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<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2026"
  xmlns:ffd="http://xbrl.sec.gov/ffd/2026"
  xmlns:iso4217="http://www.xbrl.org/2003/iso4217"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
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  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <link:schemaRef
      xlink:href="https://xbrl.sec.gov/ffd/2026/ffd-2026.xsd"
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    <context id="rc">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
        </entity>
        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
        </period>
    </context>
    <context id="offrl_1">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
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        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
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    </context>
    <context id="offrl_2">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>2</dei:lineNo>
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        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
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    </context>
    <context id="offrl_3">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>3</dei:lineNo>
                </xbrldi:typedMember>
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        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
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    <context id="offrl_4">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>4</dei:lineNo>
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        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
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    <context id="offrl_5">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>5</dei:lineNo>
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        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
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    <context id="offrl_6">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
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                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>6</dei:lineNo>
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        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
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    <context id="offrl_7">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>7</dei:lineNo>
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        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
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    </context>
    <context id="offrl_8">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>8</dei:lineNo>
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        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
        </period>
    </context>
    <context id="offrl_9">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>9</dei:lineNo>
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        </entity>
        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
        </period>
    </context>
    <context id="offrl_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001228454</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>10</dei:lineNo>
                </xbrldi:typedMember>
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        </entity>
        <period>
            <startDate>2026-08-14</startDate>
            <endDate>2026-08-14</endDate>
        </period>
    </context>
    <unit id="USD">
        <measure>iso4217:USD</measure>
    </unit>
    <unit id="pure">
        <measure>pure</measure>
    </unit>
    <ffd:FormTp contextRef="rc" id="ixv-474">S-3</ffd:FormTp>
    <ffd:SubmissnTp contextRef="rc" id="ixv-475">S-3</ffd:SubmissnTp>
    <ffd:FeeExhibitTp contextRef="rc" id="ixv-476">EX-FILING FEES</ffd:FeeExhibitTp>
    <dei:EntityCentralIndexKey contextRef="rc" id="ixv-477">0001228454</dei:EntityCentralIndexKey>
    <dei:EntityRegistrantName contextRef="rc" id="ixv-478">BCB BANCORP INC</dei:EntityRegistrantName>
    <ffd:OfferingTableNa contextRef="rc" id="hiddenrcOfferingTableNa" xsi:nil="true"/>
    <ffd:OffsetTableNa contextRef="rc" id="hiddenrcOffsetTableNa">N/A</ffd:OffsetTableNa>
    <ffd:CombinedProspectusTableNa contextRef="rc" id="hiddenrcCombinedProspectusTableNa">N/A</ffd:CombinedProspectusTableNa>
    <ffd:FeeRate
      contextRef="offrl_1"
      decimals="7"
      id="ixv-482"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeRate
      contextRef="offrl_2"
      decimals="7"
      id="ixv-483"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeRate
      contextRef="offrl_3"
      decimals="7"
      id="ixv-484"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeRate
      contextRef="offrl_4"
      decimals="7"
      id="ixv-485"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeRate
      contextRef="offrl_5"
      decimals="7"
      id="ixv-486"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeRate
      contextRef="offrl_6"
      decimals="7"
      id="ixv-487"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeRate
      contextRef="offrl_7"
      decimals="7"
      id="ixv-488"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeRate
      contextRef="offrl_8"
      decimals="7"
      id="ixv-489"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeRate
      contextRef="offrl_9"
      decimals="7"
      id="ixv-490"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FormTp contextRef="rc" id="ixv-596">S-3</ffd:FormTp>
    <dei:EntityRegistrantName contextRef="rc" id="ixv-597">BCB BANCORP INC</dei:EntityRegistrantName>
