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

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-09-06</periodOfReport>

    <issuer>
        <issuerCik>0000057528</issuerCik>
        <issuerName>SNYDER'S-LANCE, INC.</issuerName>
        <issuerTradingSymbol>LNCE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001507351</rptOwnerCik>
            <rptOwnerName>WAREHIME MICHAEL A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>13024 BALLANTYNE CORPORATE PLACE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 900</rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28277</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Chairman of the Board</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001507350</rptOwnerCik>
            <rptOwnerName>WAREHIME PATRICIA A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>13024 BALLANTYNE CORPORATE PLACE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 900</rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28277</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>$.83-1/3 par value Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-09-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>19.97</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10759251</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>$.83-1/3 par value Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-09-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6697</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>19.97</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>839915</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>$.83-1/3 par value Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4000</value>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>$.83-1/3 par value Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1020018</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F6"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Warehime Enterprises, Inc.</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>$.83-1/3 par value Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>354707</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F7"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By MAW Associates, LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes shares received in exchange for shares of Snyder's of Hanover, Inc. (&quot;SOH&quot;) common stock pursuant to the Agreement and Plan of Merger among SOH, Lance, Inc. and Lima Merger Corp. (&quot;Merger Agreement&quot;).</footnote>
        <footnote id="F2">This total has been updated to reflect the correct number of shares transferred from the Michael A. Warehime 2010 GRAT and Michael A. Warehime SOH GRAT.  The incorrect number of shares was reflected in Table I, Column 5 of the preceding four Forms 4 filed by the reporting person.  An amended Form 4 for the initial transactions that took place on  8/22/11 has been filed of even date herewith.</footnote>
        <footnote id="F3">These securities are owned by Michael A. Warehime (&quot;MAW&quot;), who is member of a &quot;group&quot; with his spouse, Patricia A. Warehime (&quot;PAW&quot;), for purposes of Section 13(d) of the Exchange Act.  PAW's beneficial ownership of such securities is indirect.</footnote>
        <footnote id="F4">These securities are owned by PAW.  MAW's beneficial ownership of such securities is indirect.</footnote>
        <footnote id="F5">Restricted shares issued pursuant to the Lance, Inc. 2008 Director Stock Plan, a Rule 16b-3 Plan.</footnote>
        <footnote id="F6">These securities are owned by Warehime Enterprises, Inc. (&quot;WEI&quot;).  MAW is the majority owner, chairman and an executive officer of WEI.  MAW's and PAW's beneficial ownership of such securities is indirect.</footnote>
        <footnote id="F7">These securities are owned by MAW Associates, LP (&quot;LP&quot;).  PAW is the sole member of the general partner of LP, and MAW is an executive officer of LP. MAW's and PAW's beneficial ownership of such securities is indirect.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/Michael A. Warehime/ By Edward H. Schuth, his Attorney-In-Fact</signatureName>
        <signatureDate>2011-09-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/Patricia A. Warehime/ By Edward H. Schuth, her Attorney-In-Fact</signatureName>
        <signatureDate>2011-09-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
