Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Stock Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Related Party Transactions [Abstract] Revenue from related party Revenue from Related Parties Accounts receivable from related party Accounts Receivable, Related Parties Accounting Policies [Abstract] Revenues and reimbursements Reimbursement Revenue Commitments and Contingencies Disclosure [Abstract] Purchase commitments, net of advances Other Commitment, Due in Next Twelve Months Percentage of export-oriented units established Export Oriented Units Established Percentage Export oriented units established percentage. Aggregate disputed amount amount related to transfer pricing and permanent establishment Aggregate Disputed Amount Related to Transfer Pricing and Permanent Establishment Aggregate disputed amount related to transfer pricing and permanent establishment Total bank guarantees and deposits in respect of contingencies Total Bank Guarantees And Deposits In Respect Of Contingencies Total Bank Guarantees and Deposits in Respect of Contingencies Amounts paid as deposits in respect of contingencies Amounts Paid As Deposits In Respect Of Contingencies Amounts paid as deposits in respect of Contingencies. Bank guarantee issued Bank Guarantee Issued Bank Guarantee Issued Compensation and Retirement Disclosure [Abstract] Change in projected benefit obligation: Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Projected benefit obligation at the beginning of the year Defined Benefit Plan, Benefit Obligation Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Benefits paid Defined Benefit Plan, Benefits Paid Actuarial (gain)/loss Defined Benefit Plan, Actuarial Gain (Loss) Acquisition Defined Benefit Plan, Business Combinations and Acquisitions, Benefit Obligation Effect of exchange rate changes Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss) Projected benefit obligation at the end of the year Unfunded amount–non-current Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent Unfunded amount–current Defined Benefit Plan Unfunded Status Current Defined benefit plan unfunded status current. Total accrued liability Defined Benefit Plan Unfunded Status Defined benefit plan unfunded status. Accumulated benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Accounts Payable and Accrued Liabilities, Current [Abstract] Accrued expenses Accrued Expenses Current Accrued expenses. Derivative instruments Derivative Instruments and Hedges, Liabilities Client liability account Payables to Customers Others Other Liabilities, Current Accrued expenses and other current liabilities Accrued Liabilities, Current Equity [Abstract] Schedule of Accumulated Other Comprehensive Loss Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Amortization of Actuarial loss Defined Benefit Plan Actuarial Gain Loss Included In Net Gratuity Cost Defined benefit plan actuarial gain loss included in net gratuity cost. Net gratuity cost Defined Benefit Plan, Net Periodic Benefit Cost Leases [Abstract] Rent expense Operating Leases, Rent Expense, Net Cancelable and non-cancelable operating leases Deferred Rent Credit Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value, Measurement Inputs, Disclosure [Text Block] Income Tax Disclosure [Abstract] Domestic Income (Loss) from Continuing Operations before Income Taxes, Domestic Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Income before income tax expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Earnings Per Share [Abstract] Earnings Per Share Earnings Per Share [Text Block] Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] Derivative instruments Derivative Asset, Current Advances to suppliers Prepaid Supplies Receivables from statutory authorities Service Taxes Receivable, Current Service Taxes Receivable, Current Others Other Assets, Miscellaneous, Current Other current assets Other Assets, Current Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Summary of Fair Value of Foreign Currency Exchange Contracts Schedule of Foreign Exchange Contracts, Statement of Financial Position [Table Text Block] Summary of Effect of Foreign Currency Exchange Contracts on Consolidated Statements of Income Derivative Instruments, Gain (Loss) [Table Text Block] Business Combinations, Goodwill And Intangible Assets Disclosure [Abstract] Business Combinations, Goodwill And Intangible Assets Disclosure [Abstract] 2018 Finite-Lived Intangible Assets, Amortization Expense, Next Rolling Twelve Months 2019 Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Two 2020 Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Three 2021 Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Four 2022 Finite-Lived Intangible Assets, Amortization Expense, Rolling Year Five 2023 and thereafter Finite-Lived Intangible Assets, Amortization Expense, Rolling after Year Five Total Finite-Lived Intangible Assets, Net Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2015 Stock Options Plan Two Thousand Fifteen Stock Options Plan [Member] Two Thousand Fifteen Stock Options Plan [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Increase in number of shares available for grant Share Based Compensation Arrangement By Share Based Payment Award, Increase In Number Of Shares Available For Grant Share Based Compensation Arrangement By Share Based Payment Award, Increase In Number Of Shares Available For Grant Number of shares available for grant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Stock issued on exercise/vesting of equity awards (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Expiring period of equity options to employees Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Statement of Financial Position [Abstract] Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock shares authorized Preferred Stock, Shares Authorized Preferred stock shares issued Preferred Stock, Shares Issued Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock shares authorized Common Stock, Shares Authorized Common stock shares issued Common Stock, Shares, Issued Common stock shares outstanding Common Stock, Shares, Outstanding Less shares held in treasury at cost Treasury Stock, Shares Allocation of Purchase Price to Assets Acquired and Liabilities Assumed Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Unaudited Pro Forma Financial Information Business Acquisition, Pro Forma Information [Table Text Block] Summary of Company's Goodwill Schedule of Goodwill [Table Text Block] Schedule of Finite-Lived Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Indefinite-Lived Intangible Assets Schedule of Indefinite-Lived Intangible Assets [Table Text Block] Amortization of Intangible Assets Finite-lived Intangible Assets Amortization Expense [Table Text Block] Estimated Future Amortization of Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Document And Entity Information [Abstract] Document and entity information. Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Trading Symbol Trading Symbol Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Public Float Entity Public Float Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Health Integrated, Inc. Health Integrated, Inc. [Member] Health Integrated, Inc. [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Customer relationships Customer Relationships [Member] Developed technology Developed Technology Rights [Member] Trade names and trademarks Trademarks and Trade Names [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Tangible Assets Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Tangible Assets Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Tangible Assets Liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Identifiable Intangible Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Goodwill Goodwill Total purchase price Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract] 2018 Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months 2019 Defined Benefit Plan, Expected Future Benefit Payments, Year Two 2020 Defined Benefit Plan, Expected Future Benefit Payments, Year Three 2021 Defined Benefit Plan, Expected Future Benefit Payments, Year Four 2022 Defined Benefit Plan, Expected Future Benefit Payments, Year Five 2023 to 2027 Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter Numerators: Net Income (Loss) Attributable to Parent [Abstract] Net income Net Income (Loss) Attributable to Parent Denominators: Weighted Average Number of Shares Outstanding, Basic [Abstract] Basic weighted average common shares outstanding Weighted Average Number of Shares Outstanding, Basic Dilutive effect of share based awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Diluted weighted average common shares outstanding Weighted Average Number of Shares Outstanding, Diluted Earnings per share: Earnings Per Share, Basic and Diluted [Abstract] Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Weighted average common shares considered anti-dilutive and not included in computing diluted earnings per share Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Business Combinations [Abstract] Revenues Business Acquisition, Pro Forma Revenue Net income Business Acquisition, Pro Forma Net Income (Loss) Earnings per share: Business Acquisition, Earnings Per Share [Abstract] Business Acquisition, Earnings Per Share [Abstract] Basic (in dollars per share) Business Acquisition, Pro Forma Earnings Per Share, Basic Diluted (in dollars per share) Business Acquisition, Pro Forma Earnings Per Share, Diluted Current provision: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Domestic Current Federal, State and Local, Tax Expense (Benefit) Foreign Current Foreign Tax Expense (Benefit) Total Current Income Tax Expense (Benefit) Deferred provision/(benefit): Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Domestic Deferred Federal Income Tax Expense (Benefit) Foreign Deferred Foreign Income Tax Expense (Benefit) Total Deferred Income Tax Expense (Benefit) Income tax expense Income Tax Expense (Benefit) 2018 Capital Leases, Future Minimum Payments, Next Rolling Twelve Months 2019 Capital Leases, Future Minimum Payments, Due in Rolling Year Two 2020 Capital Leases, Future Minimum Payments, Due in Rolling Year Three 2021 Capital Leases, Future Minimum Payments, Due in Rolling Year Four Total minimum lease payments Capital Leases, Future Minimum Payments Due Less: amount representing interest Capital Leases, Future Minimum Payments, Interest Included in Payments Present value of minimum lease payments Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments Less: current portion Capital Lease Obligations, Current Long term capital lease obligation Capital Lease Obligations, Noncurrent Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Derivatives Designated as Hedging Instruments Designated as Hedging Instrument [Member] Derivative not designated as hedging instruments Not Designated as Hedging Instrument [Member] Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Derivatives in cash flow hedging relationships Cash Flow Hedging [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Foreign exchange contracts Foreign Exchange Contract [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Foreign exchange contracts outstanding Derivative, Notional Amount Net derivative losses which could be reclassified into earnings within the next 12 months Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months Maximum outstanding term of cash flow hedges Maximum Length of Time Hedged in Cash Flow Hedge Gain/(losses) that reclassified from AOCI into earning for discontinued hedging transactions Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net Capital Structure Stockholders' Equity Note Disclosure [Text Block] Basis of Preparation Basis of Accounting, Policy [Policy Text Block] Principles of Consolidation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Foreign Currency Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Cash and Cash Equivalents and Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Investments Investment, Policy [Policy Text Block] Accounts Receivable Receivables, Policy [Policy Text Block] Property and equipment Property, Plant and Equipment, Policy [Policy Text Block] Software Development Costs Research, Development, and Computer Software, Policy [Policy Text Block] Business Combinations, Goodwill and Other Intangible Assets Business Combinations Policy [Policy Text Block] Investment in equity affiliate Equity Method Investments, Policy [Policy Text Block] Impairment of long-lived assets Impairment or Disposal of Long-Lived Assets, Including Intangible Assets, Policy [Policy Text Block] Derivative Financial Instruments Derivatives, Policy [Policy Text Block] Employee Benefits Pension and Other Postretirement Plans, Nonpension Benefits, Policy [Policy Text Block] Stock-Based Compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Financial Instruments and Concentration of Credit Risk Financial Instruments And Concentration Of Credit Risk Policy [Policy Text Block] Financial instruments and concentration of credit risk. Lease Obligations Lease, Policy [Policy Text Block] Government Grants Government Grants [Policy Text Block] Government Grants [Policy Text Block] Earnings per share Earnings Per Share, Policy [Policy Text Block] Commitments and contingencies Commitments and Contingencies, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Property, Plant and Equipment [Abstract] Cost Capitalized Computer Software, Gross Less : Accumulated amortization Capitalized Computer Software, Accumulated Amortization Net Capitalized Computer Software, Net Summary of Components of Income Before Income Taxes Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Summary of Income Tax Expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Summary of Effective Income Tax Rate Differs from Amount Computed by Applying U.S. Federal Statutory Income Tax Rate to Income Before Income Taxes Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Summary of Components of Deferred Tax Balances Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Summary of Activity Related to Gross Unrecognized Tax Benefits Schedule Of Unrecognized Tax Benefits Table [Table Text Block] A summary of unrecognized tax benefits recognized during the period. An unrecognized tax benefit is the difference between a tax position