, 2019 and December 31, 2018 , was $7,928 and $9,920 , respectively, and was classified as Deferred compensation due to employees 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 six months ended June 30, 2019 . Equity-Classified Equity-Settled Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested performance-based awards outstanding at January 1, 2019 29,592 $ 121.75 Awards modified (29,592 ) $ 121.75 Unvested performance-based awards outstanding at June 30, 2019 — $ — During the first quarter of 2019, the Company and holders of the unvested performance-based equity-classified RSUs mutually agreed to cancel the performance-based RSU awards and the Company issued service-based stock option and RSU awards with four-year vesting terms to those same recipients. As of June 30, 2019, there is no

INCOME TAXES

INCOME TAXES	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES In determining its interim provision for/(benefit from) 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 June 30, 2019 and 2018 were 16.6% and 12.0% , respectively, and 11.3% and (9.2)% during the six months ended June 30, 2019 and 2018 , respectively. The Company’s effective tax rates benefited from excess tax benefits recorded upon vesting or exercise of stock-based awards of $4,741 and $5,440 during the three months ended June 30, 2019 and 2018 , respectively, and $16,254 and $10,130 during the six months ended June 30, 2019 and 2018 , respectively. The interim benefit from income taxes in the three and six months ended June 30, 2018 was favorably impacted by the recognition of $706 and $25,340 , respectively, of net deferred tax assets resulting from the Company’s decision to change the tax status and to classify most of its foreign subsidiaries as disregarded for U.S. income tax purposes. This was partially offset by a provisional $2,157 increase in income taxes payable associated with the one-time transition tax on accumulated foreign subsidiary earnings not previously subject to U.S. income tax imposed by the Tax Cuts and Jobs Act (“U.S. Tax Act”) recorded in the first quarter of 2018 and impacting the six months ended June 30, 2018.

EARNINGS PER SHARE

EARNINGS PER SHARE	6 Months Ended
	Jun. 30, 2019
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. 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 Six Months Ended 2019 2018 2019 2018 Numerator for basic and diluted earnings per share: Net income $ 58,777 $ 50,255 $ 119,531 $ 114,673 Numerator for basic and diluted earnings per share $ 58,777 $ 50,255 $ 119,531 $ 114,673 Denominator: Weighted average common shares for basic earnings per share 54,681,959 53,517,124 54,464,753 53,299,038 Net effect of dilutive stock options, restricted stock units and restricted stock awards 2,932,325 3,069,885 2,961,810 3,115,948 Weighted average common shares for diluted earnings per share 57,614,284 56,587,009 57,426,563 56,414,986 Net income per share: Basic $ 1.07 $ 0.94 $ 2.19 $ 2.15 Diluted $ 1.02 $ 0.89 $ 2.08 $ 2.03 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 168,451 and 97,327 during the three and six months ended June 30, 2019 , respectively. 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 155,142 and 104,186 during the three and six months ended June 30, 2018, respectively.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2019
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.

SEGMENTS INFORMATION

SEGMENTS INFORMATION	6 Months Ended
	Jun. 30, 2019
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 acquisition-related intangible assets, 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/(benefit from) 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. Revenues from external customers and operating profit, before unallocated expenses, by reportable segments for the three and six months ended June 30, 2019 and 2018 , were as follows: Three Months Ended Six Months Ended 2019 2018 2019 2018 Segment revenues: North America $ 331,039 $ 257,103 $ 641,728 $ 488,299 Europe 197,452 171,495 391,675 344,838 Russia 23,201 17,380 39,781 37,166 Total segment revenues $ 551,692 $ 445,978 $ 1,073,184 $ 870,303 Segment operating profit: North America $ 69,347 $ 51,221 $ 133,804 $ 95,181 Europe 27,679 26,568 59,464 55,458 Russia 5,652 2,321 6,241 7,668 Total segment operating profit $ 102,678 $ 80,110 $ 199,509 $ 158,307 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 and six months ended June 30, 2019 and 2018 . Accounts receivable and unbilled revenues are generally dispersed across the Company’s customers in proportion to their revenues. There were no customers individually exceeding 10% of total accounts receivable and unbilled revenues as of June 30, 2019 and December 31, 2018 . Reconciliation of segment revenues to consolidated revenues and segment operating profit to consolidated income before provision for/(benefit from) income taxes is presented below: Three Months Ended Six Months Ended 2019 2018 2019 2018 Total segment revenues $ 551,692 $ 445,978 $ 1,073,184 $ 870,303 Other income included in segment revenues (105 ) (331 ) (264 ) (508 ) Revenues $ 551,587 $ 445,647 $ 1,072,920 $ 869,795 Total segment operating profit: $ 102,678 $ 80,110 $ 199,509 $ 158,307 Unallocated amounts: Other income included in segment revenues (105 ) (331 ) (264 ) (508 ) Stock-based compensation expense (15,697 ) (14,810 ) (37,553 ) (31,406 ) Non-corporate taxes (2,438 ) (2,418 ) (4,166 ) (4,978 ) Professional fees (555 ) (1,400 ) (2,324 ) (3,316 ) Depreciation and amortization expense (2,603 ) (1,974 ) (4,743 ) (3,743 ) Bank charges (686 ) (579 ) (1,292 ) (1,168 ) One-time charges and other acquisition-related expenses (815 ) (1,241 ) (1,361 ) (1,861 ) Other operating expenses (6,897 ) (3,120 ) (10,266 ) (8,393 ) Income from operations 72,882 54,237 137,540 102,934 Interest and other income, net 1,190 1,052 4,266 501 Foreign exchange (loss)/gain (3,562 ) 1,830 (7,046 ) 1,583 Income before provision for/(benefit from) income taxes $ 70,510 $ 57,119 $ 134,760 $ 105,018 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 $ 48,984 $ 50,085 United States 13,799 13,101 Russia 12,563 9,902 Ukraine 12,535 8,433 India 6,755 7,019 Hungary 3,345 3,168 China 2,904 2,651 Poland 2,876 2,637 Other 7,414 5,650 Total $ 111,175 $ 102,646 The table below presents information about the Company’s revenues by customer location for the three and six months ended June 30, 2019 and 2018 . Three Months Ended Six Months Ended 2019 2018 2019 2018 United States $ 318,988 $ 246,831 $ 618,668 $ 470,514 United Kingdom 69,042 50,103 134,781 101,833 Switzerland 35,364 34,268 71,597 69,872 Netherlands 21,039 17,254 41,655 34,903 Germany 19,622 20,111 38,776 39,599 Russia 22,460 16,909 38,352 36,321 Canada 15,785 17,620 32,757 33,383 Other 49,287 42,551 96,334 83,370 Total $ 551,587 $ 445,647 $ 1,072,920 $ 869,795

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	6 Months Ended
	Jun. 30, 2019
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On July 1, 2019 , the Company acquired 100% of Competentum-USA Ltd. and its affiliates, a full-stack educational content services company, and its learning platform, ShareKnowledge. The Company paid approximately $11,200 in cash at closing and could pay up to $3,000

