<?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="anab-20230207.xsd" xlink:type="simple"/>
    <context id="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001370053</identifier>
        </entity>
        <period>
            <startDate>2023-02-07</startDate>
            <endDate>2023-02-07</endDate>
        </period>
    </context>
    <dei:EntityCentralIndexKey
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF80L2ZyYWc6ZjBhZjcwMWQ2MGYxNGQ0OWE3NTM2NjA1ZjY1NTZkZWUvdGFibGU6OGJhMGFjZTFiMTg5NGU2MDgyOWIxY2I4NGJiNWMyYmMvdGFibGVyYW5nZTo4YmEwYWNlMWIxODk0ZTYwODI5YjFjYjg0YmI1YzJiY18yLTEtMS0xLTYzNTI3_4387ba49-958e-4939-a9fa-9b90c3f8a378">0001370053</dei:EntityCentralIndexKey>
    <dei:CurrentFiscalYearEndDate
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF80L2ZyYWc6ZjBhZjcwMWQ2MGYxNGQ0OWE3NTM2NjA1ZjY1NTZkZWUvdGFibGU6OGJhMGFjZTFiMTg5NGU2MDgyOWIxY2I4NGJiNWMyYmMvdGFibGVyYW5nZTo4YmEwYWNlMWIxODk0ZTYwODI5YjFjYjg0YmI1YzJiY18zLTEtMS0xLTYzNzE2_0222e640-31bd-4ad8-b373-d61d450b68de">--12-31</dei:CurrentFiscalYearEndDate>
    <dei:AmendmentFlag
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF80L2ZyYWc6ZjBhZjcwMWQ2MGYxNGQ0OWE3NTM2NjA1ZjY1NTZkZWUvdGFibGU6OGJhMGFjZTFiMTg5NGU2MDgyOWIxY2I4NGJiNWMyYmMvdGFibGVyYW5nZTo4YmEwYWNlMWIxODk0ZTYwODI5YjFjYjg0YmI1YzJiY181LTEtMS0xLTYzNTI3_f548de14-03bf-4ad0-9084-918ffba64756">false</dei:AmendmentFlag>
    <dei:DocumentType
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzYy_4f0a6564-d51c-44a6-bf61-7a8ff907a6a8">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xOTE_22bf7c3d-948f-4687-a29a-a101534f497f">2023-02-07</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzcz_2159ff39-5723-4ed7-bd0c-0fa5bcdee507">ANAPTYSBIO, INC</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGFibGU6YzNkYWQ3M2E5MzliNDFiMDk0ODBiZTExNTYwZmI3ZmYvdGFibGVyYW5nZTpjM2RhZDczYTkzOWI0MWIwOTQ4MGJlMTE1NjBmYjdmZl8wLTAtMS0xLTYzNTI3_6e81c250-20d3-43f0-b1bc-82384b5865ed">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGFibGU6YzNkYWQ3M2E5MzliNDFiMDk0ODBiZTExNTYwZmI3ZmYvdGFibGVyYW5nZTpjM2RhZDczYTkzOWI0MWIwOTQ4MGJlMTE1NjBmYjdmZl8wLTEtMS0xLTYzNTI3_ba97f833-e279-4c46-81a3-eb2562003d20">001-37985</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGFibGU6YzNkYWQ3M2E5MzliNDFiMDk0ODBiZTExNTYwZmI3ZmYvdGFibGVyYW5nZTpjM2RhZDczYTkzOWI0MWIwOTQ4MGJlMTE1NjBmYjdmZl8wLTItMS0xLTYzNTI3_5277cde9-79e5-435f-87a5-baa22936c054">20-3828755</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzY5_df156b21-882d-46b1-8384-09728a7e26b6">10770 Wateridge Circle</dei:EntityAddressAddressLine1>
    <dei:EntityAddressAddressLine2
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzYz_fcc31df3-061d-43fb-a76c-4c6380e202fa">Suite 210,</dei:EntityAddressAddressLine2>
    <dei:EntityAddressCityOrTown
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzU3_47a06ffd-7bc4-4177-bbc8-8ef0ee977a2f">San Diego</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzY1_c7a3c7ec-58c1-4c3e-87a8-e63b8f8ee914">CA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzU4_33ce1141-6643-4f72-9737-7a16655cb9b6">92121</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzcw_5d9f454d-f62f-425e-8cb7-9d4cd6da89ff">858</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzcx_4f1617c4-17db-4139-a922-cd14956a1418">362-6295</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzYw_be8a3ee4-8120-42dd-9756-171dcbcb1e45">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzY2_19e64771-1772-49e0-843d-65fd490e9fe7">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzcy_d48c218c-fca5-437c-8053-afed0cd2c1ef">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzY3_3f41c99b-5397-473c-a1c2-fd836360e7f9">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGFibGU6ZjRiODM4ZmZjNjAyNDZlZTgxZmQ3NmVlNDhmNDVhODUvdGFibGVyYW5nZTpmNGI4MzhmZmM2MDI0NmVlODFmZDc2ZWU0OGY0NWE4NV8xLTAtMS0xLTYzNTI3_e60699b3-a818-491e-b364-d0896663ccd8">Common Stock, par value $0.001 per share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGFibGU6ZjRiODM4ZmZjNjAyNDZlZTgxZmQ3NmVlNDhmNDVhODUvdGFibGVyYW5nZTpmNGI4MzhmZmM2MDI0NmVlODFmZDc2ZWU0OGY0NWE4NV8xLTEtMS0xLTYzNTI3_7bece51a-71a2-4b95-9e7f-65a238c7eb10">ANAB</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGFibGU6ZjRiODM4ZmZjNjAyNDZlZTgxZmQ3NmVlNDhmNDVhODUvdGFibGVyYW5nZTpmNGI4MzhmZmM2MDI0NmVlODFmZDc2ZWU0OGY0NWE4NV8xLTItMS0xLTYzNTI3_6021ccad-5665-40a5-88c9-a01d80059b42">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="i9eaf6a405f714ce295af350fd34e4c32_D20230207-20230207"
      id="id3VybDovL2RvY3MudjEvZG9jOmU3NTdkOTY2YmM3ZTRlZGFhMjhiMzkzZDViZjE0MzQ4L3NlYzplNzU3ZDk2NmJjN2U0ZWRhYTI4YjM5M2Q1YmYxNDM0OF8xL2ZyYWc6OWRiNDUzYjFlMjUzNDE4YTlmNDNhZWFjYzYxNTZkMGEvdGV4dHJlZ2lvbjo5ZGI0NTNiMWUyNTM0MThhOWY0M2FlYWNjNjE1NmQwYV8xNzY4_8fb9a7d9-48d6-4952-8a85-397aafac2c5f">false</dei:EntityEmergingGrowthCompany>
</xbrl>