taken in a tax return and the amounts recognized in the financial statements for which it is more likely than not, based on the technical merits of the position, that the tax position will not be sustained upon examination. Statement of Comprehensive Income [Abstract] Other comprehensive income: Other Comprehensive Income (Loss), Net of Tax [Abstract] Unrealized gain/(loss) on effective cash flow hedges, net of taxes $5,821, $1,734 and $109, respectively Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Foreign currency translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Retirement benefits, net of taxes $164, ($204) and $22, respectively Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax Reclassification adjustments Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax [Abstract] Realized loss/(gain) on cash flow hedges, net of taxes ($2,110), ($1,190) and ($49), respectively(1) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Retirement benefits, net of taxes $104, $63 and $53, respectively(2) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Net of Tax Total other comprehensive income/(loss) Other Comprehensive Income (Loss), Net of Tax Total comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Leasehold benefits Leasehold Benefits [Member] Leasehold benefits. Non-compete agreements Noncompete Agreements [Member] Trade names and trademarks Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Estimated useful lives of intangible assets Finite-Lived Intangible Asset, Useful Life Other Nonoperating Income (Expense) [Abstract] Other Income, net Interest and Other Income [Text Block] Quarterly Financial Information Disclosure [Abstract] Quarterly Financial Data (Unaudited) Quarterly Financial Information [Text Block] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Accrued expenses and other current liabilities Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] Liabilities, Noncurrent [Abstract] Derivative instruments Derivative Instruments and Hedges, Liabilities, Noncurrent Unrecognized tax benefits Liability for Uncertainty in Income Taxes, Noncurrent Deferred rent Deferred Rent Credit, Noncurrent Retirement benefits Others Other Liabilities, Noncurrent Non-current liabilities Liabilities, Other than Long-term Debt, Noncurrent Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted Stock and Restricted Stock Units Restricted Stock and Restricted Stock Units [Member] Restricted Stock and Restricted Stock Units [Member] Performance Based Stock Awards Performance Based Stock Awards [Member] Performance Based Stock Awards [Member] Costs Related to Company's Stock-Based Compensation Plan Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Stock Based Compensation Stock Option Activity Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Company's Stock Options Outstanding and Stock Options Vested and Exercisable Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block] Restricted Stock Activity Under Company's Stock Plans Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block] Weighted Average Valuation Assumptions for Market Condition Performance Restricted Stock Units Schedule of Share-Based, Stock Units, Valuation Assumptions [Table Text Block] Schedule of Share-Based, Stock Units, Valuation Assumptions [Table Text Block] Schedule of Accrued Liabilities and Other Current Liabilities Schedule of Accrued Liabilities [Table Text Block] Summary of Quarterly Results Quarterly Financial Information [Table Text Block] Revenue Based PRSUs Revenue Based Performance Restricted Stock Units [Member] Revenue Based Performance Restricted Stock Units [Member] Market Condition Based PRSUs Market Condition Based Performance Restricted Stock Units [Member] Market Condition Based Performance Restricted Stock Units [Member] Amendment And Restatement Of The 2006 Omnibus Award Plan (2015 Plan) Amendment And Restatement Of The 2006 Omnibus Award Plan (2015 Plan) [Member] Amendment And Restatement Of The 2006 Omnibus Award Plan (2015 Plan) [Member] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Year One Share-based Compensation Award, Tranche One [Member] Year Two Share-based Compensation Award, Tranche Two [Member] Performance based percentage Percentage Of Performance Criteria Achieved And Shares Vested Percentage Of Performance Criteria Achieved And Shares Vested Percentage of award vesting rights Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Percentage of target shares an employee can earn Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Target Shares Earned Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Target Shares Earned Unrecognized compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options Cost not yet recognized, period for recognition Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Number, granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 2018 Operating Leases, Future Minimum Payments, Next Rolling Twelve Months 2019 Operating Leases, Future Minimum Payments, Due in Rolling Year Two 2020 Operating Leases, Future Minimum Payments, Due in Rolling Year Three 2021 Operating Leases, Future Minimum Payments, Due in Rolling Year Four 2022 Operating Leases, Future Minimum Payments, Due in Rolling Year Five 2023 and thereafter Operating Leases, Future Minimum Payments, Due in Rolling after Year Five Total operating lease payments Operating Leases, Future Minimum Payments Due Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring Fair Value, Measurements, Recurring [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Assets Assets, Fair Value Disclosure [Abstract] Money market and mutual funds Money Market And Mutual Fund Fair Value Disclosure Money market and mutual fund fair value disclosure. Derivative financial instruments Foreign Currency Contract, Asset, Fair Value Disclosure Total Assets, Fair Value Disclosure Liabilities Liabilities, Fair Value Disclosure [Abstract] Derivative financial instruments Foreign Currency Contracts, Liability, Fair Value Disclosure Fair value of earn-out consideration Nonfinancial Liabilities Fair Value Disclosure Total Financial and Nonfinancial Liabilities, Fair Value Disclosure Deferred tax assets: Components of Deferred Tax Assets [Abstract] Tax credit carry forward Deferred Tax Assets, Tax Credit Carryforwards Depreciation and amortization Deferred Tax Assets Depreciation And Amortization Deferred tax assets depreciation and amortization. Stock-based compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Accrued employee costs and other expenses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Net operating loss carry forwards Deferred Tax Assets, Operating Loss Carryforwards Unrealized exchange loss Deferred Tax Assets, Unrealized Currency Losses Deferred rent Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Deferred Rent Others Deferred Tax Assets, Other Deferred tax assets Deferred Tax Assets, Gross Valuation allowance Deferred Tax Assets, Valuation Allowance Deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Deferred tax liabilities: Components of Deferred Tax Liabilities [Abstract] Unrealized exchange gain Deferred Tax Liabilities, Unrealized Currency Transaction Gains Intangible assets Deferred Tax Liabilities, Intangible Assets Others Deferred Tax Liabilities, Other Deferred tax liabilities: Deferred Tax Liabilities, Net Net deferred tax assets Deferred Tax Assets, Net Summary of Non-Current Liabilities Other Noncurrent Liabilities [Table Text Block] Business Combinations, Goodwill and Intangible Assets Business Combination, Goodwill, And Intangible Assets Disclosure [Text Block] Business Combination, Goodwill, And Intangible Assets Disclosure [Text Block] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Exercise Price Range [Axis] Exercise Price Range [Axis] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] $8.00 to $15.00 Range One [Member] Range one member. $15.01 to $21.00 Range Two [Member] Range TWO member. $21.01 to $28.00 Range Three [Member] Range three member. Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Range of Exercise Prices, lower range limit (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit Range of Exercise Prices, upper range limit (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit Options Outstanding (in shares) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options Options Outstanding, Weighted-Average Exercise Price (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price Segment Reporting [Abstract] Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Insurance Insurance [Member] Insurance [Member] Healthcare Healthcare [Member] Healthcare [Member] TT&L Travel, Transportation and Logistics [Member] Travel, Transportation and Logistics [Member] F&A Finance and Accounting [Member] Finance and Accounting [Member] All Other Other Operations Management [Member] Other Operations Management [Member] Analytics Analytics [Member] Analytics [Member] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] BPM and related services BPM and Related Services [Member] BPM and Related Services [Member] Analytics services Analytics Services [Member] Analytics Services [Member] Revenues and cost of revenues for Company's reportable segments [Line Items] Revenue from External Customer [Line Items] Revenues, net Sales Revenue, Services, Net Cost of revenues (exclusive of depreciation and amortization) Cost of Services, Excluding Depreciation, Depletion, and Amortization Gross profit Gross Profit Operating expenses Operating Expenses Foreign exchange gain, interest expense and other income, net Nonoperating Income (Expense) Income tax expense Net income Number of operating segments, industry focused Number of Operating Segments, Industry Focused Number of Operating Segments, Industry Focused Number of operating segments, finance and accounting Number of Operating Segments, Finance and Accounting Services Number of Operating Segments, Finance and Accounting Services Property and Equipment Property, Plant and Equipment Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Nature of operation and organization Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Finite-lived intangible assets, gross Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Indefinite-lived intangible assets, trade names and trademarks Indefinite-Lived Intangible Assets (Excluding Goodwill) Intangible assets, gross Intangible Assets, Gross (Excluding Goodwill) Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Restricted Stock Restricted Stock [Member] Restricted Stock Units Restricted Stock Units (RSUs) [Member] Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Number, outstanding, beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Number, vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Number, forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Number, outstanding, ending balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Weighted-average fair value, outstanding, beginning balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Weighted-average fair value, granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted-average fair value, vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Weighted-average fair value, forfeited (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Weighted-average fair value, outstanding, ending balance (in dollars per share) Restricted stock units vested for which underlying common stock to be issued (in shares) Restricted Stock Units Vested For Which Underlying Common Stock To Be Issued Restricted Stock Units Vested For Which Underlying Common Stock To Be Issued Restricted stock units vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number Derivatives and Hedge Accounting Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivatives in fair value hedging relationships Fair Value Hedging [Member] Derivative designated as hedging instruments (Gain)/loss recognized in AOCI Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net (Gain)/loss recognized in consolidated statements of income Foreign Currency Transaction Gain (Loss), before Tax Future Minimum Lease Payments under Capital Leases Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block] Future Minimum Lease Payments under Non-Cancelable Operating Lease Agreements Expiring After December 31, 2017 Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Rent Expense Schedule of Rent Expense [Table Text Block] Schedule of Deferred Rent Schedule of Other Assets and Other Liabilities [Table Text Block] Amortization of Intangible Assets Amortization of Intangible Assets Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Cost of revenue Cost of Sales [Member] General and administrative expenses General and Administrative Expense [Member] Selling and marketing expenses Selling and Marketing Expense [Member] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Stock-based compensation expenses Allocated Share-based Compensation Expense Interest and dividend income Investment Income, Interest and Dividend Gain on mutual fund investments Gain (Loss) on Investments Change in fair value of earn-out consideration Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability Other, net Other Miscellaneous Nonoperating Income (Expense) Other Miscellaneous Nonoperating Income (Expense) Other income, net Other Nonoperating Income (Expense) Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] Revenues and Cost of Revenues for Company's Reportable Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Revenues Based on Geographical Information Revenue from External Customers by Geographic Areas [Table Text Block] Property and Equipment, Net Based on Geographical Information Long-lived Assets by Geographic Areas [Table Text Block] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Network equipment and computers Technology Equipment [Member] Software Software and Software Development Costs [Member] Leasehold improvements Leasehold Improvements [Member] Office furniture and equipment Furniture and Fixtures [Member] Motor vehicles Vehicles [Member] Buildings Building [Member] Land Land [Member] Capital work in progress Construction in Progress [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Owned Assets: Property, Plant and Equipment, Net, Excluding Capital Leased Assets [Abstract] Estimated useful life Property, Plant and Equipment, Useful Life Owned