EPAM Systems (EPAM) 10-Q8 May 172017 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2017	Apr. 28, 2017
Document Documentand Entity Information [Abstract]
Entity Registrant Name	EPAM Systems, Inc.
Entity Central Index Key	1,352,010
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		51,839,547
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Document Period End Date	Mar. 31, 2017
Document Type	10-Q
Amendment Flag	false
Trading Symbol	EPAM

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 398,419	$ 362,025
Restricted cash	268	2,400
Time deposits	403	403
Accounts receivable, net of allowance of $1,241 and $1,434, respectively	176,686	199,982
Unbilled revenues	102,838	63,325
Prepaid and other current assets, net of allowance of $406 and $644, respectively	26,702	15,690
Employee loans, net of allowance of $0 and $0, respectively	2,694	2,726
Total current assets	708,010	646,551
Property and equipment, net	75,962	73,616
Restricted cash	245	239
Employee loans, net of allowance of $0 and $0, respectively	2,975	3,252
Intangible assets, net	49,668	51,260
Goodwill	110,291	109,289
Deferred tax assets	29,211	31,005
Other long-term assets, net of allowance of $138 and $132, respectively	10,625	10,599
Total assets	986,987	925,811
Current liabilities
Accounts payable	3,256	3,213
Accrued expenses and other liabilities	32,451	49,895
Due to employees	44,951	32,203
Deferred compensation due to employees	6,838	5,900
Taxes payable	35,395	25,008
Total current liabilities	122,891	116,219
Long-term debt	25,040	25,048
Other long-term liabilities	3,954	3,132
Total liabilities	151,885	144,399
Commitments and contingencies (Note 8)
Stockholders’ equity
Common stock, $0.001 par value; 160,000,000 authorized; 51,683,500 and 51,117,422 shares issued, 51,663,765 and 51,097,687 shares outstanding at March 31, 2017 and December 31, 2016, respectively	51	50
Additional paid-in capital	396,829	374,907
Retained earnings	469,701	444,320
Treasury stock	(177)	(177)
Accumulated other comprehensive loss	(31,302)	(37,688)
Total stockholders’ equity	835,102	781,412
Total liabilities and stockholders’ equity	$ 986,987	$ 925,811

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets
Accounts receivable allowance	$ 1,241	$ 1,434
Employee loans current allowance	406	644
Employee loans current allowance	0	0
Assets, Noncurrent [Abstract]
Employee loans long-term allowance	0	0
Other long-term assets allowance	$ 138	$ 132
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 )	51,683,500	51,117,422
Common stock, shares outstanding (in shares)	51,663,765	51,097,687

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenues	$ 324,651	$ 264,482
Operating expenses:
Cost of revenues (exclusive of depreciation and amortization)	207,730	167,381
Selling, general and administrative expenses	78,453	61,494
Depreciation and amortization expense	6,672	5,102
Other operating expenses, net	830	174
Income from operations	30,966	30,331
Interest and other income, net	584	1,211
Foreign exchange loss	(2,955)	(1,290)
Income before provision for income taxes	28,595	30,252
Provision for income taxes	4,954	6,353
Net income	23,641	23,899
Foreign currency translation adjustments	6,386	4,699
Comprehensive income	$ 30,027	$ 28,598
Net income per share:
Basic (in dollars per share)	$ 0.46	$ 0.48
Diluted (in dollars per share)	$ 0.44	$ 0.45
Shares used in calculation of net income per share:
Basic (in shares)	50,958	49,714
Diluted (in shares)	53,889	52,883

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income	$ 23,641	$ 23,899
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,672	5,102
Bad debt (recovery)/expense	(517)	552
Deferred taxes	2,595	(482)
Stock-based compensation expense	15,776	10,964
Excess tax benefit on stock-based compensation plans	0	(2,040)
Other	651	50
(Increase)/decrease in operating assets:
Accounts receivable	24,635	16,993
Unbilled revenues	(39,485)	(18,559)
Prepaid expenses and other assets	(79)	(1,383)
Increase/(decrease) in operating liabilities:
Accounts payable	77	671
Accrued expenses and other liabilities	(18,484)	(34,153)
Due to employees	8,611	12,420
Taxes payable	7,135	(3,173)
Net cash provided by operating activities	31,228	10,861
Cash flows from investing activities:
Purchases of property and equipment	(5,725)	(6,185)
Employee housing loans issued	370	0
Proceeds from repayments of employee housing loans	689	470
Decrease in restricted cash and time deposits, net	38	30,000
Increase in other long-term assets, net	(313)	(774)
Other investing activities, net	37	(91)
Net cash (used in)/provided by investing activities	(5,644)	23,420
Cash flows from financing activities:
Proceeds from stock option exercises	10,606	3,108
Excess tax benefit on stock-based compensation plans	0	2,040
Payments of withholding taxes related to net share settlements of restricted stock units	(2,694)	0
Proceeds from debt (Note 4)	0	20,000
Repayment of debt (Note 4)	(30)	(15,031)
Proceeds from government grants	0	135
Acquisition of business, deferred consideration	0	(463)
Net cash provided by financing activities	7,882	9,789
Effect of exchange rate changes on cash and cash equivalents	2,928	1,358
Net increase in cash and cash equivalents	36,394	45,428
Cash and cash equivalents, beginning of period	362,025	199,449
Cash and cash equivalents, end of period	$ 398,419	$ 244,877

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	Mar. 31, 2017
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES EPAM Systems, Inc. (the “Company” or “EPAM”) is a leading global provider of software product development and digital platform engineering services to clients located around the world, primarily in North America, Europe, Asia and Australia. The Company has expertise in various industries, including software and hi-tech, financial services, media and entertainment, travel and hospitality, retail and distribution and life sciences and healthcare. The Company is incorporated in Delaware and headquartered 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”) 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, 2016 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 our 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. Change in Presentation of Certain Financial Information — During the first quarter of 2017, the Company changed the presentation of geographic area information about its consolidated revenues. Historically, information about geographic mix of revenues excluded reimbursable expenses and other revenues, which primarily included travel and entertainment costs that are chargeable to clients. Effective January 1, 2017, the Company reports geographic area information about reimbursable expenses and other revenues based on location of clients to which these costs are chargeable. Accordingly, the Company has changed the presentation of revenues by client location for the three months ended March 31, 2016 to conform to the current period presentation. These changes did not result in any adjustments to the Company’s previously issued financial statements and were applied retrospectively beginning on January 1, 2015. Comparative information for the three months ended March 31, 2016 follows: Three Months Ended March 31, 2016 As reported After Reclassification (in thousands except percentages) United States $ 135,558 51.3 % $ 136,639 51.7 % United Kingdom 42,990 16.3 % 43,560 16.5 % Switzerland 30,765 11.6 % 30,852 11.7 % Canada 15,701 5.9 % 15,846 6.0 % Russia 8,952 3.4 % 8,965 3.4 % Germany 8,706 3.3 % 8,739 3.3 % Hong Kong 5,754 2.2 % 5,944 2.2 % Sweden 4,060 1.5 % 4,128 1.5 % Netherlands 2,547 1.0 % 2,647 1.0 % Ireland 1,184 0.4 % 1,186 0.4 % Italy 636 0.2 % 668 0.3 % Denmark 405 0.2 % 410 0.2 % China 294 0.1 % 294 0.1 % Other locations 4,484 1.7 % 4,604 1.7 % Reimbursable expenses and other revenues 2,446 0.9 % — — % Total $ 264,482 100.0 % $ 264,482 100.0 % Revenue Recognition — The Company recognizes revenue when the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery has occurred; (3) the sales price is fixed or determinable; and (4) collectability is reasonably assured. Determining whether and when some of these criteria have been satisfied often involves assumptions and judgments that can have a significant impact on the timing and amount of revenue reported. The Company derives its revenues from a variety of service offerings, which represent specific competencies of its IT professionals. Contracts for these services have different terms and conditions based on the scope, deliverables, and complexity of the engagement, which require management to make judgments and estimates in determining the appropriate revenue recognition. Fees for these contracts may be in the form of time-and-materials or fixed-price arrangements. If there is an uncertainty about the project completion or receipt of payment for the services, revenue is deferred until the uncertainty is sufficiently resolved. At the time revenue is recognized, the Company provides for any contractual deductions and reduces the revenue accordingly. The Company reports gross reimbursable “out-of-pocket” expenses incurred as both revenues and cost of revenues in the condensed consolidated statements of income and comprehensive income. The Company defers amounts billed to its clients for revenues not yet earned. Such amounts are anticipated to be recorded as revenues when services are performed in subsequent periods. Unbilled revenue is recorded when services have been provided but billed subsequent to the period end in accordance with the contract terms. Fair Value of Financial Instruments — The Company makes assumptions about fair values of its financial assets and liabilities in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 820, “Fair Value Measurement”, and utilizes the following fair value hierarchy in determining inputs used for valuation: Level 1 — Quoted prices for identical assets or liabilities in active markets. Level 2 — Inputs other than quoted prices within Level 1 that are observable either directly or indirectly, including quoted prices in markets that are not active, quoted prices in active markets for similar assets or liabilities, and observable inputs other than quoted prices such as interest rates or yield curves. Level 3 — Unobservable inputs reflecting our view about the assumptions that market participants would use in pricing the asset or liability. Where the fair values of financial assets and liabilities recorded in the condensed consolidated balance sheets cannot be derived from an active market, they are determined using a variety of valuation techniques. These valuation techniques include a net present value technique, comparison to similar instruments with market observable inputs, option pricing models and other relevant valuation models. To the extent possible, observable market data is used as inputs into these models but when it is not feasible, a degree of judgment is required to establish fair values. Changes in fair value could cause a material impact to, and volatility in the Company’s operating results. See Note 3 for disclosures related to fair value. Business Combinations — The Company accounts for its business combinations using the acquisition accounting method, which requires it to determine the fair value of net assets acquired and the related goodwill and other intangible assets in accordance with the FASB ASC Topic 805, “Business Combinations.” The Company identifies and attributes fair values and estimated lives to the intangible assets acquired and allocates the total cost of an acquisition to the underlying net assets based on their respective estimated fair values. Determining the fair value of assets acquired and liabilities assumed requires management’s judgment and involves the use of significant estimates, including projections of future cash inflows and outflows, discount rates, asset lives and market multiples. There are different valuation models for each component, the selection of which requires considerable judgment. These determinations will affect the amount of amortization expense recognized in future periods. The Company bases its fair value estimates on assumptions it believes are reasonable, but recognizes that the assumptions are inherently uncertain. All acquisition-related costs, other than the costs to issue debt or equity securities, are accounted for as expenses in the period in which they are incurred. Changes in fair value of contingent consideration arrangements that are not measurement period adjustments are recognized in earnings. Payments to settle contingent consideration, if any, are reflected in cash flows from financing activities and the changes in fair value are reflected in cash flows from operating activities in the Company’s condensed consolidated statements of cash flows. The acquired assets typically consist of customer relationships, trade names, non-competition agreements, and workforce and as a result, a substantial portion of the purchase price is usually allocated to goodwill and other intangible assets. Goodwill and Other Intangible Assets — Goodwill and intangible assets that have indefinite useful lives are accounted for in accordance with FASB ASC 350, “Intangibles - Goodwill and Other.” The Company conducts its evaluation of goodwill impairment at the reporting unit level on an annual basis during its fourth quarter, and more frequently if events or circumstances indicate that the carrying value of a reporting unit exceeds its fair value. A reporting unit is an operating segment or one level below. The Company does not have intangible assets that have indefinite useful lives. Intangible assets that have finite useful lives are amortized over their estimated useful lives on a straight-line basis. When facts and circumstances indicate potential impairment of amortizable intangible assets, the Company evaluates the recoverability of the asset’s carrying value, using estimates of future cash flows over the remaining asset life. The estimates of future cash flows attributable to intangible assets require significant judgment based on the Company’s historical and anticipated results. Any impairment loss is measured by the excess of carrying value over fair value. Stock-Based Compensation — The Company recognizes the cost of its stock-based incentive awards based on the fair value of the award at the date of grant, net of estimated forfeitures. The cost is expensed evenly over the service period. The service period is the period over which the employee performs the related services, which is normally the same as the vesting period. Over time, the forfeiture assumption is adjusted to the actual forfeiture rate and such change may affect the timing of the total amount of expense recognized over the vesting period. Equity-based awards that do not require future service are expensed immediately. Equity-based awards that do not meet the criteria for equity classification are recorded as liabilities and adjusted to fair value at the end of each reporting period. Off-Balance Sheet Financial Instruments — The Company uses FASB ASC Topic 825, “Financial Instruments” to identify and disclose off-balance sheet financial instruments, which include credit instruments, such as commitments to make employee loans and related guarantees, standby letters of credit and certain guarantees issued under customer contracts. The face amount for these items represents the exposure to loss, before considering available collateral or the borrower’s ability to repay. Loss contingencies arising from off-balance sheet financial instruments are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. The Company does not believe such matters exist that will have a material effect on the condensed consolidated financial statements.

