<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xml:lang="en-US"
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2021"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="exls-20210729.xsd" xlink:type="simple"/>
    <context id="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001297989</identifier>
        </entity>
        <period>
            <startDate>2021-07-29</startDate>
            <endDate>2021-07-29</endDate>
        </period>
    </context>
    <dei:AmendmentFlag
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml80L2ZyYWc6YWQ1MDNjYzYxOTY0NDAxZTkxZjk3N2Y5NDRkYzhlZTEvdGFibGU6MDc5OWE5OTM0YTljNDJkOWI2MWFmNjI4OWFlYzQyMTkvdGFibGVyYW5nZTowNzk5YTk5MzRhOWM0MmQ5YjYxYWY2Mjg5YWVjNDIxOV8wLTEtMS0xLTA_ad125087-27e9-49b9-bc8b-3d5db12e08bc">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml80L2ZyYWc6YWQ1MDNjYzYxOTY0NDAxZTkxZjk3N2Y5NDRkYzhlZTEvdGFibGU6MDc5OWE5OTM0YTljNDJkOWI2MWFmNjI4OWFlYzQyMTkvdGFibGVyYW5nZTowNzk5YTk5MzRhOWM0MmQ5YjYxYWY2Mjg5YWVjNDIxOV8xLTEtMS0xLTA_f4bf8202-6392-4719-b478-d55dd0198bd5">0001297989</dei:EntityCentralIndexKey>
    <dei:DocumentType
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGV4dHJlZ2lvbjozZmNiMmFkZGRhNDQ0YTQyYTAxMDFmNjQ1ODM1MzhiYV8xMTgy_249e663d-3847-4e00-9efd-4bc6ee5f3f2b">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGV4dHJlZ2lvbjozZmNiMmFkZGRhNDQ0YTQyYTAxMDFmNjQ1ODM1MzhiYV8zNDg_2e03f369-59b4-4fb7-aa12-4b7ca817687d">2021-07-29</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGV4dHJlZ2lvbjozZmNiMmFkZGRhNDQ0YTQyYTAxMDFmNjQ1ODM1MzhiYV8xMTc5_03c6b005-d34f-4240-bbdb-236313ac74de">EXLSERVICE HOLDINGS, INC.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6MTQ1YjU1YzQ4NWZkNGNkOWFkZjQ5MThhMGQ3NTA1MDIvdGFibGVyYW5nZToxNDViNTVjNDg1ZmQ0Y2Q5YWRmNDkxOGEwZDc1MDUwMl8wLTAtMS0xLTA_6336b714-f023-4b77-82a5-bffe18ca1464">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6MTQ1YjU1YzQ4NWZkNGNkOWFkZjQ5MThhMGQ3NTA1MDIvdGFibGVyYW5nZToxNDViNTVjNDg1ZmQ0Y2Q5YWRmNDkxOGEwZDc1MDUwMl8wLTEtMS0xLTA_8ca7744f-d7b2-4899-836a-1c0db756f523">001-33089</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6MTQ1YjU1YzQ4NWZkNGNkOWFkZjQ5MThhMGQ3NTA1MDIvdGFibGVyYW5nZToxNDViNTVjNDg1ZmQ0Y2Q5YWRmNDkxOGEwZDc1MDUwMl8wLTItMS0xLTA_3941fd00-8e69-4ca0-912c-72a1c80ead16">82-0572194</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6YzExZmZlZGM3MWJlNGQ5NzhkNmJmNzAxMWZhY2E5ZTUvdGFibGVyYW5nZTpjMTFmZmVkYzcxYmU0ZDk3OGQ2YmY3MDExZmFjYTllNV8wLTEtMS0xLTA_c1fe3ca7-3d39-4f9f-a73f-5dd8d70810ec">320 Park Avenue,</dei:EntityAddressAddressLine1>
    <dei:EntityAddressAddressLine2
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6YzExZmZlZGM3MWJlNGQ5NzhkNmJmNzAxMWZhY2E5ZTUvdGFibGVyYW5nZTpjMTFmZmVkYzcxYmU0ZDk3OGQ2YmY3MDExZmFjYTllNV8wLTItMS0xLTA_b5c4085c-a328-49ac-9e7f-64a0976613b2">29th Floor,</dei:EntityAddressAddressLine2>
    <dei:EntityAddressPostalZipCode
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6YzExZmZlZGM3MWJlNGQ5NzhkNmJmNzAxMWZhY2E5ZTUvdGFibGVyYW5nZTpjMTFmZmVkYzcxYmU0ZDk3OGQ2YmY3MDExZmFjYTllNV8wLTMtMS0xLTA_1ed4f53f-229b-490a-9b53-3efde072d0d5">10022</dei:EntityAddressPostalZipCode>