BUSINESS AND SUMMARY OF SIGNI_2

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 2019
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, PA.
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 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, 2018
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.
Adoption of New Accounting Standards	Adoption of New Accounting Standards Unless otherwise discussed below, the adoption of new accounting standards did not have an impact on the Company’s consolidated financial position, results of operations, changes in stockholders’ equity and cash flows. Leases — In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-02, Leases (“Topic 842”). The standard supersedes previously existing lease guidance (“Topic 840”) and requires entities to recognize all leases, with the exception of leases with a term of twelve months or less, on the balance sheet as right-of-use assets (“RoU Assets”) and lease liabilities. The guidance also changes disclosure requirements with a focus on providing information that will enable users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The Company adopted Topic 842, effective January 1, 2019, using the optional transition approach, which allows the Company to apply the provisions of the standard at the effective date without adjusting the comparable periods and carry forward disclosures under previously existing guidance for those periods presented within the Company’s financial statements. The Company determines if an arrangement is a lease or contains a lease at inception. The Company performs an assessment and classifies the lease as either an operating lease or a financing lease at the lease commencement date with a right-of-use asset and a lease liability recognized in the statement of financial position under both classifications. The Company does not have finance leases that are material to the Company’s condensed consolidated financial statements. Lease liabilities are initially measured at the present value of lease payments not yet paid. The present value is determined by applying the readily determinable rate implicit in the lease or, if not available, the incremental borrowing rate of the lessee. The Company determines the incremental borrowing rate of the lessee on a lease-by-lease basis by developing an estimated centralized U.S. dollar borrowing rate for a fully collateralized obligation with a term similar to the lease term, and adjusts the rate to reflect the incremental risk associated with the currency in which the lease is denominated. Lease agreements of the Company may include options to extend or terminate the lease and the Company includes such options in the lease term when it is reasonably certain that the Company will exercise that option. RoU Assets are recognized based on the initial measurement of the lease liabilities plus initial direct costs less lease incentives and, according to the guidance for long-lived assets, RoU Assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Lease expense for operating leases is recognized on a straight-line basis over the lease term. The Company elected a practical expedient to account for lease and non-lease components together as a single lease component. The Company also elected the short-term lease recognition exemption for all classes of lease assets with an original term of twelve months or less. As part of the transition, the Company elected a package of practical expedients allowing it to carry forward historical accounting for any expired or existing contracts that are or contain lease contracts, including classification of such contracts and initial direct costs associated with them. The adoption of Topic 842 on January 1, 2019 resulted in the recognition of RoU Assets for operating leases of $177,597 and operating lease liabilities of $173,863 . The adoption of Topic 842 did not have an impact on the condensed consolidated statement of income and comprehensive income, condensed consolidated statement of changes in stockholders’ equity or the condensed consolidated statement of cash flows. See Note 6 “Leases” in the condensed consolidated interim financial statements for additional information regarding leases. 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. Measurement of Credit Losses on Financial Instruments — Effective January 1, 2020, the Company will be required to adopt the amended guidance of FASB ASC Topic 326, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , (with early adoption permitted effective January 1, 2019.) The amendments in this update change how companies measure and recognize credit impairment for many financial assets. The new expected credit loss model will require 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. Entities are required to adopt the standard using a modified-retrospective approach through a cumulative effect adjustment to retained earnings as of the beginning of the period of adoption. The Company has not yet completed its assessment of the impact of the new guidance on its consolidated financial statements and will adopt the standard on January 1, 2020.

FAIR VALUE MEASUREMENTS FAIR VA

FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS (Policies)	6 Months Ended
	Jun. 30, 2019
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 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 estimated future payments were then discounted to present value using a rate based on the weighted-average cost of capital of guideline companies. 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)	6 Months Ended
	Jun. 30, 2019
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 sheet 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.

REVENUES (Policies)

REVENUES (Policies)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Unbilled Revenues	Contract assets included in Unbilled revenues are recorded when services have been provided but the Company does not have an unconditional right to receive consideration.
Impairment Loss	The Company recognizes an impairment loss when the contract carrying amount is greater than the remaining consideration expected less the remaining costs of providing services.
Deferred Revenues	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.

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	6 Months Ended
	Jun. 30, 2019
Business Combinations [Abstract]
Fair Values of Net Assets Acquired and Liabilities Assumed	The following table summarizes the estimated fair values of the assets acquired and liabilities assumed as of the date of acquisition and updated for any changes as of June 30, 2019 for each respective acquisition: Continuum Think test IO As of March 15, 2018 As of November 1, 2018 As of April 30, 2019 Cash and cash equivalents $ 2,251 $ 2,344 $ 968 Accounts receivable 6,676 2,259 727 Unbilled revenues 2,463 284 — Prepaid expenses and other current assets 936 609 96 Goodwill 26,617 22,482 11,883 Intangible assets 14,450 6,882 6,364 Property and equipment and other noncurrent assets 8,902 642 154 Total assets acquired $ 62,295 $ 35,502 $ 20,192 Accounts payable, accrued expenses and other current liabilities $ 2,745 $ 2,205 $ 1,251 Due to employees 1,001 13 7 Long-term debt 3,220 — — Other noncurrent liabilities 490 1,040 1,730 Total liabilities assumed $ 7,456 $ 3,258 $ 2,988 Net assets acquired $ 54,839 $ 32,244 $ 17,204
Fair Values and Useful Lives of Intangible Assets Acquired	As of June 30, 2019 , the following table presents the estimated fair values and useful lives of intangible assets acquired from Continuum, Think and test IO: Continuum Think test IO Weighted Average Useful Life (in years) Amount Weighted Average Useful Life (in years) Amount Weighted Average Useful Life (in years) Amount Customer relationships 6.5 $ 5,800 7 $ 6,117 3 $ 2,121 Favorable lease 11.2 5,500 — — — — Software — — — — 5 4,243 Contract royalties 8 1,900 — — — — Trade names 5 1,250 5 765 — — Total $ 14,450 $ 6,882 $ 6,364

GOODWILL (Tables)

GOODWILL (Tables)	6 Months Ended
	Jun. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill By Reportable Segment	Goodwill by reportable segment was as follows: North America Europe Total Balance as of January 1, 2019 $ 103,542 $ 63,290 $ 166,832 test IO acquisition 3,177 8,706 11,883 Effect of net foreign currency exchange rate changes 162 337 499 Balance as of June 30, 2019 $ 106,881 $ 72,333 $ 179,214

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2019
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 June 30, 2019 and December 31, 2018: As of June 30, 2019 Balance Level 1 Level 2 Level 3 Foreign exchange derivative assets $ 2,689 $ — $ 2,689 $ — Total assets measured at fair value on a recurring basis $ 2,689 $ — $ 2,689 $ — Contingent consideration $ 7,720 $ — $ — $ 7,720 Total liabilities measured at fair value on a recurring basis $ 7,720 $ — $ — $ 7,720 As of December 31, 2018 Balance Level 1 Level 2 Level 3 Foreign exchange derivative assets $ 181 $ — $ 181 $ — Total assets measured at fair value on a recurring basis $ 181 $ — $ 181 $ — Foreign exchange derivative liabilities $ 3,475 $ — $ 3,475 $ — Contingent consideration 7,468 — — 7,468 Total liabilities measured at fair value on a recurring basis $ 10,943 $ — $ 3,475 $ 7,468
Acquisition-Related Contractual Contingent Liabilities Roll Forward	A reconciliation of the beginning and ending balances of Level 3 acquisition-related contractual contingent liabilities using significant unobservable inputs for the six months ended June 30, 2019 is as follows: Amount Contingent consideration liabilities as of January 1, 2019 $ 7,468 Payment of contingent consideration (1,104 ) Changes in fair value of contingent consideration included in Interest and other income, net 1,356 Contingent consideration liabilities as of June 30, 2019 $ 7,720
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 June 30, 2019 Financial Assets: Cash and cash equivalents $ 777,365 $ 777,365 $ 777,365 $ — $ — Restricted cash $ 1,184 $ 1,184 $ 1,184 $ — $ — Employee loans $ 2,884 $ 2,884 $ — $ — $ 2,884 Financial Liabilities: Borrowings under the 2017 Credit Facility $ 25,017 $ 25,017 $ — $ 25,017 $ — Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 December 31, 2018 Financial Assets: Cash and cash equivalents $ 770,560 $ 770,560 $ 770,560 $ — $ — Restricted cash $ 1,151 $ 1,151 $ 1,151 $ — $ — Employee loans $ 3,525 $ 3,525 $ — $ — $ 3,525 Financial Liabilities: Borrowings under the 2017 Credit Facility $ 25,020 $ 25,020 $ — $ 25,020 $ —

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	6 Months Ended
	Jun. 30, 2019
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 June 30, 2019 and December 31, 2018 were as follows: As of June 30, 2019 As of December 31, 2018 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 $ 2,689 $ 181 Accrued expenses and other current liabilities $ — $ 3,475
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 and six months ended June 30, 2019 and 2018 were as follows: Three Months Ended Six Months Ended 2019 2018 2019 2018 Foreign exchange forward contracts - Designated as hedging instruments: Change in fair value recognized in accumulated other comprehensive loss $ 1,984 $ (2,696 ) $ 5,983 $ (2,606 ) Net gain/(loss) reclassified from accumulated other comprehensive loss into cost of revenues (exclusive of depreciation and amortization) $ 342 $ (937 ) $ (110 ) $ (937 ) Foreign exchange forward contracts - Not designated as hedging instruments: Net gain recognized in foreign exchange (loss)/gain $ — $ — $ — $ 44

LEASES (Tables)