GOODWILL

GOODWILL	3 Months Ended
GOODWILL	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL	GOODWILL Goodwill by reportable segment was as follows: North America Europe Total Balance as of January 1, 2017 $ 76,812 $ 32,477 $ 109,289 Other acquisitions purchase accounting adjustment (352 ) 352 — Effect of net foreign currency exchange rate changes 144 858 1,002 Balance as of March 31, 2017 $ 76,604 $ 33,687 $ 110,291 There were no accumulated impairment losses in the North America or Europe reportable segments as of March 31, 2017 or December 31, 2016 .

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
FAIR VALUE MEASUREMENTS	Mar. 31, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Company carries contingent liabilities and certain equity-based awards at fair value on a recurring basis on its consolidated balance sheets. Changes in the fair values of these financial liabilities are recorded in cost of revenues and selling, general and administrative expenses on the Company’s consolidated statements of income and comprehensive income. The following tables show the fair values of the Company’s financial liabilities measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 : As of March 31, 2017 Balance Level 1 Level 2 Level 3 Performance-based equity awards $ 6,754 $ 6,754 $ — $ — Cash-settled restricted stock units 84 84 — — Total liabilities measured at fair value on a recurring basis $ 6,838 $ 6,838 $ — $ — As of December 31, 2016 Balance Level 1 Level 2 Level 3 Performance-based equity awards $ 3,789 $ 3,789 $ — $ — Cash-settled restricted stock units 2,111 2,111 — — Total liabilities measured at fair value on a recurring basis $ 5,900 $ 5,900 $ — $ — Performance-based equity awards carried at fair value on a recurring basis represent contractual liabilities related to certain business combination transactions completed in 2014. During the determination period, the Company classified the performance-based equity awards within Level 3. The Company estimated the fair value of these liabilities based on transaction-specific inputs by discounting the expected cash flows to a present value, after taking into account estimated probabilities of reaching specified performance targets, as appropriate. During the year ended December 31, 2016, the company reclassified these liabilities from Level 3 to Level 1. The fair value of the cash-settled restricted stock units is measured using prices for which observable market information is available. 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 Company uses the following methods to estimate the fair values of its financial instruments: • for financial instruments that have quoted market prices, those quoted prices are used to estimate fair value; • for financial instruments for which no quoted market prices are available, fair value is estimated using information obtained from independent third parties, or by discounting the expected cash flows using an estimated current market interest rate for the financial instrument. • for financial instruments for which no quoted market prices are available and that have no defined maturity, have a remaining maturity of 360 days or less, or reprice frequently to a market rate, the Company assumes that the fair value of these instruments approximates their reported value, after taking into consideration any applicable credit risk; The generally short duration of certain of the Company’s assets and liabilities results in a significant number of assets and liabilities for which fair value equals or closely approximates the amount recorded on the Company’s consolidated balance sheets. These types of assets and liabilities which are reported on the Company’s consolidated balance sheets include: • cash and cash equivalents; • time deposits and restricted cash; • employee loans and notes receivable; • borrowings under the 2014 Credit Facility (Note 4 ) In addition, due to the relatively short duration of certain loans, the Company considers fair value for these loans to approximate their carrying amounts. The fair value of other types of loans, such as employee loans issued under the Housing Program, is estimated using information on the rates of return that market participants in Belarus would require when investing in unsecured U.S. dollar-denominated government bonds with similar maturities (a “risk-free rate”), after taking into consideration any applicable credit and liquidity risk. The following tables present the reported amounts and estimated fair values of the financial assets and liabilities for which disclosure of fair value is required, as they would be categorized within the fair-value hierarchy, as of the dates indicated: Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 March 31, 2017 Financial Assets: Cash and cash equivalents $ 398,419 $ 398,419 $ 398,419 $ — $ — Time deposits and restricted cash 916 916 — 916 — Employee loans 5,669 5,669 — — 5,669 Financial Liabilities: Borrowing under 2014 Credit Facility $ 25,022 $ 25,022 $ — $ 25,022 $ — Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 December 31, 2016 Financial Assets: Cash and cash equivalents $ 362,025 $ 362,025 $ 362,025 $ — $ — Time deposits and restricted cash $ 3,042 $ 3,042 $ — $ 3,042 $ — Employee loans $ 5,978 $ 5,978 $ — $ — $ 5,978 Financial Liabilities: Borrowing under 2014 Credit Facility $ 25,019 $ 25,019 $ — $ 25,019 $ —

DEBT

DEBT	3 Months Ended
DEBT	Mar. 31, 2017
Debt Disclosure [Abstract]
DEBT	DEBT Revolving Line of Credit — On September 12, 2014, the Company entered into a credit facility (the “2014 Credit Facility”) with PNC Bank, National Association; Santander Bank, N.A; and Silicon Valley Bank (collectively the “Lenders”) to replace its former revolving loan agreement. The 2014 Credit Facility provides for a borrowing capacity of $100,000 , with potential to increase the credit facility up to $200,000 if certain conditions are met. The 2014 Credit Facility matures on September 12, 2019 . Borrowings under the 2014 Credit Facility may be denominated in U.S. dollars or, up to a maximum of $50,000 equivalent in British pounds sterling, Canadian dollars, euros or Swiss francs (or other currencies as may be approved by the Lenders). Borrowings under the 2014 Credit Facility bear interest at either a base rate or Euro-rate plus a margin based on the Company’s leverage ratio. Base rate is equal to the highest of (a) the Federal Funds Open Rate, plus 0.5% , (b) the Prime Rate, and (c) the Daily LIBOR Rate, plus 1.0% . The 2014 Credit Facility is collateralized with: (a) all tangible and intangible assets of the Company, and its U.S.-based subsidiaries including all accounts, general intangibles, intellectual property rights and equipment; and (b) all of the outstanding shares of capital stock and other equity interests in U.S.-based subsidiaries of the Company, and 65.0% of the outstanding shares of capital stock and other equity interests in certain of the Company’s foreign subsidiaries. The 2014 Credit Facility includes customary business and financial covenants and restricts the Company’s ability to make or pay dividends (other than certain intercompany dividends) unless no potential or actual event of default has occurred or would be triggered. As of March 31, 2017 , the Company was in compliance with all covenants contained in the 2014 Credit Facility. As of March 31, 2017 and December 31, 2016 , the outstanding debt of the Company under the 2014 Credit Facility was $25,000 , and is subject to a LIBOR-based interest rate, which resets regularly at issuance, based on lending terms. In addition, the Company has a $942 unused irrevocable standby letter of credit associated with its insurance program that was issued under the 2014 Credit Facility. As of March 31, 2017 and December 31, 2016 , the borrowing capacity of the Company under the 2014 Credit Facility was $74,058 .

