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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-02-04</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001243867</rptOwnerCik>
            <rptOwnerName>GILMORE DENNIS J</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>
            <isOfficer>1</isOfficer>
            <officerTitle>Chief Executive Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-02-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>116453</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.13</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>923761</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-02-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>116453</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25.12</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>807308</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                    <footnoteId id="F8"/>
                    <footnoteId id="F9"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2244.943</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 401(k) Plan Trust</value>
                    <footnoteId id="F10"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>13.13</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2014-02-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>116453</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-02-26</value>
                <footnoteId id="F11"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-02-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>116453</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>15.70</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2006-02-28</value>
                <footnoteId id="F12"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-02-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>139744</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>139744</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>20.40</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2006-12-08</value>
                <footnoteId id="F13"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-12-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>139744</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>139744</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The cashless option exercise and sales reported on this Form 4 were executed pursuant to the reporting person's 10b5-1 trading plan.</footnote>
        <footnote id="F2">The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $24.95 to $25.33, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.</footnote>
        <footnote id="F3">Includes 20,481 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 39,504 FAC RSUs, of which 32,784 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 3/4/10, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F4">Includes 57,705 unvested RSUs acquired in a pro rata distribution by FAC on account of an original grant of 57,551 FAC RSUs, of which 57,897 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 3/3/11, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F5">Includes 151,683 unvested RSUs acquired pursuant to a grant of performance based RSUs on account of an original grant of 212,765 RSUs and shares acquired through automatic dividend reinvestment, which vest in three equal annual increments commencing on 6/3/13, the first business day following the third anniversary of the grant, pursuant to the Form of RSU Award Agreement filed as Exhibit 10(i) to the issuer's Quarterly Report on Form 10-Q for the period ended June 30, 2010.</footnote>
        <footnote id="F6">Includes 49,369 unvested RSUs acquired pursuant to an original grant of 93,498 RSUs and shares acquired through automatic dividend reinvestment, vesting in four equal annual increments commencing 3/3/12, the first anniversary of the grant.</footnote>
        <footnote id="F7">Includes 28,202 unvested RSUs acquired pursuant to an original grant of 53,282 RSUs and shares acquired through automatic dividend reinvestment, vesting in four equal annual increments commencing 3/31/12, the first anniversary of the grant.</footnote>
        <footnote id="F8">Includes 83,284 unvested RSUs acquired pursuant to an original grant of 106,959 RSUs and shares acquired through automatic dividend reinvestment, vesting in four equal annual increments commencing 3/1/13, the first anniversary of the grant made on 2/29/12.</footnote>
        <footnote id="F9">Includes 121,506 unvested RSUs, acquired pursuant to an original grant of 119,126 RSUs and shares acquired through automatic dividend reinvestment, vesting in four equal annual increments commencing 3/4/14, the first anniversary of the grant.</footnote>
        <footnote id="F10">Amount shown consists of shares contributed by issuer as company match, shares purchased for the reporting person's account and shares acquired through automatic reinvestment of dividends paid as reported in most recent account statement in transactions exempt under rules 16a-3(f)(1)(i)(B) and 16b-3(c).</footnote>
        <footnote id="F11">The vesting schedule of the original FAC option, vesting in five equal annual increments commencing 2/26/05, the first anniversary of the grant, has been carried over to the issuer options.</footnote>
        <footnote id="F12">The vesting schedule of the original FAC option, vesting in five equal annual increments commencing 2/28/06, the first anniversary of the grant, has been carried over to the issuer options.</footnote>
        <footnote id="F13">The vesting schedule of the original FAC option, vesting in five equal annual increments commencing 12/8/06, the first anniversary of the grant, has been carried over to the issuer options.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Greg L. Smith, attorney-in-fact for Dennis J. Gilmore</signatureName>
        <signatureDate>2014-02-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