assets, gross Property, Plant and Equipment, Gross, Excluding Capital Leased Assets Less: Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Excluding Capital Leased Assets Owned assets, net Property, Plant and Equipment, Net, Excluding Capital Leased Assets Assets under capital leases: Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract] Assets under capital leases, gross Capital Leased Assets, Gross Less: Accumulated depreciation Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation Assets under capital leases, net Capital Leases, Balance Sheet, Assets by Major Class, Net Property and Equipment, net Property, Plant and Equipment, Net Leases Leases of Lessee Disclosure [Text Block] Other Income, net Interest and Other Income [Table Text Block] Unrealized gain/(loss) on effective cash flow hedges, tax Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Retirement benefits, tax Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax Realized (gain)/loss on cash flow hedges, tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax Retirement benefits, tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Tax Non-current liabilities Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Noncurrent [Text Block] Related Party Disclosures Related Party Transactions Disclosure [Text Block] Number of operating segments Number of Operating Segments Number of operating segments, operations management Number of Operating Segments, Operations Management Services Number of Operating Segments, Operations Management Services Number of operating segments, company provides operations management services Number of Operating Segments, Company Provides Operations Management Services Number of Operating Segments, Company Provides Operations Management Services Number of operating segments, non-operations management services Number of Operating Segments, Non-Operations Management Services Number of Operating Segments, Non-Operations Management Services Number of reportable segments Number of Reportable Segments Equity Method Investments and Joint Ventures [Abstract] Investment in equity affiliate Equity Method Investments and Joint Ventures Disclosure [Text Block] Schedule of Acquired Finite-Lived Intangible Asset by Major Class [Table] Schedule of Acquired Finite-Lived Intangible Asset by Major Class [Table] Acquired Finite-Lived Intangible Assets [Line Items] Acquired Finite-Lived Intangible Assets [Line Items] Weighted average life of intangible assets Finite-Lived Intangible Assets, Remaining Amortization Period Segment & Geographical Information Segment Reporting Disclosure [Text Block] Class of Treasury Stock [Table] Class of Treasury Stock [Table] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] 2014 Repurchase Program Two Thousand Fourteen Repurchase Program [Member] Two thousand fourteen repurchase program. 2017 Repurchase Program Two Thousand Seventeen Repurchase Program [Member] Two Thousand Seventeen Repurchase Program [Member] 2014 and 2017 Repurchase Program Two Thousand Fourteen and Two Thousand Seventeen Repurchase Program [Member] Two Thousand Fourteen and Two Thousand Seventeen Repurchase Program [Member] Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Number of classes of common stock outstanding Number Of Classes Of Common Stock Outstanding Number Of Classes Of Common Stock Outstanding Acquisition of restricted stock from employees in connection with withholding tax payments (in shares) Shares Paid for Tax Withholding for Share Based Compensation Withholding tax payments related to the vesting of restricted stock for total consideration Payments Related to Tax Withholding for Share-based Compensation Weighted average purchase price per share prior to the vesting date (in dollars per share) Accelerated Share Repurchases, Final Price Paid Per Share Stock repurchase program, period start (year) Stock Repurchase Program Period Start Stock repurchase program period start. Stock repurchase program, period end (year) Stock Repurchase Program Period End Stock repurchase program period end. Repurchase of common stock authorized by board of directors up to Stock Repurchase Program, Authorized Amount Additional authorized amount Stock Repurchase Program, Additional Authorized Amount Stock Repurchase Program, Additional Authorized Amount Authorized increase in repurchase amount Stock Repurchase Program, Authorized Increase in Repurchase Amount Per Period Stock Repurchase Program, Authorized Increase in Repurchase Amount Per Period Authorized increase in repurchase amount, 2018 Stock Repurchase Program, Authorized Increase in Repurchase Amount Per Period, Year Two Stock Repurchase Program, Authorized Increase in Repurchase Amount Per Period, Year Two Authorized increase in repurchase amount, 2019 Stock Repurchase Program, Authorized Increase in Repurchase Amount Per Period, Year Three Stock Repurchase Program, Authorized Increase in Repurchase Amount Per Period, Year Three Common stock shares purchased under the repurchase program Treasury Stock, Shares, Acquired Common stock aggregate purchase price including commissions Common Stock Aggregate Purchase Price Including Commission Common stock aggregate purchase price including commission. Common stock average purchase price per share (in dollars per share) Treasury Stock Acquired, Average Cost Per Share Cumulative currency translation adjustments Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Unrealized gain on cash flow hedges, net of taxes of $4,918 and $1,207 Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Retirement benefits, net of taxes of ($74) and ($342) Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Unrealized gain on cash flow hedges, taxes Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Tax Portion Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Tax Portion Retirement benefits, taxes Accumulated Other Comprehensive Income (Loss), Defined Benefit Pension And Other Post Retirement Plans, Tax Accumulated Other Comprehensive Income (Loss), Defined Benefit Pension And Other Post Retirement Plans, Tax Assets and Liabilities Measured at Fair Value Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Other Current Assets Schedule of Other Current Assets [Table Text Block] Debt Disclosure [Abstract] Line of Credit Facility [Table] Line of Credit Facility [Table] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility Revolving Credit Facility [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Credit Facility Credit Facility [Member] Credit Facility [Member] New Credit Agreement New Credit Agreement [Member] New Credit Agreement [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Prime Rate Prime Rate [Member] London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Notes Payable, Other Payables Notes Payable, Other Payables [Member] Credit Facilities [Line Items] Line of Credit Facility [Line Items] Revolving credit facility Long-term Line of Credit Option to increase additional credit facility Line Of Credit Facility Option For Additional Borrowing Capacity Line of credit facility option for additional borrowing capacity. Line of credit interest rate during period Line of Credit Facility, Interest