INCOME TAXES

INCOME TAXES	3 Months Ended
INCOME TAXES	Mar. 31, 2017
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES In determining its quarterly provision for income taxes, the Company uses an estimated annual effective tax rate, which is based on expected annual profit before tax, statutory tax rates and tax planning opportunities available in the various jurisdictions in which the Company operates. Certain significant or unusual items are separately recognized in the quarter in which they occur and can be a source of variability in the effective tax rates from quarter to quarter. The Company’s worldwide effective tax rate for the three months ended March 31, 2017 and 2016 was 17.3% and 21.0% , respectively. The decrease in the three months ended March 31, 2017 as compared to the same period last year was primarily due to the recognition of excess tax benefits of $1,695 following the adoption of ASU No. 2016-09 in the first quarter of fiscal year 2017. Refer to Note 10 , “Recent Accounting Pronouncements,” for further information. Our Belarus subsidiary is eligible for certain income tax holiday benefits granted by the local government for its export activities conducted within the Hi-Tech Park. Income tax holidays are effective for 15 years starting from 2006. Other subsidiaries of the Company are primarily taxed at the jurisdictions’ statutory rate most of which are lower than U.S. federal statutory rates.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	3 Months Ended
STOCK-BASED COMPENSATION	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION The following costs related to the Company’s stock compensation plans were included in the condensed consolidated statements of income and comprehensive income: Three Months Ended 2017 2016 Cost of revenues $ 5,350 $ 3,644 Selling, general and administrative expenses - Acquisition related 4,574 3,010 Selling, general and administrative expenses - All other 5,852 4,310 Total $ 15,776 $ 10,964 Equity Plans 2012 Non-Employee Directors Compensation Plan — On January 11, 2012, the Company approved the 2012 Non-Employee Directors Compensation Plan (“2012 Directors Plan”) to be used to issue equity awards to its non-employee directors. The Company authorized 600,000 shares of common stock to be reserved for issuance under the plan. The 2012 Directors Plan will expire after 10 years and is administered by the Company’s Board of Directors. As of March 31, 2017 , 547,560 shares remained available for issuance under the 2012 Directors Plan. 2015 Long-Term Incentive Plan — On June 11, 2015, the Company's stockholders approved the 2015 Long Term Incentive Plan (“2015 Plan”) to be used to issue equity awards to company personnel. As of March 31, 2017 , 5,681,902 shares remained available for issuance under the 2015 Plan. All of the stock option awards issued pursuant to the 2015 Plan expire 10 years from the date of grant. 2012 Long-Term Incentive Plan — On January 11, 2012, the Company approved the 2012 Long-Term Incentive Plan (“2012 Plan”) to be used to issue equity grants to company personnel. In June 2015, the 2012 Plan was discontinued; however, outstanding awards remain subject to the terms of the 2012 Plan and any shares that are subject to an award that was previously granted under the 2012 Plan and that expire or terminate for any reason prior to exercise will become available for issuance under the 2015 Plan. All of the stock option awards issued pursuant to the 2012 Plan expire 10 years from the date of grant. 2006 Stock Option Plan — Effective May 31, 2006, the Board of Directors of the Company adopted the 2006 Stock Option Plan (the “2006 Plan”) to grant stock options to directors, employees, and certain independent contractors. In January 2012, the 2006 Plan was discontinued; however, outstanding awards remain subject to the terms of the 2006 Plan and any shares that are subject to an option award that was previously granted under the 2006 Plan and that expire or terminate for any reason prior to exercise will become available for issuance under the 2015 Plan. All of the awards issued pursuant to the 2006 Plan expire 10 years from the date of grant. Stock Options Stock option activity under the Company’s plans is set forth below: Number of Options Weighted Average Exercise Price Aggregate Intrinsic Value Options outstanding at January 1, 2017 6,637,239 $ 37.20 $ 179,936 Options granted 234,990 73.27 529 Options exercised (486,524 ) 27.92 (23,159 ) Options forfeited/cancelled (75,456 ) 57.87 (1,332 ) Options outstanding at March 31, 2017 6,310,249 $ 39.06 $ 230,072 Options vested and exercisable at March 31, 2017 4,302,714 $ 30.84 $ 192,245 Options expected to vest 1,891,705 $ 56.33 $ 36,302 As of March 31, 2017 , total remaining unrecognized compensation expense related to unvested stock options, net of forfeitures was approximately $42,801 . The expense is expected to be recognized over a weighted-average period of 1.6 years . As of March 31, 2017 , the weighted average remaining contractual term was 6.2 years for fully vested and exercisable outstanding options and 8.1 years for outstanding options expected to vest. As of March 31, 2017 , a total of 176,758 shares underlying options exercised through March 31, 2017 , were in transfer with the Company’s transfer agent. There were no material changes with respect to the assumptions used in the Black-Scholes option valuation model during the three months ended March 31, 2017 , as compared with the assumptions disclosed in Note 14 to the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016 . Restricted Stock and Restricted Stock Units Under the Company’s 2012 Directors Plan, the Company grants awards of restricted stock to non-employee directors until April 2017, and thereafter, restricted stock units (“RSUs”). Under the Company’s 2015 Plan (and prior to its approval, under the 2012 Plan), the Company grants awards of RSUs to Company personnel. In addition, the Company has issued in the past, and may issue in the future its equity securities to compensate employees of acquired businesses for future services. Equity-based awards granted in connection with acquisitions of businesses are generally issued in the form of service-based awards (dependent on continuing employment only) and performance-based awards, which are granted and vest only if certain specified performance conditions are met. The awards issued in connection with acquisitions of businesses are subject to the terms and conditions contained in the applicable award agreement and acquisition documents with a typical vesting period of three years , with 33.3% of the awards granted vesting in equal installments on the first, second and third anniversaries of the grant. Service-Based Awards The table below summarizes activity related to the Company’s equity-classified and liability-classified service-based awards for the three months ended March 31, 2017 . 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, 2017 154,125 $ 40.89 485,188 $ 67.69 204,501 $ 70.53 Awards granted — — 380,577 73.27 138,584 73.27 Awards modified — — (2,570 ) 48.49 2,570 73.27 Awards vested (1,437 ) 20.64 (116,183 ) 65.32 (51,928 ) 70.56 Awards forfeited/cancelled — — (19,036 ) 67.45 (616 ) 70.52 Unvested service-based awards outstanding at March 31, 2017 152,688 $ 41.08 727,976 $ 71.06 293,111 $ 71.84 As of March 31, 2017 , the aggregate unrecognized compensation expense for all outstanding service-based restricted stock was $1,783 . This expense is expected to be recognized over the next 1.1 years using the weighted average method. As of March 31, 2017 , the aggregate unrecognized compensation expense for all outstanding service-based equity-classified RSUs was $45,693 . This expense is expected to be recognized over the next 2.2 years using the weighted average method. As of March 31, 2017 , the aggregate unrecognized compensation expense for all outstanding service-based liability-classified RSUs was $19,842 . This expense is expected to be recognized over the next 2.2 years using the weighted average method. Performance -Based Awards Summarized activity related to the Company’s performance-based awards for the three months ended March 31, 2017 , was as follows: Equity-Classified Restricted Stock Liability-Classified Restricted Stock Equity-Classified Equity-Settled Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested performance-based awards outstanding at January 1, 2017 5,573 $ 33.47 105,602 $ 38.86 4,667 $ 70.22 Awards granted — — — — — — Awards vested (2,552 ) 36.57 — — — — Awards forfeited/cancelled — — — — — — Unvested performance-based awards outstanding at March 31, 2017 3,021 $ 30.85 105,602 $ 38.86 4,667 $ 70.22 As of March 31, 2017 , the aggregate unrecognized compensation expense for all outstanding performance-based equity-classified restricted stock was $89 . This expense is expected to be recognized over the next 1.0 year using the weighted average method. As of March 31, 2017 , the aggregate unrecognized compensation expense for all outstanding performance-based liability-classified restricted stock was $1,221 . This expense is expected to be recognized over the next 1.0 year using the weighted average method. As of March 31, 2017 , the aggregate unrecognized compensation expense for all outstanding performance-based equity-classified RSUs was $389 . This expense is expected to be recognized over the next 1.2 years using the weighted average method. Modifications During the three months ended March 31, 2017, the Company modified certain awards held by a named executive officer of the Company in connection with the execution of a separation agreement on February 28, 2017. Fair value of the modified awards immediately before and after modification was $0 and $563 , respectively. The Company also reclassified certain awards from equity to liability when it became probable that it would settle the awards in cash. As a result of these modifications, the Company recorded incremental share-based compensation expense for the three months ended March 31, 2017 of $167 .

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
EARNINGS PER SHARE	Mar. 31, 2017
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Basic earnings per share is computed by dividing 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 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 2017 2016 Numerator for basic and diluted earnings per share: Net income $ 23,641 $ 23,899 Numerator for basic and diluted earnings per share $ 23,641 $ 23,899 Denominator: Weighted average common shares for basic earnings per share 50,958 49,714 Net effect of dilutive stock options, restricted stock units and restricted stock awards 2,931 3,169 Weighted average common shares for diluted earnings per share 53,889 52,883 Net income per share: Basic $ 0.46 $ 0.48 Diluted $ 0.44 $ 0.45 The number of shares underlying equity-based awards excluded from the calculation of diluted earnings per share because the effect would be anti-dilutive, was 2,272 and 2,218 during the three months ended March 31, 2017 and 2016, respectively.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
COMMITMENTS AND CONTINGENCIES	Mar. 31, 2017
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 such as title to assets and intellectual property rights associated with certain arrangements. 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, it 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 adverse effect on the Company’s business, financial condition, results of operations and cash flows.

SEGMENTS INFORMATION

SEGMENTS INFORMATION	3 Months Ended
SEGMENTS INFORMATION	Mar. 31, 2017
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION The Company determines its business segments and reports segment information in accordance with the management approach, which designates internal reporting used by management to make operating decisions and assess performance as the source of the Company’s reportable segments. The Company manages its business primarily based on the geographic managerial responsibility for its client base. As managerial responsibility for a particular client relationship generally correlates with the client’s geographic location, there is a high degree of similarity between client locations and the geographic boundaries of the Company’s reportable segments. In some cases, managerial responsibility for a particular client is assigned to a management team in another region and is usually based on the strength of the relationship between client executives and particular members of EPAM’s senior management team. In such cases, the client’s activity would be reported through the management team’s reportable segment. The Company’s reportable segments are North America, Europe, Russia and Other. The revenues in the Other segment represented less than 1% of total segment revenues in 2015 due to the ending of certain customer relationships and contractual changes with other clients. As no substantial clients remained in the segment, during the first quarter of 2016, the Company shifted managerial responsibility for the remaining clients to the Russia segment. This change did not represent a change in the Company’s segments but rather a movement in responsibility for several clients that represented less than 1% of total segment revenue. The Company’s Chief Operating Decision Maker (“CODM”) evaluates performance and allocates resources based on the segment’s revenues and operating profit. Segment operating profit is defined as income from operations before unallocated costs. Generally, operating expenses for each reportable segment have similar characteristics and are subject to similar factors, pressures and challenges. 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 expenses that are not controllable at the segment level are not allocated to specific segments. Such “unallocated” expenses are deducted against the Company’s total income from operations and are not allocated to individual segments in internal management reports used by the CODM. Revenues from external customers and operating profit/(loss), before unallocated expenses, for the North America, Europe, and Russia reportable segments for the three months ended March 31, 2017 and 2016 , were as follows: Three Months Ended 2017 2016 Segment revenues: North America $ 178,303 $ 147,490 Europe 132,707 107,843 Russia 13,693 9,481 Total segment revenues $ 324,703 $ 264,814 Segment operating profit: North America $ 37,092 $ 30,655 Europe 19,811 16,832 Russia 3,549 1,160 Total segment operating profit $ 60,452 $ 48,647 Intersegment transactions were excluded from the above on the basis that they are neither included into the measure of a segment’s profit and loss by the CODM, nor provided to the CODM on a regular basis. During the three months ended March 31, 2016 , revenues from one customer, UBS AG , were $35,669 and accounted for more than 10% of total revenues. Revenues from this customer were included in the Company’s Europe segment in the periods indicated. There were no customers that accounted for more than 10% of total revenues during the three months ended March 31, 2017 . Accounts receivable and unbilled revenues are generally dispersed across our clients in proportion to their revenues. As of March 31, 2017 , accounts receivable from one customer, UBS AG , individually exceeded 10% and accounted for 11.9% of our total accounts receivable. As of March 31, 2017 , unbilled revenues from one customer, Expedia , individually exceeded 10% and accounted for 10.3% of our unbilled revenues. Reconciliation of segment revenues to consolidated revenues and segment operating profit to consolidated income before provision for income taxes is presented below: Three Months Ended 2017 2016 Total segment revenues $ 324,703 $ 264,814 Other revenues (52 ) (332 ) Revenues $ 324,651 $ 264,482 Total segment operating profit: $ 60,452 $ 48,647 Unallocated amounts: Other revenues (52 ) (332 ) Stock-based compensation expense (15,776 ) (10,964 ) Non-corporate taxes (3,451 ) (1,080 ) Professional fees (2,344 ) (1,726 ) Depreciation and amortization (1,975 ) (1,691 ) Bank charges (397 ) (341 ) One-time charges (568 ) — Other corporate expenses (4,923 ) (2,182 ) Income from operations 30,966 30,331 Interest and other income, net 584 1,211 Foreign exchange loss (2,955 ) (1,290 ) Income before provision for income taxes $ 28,595 $ 30,252 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. Geographical information about the Company’s long-lived assets based on physical location of the assets was as follows: As of As of Belarus $ 47,124 $ 46,011 Russia 7,853 7,203 Ukraine 5,847 5,610 Hungary 3,384 3,485 United States 3,013 2,618 Poland 2,498 2,213 China 1,785 1,887 India 1,530 1,650 Other 2,928 2,939 Total $ 75,962 $ 73,616 Information about the Company’s revenues by client location, including reimbursable expenses of $3,925 and $2,446 for the three months ended March 31, 2017 and 2016 , respectively, is as follows: Three Months Ended 2017 2016 United States $ 176,830 $ 136,639 United Kingdom 46,594 43,560 Switzerland 29,096 30,852 Russia 13,209 8,965 Canada 12,494 15,846 Germany 12,094 8,739 Netherlands 8,671 2,647 Sweden 7,466 4,128 Hong Kong 4,777 5,944 United Arab Emirates 2,048 — China 1,584 294 Ireland 1,389 1,186 Italy 1,280 668 Denmark 1,253 410 Other locations 5,866 4,604 Revenues $ 324,651 $ 264,482