LEASES (Tables)	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Components of Lease Expenses	During the three and six months ended June 30, 2019 , the components of lease expense were as follows: Income Statement Classification Three Months Ended Six Months Ended Operating lease cost Selling, general and administrative expenses $ 15,196 $ 28,915 Variable lease cost Selling, general and administrative expenses 1,999 4,096 Short-term lease cost Selling, general and administrative expenses 1,006 1,904 Sublease income Interest and other income, net (477 ) (932 ) Total lease cost $ 17,724 $ 33,983
Supplemental Cash Flow Information	Supplemental cash flow information related to leases was as follows: Three Months Ended Six Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows used for operating leases $ 14,105 $ 28,801 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 40,722 $ 53,547 Non-cash net increase due to lease modifications: Operating lease right-of-use assets $ 8,324 $ 3,150 Operating lease liabilities $ 8,358 $ 3,252
Weighted Average Lease Terms and Discount Rates	Weighted average remaining lease term and discount rate as of June 30, 2019 is as follows: As of Weighted average remaining lease term, in years: Operating leases 6.2 Weighted average discount rate: Operating leases 3.6 %
Maturity of Operating Lease Liabilities	As of June 30, 2019 , operating lease liabilities will mature as follows: Year ending December 31, Lease Payments 2019 (excluding six months ended June 30, 2019) $ 29,047 2020 49,610 2021 41,267 2022 26,122 2023 19,659 Thereafter 64,305 Total lease payments 230,010 Less: imputed interest (23,444 ) Total $ 206,566

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	6 Months Ended
	Jun. 30, 2019
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 3.4 % 3.5 % Irrevocable standby letters of credit $ 379 $ 382 Available borrowing capacity $ 274,621 $ 274,618 Current maximum borrowing capacity $ 300,000 $ 300,000

REVENUES (Tables)

REVENUES (Tables)	6 Months Ended
	Jun. 30, 2019
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 June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Customer Locations North America $ 323,221 $ 11,553 $ 16 $ 334,790 $ (2 ) $ 334,788 Europe 5,233 172,099 99 177,431 (86 ) 177,345 CIS 2,005 — 23,086 25,091 — 25,091 APAC 580 13,800 — 14,380 (17 ) 14,363 Revenues $ 331,039 $ 197,452 $ 23,201 $ 551,692 $ (105 ) $ 551,587 Six Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Customer Locations North America $ 626,966 $ 24,444 $ 32 $ 651,442 $ (2 ) $ 651,440 Europe 9,980 340,866 240 351,086 (233 ) 350,853 CIS 3,744 13 39,509 43,266 (1 ) 43,265 APAC 1,038 26,352 — 27,390 (28 ) 27,362 Revenues $ 641,728 $ 391,675 $ 39,781 $ 1,073,184 $ (264 ) $ 1,072,920 Three Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Customer Locations North America $ 250,273 $ 14,177 $ 14 $ 264,464 $ (13 ) $ 264,451 Europe 3,086 146,998 — 150,084 (280 ) 149,804 CIS 2,089 28 17,294 19,411 — 19,411 APAC 1,655 10,292 72 12,019 (38 ) 11,981 Revenues $ 257,103 $ 171,495 $ 17,380 $ 445,978 $ (331 ) $ 445,647 Six Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Customer Locations North America $ 476,343 $ 27,538 $ 29 $ 503,910 $ (13 ) $ 503,897 Europe 5,826 297,478 42 303,346 (457 ) 302,889 CIS 4,092 91 37,008 41,191 — 41,191 APAC 2,038 19,731 87 21,856 (38 ) 21,818 Revenues $ 488,299 $ 344,838 $ 37,166 $ 870,303 $ (508 ) $ 869,795 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 June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Industry Verticals Financial Services $ 43,531 $ 58,966 $ 18,009 $ 120,506 $ (101 ) $ 120,405 Travel & Consumer 48,178 56,175 2,761 107,114 — 107,114 Software & Hi-Tech 85,600 19,442 478 105,520 (2 ) 105,518 Business Information & Media 62,340 35,692 104 98,136 (1 ) 98,135 Life Sciences & Healthcare 54,287 4,907 4 59,198 — 59,198 Emerging Verticals 37,103 22,270 1,845 61,218 (1 ) 61,217 Revenues $ 331,039 $ 197,452 $ 23,201 $ 551,692 $ (105 ) $ 551,587 Six Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Industry Verticals Financial Services $ 81,925 $ 120,954 $ 31,041 $ 233,920 $ (254 ) $ 233,666 Travel & Consumer 95,178 111,377 4,885 211,440 — 211,440 Software & Hi-Tech 164,721 39,812 918 205,451 (2 ) 205,449 Business Information & Media 124,701 68,228 244 193,173 (6 ) 193,167 Life Sciences & Healthcare 104,443 9,463 66 113,972 — 113,972 Emerging Verticals 70,760 41,841 2,627 115,228 (2 ) 115,226 Revenues $ 641,728 $ 391,675 $ 39,781 $ 1,073,184 $ (264 ) $ 1,072,920 Three Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Industry Verticals Financial Services $ 26,732 $ 62,496 $ 14,091 $ 103,319 $ (331 ) $ 102,988 Travel & Consumer 47,104 52,120 1,792 101,016 — 101,016 Software & Hi-Tech 64,536 19,857 624 85,017 — 85,017 Business Information & Media 59,532 18,117 — 77,649 — 77,649 Life Sciences & Healthcare 32,876 5,649 — 38,525 — 38,525 Emerging Verticals 26,323 13,256 873 40,452 — 40,452 Revenues $ 257,103 $ 171,495 $ 17,380 $ 445,978 $ (331 ) $ 445,647 Six Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Industry Verticals Financial Services $ 48,688 $ 128,314 $ 30,316 $ 207,318 $ (508 ) $ 206,810 Travel & Consumer 87,791 101,574 3,465 192,830 — 192,830 Software & Hi-Tech 125,100 40,151 1,388 166,639 — 166,639 Business Information & Media 116,869 36,987 — 153,856 — 153,856 Life Sciences & Healthcare 60,343 10,472 — 70,815 — 70,815 Emerging Verticals 49,508 27,340 1,997 78,845 — 78,845 Revenues $ 488,299 $ 344,838 $ 37,166 $ 870,303 $ (508 ) $ 869,795 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 June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Contract Types Time-and-material $ 300,326 $ 167,581 $ 12,047 $ 479,954 $ — $ 479,954 Fixed-price 29,681 29,204 10,943 69,828 — 69,828 Licensing 624 142 196 962 — 962 Other revenues 408 525 15 948 (105 ) 843 Revenues $ 331,039 $ 197,452 $ 23,201 $ 551,692 $ (105 ) $ 551,587 Six Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Contract Types Time-and-material $ 585,051 $ 335,794 $ 23,319 $ 944,164 $ — $ 944,164 Fixed-price 54,421 54,450 16,230 125,101 — 125,101 Licensing 1,460 540 202 2,202 — 2,202 Other revenues 796 891 30 1,717 (264 ) 1,453 Revenues $ 641,728 $ 391,675 $ 39,781 $ 1,073,184 $ (264 ) $ 1,072,920 Three Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Contract Types Time-and-material $ 233,747 $ 156,637 $ 9,765 $ 400,149 $ — $ 400,149 Fixed-price 22,483 14,081 7,607 44,171 — 44,171 Licensing 638 327 1 966 — 966 Other revenues 235 450 7 692 (331 ) 361 Revenues $ 257,103 $ 171,495 $ 17,380 $ 445,978 $ (331 ) $ 445,647 Six Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Contract Types Time-and-material $ 448,063 $ 316,103 $ 19,861 $ 784,027 $ — $ 784,027 Fixed-price 38,475 27,034 17,279 82,788 — 82,788 Licensing 1,300 946 11 2,257 — 2,257 Other revenues 461 755 15 1,231 (508 ) 723 Revenues $ 488,299 $ 344,838 $ 37,166 $ 870,303 $ (508 ) $ 869,795 Timing of Revenue Recognition The following tables present the timing of revenue recognition for the periods indicated: Three Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 220 $ 197 $ — $ 417 $ (105 ) $ 312 Transferred over time 330,819 197,255 23,201 551,275 — 551,275 Revenues $ 331,039 $ 197,452 $ 23,201 $ 551,692 $ (105 ) $ 551,587 Six Months Ended June 30, 2019 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 624 $ 402 $ 1 $ 1,027 $ (264 ) $ 763 Transferred over time 641,104 391,273 39,780 1,072,157 — 1,072,157 Revenues $ 641,728 $ 391,675 $ 39,781 $ 1,073,184 $ (264 ) $ 1,072,920 Three Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 294 $ 634 $ — $ 928 $ (331 ) $ 597 Transferred over time 256,809 170,861 17,380 445,050 — 445,050 Revenues $ 257,103 $ 171,495 $ 17,380 $ 445,978 $ (331 ) $ 445,647 Six Months Ended June 30, 2018 Reportable Segments North America Europe Russia Total Segment Revenues Other Income Included in Segment Revenues Consolidated Revenues Timing of Revenue Recognition Transferred at a point of time $ 638 $ 1,062 $ 10 $ 1,710 $ (508 ) $ 1,202 Transferred over time 487,661 343,776 37,156 868,593 — 868,593 Revenues $ 488,299 $ 344,838 $ 37,166 $ 870,303 $ (508 ) $ 869,795
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 June 30, 2019 . 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 $ 10,534 $ 4,104 $ 217 $ — $ 14,855
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 Unbilled revenues $ 23,381 $ 13,522 Contract liabilities included in Accrued expenses and other current liabilities $ 6,321 $ 4,558 Contract liabilities included in Other noncurrent liabilities $ 3 $ 224

