<?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/2021q4"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="crdf-20220609.xsd" xlink:type="simple"/>
    <context id="i2c439b69a610482e811d00f10981f84e_D20220609-20220609">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001213037</identifier>
        </entity>
        <period>
            <startDate>2022-06-09</startDate>
            <endDate>2022-06-09</endDate>
        </period>
    </context>
    <dei:EntityCentralIndexKey
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF80L2ZyYWc6Y2JhZjEwZTg1OThhNDE0M2JiMThkZTA5ZmI5OTQ5NTEvdGFibGU6MjNiZDBiNTg1NTlmNGQwNDg3OTUzZGEwNGMzMTVmMTMvdGFibGVyYW5nZToyM2JkMGI1ODU1OWY0ZDA0ODc5NTNkYTA0YzMxNWYxM18yLTEtMS0xLTM0NzMy_40ab8793-5691-45c7-928e-6edf1100ce52">0001213037</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF80L2ZyYWc6Y2JhZjEwZTg1OThhNDE0M2JiMThkZTA5ZmI5OTQ5NTEvdGFibGU6MjNiZDBiNTg1NTlmNGQwNDg3OTUzZGEwNGMzMTVmMTMvdGFibGVyYW5nZToyM2JkMGI1ODU1OWY0ZDA0ODc5NTNkYTA0YzMxNWYxM18zLTEtMS0xLTM0NzMy_51a45d61-006c-4d94-91a2-09b2f7941adc">false</dei:AmendmentFlag>
    <dei:DocumentType
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzM1_4f7fd92c-a26f-47e8-9ee5-45439688469a">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N18yMjg_e2fa5f91-ae85-4adb-b1e0-c2853e40e644">2022-06-09</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzMw_b109bb8b-c2aa-4722-a665-9e9b150b7f30">Cardiff Oncology,&#160;Inc.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGFibGU6M2VkNTYyMjkyNGRhNGFlNmI5MDE5NzcwZTc4ZTRlNjUvdGFibGVyYW5nZTozZWQ1NjIyOTI0ZGE0YWU2YjkwMTk3NzBlNzhlNGU2NV8wLTAtMS0xLTM0NzMy_5c3e4b38-a8b9-4025-879a-90ee9059f429">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGFibGU6M2VkNTYyMjkyNGRhNGFlNmI5MDE5NzcwZTc4ZTRlNjUvdGFibGVyYW5nZTozZWQ1NjIyOTI0ZGE0YWU2YjkwMTk3NzBlNzhlNGU2NV8wLTEtMS0xLTM0NzMy_6608129f-7ac2-4cea-9c28-b08828566b32">001-35558</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGFibGU6M2VkNTYyMjkyNGRhNGFlNmI5MDE5NzcwZTc4ZTRlNjUvdGFibGVyYW5nZTozZWQ1NjIyOTI0ZGE0YWU2YjkwMTk3NzBlNzhlNGU2NV8wLTItMS0xLTM0NzMy_26dfc822-91ec-45a6-a42f-0e8552741111">27-2004382</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzMx_80ef9523-0ddd-416b-bbdf-36afb7cf92f5">11055 Flintkote Avenue</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzM2_b271fb83-19a5-49ec-9319-cf206c3aaa4a">San Diego</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzMy_ed42066e-af8a-4b58-a29f-bcf8ed0c5399">CA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzM3_c32729c3-45b9-46f8-8749-1e4c0e675249">92121</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzM4_d20e8298-213d-41dc-875e-ae97f55f7d08">(858)</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzM5_57bb5f98-b953-44d2-accd-43e29cfdea0d">952-7570</dei:LocalPhoneNumber>
    <dei:Security12bTitle
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGFibGU6MTJjODU3ZTBkMWEwNGE0ZmE4ODg5OWNiYzI3NTQzMTkvdGFibGVyYW5nZToxMmM4NTdlMGQxYTA0YTRmYTg4ODk5Y2JjMjc1NDMxOV8xLTAtMS0xLTM0NzMy_31fdae47-d4a1-4a6e-a035-a1c8ef76fa9a">Common Stock</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGFibGU6MTJjODU3ZTBkMWEwNGE0ZmE4ODg5OWNiYzI3NTQzMTkvdGFibGVyYW5nZToxMmM4NTdlMGQxYTA0YTRmYTg4ODk5Y2JjMjc1NDMxOV8xLTItMS0xLTM0NzMy_94eb7935-6771-4ff2-907b-65e7460c5bcc">CRDF</dei:TradingSymbol>
    <dei:WrittenCommunications
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzI3_d5c35cc0-73b0-4bfa-a82e-047bed0aca71">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzI4_47d07e85-571b-4267-b4f3-61689d04641c">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzI5_58062725-d6a2-4788-b752-ac99b1ae77de">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzQw_7125c070-0d99-4264-a017-84e233402a0d">false</dei:PreCommencementIssuerTenderOffer>
    <dei:EntityEmergingGrowthCompany
      contextRef="i2c439b69a610482e811d00f10981f84e_D20220609-20220609"
      id="id3VybDovL2RvY3MudjEvZG9jOmRiOWM3ODgyYTJiMTRlNDNhOTZkY2FkNDAyMzNkYzg0L3NlYzpkYjljNzg4MmEyYjE0ZTQzYTk2ZGNhZDQwMjMzZGM4NF8xL2ZyYWc6YWJmZjI5ZTg2YmMzNDMwYmI4ODBhMDM1ODk1MzE4NTcvdGV4dHJlZ2lvbjphYmZmMjllODZiYzM0MzBiYjg4MGEwMzU4OTUzMTg1N180MzMz_7274cf0e-e29e-41b8-ab22-3cf259278113">false</dei:EntityEmergingGrowthCompany>
</xbrl>