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	3 Months Ended
RECENT ACCOUNTING PRONOUNCEMENTS	Mar. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS 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, and cash flows. Stock-Based Compensation — Effective January 1, 2017, the Company adopted Accounting Standard Update (“ASU”) No. 2016-09, Compensation — Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . The provisions of the new guidance affecting the Company require excess tax benefits and tax deficiencies to be recorded in the income statement when the awards vest or are settled; remove the requirement to include hypothetical excess tax benefits in the application of the treasury stock method when computing earnings per share; and provided for a new policy election to either: (1) continue applying forfeiture rate estimates in the determination of compensation cost, or (2) account for forfeitures as a reduction of share-based compensation cost as they occur. The new guidance also requires cash flows related to excess tax benefits to be classified as an operating activity in the cash flow statement and now requires shares withheld for tax withholding purposes to be classified as a financing activity. As a result of this adoption: • the Company prospectively recognized discrete tax benefits of $1,695 in the provision for income taxes line item of its condensed consolidated statements of income and comprehensive income for the three months ended March 31, 2017 related to excess tax benefits upon vesting or settlement of stock-based awards in that period; • the Company recognized a $1,740 increase in beginning retained earnings for previously unrecognized tax benefits using the modified retrospective method of transition, as required by the standard; • the Company elected to adopt the cash flow presentation of the excess tax benefits prospectively where these benefits are classified along with other income tax cash flows as operating cash flows. Accordingly, prior period information has not been restated; • the Company elected to continue to estimate the number of stock-based awards expected to forfeit, rather than electing to account for forfeitures as they occur to determine the amount of compensation cost to be recognized in each period; • the Company excluded the excess tax benefits from the assumed proceeds available to repurchase shares in the computation of our diluted earnings per share for the three months ended March 31, 2017. The adoption of this provision did not have a material impact on the Company’s diluted earnings per share for the three months ended March 31, 2017; • the remaining amendments to this standard, as noted above, are either not applicable, or do not change the Company's current accounting practices and thus do not impact its condensed consolidated financial statements. Simplifying the Measurement for Goodwill — Effective January 1, 2017, the Company early adopted the new accounting guidance simplifying the accounting for goodwill impairment. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The new guidance is adopted on a prospective basis. The adoption of this amended guidance did not have an impact on the Company’s financial results. 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. Revenue Recognition — In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) . The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 will replace most existing revenue recognition guidance in GAAP and permits the use of either the retrospective or modified retrospective transition method. The update requires significant additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments. ASU 2014-09, as amended by ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date , is effective for years beginning after December 15, 2017, including interim periods, with early adoption permitted for years beginning after December 15, 2016. Since the issuance of ASU 2014-09, the FASB has issued additional interpretive guidance, including new accounting standards updates, that clarify certain points of the standard and modify certain requirements. The Company has performed a review of the requirements of the new revenue standard and is monitoring the activity of the FASB and the transition resource group as it relates to specific interpretive guidance. It is reviewing customer contracts and is in the process of applying the five-step model of the new standard to each contract category it has identified and will compare the results to its current accounting practices. The Company plans to adopt ASU 2014-09, as well as other clarifications and technical guidance issued by the FASB related to this new revenue standard, on January 1, 2018. The Company expects the new standard could change the amount and timing of revenue and costs under certain arrangement types. The Company is also assessing pricing provisions contained in certain of its customer contracts, which may represent variable consideration or may provide the customer with a material right, potentially resulting in a different allocation of the transaction price than under current guidance. Due to the complexity of certain of the Company’s contracts, the actual revenue recognition treatment required under the new standard for these arrangements may be dependent on contract-specific terms and may vary in some instances. The Company has not yet determined what impact the new guidance will have on its consolidated financial statements and/or related disclosures or concluded on the transition method. The Company expects to further its assessment of the financial impact of the new guidance on its consolidated financial statements in 2017. Leases — Effective January 1, 2019, the Company will be required to adopt the new guidance of ASC Topic 842, Leases (with early adoption permitted effective January 1, 2018.) This amendment supersedes previous accounting guidance (Topic 840) and requires all leases, with the exception of leases with a term of twelve months or less, to be recorded on the balance sheet as lease assets and lease liabilities. The standard requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that entities may elect to apply. These practical expedients relate to the identification and classification of leases that commenced before the effective date, initial direct costs for leases that commenced before the effective date, and the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset. An entity that elects to apply the practical expedients will, in effect, continue to account for leases that commence before the effective date in accordance with previous GAAP unless the lease is modified, except that lessees are required to recognize a right-of-use asset and a lease liability for all operating leases at each reporting date based on the present value of the remaining minimum rental payments that were tracked and disclosed under previous GAAP. The transition guidance in Topic 842 also provides specific guidance for the amounts previously recognized in accordance with the business combinations guidance for leases. The Company has not yet completed its assessment of the impact of the new guidance on its consolidated financial statements, when it will adopt the standard, or concluded on whether it will elect to apply practical expedients. Measurement of Credit Losses on Financial Instruments — Effective January 1, 2020, the Company will be required to adopt the amended guidance of 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 or concluded on when it will adopt the standard. Tax Accounting for Intra-Entity Asset Transfers — Effective January 1, 2018, with early adoption permitted, the Company will be required to adopt the accounting guidance ASU 2016-16, Accounting for Income Taxes: Intra-Entity Asset Transfers of Assets Other than Inventory, that will require the tax effects of intra-entity asset transfers to be recognized in the period when the transfer occurs. Under current guidance, the tax effects of intra-entity sales of assets are deferred until the transferred asset is sold to a third party or otherwise recovered through use. The new guidance does not apply to intra-entity transfers of inventory and is required to be applied on a modified retrospective basis 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 or concluded on when it will adopt the standard.

SUMMARY OF SIGNIFICANT ACCOUN16

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Mar. 31, 2017
Accounting Policies [Abstract]
Nature of Operations	EPAM Systems, Inc. (the “Company” or “EPAM”) is a leading global provider of software product development and digital platform engineering services to clients located around the world, primarily in North America, Europe, Asia and Australia. The Company has expertise in various industries, including software and hi-tech, financial services, media and entertainment, travel and hospitality, retail and distribution and life sciences and healthcare. The Company is incorporated in Delaware and headquartered 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”) 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, 2016 included in its Annual Report on Form 10-K.
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 our 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.
Change in Presentation of Certain Financial Information	Change in Presentation of Certain Financial Information — During the first quarter of 2017, the Company changed the presentation of geographic area information about its consolidated revenues. Historically, information about geographic mix of revenues excluded reimbursable expenses and other revenues, which primarily included travel and entertainment costs that are chargeable to clients. Effective January 1, 2017, the Company reports geographic area information about reimbursable expenses and other revenues based on location of clients to which these costs are chargeable. Accordingly, the Company has changed the presentation of revenues by client location for the three months ended March 31, 2016 to conform to the current period presentation. These changes did not result in any adjustments to the Company’s previously issued financial statements and were applied retrospectively beginning on January 1, 2015. Comparative information for the three months ended March 31, 2016 follows: Three Months Ended March 31, 2016 As reported After Reclassification (in thousands except percentages) United States $ 135,558 51.3 % $ 136,639 51.7 % United Kingdom 42,990 16.3 % 43,560 16.5 % Switzerland 30,765 11.6 % 30,852 11.7 % Canada 15,701 5.9 % 15,846 6.0 % Russia 8,952 3.4 % 8,965 3.4 % Germany 8,706 3.3 % 8,739 3.3 % Hong Kong 5,754 2.2 % 5,944 2.2 % Sweden 4,060 1.5 % 4,128 1.5 % Netherlands 2,547 1.0 % 2,647 1.0 % Ireland 1,184 0.4 % 1,186 0.4 % Italy 636 0.2 % 668 0.3 % Denmark 405 0.2 % 410 0.2 % China 294 0.1 % 294 0.1 % Other locations 4,484 1.7 % 4,604 1.7 % Reimbursable expenses and other revenues 2,446 0.9 % — — % Total $ 264,482 100.0 % $ 264,482 100.0 %
Revenue Recognition	Revenue Recognition — The Company recognizes revenue when the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery has occurred; (3) the sales price is fixed or determinable; and (4) collectability is reasonably assured. Determining whether and when some of these criteria have been satisfied often involves assumptions and judgments that can have a significant impact on the timing and amount of revenue reported. The Company derives its revenues from a variety of service offerings, which represent specific competencies of its IT professionals. Contracts for these services have different terms and conditions based on the scope, deliverables, and complexity of the engagement, which require management to make judgments and estimates in determining the appropriate revenue recognition. Fees for these contracts may be in the form of time-and-materials or fixed-price arrangements. If there is an uncertainty about the project completion or receipt of payment for the services, revenue is deferred until the uncertainty is sufficiently resolved. At the time revenue is recognized, the Company provides for any contractual deductions and reduces the revenue accordingly. The Company reports gross reimbursable “out-of-pocket” expenses incurred as both revenues and cost of revenues in the condensed consolidated statements of income and comprehensive income. The Company defers amounts billed to its clients for revenues not yet earned. Such amounts are anticipated to be recorded as revenues when services are performed in subsequent periods. Unbilled revenue is recorded when services have been provided but billed subsequent to the period end in accordance with the contract terms.
Fair Value of Financial Instruments	Fair Value of Financial Instruments — The Company makes assumptions about fair values of its financial assets and liabilities in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 820, “Fair Value Measurement”, and utilizes the following fair value hierarchy in determining inputs used for valuation: Level 1 — Quoted prices for identical assets or liabilities in active markets. Level 2 — Inputs other than quoted prices within Level 1 that are observable either directly or indirectly, including quoted prices in markets that are not active, quoted prices in active markets for similar assets or liabilities, and observable inputs other than quoted prices such as interest rates or yield curves. Level 3 — Unobservable inputs reflecting our view about the assumptions that market participants would use in pricing the asset or liability. Where the fair values of financial assets and liabilities recorded in the condensed consolidated balance sheets cannot be derived from an active market, they are determined using a variety of valuation techniques. These valuation techniques include a net present value technique, comparison to similar instruments with market observable inputs, option pricing models and other relevant valuation models. To the extent possible, observable market data is used as inputs into these models but when it is not feasible, a degree of judgment is required to establish fair values. Changes in fair value could cause a material impact to, and volatility in the Company’s operating results. See Note 3 for disclosures related to fair value.
Business Combinations	Business Combinations — The Company accounts for its business combinations using the acquisition accounting method, which requires it to determine the fair value of net assets acquired and the related goodwill and other intangible assets in accordance with the FASB ASC Topic 805, “Business Combinations.” The Company identifies and attributes fair values and estimated lives to the intangible assets acquired and allocates the total cost of an acquisition to the underlying net assets based on their respective estimated fair values. Determining the fair value of assets acquired and liabilities assumed requires management’s judgment and involves the use of significant estimates, including projections of future cash inflows and outflows, discount rates, asset lives and market multiples. There are different valuation models for each component, the selection of which requires considerable judgment. These determinations will affect the amount of amortization expense recognized in future periods. The Company bases its fair value estimates on assumptions it believes are reasonable, but recognizes that the assumptions are inherently uncertain. All acquisition-related costs, other than the costs to issue debt or equity securities, are accounted for as expenses in the period in which they are incurred. Changes in fair value of contingent consideration arrangements that are not measurement period adjustments are recognized in earnings. Payments to settle contingent consideration, if any, are reflected in cash flows from financing activities and the changes in fair value are reflected in cash flows from operating activities in the Company’s condensed consolidated statements of cash flows. The acquired assets typically consist of customer relationships, trade names, non-competition agreements, and workforce and as a result, a substantial portion of the purchase price is usually allocated to goodwill and other intangible assets.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets — Goodwill and intangible assets that have indefinite useful lives are accounted for in accordance with FASB ASC 350, “Intangibles - Goodwill and Other.” The Company conducts its evaluation of goodwill impairment at the reporting unit level on an annual basis during its fourth quarter, and more frequently if events or circumstances indicate that the carrying value of a reporting unit exceeds its fair value. A reporting unit is an operating segment or one level below. The Company does not have intangible assets that have indefinite useful lives. Intangible assets that have finite useful lives are amortized over their estimated useful lives on a straight-line basis. When facts and circumstances indicate potential impairment of amortizable intangible assets, the Company evaluates the recoverability of the asset’s carrying value, using estimates of future cash flows over the remaining asset life. The estimates of future cash flows attributable to intangible assets require significant judgment based on the Company’s historical and anticipated results. Any impairment loss is measured by the excess of carrying value over fair value.
Stock-based Compensation	Stock-Based Compensation — The Company recognizes the cost of its stock-based incentive awards based on the fair value of the award at the date of grant, net of estimated forfeitures. The cost is expensed evenly over the service period. The service period is the period over which the employee performs the related services, which is normally the same as the vesting period. Over time, the forfeiture assumption is adjusted to the actual forfeiture rate and such change may affect the timing of the total amount of expense recognized over the vesting period. Equity-based awards that do not require future service are expensed immediately. Equity-based awards that do not meet the criteria for equity classification are recorded as liabilities and adjusted to fair value at the end of each reporting period.
Off-Balance Sheet Financial Instruments	Off-Balance Sheet Financial Instruments — The Company uses FASB ASC Topic 825, “Financial Instruments” to identify and disclose off-balance sheet financial instruments, which include credit instruments, such as commitments to make employee loans and related guarantees, standby letters of credit and certain guarantees issued under customer contracts. The face amount for these items represents the exposure to loss, before considering available collateral or the borrower’s ability to repay. Loss contingencies arising from off-balance sheet financial instruments are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. The Company does not believe such matters exist that will have a material effect on the condensed consolidated financial statements.

