<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xml:lang="en-US"
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:cof="http://www.capitalone.com/20221001"
  xmlns:dei="http://xbrl.sec.gov/dei/2021"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:us-gaap="http://fasb.org/us-gaap/2021-01-31"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="cof-20221001.xsd" xlink:type="simple"/>
    <context id="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000927628</identifier>
        </entity>
        <period>
            <startDate>2022-10-01</startDate>
            <endDate>2022-10-01</endDate>
        </period>
    </context>
    <context id="ibe43b84079c74735be6e9538ede83417_D20221001-20221001">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000927628</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">us-gaap:CommonStockMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-10-01</startDate>
            <endDate>2022-10-01</endDate>
        </period>
    </context>
    <context id="i0958a232be624be3a7924b346a342dfa_D20221001-20221001">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000927628</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">cof:SeriesIPreferredStockMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-10-01</startDate>
            <endDate>2022-10-01</endDate>
        </period>
    </context>
    <context id="i91a397b30a3049b287e35e6e0dabb68b_D20221001-20221001">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000927628</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">cof:SeriesJPreferredStockMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-10-01</startDate>
            <endDate>2022-10-01</endDate>
        </period>
    </context>
    <context id="idd83d32ad91e4abfafb07780ae12cc7a_D20221001-20221001">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000927628</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">cof:SeriesKPreferredStockMemberMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-10-01</startDate>
            <endDate>2022-10-01</endDate>
        </period>
    </context>
    <context id="ia6e9b4c3951245b1a4920921909bd9c6_D20221001-20221001">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000927628</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">cof:SeriesLPreferredStockMemberMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-10-01</startDate>
            <endDate>2022-10-01</endDate>
        </period>
    </context>
    <context id="i0043ed2ae98d45b18ac15a636060534d_D20221001-20221001">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000927628</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">cof:SeriesNPreferredStockMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-10-01</startDate>
            <endDate>2022-10-01</endDate>
        </period>
    </context>
    <context id="i7e87b8edd65f44a3ae7908081244a1eb_D20221001-20221001">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000927628</identifier>
            <segment>
                <xbrldi:explicitMember dimension="cof:ClassofSecuritiesAxis">cof:SeniorNotesDue2024Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-10-01</startDate>
            <endDate>2022-10-01</endDate>
        </period>
    </context>
    <context id="i694cb255684a4edfa9781070d1364714_D20221001-20221001">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000927628</identifier>
            <segment>
                <xbrldi:explicitMember dimension="cof:ClassofSecuritiesAxis">cof:SeniorNotesDue2029Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-10-01</startDate>
            <endDate>2022-10-01</endDate>
        </period>
    </context>
    <dei:AmendmentFlag
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml80L2ZyYWc6OTg2Y2I5ZWIyMjQ2NDU1MWFiMGRlYjMzOTk4OTZlNjkvdGFibGU6MGE2YzNjY2FlZDNlNDcwOGFkNzI1MjQ5ZDI1OGU5ZTUvdGFibGVyYW5nZTowYTZjM2NjYWVkM2U0NzA4YWQ3MjUyNDlkMjU4ZTllNV8xLTItMS0xLTQyODUyOA_6438ed10-4d58-49a6-add9-66dc7006fbd3">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml80L2ZyYWc6OTg2Y2I5ZWIyMjQ2NDU1MWFiMGRlYjMzOTk4OTZlNjkvdGFibGU6MGE2YzNjY2FlZDNlNDcwOGFkNzI1MjQ5ZDI1OGU5ZTUvdGFibGVyYW5nZTowYTZjM2NjYWVkM2U0NzA4YWQ3MjUyNDlkMjU4ZTllNV80LTItMS0xLTQyODUyOA_2733faec-b676-4125-bfbf-054120d26545">0000927628</dei:EntityCentralIndexKey>
