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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-07-09</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>2012-07-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10137</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.21</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>743626</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-07-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10137</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>17.06</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>733489</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-07-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3837</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.21</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>737326</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>2172.506</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>8.21</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2012-07-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10137</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2003-07-23</value>
                <footnoteId id="F11"/>
            </exerciseDate>
            <expirationDate>
                <value>2012-07-23</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10137</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3837</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>8.21</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2012-07-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3837</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2003-07-23</value>
                <footnoteId id="F11"/>
            </exerciseDate>
            <expirationDate>
                <value>2012-07-23</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3837</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>9.82</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-02-27</value>
                <footnoteId id="F12"/>
            </exerciseDate>
            <expirationDate>
                <value>2013-02-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>116452</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>116452</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>13.13</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2005-02-26</value>
                <footnoteId id="F13"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-02-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>116453</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>116453</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <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="F14"/>
            </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="F15"/>
            </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 option exercises and related sale of shares to cover taxes and exercise costs reported on this Form 4 were executed pursuant to the reporting person's 10b5-1 trading plan. The trading plan provides that the subject options held by the reporting person that were in-the-money after commissions would be exercised automatically on 7/9/2012 and 7/10/2012 with a specified percentage of the resulting shares to be sold to cover taxes associated with the exercise and exercise costs, and the remaining shares to be held by the reporting person.  The options that are the subject of this Form 4 would have expired on 7/23/2012.</footnote>
        <footnote id="F2">The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $17.04 to $17.14, 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 19,709 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 37,878 FAC RSUs, of which 24,424 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 39,546 unvested RSUs acquired in a pro rata distribution by FAC 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="F5">Includes 83,737 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="F6">Includes 220,159 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 (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 71,657 shares 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="F8">Includes 40,836 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="F9">Includes 107,457 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 2/28/13, 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 7/23/03, 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 2/27/04, 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 2/26/05, the first anniversary of the grant, has been carried over to the issuer options.</footnote>
        <footnote id="F14">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="F15">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>2012-07-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
