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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-02-24</periodOfReport>

    <issuer>
        <issuerCik>0000700863</issuerCik>
        <issuerName>SUSQUEHANNA BANCSHARES INC</issuerName>
        <issuerTradingSymbol>SUSQ</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001183477</rptOwnerCik>
            <rptOwnerName>QUICK MICHAEL M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SUSQUEHANNA BANCSHARES, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>26 N. CEDAR STREET</rptOwnerStreet2>
            <rptOwnerCity>LITITZ</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>17543</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>EVP &amp; Chief Corp. Credit Off.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-02-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>26930</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>26930</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>26930</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each restricted stock unit represents a contingent right to receive one share of Susquehanna Bancshares, Inc. common stock. Grant made based on the terms of the Susquehanna Bancshares, Inc. 2015 Long-Term Incentive Plan, pursuant to the Susquehanna Bancshares, Inc. 2013 Omnibus Equity Compensation Plan.</footnote>
        <footnote id="F2">The Restricted Stock Units vest one third on each of February 24, 2016, February 24, 2017, and February 24, 2018 (each a &quot;Vesting Date&quot;); provided that the Grantee continues to be employed by, or provide service to, Susquehanna Bancshares, Inc. through the Vesting Date.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ D. Scott Freed, attorney-in-fact for Michael M. Quick</signatureName>
        <signatureDate>2015-02-25</signatureDate>
    </ownerSignature>
</ownershipDocument>