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 30, 2019
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 Six Months Ended 2019 2018 2019 2018 Cost of revenues (exclusive of depreciation and amortization) $ 7,480 $ 7,054 $ 20,261 $ 15,343 Selling, general and administrative expenses 8,217 7,756 17,292 16,063 Total $ 15,697 $ 14,810 $ 37,553 $ 31,406
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, 2019 4,082,944 $ 44.54 Options granted 131,849 $ 169.13 Options modified 17,871 $ 163.55 Options exercised (528,572 ) $ 42.52 Options forfeited/cancelled (2,624 ) $ 61.38 Options outstanding at June 30, 2019 3,701,468 $ 49.83 $ 456,287 5.2 Options vested and exercisable at June 30, 2019 3,232,985 $ 40.60 $ 428,366 4.7 Options expected to vest at June 30, 2019 435,976 $ 112.48 $ 26,427 8.4
Service-based Awards Activity	The table below summarizes activity related to the Company’s equity-classified and liability-classified service-based awards for the six months ended June 30, 2019 . 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, 2019 793 $ 63.10 797,903 $ 92.13 302,967 $ 83.99 Awards granted — $ — 274,381 $ 169.93 48,632 $ 169.13 Awards modified — $ — 6,897 $ 170.74 668 $ 168.36 Awards vested — $ — (255,903 ) $ 86.05 (110,012 ) $ 80.34 Awards forfeited/cancelled — $ — (18,742 ) $ 103.44 (2,648 ) $ 91.52 Unvested service-based awards outstanding at June 30, 2019 793 $ 63.10 804,536 $ 121.01 239,607 $ 103.10
Performance-based Awards Activity	The table below summarizes activity related to the Company’s equity-classified performance-based awards for the six months ended June 30, 2019 . Equity-Classified Equity-Settled Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested performance-based awards outstanding at January 1, 2019 29,592 $ 121.75 Awards modified (29,592 ) $ 121.75 Unvested performance-based awards outstanding at June 30, 2019 — $ —

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	6 Months Ended
	Jun. 30, 2019
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 Six Months Ended 2019 2018 2019 2018 Numerator for basic and diluted earnings per share: Net income $ 58,777 $ 50,255 $ 119,531 $ 114,673 Numerator for basic and diluted earnings per share $ 58,777 $ 50,255 $ 119,531 $ 114,673 Denominator: Weighted average common shares for basic earnings per share 54,681,959 53,517,124 54,464,753 53,299,038 Net effect of dilutive stock options, restricted stock units and restricted stock awards 2,932,325 3,069,885 2,961,810 3,115,948 Weighted average common shares for diluted earnings per share 57,614,284 56,587,009 57,426,563 56,414,986 Net income per share: Basic $ 1.07 $ 0.94 $ 2.19 $ 2.15 Diluted $ 1.02 $ 0.89 $ 2.08 $ 2.03

SEGMENTS INFORMATION (Tables)

SEGMENTS INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2019
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 and six months ended June 30, 2019 and 2018 , were as follows: Three Months Ended Six Months Ended 2019 2018 2019 2018 Segment revenues: North America $ 331,039 $ 257,103 $ 641,728 $ 488,299 Europe 197,452 171,495 391,675 344,838 Russia 23,201 17,380 39,781 37,166 Total segment revenues $ 551,692 $ 445,978 $ 1,073,184 $ 870,303 Segment operating profit: North America $ 69,347 $ 51,221 $ 133,804 $ 95,181 Europe 27,679 26,568 59,464 55,458 Russia 5,652 2,321 6,241 7,668 Total segment operating profit $ 102,678 $ 80,110 $ 199,509 $ 158,307
Reconciliation of Segment Revenues to Consolidated Revenues and Segment Operating Profit to Consolidated Income Before Provision for/(Benefit from) Income Taxes	Reconciliation of segment revenues to consolidated revenues and segment operating profit to consolidated income before provision for/(benefit from) income taxes is presented below: Three Months Ended Six Months Ended 2019 2018 2019 2018 Total segment revenues $ 551,692 $ 445,978 $ 1,073,184 $ 870,303 Other income included in segment revenues (105 ) (331 ) (264 ) (508 ) Revenues $ 551,587 $ 445,647 $ 1,072,920 $ 869,795 Total segment operating profit: $ 102,678 $ 80,110 $ 199,509 $ 158,307 Unallocated amounts: Other income included in segment revenues (105 ) (331 ) (264 ) (508 ) Stock-based compensation expense (15,697 ) (14,810 ) (37,553 ) (31,406 ) Non-corporate taxes (2,438 ) (2,418 ) (4,166 ) (4,978 ) Professional fees (555 ) (1,400 ) (2,324 ) (3,316 ) Depreciation and amortization expense (2,603 ) (1,974 ) (4,743 ) (3,743 ) Bank charges (686 ) (579 ) (1,292 ) (1,168 ) One-time charges and other acquisition-related expenses (815 ) (1,241 ) (1,361 ) (1,861 ) Other operating expenses (6,897 ) (3,120 ) (10,266 ) (8,393 ) Income from operations 72,882 54,237 137,540 102,934 Interest and other income, net 1,190 1,052 4,266 501 Foreign exchange (loss)/gain (3,562 ) 1,830 (7,046 ) 1,583 Income before provision for/(benefit from) income taxes $ 70,510 $ 57,119 $ 134,760 $ 105,018
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 $ 48,984 $ 50,085 United States 13,799 13,101 Russia 12,563 9,902 Ukraine 12,535 8,433 India 6,755 7,019 Hungary 3,345 3,168 China 2,904 2,651 Poland 2,876 2,637 Other 7,414 5,650 Total $ 111,175 $ 102,646
Revenues by Customer Location	The table below presents information about the Company’s revenues by customer location for the three and six months ended June 30, 2019 and 2018 . Three Months Ended Six Months Ended 2019 2018 2019 2018 United States $ 318,988 $ 246,831 $ 618,668 $ 470,514 United Kingdom 69,042 50,103 134,781 101,833 Switzerland 35,364 34,268 71,597 69,872 Netherlands 21,039 17,254 41,655 34,903 Germany 19,622 20,111 38,776 39,599 Russia 22,460 16,909 38,352 36,321 Canada 15,785 17,620 32,757 33,383 Other 49,287 42,551 96,334 83,370 Total $ 551,587 $ 445,647 $ 1,072,920 $ 869,795

BUSINESS AND SUMMARY OF SIGNI_3

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Leases) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
RoU Asset for operating leases	$ 210,447		$ 0
Operating lease liabilities	$ 206,566
Topic 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
RoU Asset for operating leases		$ 177,597
Operating lease liabilities		$ 173,863

ACQUISITIONS (Narrative) (Detai

ACQUISITIONS (Narrative) (Details) $ in Thousands	Apr. 30, 2019USD ($)	Nov. 01, 2018USD ($)	Mar. 15, 2018USD ($)	Dec. 31, 2018USD ($)
Continuum
Business Acquisition [Line Items]
Acquisition date			Mar. 15, 2018
Cash consideration			$ 52,515
Estimated future operating results, period			12 months
Maximum amount of earnout payable			$ 3,135
Cash collection resulted from working capital adjustment				$ 76
Continuum | Design Consultants
Business Acquisition [Line Items]
Numbers of employees acquired			125
Think
Business Acquisition [Line Items]
Acquisition date		Nov. 1, 2018
Cash consideration		$ 26,254
Estimated future operating results, period		12 months
Maximum amount of earnout payable		$ 8,156
test IO
Business Acquisition [Line Items]
Acquisition date	Apr. 30, 2019
Cash consideration	$ 17,204
Equity interest acquired	100.00%

