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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-03-24</periodOfReport>

    <issuer>
        <issuerCik>0001647509</issuerCik>
        <issuerName>Forest City Realty Trust, Inc.</issuerName>
        <issuerTradingSymbol>FCEA/FCEB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001532989</rptOwnerCik>
            <rptOwnerName>Obert Charles D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>50 PUBLIC SQUARE, SUITE 1100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CLEVELAND</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44113</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr VP, Chief Acct Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3332</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5205</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2679</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3940</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-03-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5191</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5191</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>26513</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F6"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>746.1129</value>
                    <footnoteId id="F7"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401k Plan</value>
                    <footnoteId id="F7"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>2010 Stock Option Grant (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>15.89</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2012-04-14</value>
                <footnoteId id="F8"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-04-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F8"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>2011 Stock Option Grant (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>17.72</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2013-04-13</value>
                <footnoteId id="F9"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-04-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F9"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>2014 Performance Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2017-12-31</value>
            </exerciseDate>
            <expirationDate>
                <value>1988-08-08</value>
                <footnoteId id="F10"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4271</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4271</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F10"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>2015 Performance Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2017-12-31</value>
            </exerciseDate>
            <expirationDate>
                <value>1988-08-08</value>
                <footnoteId id="F11"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3357</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3357</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F11"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>2016 Performance Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2018-12-31</value>
            </exerciseDate>
            <expirationDate>
                <value>1988-08-08</value>
                <footnoteId id="F12"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5253</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5253</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F12"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeTransaction>
            <securityTitle>
                <value>2017 Performance Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-03-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5191</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2019-12-31</value>
            </exerciseDate>
            <expirationDate>
                <value>1988-08-08</value>
                <footnoteId id="F13"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5191</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5191</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F13"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeHolding>
            <securityTitle>
                <value>2015 Out Performance Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2017-12-31</value>
            </exerciseDate>
            <expirationDate>
                <value>1988-08-08</value>
                <footnoteId id="F14"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F14"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">2013 Restricted Stock Grant - 25% vest on 4/08/2015;  25% vest on 4/08/2016; and 50% vest on 4/08/2017.</footnote>
        <footnote id="F2">2014 Restricted Stock Grant - 0% vest on 3/28/2015; 25% vest on 3/28/2016;  25% vest on 3/28/2017; and 50% vest on 3/28/2018.</footnote>
        <footnote id="F3">2015 Restricted Stock Grant - 25% vest on 3/26/2016;  25% vest on 3/26/2017; and 50% vest on 3/26/2018.</footnote>
        <footnote id="F4">2016 Restricted Stock Grant - 25% vest on 3/23/2017;  25% vest on 3/23/2018; and 50% vest on 3/23/2019.</footnote>
        <footnote id="F5">2017 Restricted Stock Grant - 25% vest on 3/24/2018;  25% vest on 3/24/2019; and 50% vest on 3/24/2020.</footnote>
        <footnote id="F6">Shares are held by transfer agent in a direct registration account.</footnote>
        <footnote id="F7">FCE's 401k Plan account, shares are held indirect. Updated to reflect current holdings.</footnote>
        <footnote id="F8">2010 Stock Option Grant - 25% exercisable 4/14/2012; 25% exercisable 4/14/2013; and 50% exercisable 4/14/2014.</footnote>
        <footnote id="F9">2011 Stock Option Grant - 25% exercisable 4/13/2013; 25% exercisable 4/13/2014; and 50% exercisable 4/13/2015.</footnote>
        <footnote id="F10">Performance Shares Award -  granted 3/28/2014 - performance period is from January 1, 2014 to December 31, 2017.  Awards will be available to the grantee at the end of the performance period provided that certain performance criteria are met. The actual number of shares earned could range from 0 to 200% of the number of Performance Shares granted.  Fair market value on date of grant is  $18.73 per share.  There is no fixed expiration date.</footnote>
        <footnote id="F11">Performance Shares Award -  granted 3/26/2015 - performance period is from January 1, 2015 to December 31, 2017.  Awards will be available to the grantee at the end of the performance period provided that certain performance criteria are met. The actual number of shares earned could range from 0 to 200% of the number of Performance Shares granted.  Fair market value on date of grant is $24.62 per share.  There is no fixed expiration date.</footnote>
        <footnote id="F12">Performance Shares Award -  granted 3/23/2016 - performance period is from January 1, 2016 to December 31, 2018.  Awards will be available to the grantee at the end of the performance period provided that certain performance criteria are met. The actual number of shares earned could range from 0 to 200% of the number of Performance Shares granted.  Fair market value on date of grant is $20.94 per share.  There is no fixed expiration date.</footnote>
        <footnote id="F13">Performance Shares Award -  granted 3/24/2017 - performance period is from January 1, 2017 to December 31, 2019.  Awards will be available to the grantee at the end of the performance period provided that certain performance criteria are met. The actual number of shares earned could range from 0 to 200% of the number of Performance Shares granted.  Fair market value on date of grant is  $21.83 per share.  There is no fixed expiration date.</footnote>
        <footnote id="F14">Out Performance Shares Award -  granted 3/27/2015 - performance period is from January 1, 2015 to December 31, 2017.  Awards will vest 50% on December 31, 2017 and 50% on December 31, 2018 and will be available to the grantee  provided that certain performance criteria are met. The actual number of shares earned could range from 0 to 300% of the number of Performance Shares granted.  Fair market value on date of grant is $25.31 per share.  There is no fixed expiration date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>J. Matthew Shady, Attorney-In-Fact for Charles D. Obert</signatureName>
        <signatureDate>2017-03-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
