<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2025"
  xmlns:ffd="http://xbrl.sec.gov/ffd/2025"
  xmlns:iso4217="http://www.xbrl.org/2003/iso4217"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  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/2025/ffd-2025.xsd"
      xlink:type="simple"/>
    <context id="c_offering_1">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000811589</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>1</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-09-23</startDate>
            <endDate>2026-09-23</endDate>
        </period>
    </context>
    <context id="c_report">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000811589</identifier>
        </entity>
        <period>
            <startDate>2026-09-23</startDate>
            <endDate>2026-09-23</endDate>
        </period>
    </context>
    <unit id="USD">
        <measure>iso4217:USD</measure>
    </unit>
    <unit id="pure">
        <measure>pure</measure>
    </unit>
    <unit id="shares">
        <measure>shares</measure>
    </unit>
    <ffd:SubmissnTp contextRef="c_report" id="fee_001">S-4</ffd:SubmissnTp>
    <ffd:FeeExhibitTp contextRef="c_report" id="fee_002">EX-FILING FEES</ffd:FeeExhibitTp>
    <dei:EntityCentralIndexKey contextRef="c_report" id="fee_003">0000811589</dei:EntityCentralIndexKey>
    <ffd:OfferingTableNa contextRef="c_report" id="fee_004" xsi:nil="true"/>
    <ffd:OffsetTableNa contextRef="c_report" id="fee_005">N/A</ffd:OffsetTableNa>
    <ffd:CombinedProspectusTableNa contextRef="c_report" id="fee_006">N/A</ffd:CombinedProspectusTableNa>
    <ffd:FormTp contextRef="c_report" id="fee_007">S-4</ffd:FormTp>
    <dei:EntityRegistrantName contextRef="c_report" id="fee_008">First Bancorp</dei:EntityRegistrantName>
    <ffd:PrevslyPdFlg contextRef="c_offering_1" id="fee_009">false</ffd:PrevslyPdFlg>
    <ffd:OfferingSctyTp contextRef="c_offering_1" id="fee_010">Equity</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="c_offering_1" id="fee_011">Common stock, no par value</ffd:OfferingSctyTitl>
    <ffd:FeesOthrRuleFlg contextRef="c_offering_1" id="fee_012">true</ffd:FeesOthrRuleFlg>
    <ffd:AmtSctiesRegd
      contextRef="c_offering_1"
      decimals="0"
      id="fee_013"
      unitRef="shares">1967018</ffd:AmtSctiesRegd>
    <ffd:MaxAggtOfferingPric
      contextRef="c_offering_1"
      decimals="INF"
      id="fee_014"
      unitRef="USD">110299932.00</ffd:MaxAggtOfferingPric>
    <ffd:FeeRate
      contextRef="c_offering_1"
      decimals="INF"
      id="fee_015"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:FeeAmt
      contextRef="c_offering_1"
      decimals="INF"
      id="fee_016"
      unitRef="USD">15232.42</ffd:FeeAmt>
    <ffd:TtlOfferingAmt
      contextRef="c_report"
      decimals="INF"
      id="fee_017"
      unitRef="USD">110299932.00</ffd:TtlOfferingAmt>
    <ffd:TtlFeeAmt
      contextRef="c_report"
      decimals="INF"
      id="fee_018"
      unitRef="USD">15232.42</ffd:TtlFeeAmt>
    <ffd:NetFeeAmt
      contextRef="c_report"
      decimals="INF"
      id="fee_019"
      unitRef="USD">15232.42</ffd:NetFeeAmt>
    <ffd:OfferingNote contextRef="c_offering_1" id="fee_020">Represents the maximum number of shares of common stock of First Bancorp that may be issued to holders of shares of common stock of First Carolina Bancshares Corporation in the merger described herein.&lt;br/&gt;&lt;br/&gt;Estimated solely for purposes of calculating the amount of the registration fee pursuant to Rule 457(f)(2) under the Securities Act of 1933, as amended, based upon the book value per share of 135,339 shares of First Carolina Bancshares Corporation common stock expected to be exchanged for First Bancorp&#x2019;s common stock in connection with the merger, as of June 30, 2026, of $814.99 per share. The registration fee was recalculated as follows: The market value of the (First Carolina Bancshares Corporation) securities to be received by First Bancorp equals 135,339 x $814.99 = $110,299,932.&lt;br/&gt;&lt;br/&gt;Computed pursuant to Rule 457(f)(2) of the Securities Act, based on a rate of $138.10 per $1,000,000 of the proposed maximum aggregate offering price. The rate of $138.10 per $1,000,000 results in a filing fee of $15,232.42.&lt;br/&gt;&lt;br/&gt;</ffd:OfferingNote>
</xbrl>