ACQUISITIONS (Fair Values of Ne

ACQUISITIONS (Fair Values of Net Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Apr. 30, 2019	Dec. 31, 2018	Nov. 01, 2018	Mar. 15, 2018
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Unbilled revenues	$ 135,786		$ 104,652
Goodwill	179,214		$ 166,832
Continuum
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Cash and cash equivalents					$ 2,251
Accounts receivable					6,676
Unbilled revenues					2,463
Prepaid and other current assets					936
Goodwill					26,617
Intangible assets					14,450
Property and equipment and other noncurrent assets					8,902
Total assets acquired					62,295
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Accounts payable, accrued expenses and other current liabilities					2,745
Due to employees					1,001
Long-term debt					3,220
Other noncurrent liabilities					490
Total liabilities assumed					7,456
Net assets acquired					$ 54,839
Think
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Cash and cash equivalents				$ 2,344
Accounts receivable				2,259
Unbilled revenues				284
Prepaid and other current assets				609
Goodwill				22,482
Intangible assets				6,882
Property and equipment and other noncurrent assets				642
Total assets acquired				35,502
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Accounts payable, accrued expenses and other current liabilities				2,205
Due to employees				13
Long-term debt				0
Other noncurrent liabilities				1,040
Total liabilities assumed				3,258
Net assets acquired				$ 32,244
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Adjustments recorded to the estimated fair values of the assets acquired and liabilities assumed at the acquisition date	$ 0
test IO
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Cash and cash equivalents		$ 968
Accounts receivable		727
Unbilled revenues		0
Prepaid and other current assets		96
Goodwill		11,883
Intangible assets		6,364
Property and equipment and other noncurrent assets		154
Total assets acquired		20,192
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Accounts payable, accrued expenses and other current liabilities		1,251
Due to employees		7
Long-term debt		0
Other noncurrent liabilities		1,730
Total liabilities assumed		2,988
Net assets acquired		$ 17,204

ACQUISITIONS (Fair Values and U

ACQUISITIONS (Fair Values and Useful Lives of Intangible Assets Acquired) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Continuum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	$ 14,450
Continuum | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	6 years 6 months
Estimated fair value of intangible assets acquired	$ 5,800
Continuum | Favorable lease
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	11 years 2 months 12 days
Estimated fair value of intangible assets acquired	$ 5,500
Continuum | Software
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	$ 0
Continuum | Contract royalties
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	8 years
Estimated fair value of intangible assets acquired	$ 1,900
Continuum | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	5 years
Estimated fair value of intangible assets acquired	$ 1,250
Think
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	$ 6,882
Think | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	7 years
Estimated fair value of intangible assets acquired	$ 6,117
Think | Favorable lease
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	0
Think | Software
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	0
Think | Contract royalties
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	$ 0
Think | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	5 years
Estimated fair value of intangible assets acquired	$ 765
test IO
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	$ 6,364
test IO | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	3 years
Estimated fair value of intangible assets acquired	$ 2,121
test IO | Favorable lease
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	$ 0
test IO | Software
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	5 years
Estimated fair value of intangible assets acquired	$ 4,243
test IO | Contract royalties
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	0
test IO | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair value of intangible assets acquired	$ 0

ACQUISITIONS (Income Statement

ACQUISITIONS (Income Statement Effect) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Business Acquisition [Line Items]
Revenues	$ 551,587	$ 445,647	$ 1,072,920	$ 869,795
test IO
Business Acquisition [Line Items]
Revenues	$ 914

GOODWILL (Goodwill Roll Forward

GOODWILL (Goodwill Roll Forward) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Goodwill [Roll Forward]
Balance as of January 1, 2019	$ 166,832
Effect of net foreign currency exchange rate changes	499
Balance as of June 30, 2019	179,214
test IO
Goodwill [Roll Forward]
Acquisition	11,883
North America
Goodwill [Roll Forward]
Balance as of January 1, 2019	103,542
Effect of net foreign currency exchange rate changes	162
Balance as of June 30, 2019	106,881
North America | test IO
Goodwill [Roll Forward]
Acquisition	3,177
Europe
Goodwill [Roll Forward]
Balance as of January 1, 2019	63,290
Effect of net foreign currency exchange rate changes	337
Balance as of June 30, 2019	72,333
Europe | test IO
Goodwill [Roll Forward]
Acquisition	$ 8,706

GOODWILL (Goodwill Accumulated

GOODWILL (Goodwill Accumulated Impaitment Losses) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
North America
Goodwill [Line Items]
Accumulated impairment loss	$ 0	$ 0
Europe
Goodwill [Line Items]
Accumulated impairment loss	$ 0	$ 0

FAIR VALUE MEASUREMENTS (Financ

FAIR VALUE MEASUREMENTS (Financial Assets and Liabilities at Fair Value on Recurring Basis) (Details) - Recurring - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financial Assets:
Total assets measured at fair value on a recurring basis	$ 2,689	$ 181
Financial Liabilities:
Contingent consideration	7,720	7,468
Total liabilities measured at fair value on a recurring basis	7,720	10,943
Foreign exchange contracts
Financial Assets:
Derivative assets	2,689	181
Financial Liabilities:
Derivative liabilities		3,475
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
Level 2
Financial Assets:
Total assets measured at fair value on a recurring basis	2,689	181
Financial Liabilities:
Contingent consideration	0	0
Total liabilities measured at fair value on a recurring basis	0	3,475
Level 2 | Foreign exchange contracts
Financial Assets:
Derivative assets	2,689	181
Financial Liabilities:
Derivative liabilities		3,475
Level 3
Financial Assets:
Total assets measured at fair value on a recurring basis	0	0
Financial Liabilities:
Contingent consideration	7,720	7,468
Total liabilities measured at fair value on a recurring basis	7,720	7,468
Level 3 | Foreign exchange contracts
Financial Assets:
Derivative assets	$ 0	0
Financial Liabilities:
Derivative liabilities		$ 0

FAIR VALUE MEASUREMENTS (Narrat

FAIR VALUE MEASUREMENTS (Narrative) (Details) - USD ($) $ in Thousands	Nov. 01, 2018	Mar. 15, 2018	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Business Acquisition, Contingent Consideration [Line Items]
Acquisition of businesses, contingent consideration					$ (1,104)	$ 0
Continuum
Business Acquisition, Contingent Consideration [Line Items]
Estimated future operating results, period		12 months
Contingent consideration liability		$ 2,400
Contingent consideration liability adjustmenteration, Liability			$ (396)	$ (900)
Think
Business Acquisition, Contingent Consideration [Line Items]
Estimated future operating results, period	12 months
Contingent consideration liability	$ 5,990
Contingent consideration liability adjustmenteration, Liability			$ 1,752

FAIR VALUE MEASUREMENTS (Acquis

FAIR VALUE MEASUREMENTS (Acquisition-Related Contractual Contingent Liabilities Roll Forward) (Details) - Level 3 $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration liabilities as of January 1, 2019	$ 7,468
Payment of contingent consideration	(1,104)
Contingent consideration liabilities as of June 30, 2019	7,720
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	$ 1,356

FAIR VALUE MEASUREMENTS (Report

FAIR VALUE MEASUREMENTS (Reported Amounts and Estimated Fair Values of the Financial Assets and Liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Balance
Financial Assets:
Cash and cash equivalents	$ 777,365	$ 770,560
Restricted cash	1,184	1,151
Employee loans	2,884	3,525
Balance | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	25,017	25,020
Estimated Fair Value
Financial Assets:
Cash and cash equivalents	777,365	770,560
Restricted cash	1,184	1,151
Employee loans	2,884	3,525
Estimated Fair Value | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	25,017	25,020
Estimated Fair Value | Level 1
Financial Assets:
Cash and cash equivalents	777,365	770,560
Restricted cash	1,184	1,151
Employee loans	0	0
Estimated Fair Value | Level 1 | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	0	0
Estimated Fair Value | Level 2
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Employee loans	0	0
Estimated Fair Value | Level 2 | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	25,017	25,020
Estimated Fair Value | Level 3
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Employee loans	2,884	3,525
Estimated Fair Value | Level 3 | Revolving credit facility | Credit Facility 2017
Financial Liabilities:
Borrowings	$ 0	$ 0

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS (Fair Value of Derivative Instruments) (Details) - Foreign exchange contracts - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
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	2,689	$ 181
Designated as hedging instruments | Cash Flow Hedging | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 0	$ 3,475