    <ffd:OfferingSctyTp contextRef="offrl_1" id="ixv-598">Equity</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_1" id="ixv-599">Common, no par value</ffd:OfferingSctyTitl>
    <ffd:Rule457oFlg contextRef="offrl_1" id="ixv-600">true</ffd:Rule457oFlg>
    <ffd:OfferingSctyTp contextRef="offrl_2" id="ixv-601">Equity</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_2" id="ixv-602">Preferred Stock, par value $0.01 per share</ffd:OfferingSctyTitl>
    <ffd:Rule457oFlg contextRef="offrl_2" id="ixv-603">true</ffd:Rule457oFlg>
    <ffd:OfferingSctyTp contextRef="offrl_3" id="ixv-604">Debt</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_3" id="ixv-605">Debt Securities</ffd:OfferingSctyTitl>
    <ffd:Rule457oFlg contextRef="offrl_3" id="ixv-606">true</ffd:Rule457oFlg>
    <ffd:OfferingSctyTp contextRef="offrl_4" id="ixv-607">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_4" id="ixv-608">Warrants</ffd:OfferingSctyTitl>
    <ffd:Rule457oFlg contextRef="offrl_4" id="ixv-609">true</ffd:Rule457oFlg>
    <ffd:OfferingSctyTp contextRef="offrl_5" id="ixv-610">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_5" id="ixv-611">Subscription Rights</ffd:OfferingSctyTitl>
    <ffd:Rule457oFlg contextRef="offrl_5" id="ixv-612">true</ffd:Rule457oFlg>
    <ffd:OfferingSctyTp contextRef="offrl_6" id="ixv-613">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_6" id="ixv-614">Depositary Shares</ffd:OfferingSctyTitl>
    <ffd:Rule457oFlg contextRef="offrl_6" id="ixv-615">true</ffd:Rule457oFlg>
    <ffd:OfferingSctyTp contextRef="offrl_7" id="ixv-616">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_7" id="ixv-617">Purchase Contracts</ffd:OfferingSctyTitl>
    <ffd:Rule457oFlg contextRef="offrl_7" id="ixv-618">true</ffd:Rule457oFlg>
    <ffd:OfferingSctyTp contextRef="offrl_8" id="ixv-619">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_8" id="ixv-620">Purchase Units</ffd:OfferingSctyTitl>
    <ffd:Rule457oFlg contextRef="offrl_8" id="ixv-621">true</ffd:Rule457oFlg>
    <ffd:OfferingSctyTp contextRef="offrl_9" id="ixv-622">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_9" id="ixv-623">Units</ffd:OfferingSctyTitl>
    <ffd:Rule457oFlg contextRef="offrl_9" id="ixv-624">true</ffd:Rule457oFlg>
    <ffd:PrevslyPdFlg contextRef="offrl_10" id="ixv-625">false</ffd:PrevslyPdFlg>
    <ffd:OfferingSctyTp contextRef="offrl_10" id="ixv-626">Unallocated (Universal) Shelf</ffd:OfferingSctyTp>
    <ffd:Rule457oFlg contextRef="offrl_10" id="ixv-627">true</ffd:Rule457oFlg>
    <ffd:MaxAggtOfferingPric
      contextRef="offrl_10"
      decimals="2"
      id="ixv-628"
      unitRef="USD">100000000.00</ffd:MaxAggtOfferingPric>
    <ffd:FeeRate
      contextRef="offrl_10"
      decimals="7"
      id="ixv-629"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeAmt
      contextRef="offrl_10"
      decimals="2"
      id="ixv-630"
      unitRef="USD">13810.00</ffd:FeeAmt>
    <ffd:TtlOfferingAmt contextRef="rc" decimals="2" id="ixv-631" unitRef="USD">100000000.00</ffd:TtlOfferingAmt>
    <ffd:TtlFeeAmt contextRef="rc" decimals="2" id="ixv-632" unitRef="USD">13810.00</ffd:TtlFeeAmt>
    <ffd:TtlPrevslyPdAmt contextRef="rc" decimals="2" id="ixv-633" unitRef="USD">0.00</ffd:TtlPrevslyPdAmt>
    <ffd:TtlOffsetAmt contextRef="rc" decimals="2" id="ixv-634" unitRef="USD">0.00</ffd:TtlOffsetAmt>
    <ffd:NetFeeAmt contextRef="rc" decimals="2" id="ixv-635" unitRef="USD">13810.00</ffd:NetFeeAmt>
    <ffd:OfferingNote contextRef="offrl_10" id="ixv-636">(1) An indeterminate number of securities of each identified class are being registered as may from time to time be offered at indeterminate prices, including an indeterminate number or amount of securities that may be issued upon the conversion, exercise, settlement or exchange of securities offered hereunder, which together shall have an aggregate initial offering price not to exceed $100,000,000. If any debt securities are issued at an original issue discount, then the principal amount of such debt securities shall be in such greater amount as shall result in an aggregate initial offering price not to exceed $100,000,000, less the aggregate dollar amount of all securities previously issued hereunder. If any securities are issued in an amount denominated in a foreign currency or composite currency, such amount shall result in an aggregate initial offering price equivalent thereto in United States dollars at the time of initial offering. Separate consideration may or may not be received for securities that are issuable on conversion, exercise, settlement or exchange of convertible or exchangeable securities. The securities registered also include such indeterminate number of shares of common stock, preferred stock and amount of debt securities as may be issued upon conversion of or exchange for debt securities that provide for conversion or exchange, or pursuant to the antidilution provisions of any such securities. In addition, pursuant to Rule 416 under the Securities Act of 1933, as amended (the "Securities Act"), the shares being registered hereunder include such indeterminate number of shares of common stock and preferred stock as may be issuable with respect to the shares being registered hereunder as a result of stock splits, stock dividends or similar transactions. (2) The proposed maximum aggregate offering price per class of security will be determined from time to time by the registrant in connection with the issuance by the registrant of the securities registered hereunder and is not specified as to each class of security pursuant to Instruction 2.A.iii.b. to the Calculation of Filing Fee Tables and Related Disclosure on Item 16(b) of Form S-3 under the Securities Act.</ffd:OfferingNote>
</xbrl>