RECENT ACCOUNTING PRONOUNCEME17

RECENT ACCOUNTING PRONOUNCEMENTS RECENT ACCOINTING PRONOUNCEMENTS (Policies)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS 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, and cash flows. Stock-Based Compensation — Effective January 1, 2017, the Company adopted Accounting Standard Update (“ASU”) No. 2016-09, Compensation — Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . The provisions of the new guidance affecting the Company require excess tax benefits and tax deficiencies to be recorded in the income statement when the awards vest or are settled; remove the requirement to include hypothetical excess tax benefits in the application of the treasury stock method when computing earnings per share; and provided for a new policy election to either: (1) continue applying forfeiture rate estimates in the determination of compensation cost, or (2) account for forfeitures as a reduction of share-based compensation cost as they occur. The new guidance also requires cash flows related to excess tax benefits to be classified as an operating activity in the cash flow statement and now requires shares withheld for tax withholding purposes to be classified as a financing activity. As a result of this adoption: • the Company prospectively recognized discrete tax benefits of $1,695 in the provision for income taxes line item of its condensed consolidated statements of income and comprehensive income for the three months ended March 31, 2017 related to excess tax benefits upon vesting or settlement of stock-based awards in that period; • the Company recognized a $1,740 increase in beginning retained earnings for previously unrecognized tax benefits using the modified retrospective method of transition, as required by the standard; • the Company elected to adopt the cash flow presentation of the excess tax benefits prospectively where these benefits are classified along with other income tax cash flows as operating cash flows. Accordingly, prior period information has not been restated; • the Company elected to continue to estimate the number of stock-based awards expected to forfeit, rather than electing to account for forfeitures as they occur to determine the amount of compensation cost to be recognized in each period; • the Company excluded the excess tax benefits from the assumed proceeds available to repurchase shares in the computation of our diluted earnings per share for the three months ended March 31, 2017. The adoption of this provision did not have a material impact on the Company’s diluted earnings per share for the three months ended March 31, 2017; • the remaining amendments to this standard, as noted above, are either not applicable, or do not change the Company's current accounting practices and thus do not impact its condensed consolidated financial statements. Simplifying the Measurement for Goodwill — Effective January 1, 2017, the Company early adopted the new accounting guidance simplifying the accounting for goodwill impairment. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The new guidance is adopted on a prospective basis. The adoption of this amended guidance did not have an impact on the Company’s financial results. 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. Revenue Recognition — In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) . The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 will replace most existing revenue recognition guidance in GAAP and permits the use of either the retrospective or modified retrospective transition method. The update requires significant additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments. ASU 2014-09, as amended by ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date , is effective for years beginning after December 15, 2017, including interim periods, with early adoption permitted for years beginning after December 15, 2016. Since the issuance of ASU 2014-09, the FASB has issued additional interpretive guidance, including new accounting standards updates, that clarify certain points of the standard and modify certain requirements. The Company has performed a review of the requirements of the new revenue standard and is monitoring the activity of the FASB and the transition resource group as it relates to specific interpretive guidance. It is reviewing customer contracts and is in the process of applying the five-step model of the new standard to each contract category it has identified and will compare the results to its current accounting practices. The Company plans to adopt ASU 2014-09, as well as other clarifications and technical guidance issued by the FASB related to this new revenue standard, on January 1, 2018. The Company expects the new standard could change the amount and timing of revenue and costs under certain arrangement types. The Company is also assessing pricing provisions contained in certain of its customer contracts, which may represent variable consideration or may provide the customer with a material right, potentially resulting in a different allocation of the transaction price than under current guidance. Due to the complexity of certain of the Company’s contracts, the actual revenue recognition treatment required under the new standard for these arrangements may be dependent on contract-specific terms and may vary in some instances. The Company has not yet determined what impact the new guidance will have on its consolidated financial statements and/or related disclosures or concluded on the transition method. The Company expects to further its assessment of the financial impact of the new guidance on its consolidated financial statements in 2017. Leases — Effective January 1, 2019, the Company will be required to adopt the new guidance of ASC Topic 842, Leases (with early adoption permitted effective January 1, 2018.) This amendment supersedes previous accounting guidance (Topic 840) and requires all leases, with the exception of leases with a term of twelve months or less, to be recorded on the balance sheet as lease assets and lease liabilities. The standard requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that entities may elect to apply. These practical expedients relate to the identification and classification of leases that commenced before the effective date, initial direct costs for leases that commenced before the effective date, and the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset. An entity that elects to apply the practical expedients will, in effect, continue to account for leases that commence before the effective date in accordance with previous GAAP unless the lease is modified, except that lessees are required to recognize a right-of-use asset and a lease liability for all operating leases at each reporting date based on the present value of the remaining minimum rental payments that were tracked and disclosed under previous GAAP. The transition guidance in Topic 842 also provides specific guidance for the amounts previously recognized in accordance with the business combinations guidance for leases. The Company has not yet completed its assessment of the impact of the new guidance on its consolidated financial statements, when it will adopt the standard, or concluded on whether it will elect to apply practical expedients. Measurement of Credit Losses on Financial Instruments — Effective January 1, 2020, the Company will be required to adopt the amended guidance of 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 or concluded on when it will adopt the standard. Tax Accounting for Intra-Entity Asset Transfers — Effective January 1, 2018, with early adoption permitted, the Company will be required to adopt the accounting guidance ASU 2016-16, Accounting for Income Taxes: Intra-Entity Asset Transfers of Assets Other than Inventory, that will require the tax effects of intra-entity asset transfers to be recognized in the period when the transfer occurs. Under current guidance, the tax effects of intra-entity sales of assets are deferred until the transferred asset is sold to a third party or otherwise recovered through use. The new guidance does not apply to intra-entity transfers of inventory and is required to be applied on a modified retrospective basis 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 or concluded on when it will adopt the standard.

SUMMARY OF SIGNIFICANT ACCOUN18

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Schedule of Reclassifications	Comparative information for the three months ended March 31, 2016 follows: Three Months Ended March 31, 2016 As reported After Reclassification (in thousands except percentages) United States $ 135,558 51.3 % $ 136,639 51.7 % United Kingdom 42,990 16.3 % 43,560 16.5 % Switzerland 30,765 11.6 % 30,852 11.7 % Canada 15,701 5.9 % 15,846 6.0 % Russia 8,952 3.4 % 8,965 3.4 % Germany 8,706 3.3 % 8,739 3.3 % Hong Kong 5,754 2.2 % 5,944 2.2 % Sweden 4,060 1.5 % 4,128 1.5 % Netherlands 2,547 1.0 % 2,647 1.0 % Ireland 1,184 0.4 % 1,186 0.4 % Italy 636 0.2 % 668 0.3 % Denmark 405 0.2 % 410 0.2 % China 294 0.1 % 294 0.1 % Other locations 4,484 1.7 % 4,604 1.7 % Reimbursable expenses and other revenues 2,446 0.9 % — — % Total $ 264,482 100.0 % $ 264,482 100.0 %

GOODWILL (Tables)

GOODWILL (Tables)	3 Months Ended
GOODWILL (Tables)	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill By Reportable Segment	Goodwill by reportable segment was as follows: North America Europe Total Balance as of January 1, 2017 $ 76,812 $ 32,477 $ 109,289 Other acquisitions purchase accounting adjustment (352 ) 352 — Effect of net foreign currency exchange rate changes 144 858 1,002 Balance as of March 31, 2017 $ 76,604 $ 33,687 $ 110,291

