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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-06-03</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000750199</issuerCik>
        <issuerName>EPL OIL &amp; GAS, INC.</issuerName>
        <issuerTradingSymbol>EPL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001246093</rptOwnerCik>
            <rptOwnerName>PULLY STEVEN J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O EPL OIL &amp; GAS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>919 MILAM STREET, SUITE 1600</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77002</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2014-06-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>36484</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On June 3, 2014, EPL Oil &amp; Gas, Inc. (the &quot;Issuer&quot;) became an indirect wholly?owned subsidiary of Energy XXI (Bermuda) Limited (&quot;EXXI&quot;), as a result of the merger of Clyde Merger Sub, Inc. (&quot;Merger Sub&quot;), a wholly-owned subsidiary of Energy XXI Gulf Coast, Inc., an indirect wholly owned subsidiary of Energy XXI (&quot;OpCo&quot;), with and into EPL (the &quot;Merger&quot;). The Merger was effected pursuant to an Agreement and Plan of Merger, dated as of March 12, 2014, by and among EXXI, EPL, OpCo and Merger Sub (as amended, the &quot;Merger Agreement&quot;).  Under the Merger Agreement, at the effective time of the Merger, each outstanding restricted share of EPL Common Stock and deferred share of EPL Common Stock fully vested at the Effective Time and was treated as a share of EPL Common Stock for all purposes of the Merger Agreement, including the right to receive the merger consideration.</footnote>
        <footnote id="F2">Based on the Mixed Election made by the Reporting Person with respect to the form of merger consideration to be received in the Merger, the Reporting Person's shares of Common Stock of the Issuer were converted in the Merger into the right to receive a combination of (a) $25.35 in cash (without interest) and 0.584 of a share of EXXI Common Stock.  The closing price for EXXI Common Stock on the NASDAQ Capital Market for June 3, 2014 was $21.11 per share.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>David Cedro, Attorney in Fact</signatureName>
        <signatureDate>2014-06-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
