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

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-02-29</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001507625</rptOwnerCik>
            <rptOwnerName>Seaton Mark Edward</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>Senior Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-02-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6477</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13207</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes 93 unvested restricted stock units (&quot;RSUs&quot;) acquired in a pro rata distribution by The First American Corporation (&quot;FAC&quot;) on account of an original grant of 197 FAC RSUs, of which 79 were unvested at the time of the distribution.  The vesting schedule of the FAC RSUs, vesting in five equal annual increments commencing 03/30/08, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F2">Includes 689 RSUs acquired in a pro rata distribution by FAC on account of an original grant of 719 FAC RSUs, of which 436 were unvested at the time of the distribution and shares acquired through automatic dividend reinvestment.  The vesting schedule of the FAC RSUs, vesting in five equal annual increments commencing 03/20/09, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F3">Includes 537 RSUs acquired in a pro rata distribution by FAC on account of an original grant of 381 FAC RSUs, of which 305 were unvested at the time of the distribution and shares acquired through automatic dividend reinvestment.  The vesting schedule of the FAC RSUs, vesting in five equal annual increments commencing 03/20/10, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F4">Includes 540 RSUs acquired in a pro rata distribution by FAC on account of an original grant of 287 FAC RSUs, all of which were unvested at the time of the distribution and shares acquired through automatic dividend reinvestment.  The vesting schedule of the FAC RSUs, vesting in five equal annual increments commencing 03/22/11, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F5">Includes 3,182 shares acquired pursuant to an original grant of 3,130 RSUs and shares acquired through automatic dividend reinvestment, vesting in four equal increments commencing 3/3/12, the first anniversary of the grant.</footnote>
        <footnote id="F6">Includes 6,477 shares acquired pursuant to a grant of RSUs, vesting in four equal increments commencing 2/28/13, the first anniversary of the grant.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Greg L. Smith, Attorney-in-Fact for Mark E. Seaton</signatureName>
        <signatureDate>2012-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