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
FAIR VALUE MEASUREMENTS (Tables)	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Financial Liabilities Measured at Fair Value on Recurring Basis	The following tables show the fair values of the Company’s financial liabilities measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 : As of March 31, 2017 Balance Level 1 Level 2 Level 3 Performance-based equity awards $ 6,754 $ 6,754 $ — $ — Cash-settled restricted stock units 84 84 — — Total liabilities measured at fair value on a recurring basis $ 6,838 $ 6,838 $ — $ — As of December 31, 2016 Balance Level 1 Level 2 Level 3 Performance-based equity awards $ 3,789 $ 3,789 $ — $ — Cash-settled restricted stock units 2,111 2,111 — — Total liabilities measured at fair value on a recurring basis $ 5,900 $ 5,900 $ — $ —
Financial Assets and Liabilities Not Measured on Recurring Basis	The following tables present the reported amounts and estimated fair values of the financial assets and liabilities for which disclosure of fair value is required, as they would be categorized within the fair-value hierarchy, as of the dates indicated: Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 March 31, 2017 Financial Assets: Cash and cash equivalents $ 398,419 $ 398,419 $ 398,419 $ — $ — Time deposits and restricted cash 916 916 — 916 — Employee loans 5,669 5,669 — — 5,669 Financial Liabilities: Borrowing under 2014 Credit Facility $ 25,022 $ 25,022 $ — $ 25,022 $ — Fair Value Hierarchy Balance Estimated Fair Value Level 1 Level 2 Level 3 December 31, 2016 Financial Assets: Cash and cash equivalents $ 362,025 $ 362,025 $ 362,025 $ — $ — Time deposits and restricted cash $ 3,042 $ 3,042 $ — $ 3,042 $ — Employee loans $ 5,978 $ 5,978 $ — $ — $ 5,978 Financial Liabilities: Borrowing under 2014 Credit Facility $ 25,019 $ 25,019 $ — $ 25,019 $ —

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	3 Months Ended
STOCK-BASED COMPENSATION (Tables)	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Costs Related to Stock Compensation Plans	The following costs related to the Company’s stock compensation plans were included in the condensed consolidated statements of income and comprehensive income: Three Months Ended 2017 2016 Cost of revenues $ 5,350 $ 3,644 Selling, general and administrative expenses - Acquisition related 4,574 3,010 Selling, general and administrative expenses - All other 5,852 4,310 Total $ 15,776 $ 10,964
Stock Option Activity	Stock option activity under the Company’s plans is set forth below: Number of Options Weighted Average Exercise Price Aggregate Intrinsic Value Options outstanding at January 1, 2017 6,637,239 $ 37.20 $ 179,936 Options granted 234,990 73.27 529 Options exercised (486,524 ) 27.92 (23,159 ) Options forfeited/cancelled (75,456 ) 57.87 (1,332 ) Options outstanding at March 31, 2017 6,310,249 $ 39.06 $ 230,072 Options vested and exercisable at March 31, 2017 4,302,714 $ 30.84 $ 192,245 Options expected to vest 1,891,705 $ 56.33 $ 36,302
Service-based Awards Activity	The table below summarizes activity related to the Company’s equity-classified and liability-classified service-based awards for the three months ended March 31, 2017 . 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, 2017 154,125 $ 40.89 485,188 $ 67.69 204,501 $ 70.53 Awards granted — — 380,577 73.27 138,584 73.27 Awards modified — — (2,570 ) 48.49 2,570 73.27 Awards vested (1,437 ) 20.64 (116,183 ) 65.32 (51,928 ) 70.56 Awards forfeited/cancelled — — (19,036 ) 67.45 (616 ) 70.52 Unvested service-based awards outstanding at March 31, 2017 152,688 $ 41.08 727,976 $ 71.06 293,111 $ 71.84
Performance-based Awards Activity	Summarized activity related to the Company’s performance-based awards for the three months ended March 31, 2017 , was as follows: Equity-Classified Restricted Stock Liability-Classified Restricted Stock Equity-Classified Equity-Settled Restricted Stock Units Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested performance-based awards outstanding at January 1, 2017 5,573 $ 33.47 105,602 $ 38.86 4,667 $ 70.22 Awards granted — — — — — — Awards vested (2,552 ) 36.57 — — — — Awards forfeited/cancelled — — — — — — Unvested performance-based awards outstanding at March 31, 2017 3,021 $ 30.85 105,602 $ 38.86 4,667 $ 70.22

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
EARNINGS PER SHARE (Tables)	Mar. 31, 2017
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 2017 2016 Numerator for basic and diluted earnings per share: Net income $ 23,641 $ 23,899 Numerator for basic and diluted earnings per share $ 23,641 $ 23,899 Denominator: Weighted average common shares for basic earnings per share 50,958 49,714 Net effect of dilutive stock options, restricted stock units and restricted stock awards 2,931 3,169 Weighted average common shares for diluted earnings per share 53,889 52,883 Net income per share: Basic $ 0.46 $ 0.48 Diluted $ 0.44 $ 0.45

SEGMENTS INFORMATION (Tables)

SEGMENTS INFORMATION (Tables)	3 Months Ended
SEGMENTS INFORMATION (Tables)	Mar. 31, 2017
Segment Reporting [Abstract]
Revenues from External Customers and Operating Profit/(Loss) Before Unallocated Expenses	Revenues from external customers and operating profit/(loss), before unallocated expenses, for the North America, Europe, and Russia reportable segments for the three months ended March 31, 2017 and 2016 , were as follows: Three Months Ended 2017 2016 Segment revenues: North America $ 178,303 $ 147,490 Europe 132,707 107,843 Russia 13,693 9,481 Total segment revenues $ 324,703 $ 264,814 Segment operating profit: North America $ 37,092 $ 30,655 Europe 19,811 16,832 Russia 3,549 1,160 Total segment operating profit $ 60,452 $ 48,647
Reconciliation of Segment Revenues to Consolidated Revenues and Segment Operating Profit to Consolidated Income Before Provision for Income Taxes	Reconciliation of segment revenues to consolidated revenues and segment operating profit to consolidated income before provision for income taxes is presented below: Three Months Ended 2017 2016 Total segment revenues $ 324,703 $ 264,814 Other revenues (52 ) (332 ) Revenues $ 324,651 $ 264,482 Total segment operating profit: $ 60,452 $ 48,647 Unallocated amounts: Other revenues (52 ) (332 ) Stock-based compensation expense (15,776 ) (10,964 ) Non-corporate taxes (3,451 ) (1,080 ) Professional fees (2,344 ) (1,726 ) Depreciation and amortization (1,975 ) (1,691 ) Bank charges (397 ) (341 ) One-time charges (568 ) — Other corporate expenses (4,923 ) (2,182 ) Income from operations 30,966 30,331 Interest and other income, net 584 1,211 Foreign exchange loss (2,955 ) (1,290 ) Income before provision for income taxes $ 28,595 $ 30,252
Geographical Information of Long-Lived Assets Based on Physical Location	Geographical information about the Company’s long-lived assets based on physical location of the assets was as follows: As of As of Belarus $ 47,124 $ 46,011 Russia 7,853 7,203 Ukraine 5,847 5,610 Hungary 3,384 3,485 United States 3,013 2,618 Poland 2,498 2,213 China 1,785 1,887 India 1,530 1,650 Other 2,928 2,939 Total $ 75,962 $ 73,616
Revenues by Client Location	Information about the Company’s revenues by client location, including reimbursable expenses of $3,925 and $2,446 for the three months ended March 31, 2017 and 2016 , respectively, is as follows: Three Months Ended 2017 2016 United States $ 176,830 $ 136,639 United Kingdom 46,594 43,560 Switzerland 29,096 30,852 Russia 13,209 8,965 Canada 12,494 15,846 Germany 12,094 8,739 Netherlands 8,671 2,647 Sweden 7,466 4,128 Hong Kong 4,777 5,944 United Arab Emirates 2,048 — China 1,584 294 Ireland 1,389 1,186 Italy 1,280 668 Denmark 1,253 410 Other locations 5,866 4,604 Revenues $ 324,651 $ 264,482

SUMMARY OF SIGNIFICANT ACCOUN24

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reclassification (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Item Effected [Line Items]
Revenues	$ 324,651	$ 264,482
Reimbursable expenses and other revenues
Item Effected [Line Items]
Revenues	3,925	2,446
United States
Item Effected [Line Items]
Revenues	176,830	136,639
United Kingdom
Item Effected [Line Items]
Revenues	46,594	43,560
Switzerland
Item Effected [Line Items]
Revenues	29,096	30,852
Canada
Item Effected [Line Items]
Revenues	12,494	15,846
Russia
Item Effected [Line Items]
Revenues	13,209	8,965
Germany
Item Effected [Line Items]
Revenues	12,094	8,739
Hong Kong
Item Effected [Line Items]
Revenues	4,777	5,944
Sweden
Item Effected [Line Items]
Revenues	7,466	4,128
Netherlands
Item Effected [Line Items]
Revenues	8,671	2,647
Ireland
Item Effected [Line Items]
Revenues	1,389	1,186
Italy
Item Effected [Line Items]
Revenues	1,280	668
Denmark
Item Effected [Line Items]
Revenues	1,253	410
China
Item Effected [Line Items]
Revenues	1,584	294
Other locations
Item Effected [Line Items]
Revenues	$ 5,866	4,604
Previously reported
Item Effected [Line Items]
Revenues		$ 264,482
Percent of Revenue		100.00%
Previously reported \| Reimbursable expenses and other revenues
Item Effected [Line Items]
Revenues		$ 2,446
Percent of Revenue		0.90%
Previously reported \| United States
Item Effected [Line Items]
Revenues		$ 135,558
Percent of Revenue		51.30%
Previously reported \| United Kingdom
Item Effected [Line Items]
Revenues		$ 42,990
Percent of Revenue		16.30%
Previously reported \| Switzerland
Item Effected [Line Items]
Revenues		$ 30,765
Percent of Revenue		11.60%
Previously reported \| Canada
Item Effected [Line Items]
Revenues		$ 15,701
Percent of Revenue		5.90%
Previously reported \| Russia
Item Effected [Line Items]
Revenues		$ 8,952
Percent of Revenue		3.40%
Previously reported \| Germany
Item Effected [Line Items]
Revenues		$ 8,706
Percent of Revenue		3.30%
Previously reported \| Hong Kong
Item Effected [Line Items]
Revenues		$ 5,754
Percent of Revenue		2.20%
Previously reported \| Sweden
Item Effected [Line Items]
Revenues		$ 4,060
Percent of Revenue		1.50%
Previously reported \| Netherlands
Item Effected [Line Items]
Revenues		$ 2,547
Percent of Revenue		1.00%
Previously reported \| Ireland
Item Effected [Line Items]
Revenues		$ 1,184
Percent of Revenue		0.40%
Previously reported \| Italy
Item Effected [Line Items]
Revenues		$ 636
Percent of Revenue		0.20%
Previously reported \| Denmark
Item Effected [Line Items]
Revenues		$ 405
Percent of Revenue		0.20%
Previously reported \| China
Item Effected [Line Items]
Revenues		$ 294
Percent of Revenue		0.10%
Previously reported \| Other locations
Item Effected [Line Items]
Revenues		$ 4,484
Percent of Revenue		1.70%
After reclassification adjustment
Item Effected [Line Items]
Revenues		$ 264,482
Percent of Revenue		100.00%
After reclassification adjustment \| Reimbursable expenses and other revenues
Item Effected [Line Items]
Revenues		$ 0
Percent of Revenue		0.00%
After reclassification adjustment \| United States
Item Effected [Line Items]
Revenues		$ 136,639
Percent of Revenue		51.70%
After reclassification adjustment \| United Kingdom
Item Effected [Line Items]
Revenues		$ 43,560
Percent of Revenue		16.50%
After reclassification adjustment \| Switzerland
Item Effected [Line Items]
Revenues		$ 30,852
Percent of Revenue		11.70%
After reclassification adjustment \| Canada
Item Effected [Line Items]
Revenues		$ 15,846
Percent of Revenue		6.00%
After reclassification adjustment \| Russia
Item Effected [Line Items]
Revenues		$ 8,965
Percent of Revenue		3.40%
After reclassification adjustment \| Germany
Item Effected [Line Items]
Revenues		$ 8,739
Percent of Revenue		3.30%
After reclassification adjustment \| Hong Kong
Item Effected [Line Items]
Revenues		$ 5,944
Percent of Revenue		2.20%
After reclassification adjustment \| Sweden
Item Effected [Line Items]
Revenues		$ 4,128
Percent of Revenue		1.50%
After reclassification adjustment \| Netherlands
Item Effected [Line Items]
Revenues		$ 2,647
Percent of Revenue		1.00%
After reclassification adjustment \| Ireland
Item Effected [Line Items]
Revenues		$ 1,186
Percent of Revenue		0.40%
After reclassification adjustment \| Italy
Item Effected [Line Items]
Revenues		$ 668
Percent of Revenue		0.30%
After reclassification adjustment \| Denmark
Item Effected [Line Items]
Revenues		$ 410
Percent of Revenue		0.20%
After reclassification adjustment \| China
Item Effected [Line Items]
Revenues		$ 294
Percent of Revenue		0.10%
After reclassification adjustment \| Other locations
Item Effected [Line Items]
Revenues		$ 4,604
Percent of Revenue		1.70%

