<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-02-05</periodOfReport>

    <issuer>
        <issuerCik>0001472787</issuerCik>
        <issuerName>First American Financial Corp</issuerName>
        <issuerTradingSymbol>FAF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001885294</rptOwnerCik>
            <rptOwnerName>Cornehl Lisa W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 FIRST AMERICAN WAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SANTA ANA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92707</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>SVP, Chief Legal Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-02-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>585</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19572.96</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes 158 unvested Restricted Stock Units (&quot;RSUs&quot;) acquired pursuant to an original grant of 532 RSUs and shares acquired through automatic dividend reinvestment, which vest in four equal annual increments commencing 2/18/2022, the first anniversary of the grant.</footnote>
        <footnote id="F2">Includes 946 unvested RSUs acquired pursuant to an original grant of 1,694 RSUs and shares acquired through automatic dividend reinvestment, which vest in four equal annual increments commencing 2/22/2023, the first anniversary of the grant.</footnote>
        <footnote id="F3">Includes 780 unvested RSUs acquired pursuant to an original grant of 2,092 RSUs and shares acquired through automatic dividend reinvestment, which vest in three equal annual increments commencing 2/22/2023, the first anniversary of the grant.</footnote>
        <footnote id="F4">Includes 3,231 unvested RSUs acquired pursuant to an original grant of 4,512 RSUs and shares acquired through automatic dividend reinvestment, which vest in three equal annual increments commencing 2/16/2024, the first anniversary of the grant.</footnote>
        <footnote id="F5">Includes 6,976 unvested RSUs acquired pursuant to an original grant of 6,734 RSUs and shares acquired through automatic dividend reinvestment, which vest in three equal annual increments commencing 2/22/2025, the first anniversary of the grant.</footnote>
        <footnote id="F6">Includes 585 unvested RSUs, acquired pursuant to an original grant of 697 Performance Stock Units and shares acquired through automatic dividend reinvestment, for which the Compensation Committee of the Board of Directors certified performance on February 5, 2025, and which will vest on 2/22/2025, the third anniversary of the grant.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Stacy S. Rust, attorney-in fact for Lisa W. Cornehl</signatureName>
        <signatureDate>2025-02-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
