<?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:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="ardx-20211130.xsd" xlink:type="simple"/>
    <context id="i07c7a0443c464482987c078b597d33f0_D20211130-20211130">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001437402</identifier>
        </entity>
        <period>
            <startDate>2021-11-30</startDate>
            <endDate>2021-11-30</endDate>
        </period>
    </context>
    <context id="i3f4b7caecf614514a179f74f2e058c13_D20211130-20211130">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001437402</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:EntityAddressesAddressTypeAxis">dei:OtherAddressMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-11-30</startDate>
            <endDate>2021-11-30</endDate>
        </period>
    </context>
    <dei:EntityCentralIndexKey
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y180L2ZyYWc6N2M0OWM2NWI1MjVlNDFiMGE2ZDlmOTg0MjQ0MGQ1OGIvdGFibGU6NTFiMDU2YTUxNWY0NDhlZjllMDYzZTNmYjJiNThjNGIvdGFibGVyYW5nZTo1MWIwNTZhNTE1ZjQ0OGVmOWUwNjNlM2ZiMmI1OGM0Yl8yLTEtMS0xLTg1ODc_c1eba482-dcf0-4f24-872b-f94cf32ff6b8">0001437402</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y180L2ZyYWc6N2M0OWM2NWI1MjVlNDFiMGE2ZDlmOTg0MjQ0MGQ1OGIvdGFibGU6NTFiMDU2YTUxNWY0NDhlZjllMDYzZTNmYjJiNThjNGIvdGFibGVyYW5nZTo1MWIwNTZhNTE1ZjQ0OGVmOWUwNjNlM2ZiMmI1OGM0Yl8zLTEtMS0xLTg1ODc_738b6963-cad7-4c0c-8ada-fda7b4d1b77e">false</dei:AmendmentFlag>
    <dei:DocumentType
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjYz_404f1bbf-408f-4fca-87ff-214e767135e5">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8yMzE_b259d70b-ad24-4d36-ade0-5740930b8394">2021-11-30</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjY0_a6160616-2186-4146-9978-b18f55bfa015">ARDELYX, INC.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6NzY5MWIyNTc3MDhiNDUzOWI5MjAxNmEyODI4YmRmMTAvdGFibGVyYW5nZTo3NjkxYjI1NzcwOGI0NTM5YjkyMDE2YTI4MjhiZGYxMF8wLTAtMS0xLTg1ODc_1bd03437-44cb-48a2-af7b-16264ba6ed45">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6NzY5MWIyNTc3MDhiNDUzOWI5MjAxNmEyODI4YmRmMTAvdGFibGVyYW5nZTo3NjkxYjI1NzcwOGI0NTM5YjkyMDE2YTI4MjhiZGYxMF8wLTEtMS0xLTg1ODc_4c0345d0-fa97-4fa6-8a41-a27f535e350d">001-36485</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6NzY5MWIyNTc3MDhiNDUzOWI5MjAxNmEyODI4YmRmMTAvdGFibGVyYW5nZTo3NjkxYjI1NzcwOGI0NTM5YjkyMDE2YTI4MjhiZGYxMF8wLTItMS0xLTg1ODc_b04f9b20-8088-4cf1-92af-5661816c7348">26-1303944</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="i3f4b7caecf614514a179f74f2e058c13_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjY1_483b402e-019b-49dc-a53c-5195a386c9f9">400 FIFTH AVE.</dei:EntityAddressAddressLine1>
    <dei:EntityAddressAddressLine2
      contextRef="i3f4b7caecf614514a179f74f2e058c13_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjU4_34675d75-bf03-4476-9340-fee56ba82184">SUITE 210</dei:EntityAddressAddressLine2>