GOODWILL - Roll Forward (Detail

GOODWILL - Roll Forward (Details) $ in Thousands	3 Months Ended
GOODWILL - Roll Forward (Details) $ in Thousands	Mar. 31, 2017USD ($)
Goodwill [Roll Forward]
Balance as of January 1, 2017	$ 109,289
Effect of net foreign currency exchange rate changes	1,002
Balance as of March 31, 2017	110,291
North America
Goodwill [Roll Forward]
Balance as of January 1, 2017	76,812
Effect of net foreign currency exchange rate changes	144
Balance as of March 31, 2017	76,604
Europe
Goodwill [Roll Forward]
Balance as of January 1, 2017	32,477
Effect of net foreign currency exchange rate changes	858
Balance as of March 31, 2017	33,687
Other Acquisitions
Goodwill [Roll Forward]
Purchase accounting adjustments	0
Other Acquisitions \| North America
Goodwill [Roll Forward]
Purchase accounting adjustments	(352)
Other Acquisitions \| Europe
Goodwill [Roll Forward]
Purchase accounting adjustments	$ 352

GOODWILL - Narrative (Details)

GOODWILL - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
North America
Goodwill [Line Items]
Accumulated impairment loss	$ 0	$ 0
Europe
Goodwill [Line Items]
Accumulated impairment loss	$ 0	$ 0

FAIR VALUE MEASUREMENTS - Finan

FAIR VALUE MEASUREMENTS - Financial Liabilities at Fair Value on Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financial Liabilities:
Total liabilities measured at fair value on a recurring basis	$ 6,838	$ 5,900
Restricted Stock
Financial Liabilities:
Performance-based equity awards	6,754	3,789
Cash-Settled Award \| Restricted Stock Units
Financial Liabilities:
Cash-settled restricted stock units	84	2,111
Level 1
Financial Liabilities:
Total liabilities measured at fair value on a recurring basis	6,838	5,900
Level 1 \| Restricted Stock
Financial Liabilities:
Performance-based equity awards	6,754	3,789
Level 1 \| Cash-Settled Award \| Restricted Stock Units
Financial Liabilities:
Cash-settled restricted stock units	84	2,111
Level 2
Financial Liabilities:
Total liabilities measured at fair value on a recurring basis	0	0
Level 2 \| Restricted Stock
Financial Liabilities:
Performance-based equity awards	0	0
Level 2 \| Cash-Settled Award \| Restricted Stock Units
Financial Liabilities:
Cash-settled restricted stock units	0	0
Level 3
Financial Liabilities:
Total liabilities measured at fair value on a recurring basis	0	0
Level 3 \| Restricted Stock
Financial Liabilities:
Performance-based equity awards	0	0
Level 3 \| Cash-Settled Award \| Restricted Stock Units
Financial Liabilities:
Cash-settled restricted stock units	$ 0	$ 0

FAIR VALUE MEASUREMENTS FAIR VA

FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS - Financial Assets and Liabilities Not Measured on Recurring Basis (Details) - Nonrecurring - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Balance
Financial Assets:
Cash and cash equivalents	$ 398,419	$ 362,025
Time deposits and restricted cash	916	3,042
Employee loans	5,669	5,978
Balance \| Revolving Credit Facility
Financial Liabilities:
Borrowing under 2014 Credit Facility	25,022	25,019
Estimated Fair Value
Financial Assets:
Cash and cash equivalents	398,419	362,025
Time deposits and restricted cash	916	3,042
Employee loans	5,669	5,978
Estimated Fair Value \| Revolving Credit Facility
Financial Liabilities:
Borrowing under 2014 Credit Facility	25,022	25,019
Estimated Fair Value \| Level 1
Financial Assets:
Cash and cash equivalents	398,419	362,025
Time deposits and restricted cash	0	0
Employee loans	0	0
Estimated Fair Value \| Level 1 \| Revolving Credit Facility
Financial Liabilities:
Borrowing under 2014 Credit Facility	0	0
Estimated Fair Value \| Level 2
Financial Assets:
Cash and cash equivalents	0	0
Time deposits and restricted cash	916	3,042
Employee loans	0	0
Financial Liabilities:
Borrowing under 2014 Credit Facility	25,022	25,019
Estimated Fair Value \| Level 3
Financial Assets:
Cash and cash equivalents	0	0
Time deposits and restricted cash	0	0
Employee loans	5,669	5,978
Estimated Fair Value \| Level 3 \| Revolving Credit Facility
Financial Liabilities:
Borrowing under 2014 Credit Facility	$ 0	$ 0

DEBT (Details)

DEBT (Details) - Credit Facility 2014 - USD ($) $ in Thousands	Sep. 12, 2014	Mar. 31, 2017	Dec. 31, 2016
Revolving Credit Facility
Debt Instrument [Line Items]
Maturity date	Sep. 12, 2019
Percentage of foreign subsidiaries outstanding shares of capital stock serves as collateral	65.00%
Line of credit, outstanding		$ 25,000	$ 25,000
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, collateralized borrowing capacity	$ 100,000
Line of credit, maximum borrowing capacity	200,000
Line of credit, remaining borrowing capacity		74,058	$ 74,058
Revolving Credit Facility \| Other currencies, excluding U.S. dollars
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity	$ 50,000
Standby Letters of Credit
Debt Instrument [Line Items]
Unused letter of credit outstanding amount		$ 942

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended
INCOME TAXES (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Effective tax rate	17.30%	21.00%
Excess tax benefit recognized	$ 1,695
Income tax holiday period	15 years

STOCK-BASED COMPENSATION - Cost

STOCK-BASED COMPENSATION - Costs Related To Stock Compensation Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 15,776	$ 10,964
Cost of revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	5,350	3,644
Selling, general and administrative expenses \| Business acquisitions
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,574	3,010
Selling, general and administrative expenses \| Organic growth
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 5,852	$ 4,310

STOCK-BASED COMPENSATION - Equi

STOCK-BASED COMPENSATION - Equity Plans Additional Information (Details) - shares	Jun. 11, 2015	Jan. 11, 2012	May 31, 2006	Mar. 31, 2017
2012 Directors Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance (in shares)		600,000
Expiration period of awards issued (in years)		10 years
Number of shares available for issuance (in shares)				547,560
2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of awards issued (in years)	10 years
Number of shares available for issuance (in shares)				5,681,902
2012 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of awards issued (in years)		10 years
2006 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of awards issued (in years)			10 years

STOCK-BASED COMPENSATION - Stoc

STOCK-BASED COMPENSATION - Stock Option Activity (Details) - Employee Stock Option $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)$ / sharesshares
Number of Options
Options outstanding at January 1, 2017 \| shares	6,637,239
Options granted \| shares	234,990
Options exercised \| shares	(486,524)
Options forfeited/cancelled \| shares	(75,456)
Options outstanding at March 31, 2017 \| shares	6,310,249
Options vested and exercisable at March 31, 2017 \| shares	4,302,714
Options expected to vest \| shares	1,891,705
Weighted Average Exercise Price
Options outstanding at January 1, 2017 \| $ / shares	$ 37.20
Options granted \| $ / shares	73.27
Options exercised \| $ / shares	27.92
Options forfeited/cancelled \| $ / shares	57.87
Options outstanding at March 31, 2017 \| $ / shares	39.06
Options vested and exercisable at March 31, 2017 \| $ / shares	30.84
Options expected to vest \| $ / shares	$ 56.33
Aggregate Intrinsic Value
Options outstanding at January 1, 2017 \| $	$ 179,936
Options granted \| $	529
Options exercised \| $	(23,159)
Options forfeited/cancelled \| $	(1,332)
Options outstanding at March 31, 2017 \| $	230,072
Options vested and exercisable at March 31, 2017 \| $	192,245
Options expected to vest \| $	$ 36,302

STOCK-BASED COMPENSATION - St34

STOCK-BASED COMPENSATION - Stock Option Additional Information (Details) - Employee Stock Option $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options exercised in transfer (in shares) \| shares	176,758
2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense \| $	$ 42,801
Weighted average period for recognition of unrecognized compensation expense (in years)	1 year 7 months
Weighted average remaining contractual term for fully vested and exercisable options (in years)	6 years 2 months 15 days
Weighted average contractual term for options expected to vest (in years)	8 years 21 days