    <dei:DocumentType
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODU3_394f7c3b-c157-40e0-a15f-5c92e89e8b32">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODUx_b8a52e73-2663-4080-b163-da7da565d2d2">2022-10-01</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODUy_824309e2-748b-4676-90bb-2d47de20e36b">CAPITAL&#160;ONE&#160;FINANCIAL&#160;CORP</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NWE2ZjJiNmU2MzUxNGZmYWIxOTBjMDAyMmQxZDcwZDYvdGFibGVyYW5nZTo1YTZmMmI2ZTYzNTE0ZmZhYjE5MGMwMDIyZDFkNzBkNl8wLTAtMS0xLTQyODUyOA_ebe0de50-c638-473d-bfed-e94a60d5e041">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NWE2ZjJiNmU2MzUxNGZmYWIxOTBjMDAyMmQxZDcwZDYvdGFibGVyYW5nZTo1YTZmMmI2ZTYzNTE0ZmZhYjE5MGMwMDIyZDFkNzBkNl8wLTItMS0xLTQyODUyOA_53df69b1-11ba-43a4-ac59-2db20d7a042b">001-13300</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NWE2ZjJiNmU2MzUxNGZmYWIxOTBjMDAyMmQxZDcwZDYvdGFibGVyYW5nZTo1YTZmMmI2ZTYzNTE0ZmZhYjE5MGMwMDIyZDFkNzBkNl8wLTMtMS0xLTQyODUyOA_ed641bf0-f2b7-4e1c-ae04-71b4d7d64fed">54-1719854</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NWE2ZjJiNmU2MzUxNGZmYWIxOTBjMDAyMmQxZDcwZDYvdGFibGVyYW5nZTo1YTZmMmI2ZTYzNTE0ZmZhYjE5MGMwMDIyZDFkNzBkNl8yLTAtMS0xLTQyODUyOA_8a4975b9-ae7a-4884-bc1e-45fc06588ae9">1680 Capital One Drive,</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NWE2ZjJiNmU2MzUxNGZmYWIxOTBjMDAyMmQxZDcwZDYvdGFibGVyYW5nZTo1YTZmMmI2ZTYzNTE0ZmZhYjE5MGMwMDIyZDFkNzBkNl8zLTAtMS0xLTQyODUyOA_004bfbfd-1484-4993-9f64-9cf856d9a302">McLean,</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NWE2ZjJiNmU2MzUxNGZmYWIxOTBjMDAyMmQxZDcwZDYvdGFibGVyYW5nZTo1YTZmMmI2ZTYzNTE0ZmZhYjE5MGMwMDIyZDFkNzBkNl8zLTEtMS0xLTQyODUyOA_755587b7-f768-4f5a-bbff-75da38e80f39">VA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NWE2ZjJiNmU2MzUxNGZmYWIxOTBjMDAyMmQxZDcwZDYvdGFibGVyYW5nZTo1YTZmMmI2ZTYzNTE0ZmZhYjE5MGMwMDIyZDFkNzBkNl8zLTMtMS0xLTQyODUyOA_4bd17c70-c005-4a4b-b70e-b5707e9c0f04">22102</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODU4_02953769-9a81-471a-bb8a-52db6939d7de">703</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODUz_3a356998-4606-4e72-af06-b3525ea669bd">720-1000</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODU0_a428f788-8870-49a0-b548-b069f85d0695">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODU1_b080b7c5-6528-4f19-836c-b8b783426255">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODQ5_079f1f04-852c-47ee-9b7e-82cf94ebcb21">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODU2_223b3e79-fb32-4797-b38e-03f75a6704c4">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="ibe43b84079c74735be6e9538ede83417_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF8xLTAtMS0xLTQyODUyOA_81f0e311-21e0-4b8f-a0d3-b8757c11894c">Common Stock (par value $.01 per share)</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="ibe43b84079c74735be6e9538ede83417_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF8xLTEtMS0xLTQyODUyOA_181fc18b-c97e-442b-85c4-e912a1c76cfa">COF</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="ibe43b84079c74735be6e9538ede83417_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF8xLTItMS0xLTQyODUyOA_a53169e0-905c-49d8-afba-914379a130ae">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="i0958a232be624be3a7924b346a342dfa_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF8yLTAtMS0xLTQyODUyOA_fd93f419-0e22-44b8-8c8d-eb1a985cffae">Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series I</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i0958a232be624be3a7924b346a342dfa_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF8yLTEtMS0xLTQyODUyOA_64e528e7-6695-4acb-ae45-910c07f40b32">COF PRI</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i0958a232be624be3a7924b346a342dfa_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF8yLTItMS0xLTQyODUyOA_9c8415db-5a4a-4ff8-b14a-2631b4a75509">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="i91a397b30a3049b287e35e6e0dabb68b_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF8zLTAtMS0xLTQyODUyOA_fe2f2c55-4db8-46ad-aa0e-2df55a6001da">Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series