Rate During Period Basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Commitment fee percentage range on unused credit facility Line of Credit Facility, Commitment Fee Percentage Interest coverage ratio, minimum Debt Instrument, Covenant, Interest Coverage Ratio, Minimum Debt Instrument, Covenant, Interest Coverage Ratio, Minimum Debt Instrument, Covenant, Leverage Ratio, Maximum Debt Instrument, Covenant, Leverage Ratio, Maximum Debt Instrument, Covenant, Leverage Ratio, Maximum Current portion of long-term borrowings Long-term Debt, Current Maturities Long term borrowings Long-term Debt, Excluding Current Maturities Issuance costs Debt Issuance Costs, Net Unamortized debt issuance costs Unamortized Deferred Finance Costs Unamortized Deferred Finance Costs Structured payable Long-term Debt Accumulated other comprehensive loss, expected to be recognized over the next fiscal year Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year Percentage of expected return on plan assets Defined Benefit Plan Expected Return On Plan Assets Percentage Defined Benefit Plan Expected Return On Plan Assets Percentage Percentage of discretionary contributions towards 401(k) Plan, maximum Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Company's contribution to the 401(k) Plan Defined Contribution Plan, Cost Recognized Contribution to various defined contribution plans Defined Contribution Plan, Employer Discretionary Contribution Amount Employee Stock Option Employee Stock Option [Member] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Number of options, outstanding, beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Number of options, granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Number of options, exercised (in shares) Number of options, forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Number of options, outstanding, ending balance (in shares) Number of options, vested and exercisable at December 31, 2017 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Weighted-average exercise price, outstanding, beginning balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Weighted-average exercise price, granted (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Weighted-average exercise price, exercised (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Weighted-average exercise price, forfeited (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Weighted-average exercise price, outstanding, ending balance (in dollars per share) Weighted average exercise price, vested and exercisable at December 31, 2017 (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price Aggregate intrinsic value, outstanding, beginning balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate intrinsic value, outstanding, ending balance Weighted-average remaining contractual life, outstanding, ending balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Aggregate intrinsic value, vested and exercisable at December 31, 2017 Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Weighted-average remaining contractual life, vested and exercisable at December 31, 2017 Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Borrowings Debt Disclosure [Text Block] Weighted-average fair value of restricted stock and RSUs granted (in dollars per share) Number of restricted stock units, vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Employee Benefit Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Rate of increase in compensation levels Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Expected long term rate of return on plan assets per annum Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets Revenues, net Net income/(loss) Earnings/(loss) per share: Weighted-average number of shares used in computing earnings per share: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Diluted (in shares) Stock compensation expense Amortization of intangibles Number, adjustment upon final determination of level of performance goal achievement (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Non Issued In Period Share Based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other than Options, Non Issued In Period Number, additionally issued due to achievement of higher-than-target performance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Issued in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Issued in Period Weighted-average fair value, adjustment upon final determination of level of performance goal achievement (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Issued in Period, Weighted Average Issue Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Issued in Period, Weighted Average Issue Date Fair Value Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Balance as of January 1, 2016 Unrecognized Tax Benefits Increases related to prior year tax positions Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Decreases related to prior year tax positions Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Increases related to current year tax positions Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Decreases related to current year tax positions Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions Effect of exchange rate changes Unrecognized Tax Benefits, Increase Resulting from Foreign Currency Translation Balance as of December 31, 2016 Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Unbilled accounts receivable Unbilled Receivables, Current Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax [Abstract] Net actuarial gain/(loss) Defined Benefit Plan, Accumulated Other Comprehensive Income Net Gains (Losses), after Tax Net prior service cost Defined Benefit Plan, Accumulated Other Comprehensive Income Net Prior Service Cost (Credit), after Tax Deferred taxes Defined Benefit Plan, Accumulated Other Comprehensive Income Deferred Tax (Benefit) Expense, After Tax Defined Benefit Plan, Accumulated Other Comprehensive Income Deferred Tax Benefit (Expense), After Tax Accumulated other comprehensive gain/(loss), net of tax Schedule of Revenues from External Customers and Property, Plant and Equipment [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] United States UNITED STATES United Kingdom UNITED KINGDOM Rest of World Rest Of World [Member] Rest of World. Total Non-United States Non-US [Member] India INDIA Philippines PHILIPPINES Revenues from External Customers and Property, Plant and Equipment [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Revenues, net Revenues [Abstract] Property, Plant and Equipment, net Property, Plant and Equipment, Net [Abstract] Property and equipment, net Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Beginning Balance Acquisitions Goodwill, Acquired During Period Currency translation adjustments Goodwill, Foreign Currency Translation Gain (Loss) Ending Balance Initial purchase consideration Business Combination, Consideration Transferred Maximum contingent consideration Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High Contingent cash consideration Business Combination, Contingent Consideration, Liability Weighted average useful life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Acquisition