STOCK-BASED COMPENSATION - Rest

STOCK-BASED COMPENSATION - Restricted Stock and Restricted Stock units Activity (Details)	3 Months Ended
	Mar. 31, 2017$ / sharesshares
Service Period \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	154,125
Awards granted \| shares	0
Awards modified \| shares	0
Awards vested \| shares	(1,437)
Awards forfeited/cancelled \| shares	0
Unvested awards outstanding at March 31, 2017 \| shares	152,688
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 40.89
Awards granted \| $ / shares	0
Awards modified \| $ / shares	0
Awards vested \| $ / shares	20.64
Awards forfeited/cancelled \| $ / shares	0
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 41.08
Service Period \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	485,188
Awards granted \| shares	380,577
Awards modified \| shares	(2,570)
Awards vested \| shares	(116,183)
Awards forfeited/cancelled \| shares	(19,036)
Unvested awards outstanding at March 31, 2017 \| shares	727,976
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 67.69
Awards granted \| $ / shares	73.27
Awards modified \| $ / shares	48.49
Awards vested \| $ / shares	65.32
Awards forfeited/cancelled \| $ / shares	67.45
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 71.06
Service Period \| Liability Classified Award \| Cash-Settled Award \| Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	204,501
Awards granted \| shares	138,584
Awards modified \| shares	2,570
Awards vested \| shares	(51,928)
Awards forfeited/cancelled \| shares	(616)
Unvested awards outstanding at March 31, 2017 \| shares	293,111
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 70.53
Awards granted \| $ / shares	73.27
Awards modified \| $ / shares	73.27
Awards vested \| $ / shares	70.56
Awards forfeited/cancelled \| $ / shares	70.52
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 71.84
Performance Target \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	5,573
Awards granted \| shares	0
Awards vested \| shares	(2,552)
Awards forfeited/cancelled \| shares	0
Unvested awards outstanding at March 31, 2017 \| shares	3,021
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 33.47
Awards granted \| $ / shares	0
Awards vested \| $ / shares	36.57
Awards forfeited/cancelled \| $ / shares	0
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 30.85
Performance Target \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	4,667
Awards granted \| shares	0
Awards vested \| shares	0
Awards forfeited/cancelled \| shares	0
Unvested awards outstanding at March 31, 2017 \| shares	4,667
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 70.22
Awards granted \| $ / shares	0
Awards vested \| $ / shares	0
Awards forfeited/cancelled \| $ / shares	0
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 70.22
Performance Target \| Liability Classified Award \| Equity-Settled Award \| Restricted Stock
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	105,602
Awards granted \| shares	0
Awards vested \| shares	0
Awards forfeited/cancelled \| shares	0
Unvested awards outstanding at March 31, 2017 \| shares	105,602
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 38.86
Awards granted \| $ / shares	0
Awards vested \| $ / shares	0
Awards forfeited/cancelled \| $ / shares	0
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 38.86

STOCK-BASED COMPENSATION - Re36

STOCK-BASED COMPENSATION - Restricted Stock and Restricted Stock Units Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Acquisition-related Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Service Period \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 1,783
Weighted average period for recognition of unrecognized compensation expense (in years)	1 year 21 days
Service Period \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 45,693
Weighted average period for recognition of unrecognized compensation expense (in years)	2 years 2 months 14 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	$ 19,842
Weighted average period for recognition of unrecognized compensation expense (in years)	2 years 2 months 17 days
Performance Target \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 89
Weighted average period for recognition of unrecognized compensation expense (in years)	1 year
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	$ 389
Weighted average period for recognition of unrecognized compensation expense (in years)	1 year 1 month 26 days
Performance Target \| Liability Classified Award \| Equity-Settled Award \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 1,221
Performance Target \| Liability Classified Award \| Equity-Settled Award \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period for recognition of unrecognized compensation expense (in years)	1 year
Year One \| Acquisition-related Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	33.30%
Year Two \| Acquisition-related Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	33.30%
Year Three \| Acquisition-related Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	33.30%

STOCK-BASED COMPENSATION STOCK-

STOCK-BASED COMPENSATION STOCK-BASED COMPENSATION - Modifications (Details) - USD ($)	Feb. 28, 2017	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Fair value of modified award before modification	$ 0
Fair value of modified award after modification	$ 563
Incremental share-based compensation expense recorded		$ 167

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator for basic and diluted earnings per share:
Net income	$ 23,641	$ 23,899
Numerator for basic and diluted earnings per share	$ 23,641	$ 23,899
Denominator:
Weighted average common shares outstanding (in shares)	50,958	49,714
Effect of dilutive securities (in shares):
Stock options, RSUs and restricted stock awards (in shares)	2,931	3,169
Denominator for diluted earnings per share (in shares)	53,889	52,883
Net income per share:
Basic (in dollars per share)	$ 0.46	$ 0.48
Diluted (in dollars per share)	$ 0.44	$ 0.45
Anti-dilutive options not included in the calculation (in shares)	2,272	2,218

SEGMENTS INFORMATION - Revenues

SEGMENTS INFORMATION - Revenues from External Customers and Operating Profit/(Loss) Before Unallocated Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 324,651	$ 264,482
Operating profit	30,966	30,331
Russia
Segment Reporting Information [Line Items]
Revenues	13,209	8,965
Operating Segments
Segment Reporting Information [Line Items]
Revenues	324,703	264,814
Operating profit	60,452	48,647
Operating Segments \| North America
Segment Reporting Information [Line Items]
Revenues	178,303	147,490
Operating profit	37,092	30,655
Operating Segments \| Europe
Segment Reporting Information [Line Items]
Revenues	132,707	107,843
Operating profit	19,811	16,832
Operating Segments \| Russia
Segment Reporting Information [Line Items]
Revenues	13,693	9,481
Operating profit	$ 3,549	$ 1,160

SEGMENTS INFORMATION - Major Cu

SEGMENTS INFORMATION - Major Customers (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)
Revenue, Major Customer [Line Items]
Revenues	$ 324,651	$ 264,482
Operating Segments
Revenue, Major Customer [Line Items]
Revenues	324,703	264,814
Operating Segments \| Europe
Revenue, Major Customer [Line Items]
Revenues	$ 132,707	$ 107,843
Sales Revenue, Net \| Customer Concentration Risk \| Operating Segments
Revenue, Major Customer [Line Items]
Number of customers	0
Sales Revenue, Net \| Customer Concentration Risk \| Operating Segments \| Europe \| UBS AG
Revenue, Major Customer [Line Items]
Number of customers		1
Revenues		$ 35,669
Accounts Receivable \| Customer Concentration Risk \| UBS AG \| Billed Revenues
Revenue, Major Customer [Line Items]
Number of customers	1
Concentration percentage	11.90%
Accounts Receivable \| Customer Concentration Risk \| Expedia \| Unbilled Revenues
Revenue, Major Customer [Line Items]
Number of customers	1
Concentration percentage	10.30%

SEGMENTS INFORMATION - Reconcil

SEGMENTS INFORMATION - Reconciliation of Segment Revenues to Consolidated Revenues and Segment Operating Profit to Consolidated Income Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 324,651	$ 264,482
Segment Reporting Information [Line Items]
Income from operations	30,966	30,331
Stock-based compensation expense	(15,776)	(10,964)
Depreciation and amortization	(6,672)	(5,102)
Interest and other income, net	584	1,211
Foreign exchange loss	(2,955)	(1,290)
Income before provision for income taxes	28,595	30,252
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	324,703	264,814
Segment Reporting Information [Line Items]
Income from operations	60,452	48,647
Unallocated Amounts
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(52)	(332)
Segment Reporting Information [Line Items]
Other revenues	(52)	(332)
Stock-based compensation expense	(15,776)	(10,964)
Non-corporate taxes	(3,451)	(1,080)
Professional fees	(2,344)	(1,726)
Depreciation and amortization	(1,975)	(1,691)
Bank charges	(397)	(341)
One-time charges	(568)	0
Other corporate expenses	$ (4,923)	$ (2,182)

SEGMENTS INFORMATION - Geograph

SEGMENTS INFORMATION - Geographical Information of Long-Lived Assets Based on Physical Location (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 75,962	$ 73,616
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	47,124	46,011
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	7,853	7,203
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	5,847	5,610
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,384	3,485
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,013	2,618
Poland
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,498	2,213
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	1,785	1,887
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	1,530	1,650
Other
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 2,928	$ 2,939

SEGMENTS INFORMATION - Revenu43

SEGMENTS INFORMATION - Revenues by Client Location (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 324,651	$ 264,482
Reimbursable expenses and other revenues
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	3,925	2,446
United States
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	176,830	136,639
United Kingdom
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	46,594	43,560
Switzerland
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	29,096	30,852
Russia
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	13,209	8,965
Canada
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	12,494	15,846
Germany
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	12,094	8,739
Netherlands
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	8,671	2,647
Sweden
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	7,466	4,128
Hong Kong
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	4,777	5,944
United Arab Emirates
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	2,048	0
China
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,584	294
Ireland
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,389	1,186
Italy
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,280	668
Denmark
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,253	410
Other locations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 5,866	$ 4,604

RECENT ACCOUNTING PRONOUNCEME44

RECENT ACCOUNTING PRONOUNCEMENTS RECENT ACCOUNTING PRONOUNCEMENT - ASU 2016-09 (Details)	3 Months Ended
	Mar. 31, 2017USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Discrete tax benefit recognized	$ 1,695,000
ASU 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Discrete tax benefit recognized	1,695
Adjustment to retained earnings for previusly unrecognized tax benefit	$ 1,740

STOCK-BASED COMPENSATION - Restricted Stock and Restricted Stock units Activity (Details)	3 Months Ended
	Mar. 31, 2017$ / sharesshares
Service Period \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	154,125
Awards granted \| shares	0
Awards modified \| shares	0
Awards vested \| shares	(1,437)
Awards forfeited/cancelled \| shares	0
Unvested awards outstanding at March 31, 2017 \| shares	152,688
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 40.89
Awards granted \| $ / shares	0
Awards modified \| $ / shares	0
Awards vested \| $ / shares	20.64
Awards forfeited/cancelled \| $ / shares	0
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 41.08
Service Period \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	485,188
Awards granted \| shares	380,577
Awards modified \| shares	(2,570)
Awards vested \| shares	(116,183)
Awards forfeited/cancelled \| shares	(19,036)
Unvested awards outstanding at March 31, 2017 \| shares	727,976
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 67.69
Awards granted \| $ / shares	73.27
Awards modified \| $ / shares	48.49
Awards vested \| $ / shares	65.32
Awards forfeited/cancelled \| $ / shares	67.45
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 71.06
Service Period \| Liability Classified Award \| Cash-Settled Award \| Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	204,501
Awards granted \| shares	138,584
Awards modified \| shares	2,570
Awards vested \| shares	(51,928)
Awards forfeited/cancelled \| shares	(616)
Unvested awards outstanding at March 31, 2017 \| shares	293,111
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 70.53
Awards granted \| $ / shares	73.27
Awards modified \| $ / shares	73.27
Awards vested \| $ / shares	70.56
Awards forfeited/cancelled \| $ / shares	70.52
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 71.84
Performance Target \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	5,573
Awards granted \| shares	0
Awards vested \| shares	(2,552)
Awards forfeited/cancelled \| shares	0
Unvested awards outstanding at March 31, 2017 \| shares	3,021
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 33.47
Awards granted \| $ / shares	0
Awards vested \| $ / shares	36.57
Awards forfeited/cancelled \| $ / shares	0
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 30.85
Performance Target \| Equity Classified Award \| Equity-Settled Award \| Restricted Stock Units
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	4,667
Awards granted \| shares	0
Awards vested \| shares	0
Awards forfeited/cancelled \| shares	0
Unvested awards outstanding at March 31, 2017 \| shares	4,667
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 70.22
Awards granted \| $ / shares	0
Awards vested \| $ / shares	0
Awards forfeited/cancelled \| $ / shares	0
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 70.22
Performance Target \| Liability Classified Award \| Equity-Settled Award \| Restricted Stock
Number of Shares
Unvested awards outstanding at January 1, 2017 \| shares	105,602
Awards granted \| shares	0
Awards vested \| shares	0
Awards forfeited/cancelled \| shares	0
Unvested awards outstanding at March 31, 2017 \| shares	105,602
Weighted Average Grant Date Fair Value Per Share
Unvested awards outstanding at January 1, 2016 \| $ / shares	$ 38.86
Awards granted \| $ / shares	0
Awards vested \| $ / shares	0
Awards forfeited/cancelled \| $ / shares	0
Unvested awards outstanding at September 30, 2016 \| $ / shares	$ 38.86