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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-01-02</periodOfReport>

    <issuer>
        <issuerCik>0001156039</issuerCik>
        <issuerName>Anthem, Inc.</issuerName>
        <issuerTradingSymbol>ANTM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001648401</rptOwnerCik>
            <rptOwnerName>Neri Antonio F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>120 MONUMENT CIRCLE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>INDIANAPOLIS</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>46204</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-01-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>341</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>341</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Phantom Stock units accrued under the Anthem, Inc. (&quot;Company&quot;) Board of Directors Compensation Program.</footnote>
        <footnote id="F2">The phantom stock units shall be payable in Company common stock upon the first to occur of (a) five years from the date of grant or (b) the date the Reporting Person ceases to be a member of the Company's board of directors, unless a later date is designated in the Reporting Person's election made under the Company's Board of Directors Deferred Compensation Plan.</footnote>
    </footnotes>

    <remarks>Exhibit List: Exhibit 24 - Power of Attorney.
On a previous Form 3 filing the &quot;insider's&quot; Power of Attorney was inadvertently attached as CORRESP (private) and is correctly attached on this new Form 4 as      POWER OF ATTORNEY (public).</remarks>

    <ownerSignature>
        <signatureName>/s/ Kathleen S. Kiefer, Attorney in fact</signatureName>
        <signatureDate>2018-01-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