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS (Changes in the Fair Value of Derivative Instruments) (Details) - Foreign exchange contracts - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Designated as hedging instruments | Cash Flow Hedging | Cost of revenues (exclusive of depreciation and amortization)
Derivative Instruments, Gain (Loss) [Line Items]
Net gain/(loss) reclassified	$ 342	$ (937)	$ (110)	$ (937)
Designated as hedging instruments | Cash Flow Hedging | Accumulated other comprehensive loss
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value	1,984	(2,696)	5,983	(2,606)
Not designated as hedging instruments | Foreign exchange loss
Derivative Instruments, Gain (Loss) [Line Items]
Net gain recognized	$ 0	$ 0	$ 0	$ 44

LEASES (Narrative) (Details)

LEASES (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Lessee, Lease, Description [Line Items]
Existence of material residual value guarantees	false
Existence of material restrictive covenants	There were no lease agreements that contained material restrictive covenants
Existance of lease agreements signed with related parties	There were no lease agreements signed with related parties
Commitments related to operating lease agreements that have not yet commenced	$ 65,266
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year
Lease term of lease agreements that have not yet commenced	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	11 years 10 months 24 days
Lease term of lease agreements that have not yet commenced	11 years 7 months 6 days

LEASES (Components of Lease Exp

LEASES (Components of Lease Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Lease, Cost [Line Items]
Total lease cost	$ 17,724	$ 33,983
Selling, general and administrative expenses
Lease, Cost [Line Items]
Operating lease cost	15,196	28,915
Variable lease cost	1,999	4,096
Short-term lease cost	1,006	1,904
Interest and other income, net
Lease, Cost [Line Items]
Sublease income	$ (477)	$ (932)

LEASES (Supplemental Cash Flow

LEASES (Supplemental Cash Flow Information) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used for operating leases	$ 14,105	$ 28,801
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	40,722	53,547
Non-cash net increase due to lease modifications:
Operating lease right-of-use assets	8,324	3,150
Operating lease liabilities	$ 8,358	$ 3,252

LEASES (Weighted Average Lease

LEASES (Weighted Average Lease Terms and Discount Rates) (Details)	Jun. 30, 2019
Weighted average remaining lease term, in years:
Operating leases	6 years 2 months 12 days
Weighted average discount rate:
Operating leases	3.60%

LEASES (Maturity of Operating L

LEASES (Maturity of Operating Lease Liabilities) (Details) $ in Thousands	Jun. 30, 2019USD ($)
Leases [Abstract]
2019 (excluding six months ended June 30, 2019)	$ 29,047
2020	49,610
2021	41,267
2022	26,122
2023	19,659
Thereafter	64,305
Total lease payments	230,010
Less: imputed interest	(23,444)
Total	$ 206,566

LONG-TERM DEBT (Details)

LONG-TERM DEBT (Details) - Credit Facility 2017 - USD ($) $ in Thousands	May 24, 2017	Jun. 30, 2019	Dec. 31, 2018
Revolving credit facility
Debt Instrument [Line Items]
Maturity date	May 24, 2022
Revolving credit facility | Federal Funds Open Rate
Debt Instrument [Line Items]
Variable interest rate spread	0.50%
Revolving credit facility | London Interbank Offered Rate (LIBOR)
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		3.40%	3.50%
Available borrowing capacity		$ 274,621	$ 274,618
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		$ 379	$ 382

