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

    <schemaVersion>X0305</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-04-13</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001422759</rptOwnerCik>
            <rptOwnerName>Leavell Christopher Michael</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>COO of Subsidiary</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-04-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>13974</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.32</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>180321</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-04-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>13974</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.32</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>194295</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-04-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>27948</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>16.98</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>166347</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                    <footnoteId id="F8"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1049.63</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by 401(k) Plan Trust</value>
                    <footnoteId id="F9"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>11.32</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2012-04-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>13974</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2004-03-12</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-03-12</value>
                <footnoteId id="F10"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>13974</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>11.32</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2012-04-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>13974</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2004-04-01</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-04-01</value>
                <footnoteId id="F11"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>13974</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>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>15.09</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2005-10-21</value>
            </exerciseDate>
            <expirationDate>
                <value>2014-10-21</value>
                <footnoteId id="F12"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20209</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20209</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>15.09</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2005-10-21</value>
            </exerciseDate>
            <expirationDate>
                <value>2014-10-21</value>
                <footnoteId id="F12"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>14726</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14726</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>19.96</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2007-01-13</value>
            </exerciseDate>
            <expirationDate>
                <value>2016-01-13</value>
                <footnoteId id="F13"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>13448</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13448</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>19.96</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2007-01-13</value>
            </exerciseDate>
            <expirationDate>
                <value>2016-01-13</value>
                <footnoteId id="F13"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>9842</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9842</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The cashless option exercise reported on this Form 4 is executed pursuant to the reporting person's 10b5-1 trading plan.</footnote>
        <footnote id="F2">Pursuant to a domestic relations order, a portion of the reporting person's shares, options and certain RSUs are held by the reporting person for the benefit of his ex-wife, who will receive either shares or the cash proceeds generated from the sale of applicable shares, after any applicable vesting and/or exercise.</footnote>
        <footnote id="F3">Includes 7,109 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 13,636 FAC RSUs, of which 8,793 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 3/4/09, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F4">Includes 12,184 unvested RSUs acquired in a pro rata distribution by FAC on account of an original grant of 12,209 FAC RSUs, of which 10,133 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 3/20/10, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F5">Includes 15,160 unvested RSUs acquired in a pro rata distribution by FAC on account of an original grant of 10,464 FAC RSUs, of which 10,527 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 3/22/11, the first anniversary of the grant, has been carried over to the issuer RSUs.</footnote>
        <footnote id="F6">Includes 73,042 unvested RSUs acquired pursuant to a grant of performance based RSUs on account of an original grant of 70,921 RSUs and shares acquired through automatic dividend reinvestment, which vest (if the performance criteria have been met) in three equal annual increments commencing on 6/1/13, 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="F7">Includes 16,994 unvested RSUs acquired pursuant to an original grant of 22,274 RSUs and shares acquired through automatic dividend reinvestment, vesting in four equal annual increments commencing 3/21/12, the first anniversary of the grant.</footnote>
        <footnote id="F8">Includes 28,441 unvested RSUs, vesting in four equal increments commencing 2/28/13, the first anniversary of the grant.</footnote>
        <footnote id="F9">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="F10">The vesting schedule of the original FAC option, vesting in five equal annual increments commencing 3/12/04, the first anniversary of the grant, has been carried over to the issuer options.</footnote>
        <footnote id="F11">The vesting schedule of the original FAC option, vesting in five equal annual increments commencing 4/1/04, 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 10/21/05, 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 1/13/07, 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 Christopher M. Leavell</signatureName>
        <signatureDate>2012-04-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
