Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2020
Accounting Policies [Abstract]
Basis of Preparation	The unaudited consolidated financial statements have been prepared in conformity with United States generally accepted accounting principles (“U.S. GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for annual financial statements and therefore should be read in conjunction with the audited consolidated financial statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2019. The unaudited consolidated financial statements reflect all adjustments (of a normal and recurring nature) that management considers necessary for a fair presentation of such statements for the interim periods presented. The unaudited consolidated statements of income for the interim periods presented are not necessarily indicative of the results for the full year or for any subsequent period.
Principles of Consolidation	The accompanying unaudited consolidated financial statements include the financial statements of ExlService Holdings and all of its subsidiaries. The standalone financial statements of subsidiaries are fully consolidated on a line-by-line basis. Intra-group balances and transactions, and gains and losses arising from intra-group transactions, are eliminated while preparing those financial statements. Accounting policies of the respective individual subsidiary and associate are aligned wherever necessary, so as to ensure consistency with the accounting policies that are adopted by the Company under U.S. GAAP. The Company’s investments in equity affiliates are initially recorded at cost and any excess purchase consideration paid over proportionate share of the fair value of the net assets of the investee at the acquisition date is recognized as goodwill. The proportionate share of net income or loss of the investee is recognized in the unaudited consolidated statements of income.
Use of Estimates	The preparation of the unaudited consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the unaudited consolidated financial statements and the unaudited consolidated statements of income during the reporting period. Although these estimates are based on management’s best assessment of the current business environment, actual results may be different from those estimates. The significant estimates and assumptions that affect the unaudited consolidated financial statements include, but are not limited to, allowance for expected credit losses, expected recoverability from customers with contingent fee arrangements, recoverability of dues from statutory authorities, assets and obligations related to employee benefit plans, deferred tax valuation allowances, income-tax uncertainties and other contingencies, valuation of derivative financial instruments, assumptions used to calculate stock-based compensation expense, assumptions used to determine the incremental borrowing rate to calculate lease liabilities and right-of-use (“ROU”) assets, lease term to calculate lease cost, depreciation and amortization periods, purchase price allocation, recoverability of long-lived assets including goodwill and intangibles, and estimated costs to complete fixed price contracts. As of June 30, 2020, the extent to which the global Coronavirus Disease 2019 pandemic (“COVID-19”) will ultimately impact the Company's business depends on numerous dynamic factors, which the Company still cannot reliably predict. As a result, many of the Company's estimates and assumptions herein required increased judgment and carry a higher degree of variability and volatility. As events continue to evolve with respect to COVID-19, the Company’s estimates may materially change in future periods.
Leases	The Company determines if an arrangement is a lease at inception of the contract. Operating leases are recorded in "operating lease right-of-use assets", "current portion of operating lease liabilities" and "operating lease liabilities, less current portion" in the Company's unaudited consolidated balance sheets. Finance leases are recorded in "property and equipment", and current and non-current portion of finance lease liabilities are presented within “accrued expenses and other current liabilities” and “other non-current liabilities,” respectively in the Company's unaudited consolidated balance sheets. ROU assets represent the Company’s right to use an underlying asset during the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. For leases in which the rate implicit in the lease is not readily determinable, the Company uses its incremental borrowing rate based on the information available at commencement date for determining the present value of lease payments. Lease terms includes the effects of options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for operating lease arrangements is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease and non-lease components, which are accounted for separately. The Company accounts for lease-related concessions to mitigate the economic effects of COVID-19 on lessees in accordance with guidance in Topic 842, Leases, to determine, on a lease-by-lease basis, whether the concession provided by lessor should be accounted for as a lease modification. The Company accounts for a modification as a separate contract when it grants an additional right of use not included in the original lease and the increase is commensurate with the standalone price for the additional right of use, adjusted for the circumstances of the particular contract. Modifications which are not accounted for as a separate contract are reassessed as of the effective date of the modification based on its modified terms and conditions and the facts and circumstances as of that date. On January 1, 2019, the date of initial application, the Company adopted Topic 842, Leases, using the modified retrospective method. The modified retrospective method provides a method of recognizing those leases which had not expired as of the date of adoption of January 1, 2019.