REVENUES (Disaggregation of Rev

REVENUES (Disaggregation of Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 551,587	$ 445,647	$ 1,072,920	$ 869,795
Transferred at a point of time
Disaggregation of Revenue [Line Items]
Revenues	312	597	763	1,202
Transferred over time
Disaggregation of Revenue [Line Items]
Revenues	551,275	445,050	1,072,157	868,593
Time-and-material
Disaggregation of Revenue [Line Items]
Revenues	479,954	400,149	944,164	784,027
Fixed-price
Disaggregation of Revenue [Line Items]
Revenues	69,828	44,171	125,101	82,788
Licensing
Disaggregation of Revenue [Line Items]
Revenues	962	966	2,202	2,257
Other revenues
Disaggregation of Revenue [Line Items]
Revenues	843	361	1,453	723
Financial Services
Disaggregation of Revenue [Line Items]
Revenues	120,405	102,988	233,666	206,810
Travel & Consumer
Disaggregation of Revenue [Line Items]
Revenues	107,114	101,016	211,440	192,830
Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Revenues	105,518	85,017	205,449	166,639
Business Information & Media
Disaggregation of Revenue [Line Items]
Revenues	98,135	77,649	193,167	153,856
Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Revenues	59,198	38,525	113,972	70,815
Emerging Verticals
Disaggregation of Revenue [Line Items]
Revenues	61,217	40,452	115,226	78,845
North America
Disaggregation of Revenue [Line Items]
Revenues	334,788	264,451	651,440	503,897
Europe
Disaggregation of Revenue [Line Items]
Revenues	177,345	149,804	350,853	302,889
CIS
Disaggregation of Revenue [Line Items]
Revenues	25,091	19,411	43,265	41,191
APAC
Disaggregation of Revenue [Line Items]
Revenues	14,363	11,981	27,362	21,818
North America
Disaggregation of Revenue [Line Items]
Segment revenues	331,039	257,103	641,728	488,299
North America | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Segment revenues	220	294	624	638
North America | Transferred over time
Disaggregation of Revenue [Line Items]
Segment revenues	330,819	256,809	641,104	487,661
North America | Time-and-material
Disaggregation of Revenue [Line Items]
Segment revenues	300,326	233,747	585,051	448,063
North America | Fixed-price
Disaggregation of Revenue [Line Items]
Segment revenues	29,681	22,483	54,421	38,475
North America | Licensing
Disaggregation of Revenue [Line Items]
Segment revenues	624	638	1,460	1,300
North America | Other revenues
Disaggregation of Revenue [Line Items]
Segment revenues	408	235	796	461
North America | Financial Services
Disaggregation of Revenue [Line Items]
Segment revenues	43,531	26,732	81,925	48,688
North America | Travel & Consumer
Disaggregation of Revenue [Line Items]
Segment revenues	48,178	47,104	95,178	87,791
North America | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Segment revenues	85,600	64,536	164,721	125,100
North America | Business Information & Media
Disaggregation of Revenue [Line Items]
Segment revenues	62,340	59,532	124,701	116,869
North America | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Segment revenues	54,287	32,876	104,443	60,343
North America | Emerging Verticals
Disaggregation of Revenue [Line Items]
Segment revenues	37,103	26,323	70,760	49,508
North America | North America
Disaggregation of Revenue [Line Items]
Segment revenues	323,221	250,273	626,966	476,343
North America | Europe
Disaggregation of Revenue [Line Items]
Segment revenues	5,233	3,086	9,980	5,826
North America | CIS
Disaggregation of Revenue [Line Items]
Segment revenues	2,005	2,089	3,744	4,092
North America | APAC
Disaggregation of Revenue [Line Items]
Segment revenues	580	1,655	1,038	2,038
Europe
Disaggregation of Revenue [Line Items]
Segment revenues	197,452	171,495	391,675	344,838
Europe | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Segment revenues	197	634	402	1,062
Europe | Transferred over time
Disaggregation of Revenue [Line Items]
Segment revenues	197,255	170,861	391,273	343,776
Europe | Time-and-material
Disaggregation of Revenue [Line Items]
Segment revenues	167,581	156,637	335,794	316,103
Europe | Fixed-price
Disaggregation of Revenue [Line Items]
Segment revenues	29,204	14,081	54,450	27,034
Europe | Licensing
Disaggregation of Revenue [Line Items]
Segment revenues	142	327	540	946
Europe | Other revenues
Disaggregation of Revenue [Line Items]
Segment revenues	525	450	891	755
Europe | Financial Services
Disaggregation of Revenue [Line Items]
Segment revenues	58,966	62,496	120,954	128,314
Europe | Travel & Consumer
Disaggregation of Revenue [Line Items]
Segment revenues	56,175	52,120	111,377	101,574
Europe | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Segment revenues	19,442	19,857	39,812	40,151
Europe | Business Information & Media
Disaggregation of Revenue [Line Items]
Segment revenues	35,692	18,117	68,228	36,987
Europe | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Segment revenues	4,907	5,649	9,463	10,472
Europe | Emerging Verticals
Disaggregation of Revenue [Line Items]
Segment revenues	22,270	13,256	41,841	27,340
Europe | North America
Disaggregation of Revenue [Line Items]
Segment revenues	11,553	14,177	24,444	27,538
Europe | Europe
Disaggregation of Revenue [Line Items]
Segment revenues	172,099	146,998	340,866	297,478
Europe | CIS
Disaggregation of Revenue [Line Items]
Segment revenues	0	28	13	91
Europe | APAC
Disaggregation of Revenue [Line Items]
Segment revenues	13,800	10,292	26,352	19,731
Russia
Disaggregation of Revenue [Line Items]
Segment revenues	23,201	17,380	39,781	37,166
Russia | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Segment revenues	0	0	1	10
Russia | Transferred over time
Disaggregation of Revenue [Line Items]
Segment revenues	23,201	17,380	39,780	37,156
Russia | Time-and-material
Disaggregation of Revenue [Line Items]
Segment revenues	12,047	9,765	23,319	19,861
Russia | Fixed-price
Disaggregation of Revenue [Line Items]
Segment revenues	10,943	7,607	16,230	17,279
Russia | Licensing
Disaggregation of Revenue [Line Items]
Segment revenues	196	1	202	11
Russia | Other revenues
Disaggregation of Revenue [Line Items]
Segment revenues	15	7	30	15
Russia | Financial Services
Disaggregation of Revenue [Line Items]
Segment revenues	18,009	14,091	31,041	30,316
Russia | Travel & Consumer
Disaggregation of Revenue [Line Items]
Segment revenues	2,761	1,792	4,885	3,465
Russia | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Segment revenues	478	624	918	1,388
Russia | Business Information & Media
Disaggregation of Revenue [Line Items]
Segment revenues	104	0	244	0
Russia | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Segment revenues	4	0	66	0
Russia | Emerging Verticals
Disaggregation of Revenue [Line Items]
Segment revenues	1,845	873	2,627	1,997
Russia | North America
Disaggregation of Revenue [Line Items]
Segment revenues	16	14	32	29
Russia | Europe
Disaggregation of Revenue [Line Items]
Segment revenues	99	0	240	42
Russia | CIS
Disaggregation of Revenue [Line Items]
Segment revenues	23,086	17,294	39,509	37,008
Russia | APAC
Disaggregation of Revenue [Line Items]
Segment revenues	0	72	0	87
Total Segments
Disaggregation of Revenue [Line Items]
Segment revenues	551,692	445,978	1,073,184	870,303
Total Segments | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Segment revenues	417	928	1,027	1,710
Total Segments | Transferred over time
Disaggregation of Revenue [Line Items]
Segment revenues	551,275	445,050	1,072,157	868,593
Total Segments | Time-and-material
Disaggregation of Revenue [Line Items]
Segment revenues	479,954	400,149	944,164	784,027
Total Segments | Fixed-price
Disaggregation of Revenue [Line Items]
Segment revenues	69,828	44,171	125,101	82,788
Total Segments | Licensing
Disaggregation of Revenue [Line Items]
Segment revenues	962	966	2,202	2,257
Total Segments | Other revenues
Disaggregation of Revenue [Line Items]
Segment revenues	948	692	1,717	1,231
Total Segments | Financial Services
Disaggregation of Revenue [Line Items]
Segment revenues	120,506	103,319	233,920	207,318
Total Segments | Travel & Consumer
Disaggregation of Revenue [Line Items]
Segment revenues	107,114	101,016	211,440	192,830
Total Segments | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Segment revenues	105,520	85,017	205,451	166,639
Total Segments | Business Information & Media
Disaggregation of Revenue [Line Items]
Segment revenues	98,136	77,649	193,173	153,856
Total Segments | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Segment revenues	59,198	38,525	113,972	70,815
Total Segments | Emerging Verticals
Disaggregation of Revenue [Line Items]
Segment revenues	61,218	40,452	115,228	78,845
Total Segments | North America
Disaggregation of Revenue [Line Items]
Segment revenues	334,790	264,464	651,442	503,910
Total Segments | Europe
Disaggregation of Revenue [Line Items]
Segment revenues	177,431	150,084	351,086	303,346
Total Segments | CIS
Disaggregation of Revenue [Line Items]
Segment revenues	25,091	19,411	43,266	41,191
Total Segments | APAC
Disaggregation of Revenue [Line Items]
Segment revenues	14,380	12,019	27,390	21,856
Other Income Included in Segment Revenues
Disaggregation of Revenue [Line Items]
Segment revenues	(105)	(331)	(264)	(508)
Other income included in segment revenues	(105)	(331)	(264)	(508)
Other Income Included in Segment Revenues | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	(105)	(331)	(264)	(508)
Other Income Included in Segment Revenues | Transferred over time
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	0	0	0	0
Other Income Included in Segment Revenues | Time-and-material
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	0	0	0	0
Other Income Included in Segment Revenues | Fixed-price
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	0	0	0	0
Other Income Included in Segment Revenues | Licensing
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	0	0	0	0
Other Income Included in Segment Revenues | Other revenues
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	(105)	(331)	(264)	(508)
Other Income Included in Segment Revenues | Financial Services
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	(101)	(331)	(254)	(508)
Other Income Included in Segment Revenues | Travel & Consumer
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	0	0	0	0
Other Income Included in Segment Revenues | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	(2)	0	(2)	0
Other Income Included in Segment Revenues | Business Information & Media
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	(1)	0	(6)	0
Other Income Included in Segment Revenues | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	0	0	0	0
Other Income Included in Segment Revenues | Emerging Verticals
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	(1)	0	(2)	0
Other Income Included in Segment Revenues | North America
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	(2)	(13)	(2)	(13)
Other Income Included in Segment Revenues | Europe
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	(86)	(280)	(233)	(457)
Other Income Included in Segment Revenues | CIS
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	0	0	(1)	0
Other Income Included in Segment Revenues | APAC
Disaggregation of Revenue [Line Items]
Other income included in segment revenues	$ (17)	$ (38)	$ (28)	$ (38)

REVENUES (Revenue Expected to b

REVENUES (Revenue Expected to be Recognized in Future Related to Remaining Performance Obligations) (Details) - Fixed-price $ in Thousands	Jun. 30, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenue related to partially or fully unsatisfied performance obligations	$ 14,855
Less than 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenue related to partially or fully unsatisfied performance obligations	10,534
1 Year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenue related to partially or fully unsatisfied performance obligations	4,104
2 Years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenue related to partially or fully unsatisfied performance obligations	217
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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Change in Contract with Customer, Asset and Liability [Abstract]
Revenues from performance obligations satisfied in previous period	$ 7,693	$ 5,452	$ 4,119	$ 6,618
Change in Contract with Customer, Liability [Abstract]
Revenue recognized	610		3,661
Unbilled revenues	23,381		23,381		$ 13,522
Accrued expenses and other current liabilities
Change in Contract with Customer, Liability [Abstract]
Deferred revenues	6,321		6,321		4,558
Other noncurrent liabilities
Change in Contract with Customer, Liability [Abstract]
Deferred revenues	$ 3		$ 3		$ 224

STOCK-BASED COMPENSATION (Compo

STOCK-BASED COMPENSATION (Components of Stock-Based Compensation Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 15,697	$ 14,810	$ 37,553	$ 31,406
Cost of revenues (exclusive of depreciation and amortization)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	7,480	7,054	20,261	15,343
Selling, general and administrative expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 8,217	$ 7,756	$ 17,292	$ 16,063

STOCK-BASED COMPENSATION (Stock

STOCK-BASED COMPENSATION (Stock Options Activity) (Details) - Employee Stock Option - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2019
Number of Options
Options outstanding at January 1, 2019	4,082,944
Options granted	131,849
Options modified	17,871
Options exercised	(528,572)
Options forfeited/cancelled	(2,624)
Options outstanding at June 30, 2019	3,701,468
Options vested and exercisable at June 30, 2019	3,232,985
Options expected to vest at June 30, 2019	435,976
Weighted Average Exercise Price
Options outstanding at January 1, 2019	$ 44.54
Options granted	169.13
Options modified	163.55
Options exercised	42.52
Options forfeited/cancelled	61.38
Options outstanding at June 30, 2019	49.83
Options vested and exercisable at June 30, 2019	40.60
Options expected to vest at June 30, 2019	$ 112.48
Aggregate Intrinsic Value
Options outstanding at June 30, 2019	$ 456,287
Options vested and exercisable at June 30, 2019	428,366
Options expected to vest at June 30, 2019	$ 26,427
Weighted Average Remaining Contractual Term (in years)
Options outstanding at June 30, 2019	5 years 2 months 12 days
Options vested and exercisable at June 30, 2019	4 years 8 months 12 days
Options expected to vest at June 30, 2019	8 years 4 months 24 days

