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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-02-27</periodOfReport>

    <issuer>
        <issuerCik>0000812900</issuerCik>
        <issuerName>SAKS INC</issuerName>
        <issuerTradingSymbol>SKS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001398544</rptOwnerCik>
            <rptOwnerName>Rodgers Michael</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SAKS INCORPORATED</rptOwnerStreet1>
            <rptOwnerStreet2>3455 HIGHWAY 80 WEST</rptOwnerStreet2>
            <rptOwnerCity>JACKSON</rptOwnerCity>
            <rptOwnerState>MS</rptOwnerState>
            <rptOwnerZipCode>39209</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP Chief IT &amp; Operations</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-02-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>17424</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.2084</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>131395</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The sale price reported in Column 4 is a weighted average price.  These shares were sold in multiple transactions at prices ranging from $11.2 to $11.215.  The reporting person undertakes to provide to Saks Incorporated, any security holder of Saks Incorporated, 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 range.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Peou Puch on behalf of Michael Rodgers</signatureName>
        <signatureDate>2013-03-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
