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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2006-02-02</periodOfReport>

    <dateOfOriginalSubmission>2006-02-03</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0000316709</issuerCik>
        <issuerName>SCHWAB CHARLES CORP</issuerName>
        <issuerTradingSymbol>SCHW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000923738</rptOwnerCik>
            <rptOwnerName>SCHWAB CHARLES R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE CHARLES SCHWAB CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>120 KEARNY STREET</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94108</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-02-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4700</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>14.62</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13863795</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On February 3, 2006, the reporting person filed a Form 4 that mistakenly included a transaction code of &quot;D&quot; instead of &quot;S&quot; to report the sale of 4,700 shares of company stock at $14.62.  All of the transactions reported on this Form 4 were open market sales.</footnote>
        <footnote id="F2">As of the date of this report, the reporting person also had an indirect beneficial ownership interest in 162,756,290 shares held in trust, 42,853,958 shares held by an LLC, 7,977,765 shares held by his spouse and 1,713,639 shares held by an ESOP.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Jane E. Fry, Attorney-in-fact</signatureName>
        <signatureDate>2006-12-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