Recent Accounting Pronouncements and Recently Adopted Accounting Pronouncements	In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (("Subtopic 715-20")): Changes to the Disclosure Requirements for Defined Benefit Plans. The amendments in this ASU remove disclosures that no longer are considered cost beneficial, clarify the specific requirements of disclosures, and add disclosure requirements identified as relevant. The amendments in this ASU are effective for fiscal years beginning after December 15, 2020. Early adoption is permitted. The adoption of this ASU is not expected to have any material effect on the Company’s consolidated financial statements. In March 2020, FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. This ASU provides optional guidance for a limited period of time to ease potential accounting impacts associated with transitioning away from reference rates that are expected to be discontinued, such as interbank offered rates and LIBOR. The ASU provides practical expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments are elective and are effective upon issuance for all entities through December 31, 2022. The Company is currently evaluating the impact of this ASU. (e) Recently Adopted Accounting Pronouncements In June 2016, FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), which requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The new guidance replaces the existing incurred loss impairment model with an expected loss model which requires the use of forward-looking information to calculate credit loss estimates. These changes will result in earlier recognition of credit losses. The allowance for credit losses is a valuation account that is to be deducted from the amortized cost of the financial asset(s) so as to present the net carrying value at the amount expected to be collected on the financial asset. The Company adopted Topic 326 as of January 1, 2020 using a modified retrospective approach through a cumulative-effect adjustment to its retained earnings. The adoption of the ASU had no impact to equity as of January 1, 2020 with a corresponding offset to accounts receivable. Further, the impact of adoption of this guidance did not have a material effect on the Company's accounting policies, processes, and systems. Refer to Note 4 - Revenues, net to the unaudited consolidated financial statements for details. In August 2018, FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Changes to the Disclosure Requirements for Fair Value Measurement. The amendments in this ASU modify the disclosure requirements on fair value measurements in Topic 820, by prescribing new disclosure requirements, and the elimination and modification of disclosure requirements based on the concepts in the Concepts Statement, including the consideration of costs and benefits. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. An entity was permitted to early adopt either the entire standard or only the provisions that eliminate or modify requirements. The early adoption of this ASU, effective January 1, 2020, did not have any material effect on the Company’s disclosures in the unaudited consolidated financial statements. In August 2018, FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software ("Subtopic 350-40"): This ASU aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). Accordingly, the ASU requires an entity (customer) in a hosting arrangement that is a service contract to follow the guidance in FASB Accounting Standard Codification Subtopic 350-40 on internal-use software to determine which implementation costs to capitalize as an asset related to the service contract and which costs to expense. The ASU 2018-15 also provides guidance on amortization and impairment of any costs capitalized, along with new presentation and disclosure requirements. The new guidance is effective for fiscal years beginning after December 15, 2019 and adoption was allowed prospectively. The adoption of this ASU effective January 1, 2020 did not have any material effect on the Company’s unaudited consolidated financial statements. In April 2019, FASB issued ASU No. 2019-04, Codification Improvements to Financial Instruments-Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Financial Instruments: Targeted Transition Relief (Topic 825). The amendments clarify the scope of the credit losses standard and address issues related to accrued interest receivable balances, recoveries, variable interest rates and prepayments, among other things. With respect to hedge accounting, the amendments address partial-term fair value hedges, fair value hedge basis adjustments, and certain transition requirements, among other things. With respect to recognizing and measuring financial instruments, the amendment in the ASU address the scope of the guidance, the requirement for remeasurement under ASC 820 when using the measurement alternative, certain disclosure requirements and which equity securities have to be remeasured at historical exchange rates. This ASU is effective for public business entities for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. Early adoption was permitted. The adoption of this ASU did not have any material effect on the Company’s unaudited consolidated financial statements. In May 2019, FASB issued ASU No. 2019-05, Financial Instruments-Credit Losses (Topic 326): Targeted Transition Relief. This ASU provides entities with the option to irrevocably elect the fair value option, on an instrument-by-instrument basis in accordance with Subtopic 825-10, for certain financial instruments that are within the scope of Subtopic 326-20, upon adopting Topic 326. The fair value option election does not apply to held-to-maturity debt securities. The amendments in this ASU provide entities with targeted transition relief that is intended to increase comparability of financial statement information for some entities that otherwise would have measured similar financial instruments using different measurement methodologies. The Company adopted Topic 326 as of January 1, 2020, whereby no such fair value election was made, accordingly, the adoption of this ASU did not have any material effect on the Company’s unaudited consolidated financial statements.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2020