    <dei:EntityAddressCityOrTown
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6YzExZmZlZGM3MWJlNGQ5NzhkNmJmNzAxMWZhY2E5ZTUvdGFibGVyYW5nZTpjMTFmZmVkYzcxYmU0ZDk3OGQ2YmY3MDExZmFjYTllNV8xLTEtMS0xLTA_64303cad-0ddb-47df-8a5b-f4a0ef54b59e">New York,</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6YzExZmZlZGM3MWJlNGQ5NzhkNmJmNzAxMWZhY2E5ZTUvdGFibGVyYW5nZTpjMTFmZmVkYzcxYmU0ZDk3OGQ2YmY3MDExZmFjYTllNV8xLTItMS0xLTA_c0c00c57-678b-4059-8574-84d0430833de">NY</dei:EntityAddressStateOrProvince>
    <dei:CityAreaCode
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGV4dHJlZ2lvbjozZmNiMmFkZGRhNDQ0YTQyYTAxMDFmNjQ1ODM1MzhiYV8xMTgw_17ae2c60-9026-4c55-a84b-f22142305c7c">212</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGV4dHJlZ2lvbjozZmNiMmFkZGRhNDQ0YTQyYTAxMDFmNjQ1ODM1MzhiYV8xMTgx_23bf8580-4188-4064-8c19-8e1c3628c51c">277-7100</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6NmM5NjA4OWI4NTQ3NDIxZWEwYmMyOTViZGMyZWRlNzIvdGFibGVyYW5nZTo2Yzk2MDg5Yjg1NDc0MjFlYTBiYzI5NWJkYzJlZGU3Ml8wLTAtMS0xLTA_9d3f0d1c-952e-4e32-965a-3f716cafedca">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6YTAzMWEwZTQ2ZThhNDJkNWFlMTJkODg4MTFkNjNmMTIvdGFibGVyYW5nZTphMDMxYTBlNDZlOGE0MmQ1YWUxMmQ4ODgxMWQ2M2YxMl8wLTAtMS0xLTA_fc38c963-63d1-4ed7-bbbf-83cd214e3c9c">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6ZDQxMWViYjgzNzJjNGQ2ZmI2ZWMyMjIyNjIzYjllOGUvdGFibGVyYW5nZTpkNDExZWJiODM3MmM0ZDZmYjZlYzIyMjI2MjNiOWU4ZV8wLTAtMS0xLTA_6a896c6b-5b87-4e3e-821e-1994dc5c16b4">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6MmY2ODAxYTQ5NDY0NDIwOGE2ODMwY2UxMjBjMjg2YWMvdGFibGVyYW5nZToyZjY4MDFhNDk0NjQ0MjA4YTY4MzBjZTEyMGMyODZhY18wLTAtMS0xLTA_c4b04841-8953-4c0f-b813-d72ed60dbfa4">false</dei:PreCommencementIssuerTenderOffer>
    <dei:EntityEmergingGrowthCompany
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6YzczYjc2OWJmZThkNGI1MWJhMjA1MTI0NGI0MDg4NjAvdGFibGVyYW5nZTpjNzNiNzY5YmZlOGQ0YjUxYmEyMDUxMjQ0YjQwODg2MF8wLTAtMS0xLTA_5674f648-ba00-4c9e-b2e4-756f76a16f23">false</dei:EntityEmergingGrowthCompany>
    <dei:Security12bTitle
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6OWM3NDQzYmVjMWYwNGNkNTgxNDdkMDg2ZGRkNmQ5NGYvdGFibGVyYW5nZTo5Yzc0NDNiZWMxZjA0Y2Q1ODE0N2QwODZkZGQ2ZDk0Zl8yLTAtMS0xLTA_bee85a8a-b548-435e-b470-c93198cf900b">Common Stock, $0.001 par value per share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6OWM3NDQzYmVjMWYwNGNkNTgxNDdkMDg2ZGRkNmQ5NGYvdGFibGVyYW5nZTo5Yzc0NDNiZWMxZjA0Y2Q1ODE0N2QwODZkZGQ2ZDk0Zl8yLTEtMS0xLTA_5733dcc3-a70d-4cc3-99cd-6a5f0510aa76">EXLS</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i79aebb8b656f45caa904c3c9b0f35418_D20210729-20210729"
      id="id3VybDovL2RvY3MudjEvZG9jOjg0YTIyOGY3YTU0ZDQ4NTI5YzhlODJhMzc4MDkyODkyL3NlYzo4NGEyMjhmN2E1NGQ0ODUyOWM4ZTgyYTM3ODA5Mjg5Ml8xL2ZyYWc6M2ZjYjJhZGRkYTQ0NGE0MmEwMTAxZjY0NTgzNTM4YmEvdGFibGU6OWM3NDQzYmVjMWYwNGNkNTgxNDdkMDg2ZGRkNmQ5NGYvdGFibGVyYW5nZTo5Yzc0NDNiZWMxZjA0Y2Q1ODE0N2QwODZkZGQ2ZDk0Zl8yLTItMS0xLTA_d28a846b-0378-425d-bc4d-f9d398de5a81">NASDAQ</dei:SecurityExchangeName>
</xbrl>