STOCK-BASED COMPENSATION (Sto_2

STOCK-BASED COMPENSATION (Stock Option Additional Information) (Details) - Employee Stock Option $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 15,264
Weighted-average remaining requisite service period	3 years

STOCK-BASED COMPENSATION (Restr

STOCK-BASED COMPENSATION (Restricted Stock and Restricted Stock Units Activity) (Details) - $ / shares	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock
Number of Shares
Unvested awards outstanding at January 1, 2019		793
Awards granted		0
Awards modified		0
Awards vested		0
Awards forfeited/cancelled		0
Unvested awards outstanding at June 30, 2019	793	793
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2019		$ 63.10
Awards granted		0
Awards modified		0
Awards vested		0
Awards forfeited/cancelled		0
Unvested awards outstanding at June 30, 2019	$ 63.10	$ 63.10
Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2019		797,903
Awards granted		274,381
Awards modified		6,897
Awards vested		(255,903)
Awards forfeited/cancelled		(18,742)
Unvested awards outstanding at June 30, 2019	804,536	804,536
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2019		$ 92.13
Awards granted		169.93
Awards modified		170.74
Awards vested		86.05
Awards forfeited/cancelled		103.44
Unvested awards outstanding at June 30, 2019	$ 121.01	$ 121.01
Service Period | Liability Classified Award | Cash-Settled Award | Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2019		302,967
Awards granted		48,632
Awards modified		668
Awards vested		(110,012)
Awards forfeited/cancelled		(2,648)
Unvested awards outstanding at June 30, 2019	239,607	239,607
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2019		$ 83.99
Awards granted		169.13
Awards modified		168.36
Awards vested		80.34
Awards forfeited/cancelled		91.52
Unvested awards outstanding at June 30, 2019	$ 103.10	$ 103.10
Performance Target | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2019		29,592
Awards modified		(29,592)
Unvested awards outstanding at June 30, 2019	0	0
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2019		$ 121.75
Awards modified		121.75
Unvested awards outstanding at June 30, 2019	$ 0	$ 0
test IO | Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock Units
Number of Shares
Awards granted	17,565

STOCK-BASED COMPENSATION (Res_2

STOCK-BASED COMPENSATION (Restricted Stock and Restricted Stock Units Additional Information) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Liability associated with RSUs	$ 7,928	$ 9,920
Service Period | Equity Classified Award | Equity-Settled Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 26
Weighted-average remaining requisite service period	1 year
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	$ 78,261
Weighted-average remaining requisite service period	2 years 10 months 24 days
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	$ 30,785
Weighted-average remaining requisite service period	2 years 3 months 18 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	$ 0
Deferred compensation due to employees | 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	$ 7,928	$ 9,920

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Schedule of Components and Changes in Income Tax Expense (Benefit) and Respective Balance Sheet Items [Line Items]
Effective tax rate	16.60%	12.00%		11.30%	(9.20%)
Excess tax benefit	$ 4,741	$ 5,440		$ 16,254	$ 10,130
Net deferred tax asset resulting from the change in tax status of foreign subsidiaries		$ 706			$ 25,340
Tax Cuts and Jobs Act
Schedule of Components and Changes in Income Tax Expense (Benefit) and Respective Balance Sheet Items [Line Items]
Provisional income tax expense			$ (2,157)

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator for basic and diluted earnings per share:
Net income	$ 58,777	$ 60,754	$ 50,255	$ 64,418	$ 119,531	$ 114,673
Numerator for basic and diluted earnings per share	$ 58,777		$ 50,255		$ 119,531	$ 114,673
Denominator:
Weighted average common shares for basic earnings per share	54,681,959		53,517,124		54,464,753	53,299,038
Net effect of dilutive stock options, restricted stock units and restricted stock awards	2,932,325		3,069,885		2,961,810	3,115,948
Weighted average common shares for diluted earnings per share	57,614,284		56,587,009		57,426,563	56,414,986
Net income per share:
Basic (in dollars per share)	$ 1.07		$ 0.94		$ 2.19	$ 2.15
Diluted (in dollars per share)	$ 1.02		$ 0.89		$ 2.08	$ 2.03
Anti-dilutive options not included in the calculation (in shares)	168,451		155,142		97,327	104,186

SEGMENTS INFORMATION (Revenues

SEGMENTS INFORMATION (Revenues from External Customers and Operating Profit Before Unallocated Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Operating profit	$ 72,882	$ 54,237	$ 137,540	$ 102,934
North America
Segment Reporting Information [Line Items]
Segment revenues	331,039	257,103	641,728	488,299
Operating profit	69,347	51,221	133,804	95,181
Europe
Segment Reporting Information [Line Items]
Segment revenues	197,452	171,495	391,675	344,838
Operating profit	27,679	26,568	59,464	55,458
Russia
Segment Reporting Information [Line Items]
Segment revenues	23,201	17,380	39,781	37,166
Operating profit	5,652	2,321	6,241	7,668
Operating Segments
Segment Reporting Information [Line Items]
Segment revenues	551,692	445,978	1,073,184	870,303
Operating profit	$ 102,678	$ 80,110	$ 199,509	$ 158,307

SEGMENTS INFORMATION (Major Cus

SEGMENTS INFORMATION (Major Customers) (Details) - Customer Concentration Risk	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenue, Segment Benchmark [Member] | Operating Segments
Revenue, Major Customer [Line Items]
Number of customers	0	0	0	0
Accounts Receivable | Billed Revenues
Revenue, Major Customer [Line Items]
Number of customers			0		0
Accounts Receivable | Unbilled Revenues
Revenue, Major Customer [Line Items]
Number of customers			0		0

(Reconciliation of Segment Reve

(Reconciliation of Segment Revenues to Consolidated Revenues and Segment Operating Profit to Consolidated Income Before Provision for/(Benefit from) Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 551,587	$ 445,647	$ 1,072,920	$ 869,795
Segment Reporting Information [Line Items]
Income from operations	72,882	54,237	137,540	102,934
Stock-based compensation expense			(37,553)	(31,406)
Depreciation and amortization expense	(11,028)	(8,962)	(21,228)	(17,138)
Interest and other income, net	1,190	1,052	4,266	501
Foreign exchange (loss)/gain	(3,562)	1,830	(7,046)	1,583
Income before provision for income taxes	70,510	57,119	134,760	105,018
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment revenues	551,692	445,978	1,073,184	870,303
Segment Reporting Information [Line Items]
Income from operations	102,678	80,110	199,509	158,307
Unallocated amounts
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment revenues	(105)	(331)	(264)	(508)
Segment Reporting Information [Line Items]
Other income included in segment revenues	(105)	(331)	(264)	(508)
Stock-based compensation expense	(15,697)	(14,810)	(37,553)	(31,406)
Non-corporate taxes	(2,438)	(2,418)	(4,166)	(4,978)
Professional fees	(555)	(1,400)	(2,324)	(3,316)
Depreciation and amortization expense	(2,603)	(1,974)	(4,743)	(3,743)
Bank charges	(686)	(579)	(1,292)	(1,168)
One-time charges and other acquisition-related expenses	(815)	(1,241)	(1,361)	(1,861)
Other operating expenses	$ (6,897)	$ (3,120)	$ (10,266)	$ (8,393)

SEGMENTS INFORMATION (Physical

SEGMENTS INFORMATION (Physical Location and Values of Long-Lived Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 111,175	$ 102,646
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	48,984	50,085
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	13,799	13,101
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	12,563	9,902
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	12,535	8,433
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	6,755	7,019
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,345	3,168
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,904	2,651
Poland
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,876	2,637
Other
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 7,414	$ 5,650

SEGMENTS INFORMATION (Revenue_2

SEGMENTS INFORMATION (Revenues by Customer Location) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 551,587	$ 445,647	$ 1,072,920	$ 869,795
United States
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	318,988	246,831	618,668	470,514
United Kingdom
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	69,042	50,103	134,781	101,833
Switzerland
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	35,364	34,268	71,597	69,872
Netherlands
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	21,039	17,254	41,655	34,903
Germany
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	19,622	20,111	38,776	39,599
Russia
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	22,460	16,909	38,352	36,321
Canada
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	15,785	17,620	32,757	33,383
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 49,287	$ 42,551	$ 96,334	$ 83,370

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Subsequent Event - Competentum-USA Ltd. $ in Thousands	Jul. 01, 2019USD ($)
Subsequent Event [Line Items]
Acquisition date	Jul. 1, 2019
Equity interest acquired	100.00%
Cash consideration	$ 11,200
Maximum amount of earnout payable	$ 3,000