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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-03-15</periodOfReport>

    <issuer>
        <issuerCik>0000726990</issuerCik>
        <issuerName>AMERICANWEST BANCORPORATION</issuerName>
        <issuerTradingSymbol>AWBC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001278367</rptOwnerCik>
            <rptOwnerName>EERKES CRAIG D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O AMERICANWEST BANCORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>41 W. RIVERSIDE AVE. SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>SPOKANE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>99201</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-03-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>16382</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>23617</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>8.32</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-03-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>722</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-03-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2010-01-04</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>722</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5722</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Received in exchange for 9,084 shares of Columbia Trust Bancorp common stock in connection with merger of Columbia Trust Bancorp into AmericanWest Bancorporation (the&quot;Merger&quot;). The shares were exchanged at an exchange rate of 1 : 1.8035 per share. The shares of AmericanWest Bancorp were valued at $25.34, based on a 20-day average, pursuant to the terms of the agreement. The shares of Columbia Trust Bancorp were valued at $45.70 prior to the effective date of the merger.</footnote>
        <footnote id="F2">Received in the Merger in exchange for an employee stock option to acquire 400 shares of Columbia Trust Bancorp common stock for $15.00 per share.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ R. Blair Reynolds, Pursuant to Power of Attorney on File</signatureName>
        <signatureDate>2006-04-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2006-03-15
0000726990
AMERICANWEST BANCORPORATION
AWBC
0001278367
EERKES CRAIG D
C/O AMERICANWEST BANCORPORATION
41 W. RIVERSIDE AVE. SUITE 400
SPOKANE
WA
99201
1
0
0
0
Common Stock
2006-03-15
4
A
0
16382
A
23617
D
Stock Option (right to buy)
8.32
2006-03-15
4
A
0
722
A
2006-03-15
2010-01-04
Common Stock
722
5722
D
Received in exchange for 9,084 shares of Columbia Trust Bancorp common stock in connection with merger of Columbia Trust Bancorp into AmericanWest Bancorporation (the"Merger"). The shares were exchanged at an exchange rate of 1 : 1.8035 per share. The shares of AmericanWest Bancorp were valued at $25.34, based on a 20-day average, pursuant to the terms of the agreement. The shares of Columbia Trust Bancorp were valued at $45.70 prior to the effective date of the merger.
Received in the Merger in exchange for an employee stock option to acquire 400 shares of Columbia Trust Bancorp common stock for $15.00 per share.
/s/ R. Blair Reynolds, Pursuant to Power of Attorney on File
2006-04-04