related costs Business Combination, Acquisition Related Costs Issued number of shares of restricted stock Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted Issued shares of restricted stock, fair value Share-based Compensation Arrangement by Share-based Payment Award Equity Instruments Other than Options, Granted in Period, Fair Value Share-based Compensation Arrangement by Share-based Payment Award Equity Instruments Other than Options, Granted in Period, Fair Value Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Retained Earnings Retained Earnings [Member] Accumulated Other Comprehensive Income/(Loss) AOCI Attributable to Parent [Member] Treasury Stock Treasury Stock [Member] Non - Controlling Interest Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance (in shares) Beginning balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Stock issued on exercise/vesting of equity awards Stock Issued During Period, Value, Stock Options Exercised Stock based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Excess tax benefit from stock based compensation Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net Acquisition of treasury stock (in shares) Acquisition of treasury stock Acquisition Of Treasury Stock Value Equity impact of the value of stock that has been repurchased during the period and has not been retired and is held in treasury. Non-controlling interest Noncontrolling Interest, Period Increase (Decrease) Other comprehensive income Impact on adoption of ASU 2016-09 Cumulative Effect of New Accounting Principle in Period of Adoption Adjusted equity balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance Ending balance (in shares) Ending balance Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Cost of revenue Cost of Services General & administrative expenses General and Administrative Expense Selling & marketing expenses Selling and Marketing Expense Depreciation & amortization Depreciation, Depletion and Amortization, Nonproduction Foreign exchange gain, net Reclassification from AOCI, before tax Reclassification from AOCI, Current Period, before Tax, Attributable to Parent Assets Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Short-term investments Short-term Investments Restricted cash Restricted Cash and Cash Equivalents, Current Accounts receivable, net Accounts Receivable, Net, Current Prepaid expenses Prepaid Expense, Current Advance income tax, net Prepaid Taxes Other current assets Total current assets Assets, Current Restricted cash Restricted Cash and Cash Equivalents, Noncurrent Deferred taxes, net Deferred Income Tax Assets, Net Intangible assets, net Other assets Other Assets, Noncurrent Investment in equity affiliate Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Total assets Assets Liabilities and Equity Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Deferred revenue Deferred Revenue, Current Accrued employee cost Employee-related Liabilities, Current Accrued expenses and other current liabilities Current portion of capital lease obligations Total current liabilities Liabilities, Current Capital lease obligations, less current portion Income taxes payable Accrued Income Taxes, Noncurrent Non-current liabilities Total liabilities Liabilities Commitments and contingencies (Note 23) Commitments and Contingencies Preferred stock, $0.001 par value; 15,000,000 shares authorized, none issued Preferred Stock, Value, Issued ExlService Holdings, Inc. stockholders’ equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock, $0.001 par value; 100,000,000 shares authorized, 36,790,751 shares issued and 33,888,733 shares outstanding as of December 31, 2017 and 35,699,819 shares issued and 33,628,109 shares outstanding as of December 31, 2016 Common Stock, Value, Issued Additional paid-in-capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Total including shares held in treasury Stockholders Equity Including Shares Held In Treasury Total stockholders' equity including shares held in treasury. Less: 2,902,018 shares as of December 31, 2017 and 2,071,710 shares as of December 31, 2016, held in treasury, at cost Treasury Stock, Value Stockholders' equity Stockholders' Equity Attributable to Parent Non-controlling interest Stockholders' Equity Attributable to Noncontrolling Interest Total equity Total liabilities and equity Liabilities and Equity Income Taxes [Table] Income Taxes [Table] Income Taxes [Table] Tax Period [Axis] Tax Period [Axis] Tax Period [Domain] Tax Period [Domain] First Five Years First Five Years [Member] First Five Years [Member] Five to Ten Years Five To Ten Years [Member] Five To Ten Years [Member] Expiration 2032 Expiration Date Two Thousand And Thirty Two [Member] Expiration Date Two Thousand And Thirty Two [Member] Income Taxes [Line Items] Income Taxes [Line Items] Income Taxes [Line Items] Effective tax rates Effective Income Tax Rate Reconciliation, Percent Re-measured net deferred tax assets and liabilities, income tax expense Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Provisional Income Tax Expense (Benefit) Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Provisional Income Tax Expense (Benefit) Provisional transition tax obligation Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Liability Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Liability Excess tax benefit Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount Number of operation centers, income tax holiday expired Number Of Operation Centers, Income Tax Holiday Expired Number Of Operation Centers, Income Tax Holiday Expired Effective tax rate in Philippines post tax exemption Effective Income Tax Rate Reconciliation Foreign Flat Income Tax Rate Effective income tax rate reconciliation foreign flat income tax rate. Percentage of tax exemption on profit Effective Income Tax Rate Reconciliation, Tax Exempt Income, Percent Effect of diluted earnings per share, tax holiday (in dollars per share) Effect On Diluted Earnings Per Share Tax Holiday Effect on diluted earnings per share tax holiday. Operating loss carryforward valuation allowance Operating Loss Carryforwards, Valuation Allowance Valuation allowance related to tax credit carry forward Tax Credit Carryforward, Valuation Allowance Operating loss carryforwards Operating Loss Carryforwards Operating loss carry forwards expiration date Operating Loss Carryforwards Expiration Year Operating loss carry forwards expiration year. Deferred income taxes provided for Company's share of undistributed net earnings of foreign operations Deferred Tax Liabilities, Undistributed Foreign Earnings Undistributed net earnings of foreign operations Undistributed Earnings of Foreign Subsidiaries Unrecognized tax benefits Recognized interest and penalties Income Tax Examination, Penalties and Interest Expense Accrued interest on unrecognized tax benefits Unrecognized Tax Benefits, Interest on Income Taxes Accrued Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Corridor Corridor Platform Inc [Member] Corridor Platform Inc [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Aggregate cost Equity Method Investment, Aggregate Cost Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Plan