J</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i91a397b30a3049b287e35e6e0dabb68b_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF8zLTEtMS0xLTQyODUyOA_0beead1b-9992-4434-bf7b-65338a764ded">COF PRJ</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i91a397b30a3049b287e35e6e0dabb68b_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF8zLTItMS0xLTQyODUyOA_cea7a679-286a-4f3c-a7c4-96c8b09e2f53">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="idd83d32ad91e4abfafb07780ae12cc7a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF80LTAtMS0xLTQyODUyOA_09f9d073-106b-46e1-baa5-3d203a21072f">Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series K</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="idd83d32ad91e4abfafb07780ae12cc7a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF80LTEtMS0xLTQyODUyOA_65540149-43a4-4d2e-991f-01cd531bba41">COF PRK</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="idd83d32ad91e4abfafb07780ae12cc7a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF80LTItMS0xLTQyODUyOA_6416674e-7491-4966-8cc9-e9f5c415fef5">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="ia6e9b4c3951245b1a4920921909bd9c6_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF81LTAtMS0xLTQyODUyOA_bf2e6b20-d66b-405b-9703-44300c467876">Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series L</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="ia6e9b4c3951245b1a4920921909bd9c6_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF81LTEtMS0xLTQyODUyOA_24f28181-8777-4cde-925e-2c1cb426a950">COF PRL</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="ia6e9b4c3951245b1a4920921909bd9c6_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF81LTItMS0xLTQyODUyOA_40722ea5-085f-44cf-8b18-8ca17b54e66a">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="i0043ed2ae98d45b18ac15a636060534d_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF82LTAtMS0xLTQyODUyOA_4ea93112-2631-4a5d-a856-ca72631b6a2f">Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series N</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i0043ed2ae98d45b18ac15a636060534d_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF82LTEtMS0xLTQyODUyOA_8c2ebfa2-5936-49c3-bdd1-bdb5f5d7b7f6">COF PRN</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i0043ed2ae98d45b18ac15a636060534d_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF82LTItMS0xLTQyODUyOA_072b6288-ad0f-4dc1-97bb-50357ef83a47">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="i7e87b8edd65f44a3ae7908081244a1eb_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF83LTAtMS0xLTQyODUyOA_b663b53d-f848-4c10-b604-2f6ff6fc302a">0.800% Senior Notes Due 2024</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i7e87b8edd65f44a3ae7908081244a1eb_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF83LTEtMS0xLTQyODUyOA_5922aa90-a87a-4a76-901b-a4ea7c0324d6">COF24</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i7e87b8edd65f44a3ae7908081244a1eb_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF83LTItMS0xLTQyODUyOA_93c5a640-c2d2-45f6-9163-affaa0b886f0">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="i694cb255684a4edfa9781070d1364714_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF84LTAtMS0xLTQyODUyOA_940d1902-a1db-4956-a021-c4ca9e8ea24c">1.650% Senior Notes Due 2029</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i694cb255684a4edfa9781070d1364714_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF84LTEtMS0xLTQyODUyOA_6bc160f2-6c02-4c09-98cc-09eab3614cb3">COF29</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i694cb255684a4edfa9781070d1364714_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGFibGU6NTg1NDQ1MTUxZDdlNDkwMWJiMzRmNDFmN2NhZDcwMWQvdGFibGVyYW5nZTo1ODU0NDUxNTFkN2U0OTAxYmIzNGY0MWY3Y2FkNzAxZF84LTItMS0xLTQyODUyOA_28c7b192-bb05-433d-ad5f-71acbc8b190d">NYSE</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="i6d3917efa3cf4df9864e5c26fcfe486a_D20221001-20221001"
      id="id3VybDovL2RvY3MudjEvZG9jOjNhZjg3YjlhOTlmNTQ3YTlhN2E1ZjI3MjJkYzM4NDYyL3NlYzozYWY4N2I5YTk5ZjU0N2E5YTdhNWYyNzIyZGMzODQ2Ml8xL2ZyYWc6OWNhZTU5NTcwNzA5NDFmODlhZWNjMjU1NWY4YjE5OGQvdGV4dHJlZ2lvbjo5Y2FlNTk1NzA3MDk0MWY4OWFlY2MyNTU1ZjhiMTk4ZF8xODUw_f51eb8a8-fbc8-4ddc-aaa2-edd9892b114b">false</dei:EntityEmergingGrowthCompany>
</xbrl>
