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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-02-04</periodOfReport>

    <issuer>
        <issuerCik>0001593538</issuerCik>
        <issuerName>NAVIENT CORP</issuerName>
        <issuerTradingSymbol>NAVI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001109264</rptOwnerCik>
            <rptOwnerName>REMONDI JOHN F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>123 JUSTISON STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>WILMINGTON</rptOwnerCity>
            <rptOwnerState>DE</rptOwnerState>
            <rptOwnerZipCode>19801</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>2016-02-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3194</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.54</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1360271.0252</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2016-02-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>25952</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.54</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1334319.0252</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2016-02-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5086</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.51</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1329232.0652</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>250</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>As custodian for child</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">As previously reported, in connection with the April 30, 2014 separation of Navient Corporation (&quot;Navient&quot;) from SLM Corporation (&quot;SLM&quot;), Navient established the Navient Corporation 2014 Omnibus Incentive Plan and issued new Navient equity awards to holders of outstanding SLM equity awards in order to maintain the intrinsic value of prior SLM award grants. On April 30, 2014, Mr. Remondi was granted 28,512 vested restricted stock units (&quot;RSUs&quot;) representing the right to receive shares of Navient common stock in the future, subject to transfer restrictions which lapse in one-third increments on February 4, 2015, February 4, 2016 and February 4, 2017. On February 4, 2016, 9,504 shares of such RSUs were settled and an additional 704 shares were issued to Mr. Remondi upon the delivery of the related dividend equivalent rights.  In connection with this settlement, 3,194 shares were withheld by Navient (as approved by the Navient Compensation and Personnel Committee) to satisfy Mr. Remondi's tax withholding obligations.</footnote>
        <footnote id="F2">As previously reported, in connection with the April 30, 2014 separation of Navient from SLM, Navient established the Navient Corporation 2014 Omnibus Incentive Plan and issued new Navient equity awards to holders of outstanding SLM equity awards in order to maintain the intrinsic value of prior SLM award grants. On April 30, 2014, Mr. Remondi was granted 166,041 RSUs representing the right to receive shares of Navient common stock in the future, which vest in one-third increments on February 4, 2015, February 4, 2016 and February 4, 2017. On February 4, 2016, 55,347 shares of such RSUs were settled and an additional 4,103 shares were issued to Mr. Remondi upon the vesting of the related dividend equivalent rights.  In connection with this settlement, 25,952 shares were withheld by Navient (as approved by the Navient Compensation and Personnel Committee) to satisfy Mr. Remondi's tax withholding obligations.</footnote>
        <footnote id="F3">As previously reported, in connection with the April 30, 2014 separation of Navient from SLM, Navient established the Navient Corporation 2014 Omnibus Incentive Plan and issued new Navient equity awards to holders of outstanding SLM equity awards in order to maintain the intrinsic value of prior SLM award grants. On April 30, 2014, Mr. Remondi was granted 20,108 vested RSUs representing the right to receive shares of Navient common stock in the future, subject to transfer restrictions which lapse in one-half increments on February 7, 2015 and February 7, 2016. On February 7, 2016, 10,054 shares of such RSUs were settled and an additional 1,029.96 shares were issued to Mr. Remondi upon the delivery of the related dividend equivalent rights.  In connection with this settlement, 5,086 shares were withheld by Navient (as approved by the Navient Compensation and Personnel Committee) to satisfy Mr. Remondi's tax withholding obligations.</footnote>
        <footnote id="F4">Also reflects the disposition of 0.96 shares settled in cash upon the delivery of the related dividend equivalent rights, in accordance with the terms of the 2014 Navient Corporation Omnibus Incentive Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Kurt T. Slawson (POA) for John F. Remondi</signatureName>
        <signatureDate>2016-02-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