assets at the beginning of the year Defined Benefit Plan, Fair Value of Plan Assets Actual return Defined Benefit Plan, Actual Return on Plan Assets Employer contribution Defined Benefit Plan, Contributions by Employer Effect of exchange rate changes Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets Plan assets at the ending of the year Summary of Change in Projected Benefit Obligation Schedule of Changes in Projected Benefit Obligations [Table Text Block] Net Gratuity Cost Schedule of Net Benefit Costs [Table Text Block] Summary of Components Accumulated Other Comprehensive Loss Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Summary of Weighted Average Actuarial Assumptions Schedule of Assumptions Used [Table Text Block] Summary of Expected Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] Change in Plan Assets Schedule of Changes in Fair Value of Plan Assets [Table Text Block] Depreciation and amortization expense Depreciation Depreciation & amortization Depreciation And Amortization [Member] Depreciation And Amortization [Member] Effect of the foreign exchange gains (losses) upon settlement of cash flow hedges Gain (Loss) on Hedging Activity Income Statement [Abstract] Cost of revenues (exclusive of depreciation and amortization) Gross profit Operating expenses: Operating Expenses [Abstract] General and administrative expenses Selling and marketing expenses Depreciation and amortization Total operating expenses Income from operations Operating Income (Loss) Foreign exchange gain, net Interest expense Interest Expense Other income, net Earnings per share: Accumulated Other Comprehensive Loss Comprehensive Income (Loss) Note [Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Stock-based compensation expense Share-based Compensation Unrealized foreign exchange (gain)/loss Foreign Currency Transaction Gain (Loss), Unrealized Deferred income tax (benefit)/expense Excess tax benefit from stock-based compensation Excess Tax Benefit from Share-based Compensation, Operating Activities Change in fair value of earn-out consideration Allowance for doubtful accounts receivable Provision for Doubtful Accounts Others, net Other Noncash Income (Expense) Change in operating assets and liabilities (net of effect of acquisitions): Increase (Decrease) in Operating Capital [Abstract] Restricted cash Increase (Decrease) in Restricted Cash for Operating Activities Accounts receivable Increase (Decrease) in Accounts Receivable Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable Increase (Decrease) in Accounts Payable Deferred revenue Increase (Decrease) in Deferred Revenue Accrued employee costs Increase (Decrease) in Other Employee-Related Liabilities Accrued expenses and other liabilities Increase (Decrease) in Other Accounts Payable and Accrued Liabilities Advance income tax, net Increase (Decrease) in Income Taxes Payable Other assets Increase (Decrease) in Other Operating Assets Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Purchase of property and equipment Payments to Acquire Property, Plant, and Equipment Investment in equity affiliate Payments to Acquire Interest in Subsidiaries and Affiliates Business acquisitions (net of cash acquired) Payments to Acquire Businesses, Net of Cash Acquired Purchase of investments Payments to Acquire Investments Proceeds from redemption of investments Proceeds from Sale, Maturity and Collection of Investments Net cash used for investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Principal payments on capital lease obligations Repayments of Long-term Capital Lease Obligations Proceeds from borrowings Proceeds from Issuance of Long-term Debt Repayments of borrowings Repayments of Debt Proceeds from non-controlling interest Proceeds from Noncontrolling Interests Payment of debt issuance costs Payments of Debt Issuance Costs Acquisition of treasury stock Payments for Repurchase of Common Stock Proceeds from exercise of stock options Proceeds from Stock Options Exercised Excess tax benefit from stock-based compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Net cash (used for)/provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net increase/(decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of year Cash and cash equivalents, end of year Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid for interest Interest Paid, Net Cash paid for taxes, net of refund Income Taxes Paid, Net Assets acquired under capital lease Capital Lease Obligations Incurred Other current assets Other Current Assets [Text Block] Schedule of Property and Equipment Property, Plant and Equipment [Table Text Block] Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Unrecognized compensation cost for unvested stock options Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options Total grant date fair value of option vested in period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value Intrinsic value of options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Expected life (years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Risk free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other current assets Other Current Assets [Member] Other assets Other Assets [Member] Accrued expense and other current liabilities Accrued Expenses And Other Current Liabilities [Member] Accrued expenses and other current liabilities. Other non-current liabilities Other Noncurrent Liabilities [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Foreign currency exchange contracts, asset Derivative Asset, Fair Value, Gross Asset Foreign currency exchange contracts, liability Derivative Liability, Fair Value, Gross Liability Expected tax expense Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount Change in valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Impact of tax holiday Effective Income Tax Rate Reconciliation, Tax Holiday, Amount Foreign tax rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Deferred tax (benefit)/provision Deferred Other Tax Expense (Benefit) Unrecognized tax benefits and interest Income Tax Reconciliation Unrecognized Tax Benefits Income tax reconciliation unrecognized tax benefits. State taxes, net of Federal taxes Effective Income Tax Rate Reconciliation, Tax Settlement, State and Local, Amount Non-deductible expenses Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount Prior year tax expense/(benefit) Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount US Tax Reform Act impact Effective Income Tax Rate Reconciliation,Tax Cuts And Jobs Act Of 2017, Amount Effective Income Tax Rate Reconciliation,Tax Cuts And Jobs Act Of 2017, Amount Excess tax benefit for stock-based compensation Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-09 Accounting Standards Update 2016-09 [Member] Accounting Standards Update 2016-09 [Member] Impact on adoption of ASU 2016-09 Deferred tax effect Deferred Income Tax Liabilities, Net Schedule of Property and Equipment, Estimated Useful Lives Summary of Lived Intangible Assets Amortized over their Estimated Useful Lives Schedule Of Finite Lived Intangible Assets Useful Lives Table [Table Text Block] Schedule of finite lived intangible assets useful lives.