The unaudited consolidated financial statements have been prepared in conformity with United States generally accepted accounting principles (“U.S. GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for annual financial statements and therefore should be read in conjunction with the audited consolidated financial statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2019.

The unaudited consolidated financial statements reflect all adjustments (of a normal and recurring nature) that management considers necessary for a fair presentation of such statements for the interim periods presented. The unaudited consolidated statements of income for the interim periods presented are not necessarily indicative of the results for the full year or for any subsequent period.

Principles of Consolidation

The accompanying unaudited consolidated financial statements include the financial statements of ExlService Holdings and all of its subsidiaries. The standalone financial statements of subsidiaries are fully consolidated on a line-by-line basis. Intra-group balances and transactions, and gains and losses arising from intra-group transactions, are eliminated while preparing those financial statements.

Accounting policies of the respective individual subsidiary and associate are aligned wherever necessary, so as to ensure consistency with the accounting policies that are adopted by the Company under U.S. GAAP.

The Company’s investments in equity affiliates are initially recorded at cost and any excess purchase consideration paid over proportionate share of the fair value of the net assets of the investee at the acquisition date is recognized as goodwill. The proportionate share of net income or loss of the investee is recognized in the unaudited consolidated statements of income.

Use of Estimates

The preparation of the unaudited consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the unaudited consolidated financial statements and the unaudited consolidated statements of income during the reporting period. Although these estimates are based on management’s best assessment of the current business environment, actual results may be different from those estimates. The significant estimates and assumptions that affect the unaudited consolidated financial statements include, but are not limited to, allowance for expected credit losses, expected recoverability from customers with contingent fee arrangements, recoverability of dues from statutory authorities, assets and obligations related to employee benefit plans, deferred tax valuation allowances, income-tax uncertainties and other contingencies, valuation of derivative financial instruments, assumptions used to calculate stock-based compensation expense, assumptions used to determine the incremental borrowing rate to calculate lease liabilities and right-of-use (“ROU”) assets, lease term to calculate lease cost, depreciation and amortization periods, purchase price allocation, recoverability of long-lived assets including goodwill and intangibles, and estimated costs to complete fixed price contracts.

As of June 30, 2020, the extent to which the global Coronavirus Disease 2019 pandemic (“COVID-19”) will ultimately impact the Company's business depends on numerous dynamic factors, which the Company still cannot reliably predict. As a result, many of the Company's estimates and assumptions herein required increased judgment and carry a higher degree of variability and volatility. As events continue to evolve with respect to COVID-19, the Company’s estimates may materially change in future periods.

Leases

The Company determines if an arrangement is a lease at inception of the contract. Operating leases are recorded in "operating lease right-of-use assets", "current portion of operating lease liabilities" and "operating lease liabilities, less current portion" in the Company's unaudited consolidated balance sheets. Finance leases are recorded in "property and equipment", and current and non-current portion of finance lease liabilities are presented within “accrued expenses and other current liabilities” and “other non-current liabilities,” respectively in the Company's unaudited consolidated balance sheets.

ROU assets represent the Company’s right to use an underlying asset during the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. For leases in which the rate implicit in the lease is not readily determinable, the Company uses its incremental borrowing rate based on the information available at commencement date for determining the present value of lease payments. Lease terms includes the effects of options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for operating lease arrangements is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease and non-lease components, which are accounted for separately.

The Company accounts for lease-related concessions to mitigate the economic effects of COVID-19 on lessees in accordance with guidance in Topic 842, Leases, to determine, on a lease-by-lease basis, whether the concession provided by lessor should be accounted for as a lease modification.

The Company accounts for a modification as a separate contract when it grants an additional right of use not included in the original lease and the increase is commensurate with the standalone price for the additional right of use, adjusted for the circumstances of the particular contract. Modifications which are not accounted for as a separate contract are reassessed as of the effective date of the modification based on its modified terms and conditions and the facts and circumstances as of that date.

On January 1, 2019, the date of initial application, the Company adopted Topic 842, Leases, using the modified retrospective method. The modified retrospective method provides a method of recognizing those leases which had not expired as of the date of adoption of January 1, 2019.

