<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:aacb="http://artiuscapital.com/20260813"
  xmlns:dei="http://xbrl.sec.gov/dei/2025"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:us-gaap="http://fasb.org/us-gaap/2025"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="aacb-20260813.xsd" xlink:type="simple"/>
    <context id="c20260813to20260813">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0002034334</identifier>
        </entity>
        <period>
            <startDate>2026-08-13</startDate>
            <endDate>2026-08-13</endDate>
        </period>
    </context>
    <context id="c20260813to20260813_StatementClassOfStockAxis_ClassAOrdinarySharesParValue00001PerShareMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0002034334</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">aacb:ClassAOrdinarySharesParValue00001PerShareMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-08-13</startDate>
            <endDate>2026-08-13</endDate>
        </period>
    </context>
    <context id="c20260813to20260813_StatementClassOfStockAxis_CommonClassAMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0002034334</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">us-gaap:CommonClassAMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-08-13</startDate>
            <endDate>2026-08-13</endDate>
        </period>
    </context>
    <context id="c20260813to20260813_StatementClassOfStockAxis_RightsEachRightEntitlingTheHolderToReceiveOneTenthOfOneClassAOrdinaryShareMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0002034334</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">aacb:RightsEachRightEntitlingTheHolderToReceiveOneTenthOfOneClassAOrdinaryShareMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-08-13</startDate>
            <endDate>2026-08-13</endDate>
        </period>
    </context>
    <dei:AmendmentFlag
      contextRef="c20260813to20260813"
      id="Fact_06a79acba8b84284922353b6c66b7b89">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey
      contextRef="c20260813to20260813"
      id="Fact_6ae5b030c6094e25a60df3012a1ea3c9">0002034334</dei:EntityCentralIndexKey>
    <dei:Security12bTitle
      contextRef="c20260813to20260813_StatementClassOfStockAxis_CommonClassAMember"
      id="Fact_033e478d380d4bdfb61574b69d0a96bb">Units, each consisting of one Class A ordinary share</dei:Security12bTitle>
    <dei:DocumentType
      contextRef="c20260813to20260813"
      id="Fact_afbc51a63ae14594b3728f298e1ab08a">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="c20260813to20260813"
      id="Fact_360adccf2e594060b280896352b130f1">2026-08-13</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="c20260813to20260813"
      id="Fact_e4f5dea7c4904769ae9ff754346812d8">ARTIUS II ACQUISITION INC.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="c20260813to20260813"
      id="Fact_f7690d3d4e7a41519eab4596f8691c42">E9</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="c20260813to20260813"
      id="Fact_6d96f3493a514659ba804a4322db4295">1-42521</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="c20260813to20260813"
      id="Fact_9cb7142b08c74e10a8e85365190fcbe0">98-1802901</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="c20260813to20260813"
      id="Fact_d72a574367c34c298d5cca5c7c62e640">3 Columbus Circle</dei:EntityAddressAddressLine1>
    <dei:EntityAddressAddressLine2
      contextRef="c20260813to20260813"
      id="Fact_7b5919e29f9d4ccd9f23aefbfd58abd7">Suite 1609</dei:EntityAddressAddressLine2>
    <dei:EntityAddressCityOrTown
      contextRef="c20260813to20260813"
      id="Fact_ec6eb1f9a89a466893f58bcc55bd113f">New York</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="c20260813to20260813"
      id="Fact_4e3f64edb72247109e460a3faa5a2f49">NY</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="c20260813to20260813"
      id="Fact_7c626d6fd34a40648c49df14e7d1889e">10019</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="c20260813to20260813"
      id="Fact_10fe5ede885744d78b4b7e09b02cbf3a">212</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="c20260813to20260813"
      id="Fact_e9b14a81aa774d87884fdf63781d8685">309-7668</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="c20260813to20260813"
      id="Fact_9dd1f94702fb4e048e7872530abd8281">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="c20260813to20260813"
      id="Fact_f678fb11ca104e3883715325114468bf">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="c20260813to20260813"
      id="Fact_0a8ac4df60524aaeb40e7a7a2eb4de76">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="c20260813to20260813"
      id="Fact_70a4387882694fb18976797f8a9b97ac">false</dei:PreCommencementIssuerTenderOffer>
    <dei:TradingSymbol
      contextRef="c20260813to20260813_StatementClassOfStockAxis_CommonClassAMember"
      id="Fact_a0623a05f9d04c53bccbb9f1124029be">AACBU</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="c20260813to20260813_StatementClassOfStockAxis_CommonClassAMember"
      id="Fact_647ba9cb75ae481f946c4425fbc630b9">NASDAQ</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="c20260813to20260813_StatementClassOfStockAxis_ClassAOrdinarySharesParValue00001PerShareMember"
      id="Fact_bbbe9ed3c48c458a8536df6e2a00b807">Class A ordinary shares, par value $0.0001 per share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="c20260813to20260813_StatementClassOfStockAxis_ClassAOrdinarySharesParValue00001PerShareMember"
      id="Fact_38e5102456ae4f9499b8487bed38cdad">AACB</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="c20260813to20260813_StatementClassOfStockAxis_ClassAOrdinarySharesParValue00001PerShareMember"
      id="Fact_7524e3708cdc460a839f2d730c42aca7">NASDAQ</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="c20260813to20260813_StatementClassOfStockAxis_RightsEachRightEntitlingTheHolderToReceiveOneTenthOfOneClassAOrdinaryShareMember"
      id="Fact_9a9938d173334e96af9e9a6a4105737e">Rights, each right entitling the holder to receive one tenth of one Class A ordinary share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="c20260813to20260813_StatementClassOfStockAxis_RightsEachRightEntitlingTheHolderToReceiveOneTenthOfOneClassAOrdinaryShareMember"
      id="Fact_d06bd62a776b415d969a57b53ab615c3">AACBR</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="c20260813to20260813_StatementClassOfStockAxis_RightsEachRightEntitlingTheHolderToReceiveOneTenthOfOneClassAOrdinaryShareMember"
      id="Fact_b7384f74f27b46339709c54f39adf403">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="c20260813to20260813"
      id="Fact_d2a5322cf8a84d31ac92d260e85e7fdc">true</dei:EntityEmergingGrowthCompany>
    <dei:EntityExTransitionPeriod
      contextRef="c20260813to20260813"
      id="Fact_f46413ad1dc346ef973c2923e11af928">false</dei:EntityExTransitionPeriod>
</xbrl>
