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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-07-01</periodOfReport>

    <issuer>
        <issuerCik>0000899051</issuerCik>
        <issuerName>ALLSTATE CORP</issuerName>
        <issuerTradingSymbol>ALL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001614718</rptOwnerCik>
            <rptOwnerName>KEANE MARGARET M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE ALLSTATE CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>3100 SANDERS ROAD</rptOwnerStreet2>
            <rptOwnerCity>NORTHBROOK</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60062</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-07-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>194</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>160.54</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14003.058</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Stock acquired pursuant to election to receive stock in lieu of cash compensation under The Allstate Corporation 2017 Equity Compensation Plan for Non-Employee Directors.</footnote>
        <footnote id="F2">Balance also reflects 39.698 shares acquired during the period of April 3, 2024, to July 2, 2024, through the Shareowner Service Plus Plan, which reinvests dividends paid on The Allstate Corporation common shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Meghan E. Jauhar, attorney-in-fact for Margaret M. Keane</signatureName>
        <signatureDate>2024-07-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
