<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2026"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="asrv-20260721.xsd" xlink:type="simple"/>
    <context id="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000707605</identifier>
        </entity>
        <period>
            <startDate>2026-07-21</startDate>
            <endDate>2026-07-21</endDate>
        </period>
    </context>
    <dei:EntityCentralIndexKey
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Tc_Po95XxhI8E2gXs-SAsZVWw_2_1">0000707605</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Tc_Q8qQ2F2nwUy2QsgyOObMlQ_3_1">false</dei:AmendmentFlag>
    <dei:DocumentType
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_v_X47mLC00GfbvuBsKFh8A">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_FpNVHg45zEW17ne_3KYzAQ">2026-07-21</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_eWm23l6NWEWBBnTG3nO7HQ">AMERISERV FINANCIAL, Inc.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Tc_uYLey56WdUC_1L0uZvovyg_1_0">PA</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Tc_KCtQH6RtQ0K6dJfVyxSb8w_1_2">0-11204</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Tc_Kd3UalSfbUGu-U67pXhl_A_1_4">25-1424278</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_847OCtv6CEK_SAe9DqIhjA">Main and Franklin Streets</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_y3Q8LU5qFkyvqj_ZUiRCSg">Johnstown</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_2VrnlPgoj0CbLB0IJLs07A">PA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Tc_pXPOmu7it0S72jNcGW9NCw_1_1">15901</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_mkvPppqV80aCvKlHPYix6w">814</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_S4Ct_g4ZOEm1K8KMwQr7fQ">533-5300</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_S9N-eNoikk6Zu0WufXsEOw">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_olNTvlcPT0iJPqIbRAM89w">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_ybsJkLr4OkiHkhxBaokpVA">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_AXhpVENSJ0qzoTlQB7ANtQ">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Tc_U-Ig0jucSUCVmqiPqKLEVA_1_0">Common Stock</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Tc_6f4UidulTkOGbGQVY3f0BQ_1_2">ASRV</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Tc_E46SbAPXmk2QMH39hRW9vw_1_4">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="Duration_7_21_2026_To_7_21_2026_RnhunOTwa0Skva1MY5TUgA"
      id="Narr_5Rx7-4w-tUKdlZvzriVpRA">false</dei:EntityEmergingGrowthCompany>
</xbrl>
