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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-02-24</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001706594</rptOwnerCik>
            <rptOwnerName>GILYARD REGINALD HAROLD</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>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-02-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2522</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>21938.88</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes 2,522 unvested Restricted Stock Units (&quot;RSUs&quot;) acquired pursuant to a grant vesting 2/24/2026, the first anniversary of the grant.</footnote>
        <footnote id="F2">Includes 588.096 shares acquired through a dividend reinvestment plan administered by the reporting person's broker since the reporting person's last filing made pursuant to Section 16(a) of the Securities Exchange Act of 1934. Fractional share amounts may vary slightly from prior reports due to rounding.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Stacy S. Rust, attorney-in-fact for Reginald H. Gilyard</signatureName>
        <signatureDate>2025-02-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
