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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-03-21</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001194560</rptOwnerCik>
            <rptOwnerName>CHRISTENSON GLENN C</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>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-03-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3247</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15698</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>54000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Family Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes 1,448 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 1,707 FAC RSUs, of which 1,215 were unvested at the time of the distribution and shares acquired through automatic dividend reinvestment.  The vesting schedule of the FAC RSUs, vesting in three equal annual increments commencing 6/20/2009, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F2">Includes 2,049 unvested RSUs acquired in a pro rata distribution by FAC on account of an original grant of 2,489 FAC RSUs, of which 1,724 were unvested at the time of the distribution and shares acquired through automatic dividend reinvestment.  The vesting schedule of the FAC RSUs, vesting in three equal annual increments commencing 3/4/2010, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F3">Includes 2,739 unvested RSUs acquired in a pro rata distribution by FAC on account of an original grant of 1,731 FAC RSUs, of which 1,741 were unvested at the time of the distribution and shares acquired through automatic dividend reinvestment.  The vesting schedule of the FAC RSUs, vesting in three equal annual increments commencing 3/3/2011, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F4">Includes 3,247 shares acquired pursuant to a grant of RSUs vesting in three equal annual increments commencing 3/21/12, the first anniversary of the grant.</footnote>
        <footnote id="F5">The number of RSUs acquired in the distribution is equal to the number of unvested FAC RSUs held by the reporting person at the time of the distribution multiplied by $32.84/$14.10, which represents the last FAC trading price divided by the when-issued trading price of the issuer on June 1, 2010.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Jeffrey S. Robinson, Attorney-in-Fact for Glenn C. Christenson</signatureName>
        <signatureDate>2011-03-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