    <dei:EntityAddressCityOrTown
      contextRef="i3f4b7caecf614514a179f74f2e058c13_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjU5_3a12a832-524b-46fe-bf12-1aae29539ce6">WALTHAM</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="i3f4b7caecf614514a179f74f2e058c13_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjU2_a983af39-e060-40d2-a21d-9423ee0f3444">MA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="i3f4b7caecf614514a179f74f2e058c13_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjU3_bd705434-0586-4fe2-849b-3bfc0d67f5a6">02451</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjU0_cce745aa-0dd1-44f7-a912-03d215f0ff9c">510</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjYx_53a1ae2d-f80e-426a-8b6b-08afcbb57196">745-1700</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6MWViYWEzOWE5MjM1NDFmNDg3NzAyZDE0ZmVkZjU0NjAvdGFibGVyYW5nZToxZWJhYTM5YTkyMzU0MWY0ODc3MDJkMTRmZWRmNTQ2MF8wLTAtMS0xLTg1ODc_3ecf3c70-3d7f-4c0a-9fd0-dc4bf93d8f93">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6MWViYWEzOWE5MjM1NDFmNDg3NzAyZDE0ZmVkZjU0NjAvdGFibGVyYW5nZToxZWJhYTM5YTkyMzU0MWY0ODc3MDJkMTRmZWRmNTQ2MF8xLTAtMS0xLTg1ODc_a752bc70-0fac-4cf5-a9c9-00bb3958ca17">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6MWViYWEzOWE5MjM1NDFmNDg3NzAyZDE0ZmVkZjU0NjAvdGFibGVyYW5nZToxZWJhYTM5YTkyMzU0MWY0ODc3MDJkMTRmZWRmNTQ2MF8yLTAtMS0xLTg1ODc_468cbf23-8c60-4873-bbb0-6383d8a03450">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6MWViYWEzOWE5MjM1NDFmNDg3NzAyZDE0ZmVkZjU0NjAvdGFibGVyYW5nZToxZWJhYTM5YTkyMzU0MWY0ODc3MDJkMTRmZWRmNTQ2MF8zLTAtMS0xLTg1ODc_4ce036e0-719f-4bde-92f6-1266a0d17e30">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6ZjE5NjUzNmIzMDZkNDYwMGJmNmZkNzVjZTM1MDMzNTcvdGFibGVyYW5nZTpmMTk2NTM2YjMwNmQ0NjAwYmY2ZmQ3NWNlMzUwMzM1N18xLTAtMS0xLTg1ODc_2e637643-ea11-4d92-9196-d83031b2b892">Common Stock, par value $0.0001</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6ZjE5NjUzNmIzMDZkNDYwMGJmNmZkNzVjZTM1MDMzNTcvdGFibGVyYW5nZTpmMTk2NTM2YjMwNmQ0NjAwYmY2ZmQ3NWNlMzUwMzM1N18xLTItMS0xLTg1ODc_8bcbc84c-2328-44ee-a5ea-69d7db977a9f">ARDX</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGFibGU6ZjE5NjUzNmIzMDZkNDYwMGJmNmZkNzVjZTM1MDMzNTcvdGFibGVyYW5nZTpmMTk2NTM2YjMwNmQ0NjAwYmY2ZmQ3NWNlMzUwMzM1N18xLTQtMS0xLTg1ODc_b56f3c84-ee36-4649-9726-2879d8532bf7">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="i07c7a0443c464482987c078b597d33f0_D20211130-20211130"
      id="id3VybDovL2RvY3MudjEvZG9jOmQ3ZjdlNzRhOGNjNjQyYzI4Yjc1ZjVlZWFhZmNmODZjL3NlYzpkN2Y3ZTc0YThjYzY0MmMyOGI3NWY1ZWVhYWZjZjg2Y18xL2ZyYWc6NTRhMTg0YWE2ZjY4NDcxZmI4NzZjMGIxODFiOWE5OWEvdGV4dHJlZ2lvbjo1NGExODRhYTZmNjg0NzFmYjg3NmMwYjE4MWI5YTk5YV8xMjYy_93cf2497-7a69-43a1-a01b-4f8bb3ab4639">false</dei:EntityEmergingGrowthCompany>
</xbrl>