Recent Accounting Pronouncements and Recently Adopted Accounting Pronouncements

In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (("Subtopic 715-20")): Changes to the Disclosure Requirements for Defined Benefit Plans. The amendments in this ASU remove disclosures that no longer are considered cost beneficial, clarify the specific requirements of disclosures, and add disclosure requirements identified as relevant. The amendments in this ASU are effective for fiscal years beginning after December 15, 2020. Early adoption is permitted. The adoption of this ASU is not expected to have any material effect on the Company’s consolidated financial statements.

In March 2020, FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. This ASU provides optional guidance for a limited period of time to ease potential accounting impacts associated with transitioning away from reference rates that are expected to be discontinued, such as interbank offered rates and LIBOR. The ASU provides practical expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments are elective and are effective upon issuance for all entities through December 31, 2022. The Company is currently evaluating the impact of this ASU.

(e) Recently Adopted Accounting Pronouncements

In June 2016, FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), which requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The new guidance replaces the existing incurred loss impairment model with an expected loss model which requires the use of forward-looking information to calculate credit loss estimates. These changes will result in earlier recognition of credit losses. The allowance for credit losses is a valuation account that is to be deducted from the amortized cost of the financial asset(s) so as to present the net carrying value at the amount expected to be collected on the financial asset. The Company adopted Topic 326 as of January 1, 2020 using a modified retrospective approach through a cumulative-effect adjustment to its retained earnings. The adoption of the ASU had no impact to equity as of January 1, 2020 with a corresponding offset to accounts receivable. Further, the impact of adoption of this guidance did not have a material effect on the Company's accounting policies, processes, and systems. Refer to Note 4 - Revenues, net to the unaudited consolidated financial statements for details.

In August 2018, FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Changes to the Disclosure Requirements for Fair Value Measurement. The amendments in this ASU modify the disclosure requirements on fair value measurements in Topic 820, by prescribing new disclosure requirements, and the elimination and modification of disclosure requirements based on the concepts in the Concepts Statement, including the consideration of costs and benefits. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. An entity was permitted to early adopt either the entire standard or only the provisions that eliminate or modify requirements. The early adoption of this ASU, effective January 1, 2020, did not have any material effect on the Company’s disclosures in the unaudited consolidated financial statements.

In August 2018, FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software ("Subtopic 350-40"): This ASU aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). Accordingly, the ASU requires an entity (customer) in a hosting arrangement that is a service contract to follow the guidance in FASB Accounting Standard Codification Subtopic 350-40 on internal-use software to determine which implementation costs to capitalize as an asset related to the service contract and which costs to expense. The ASU 2018-15 also provides guidance on amortization and impairment of any costs capitalized, along with new presentation and disclosure requirements. The new guidance is effective for fiscal years beginning after December 15, 2019 and adoption was allowed prospectively. The adoption of this ASU effective January 1, 2020 did not have any material effect on the Company’s unaudited consolidated financial statements.

In April 2019, FASB issued ASU No. 2019-04, Codification Improvements to Financial Instruments-Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Financial Instruments: Targeted Transition Relief (Topic 825). The amendments clarify the scope of the credit losses standard and address issues related to accrued interest receivable balances, recoveries, variable interest rates and prepayments, among other things. With respect to hedge accounting, the amendments address partial-term fair value hedges, fair value hedge basis adjustments, and certain transition requirements, among other things. With respect to recognizing and measuring financial instruments, the amendment in the ASU address the scope of the guidance, the requirement for remeasurement under ASC 820 when using the measurement alternative, certain disclosure requirements and which equity securities have to be remeasured at historical exchange rates. This ASU is effective for public business entities for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. Early adoption was permitted. The adoption of this ASU did not have any material effect on the Company’s unaudited consolidated financial statements.

In May 2019, FASB issued ASU No. 2019-05, Financial Instruments-Credit Losses (Topic 326): Targeted Transition Relief. This ASU provides entities with the option to irrevocably elect the fair value option, on an instrument-by-instrument basis in accordance with Subtopic 825-10, for certain financial instruments that are within the scope of Subtopic 326-20, upon adopting Topic 326. The fair value option election does not apply to held-to-maturity debt securities. The amendments in this ASU provide entities with targeted transition relief that is intended to increase comparability of financial statement information for some entities that otherwise would have measured similar financial instruments using different measurement methodologies. The Company adopted Topic 326 as of January 1, 2020, whereby no such fair value election was made, accordingly, the adoption of this ASU did not have any material effect on the Company’s unaudited consolidated financial statements.