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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-05-12</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001329751</rptOwnerCik>
            <rptOwnerName>Kelleher Diane Lea</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>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP/Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-05-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>23.20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8500</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The Amount of Securities Beneficially Owned Following the Reported Transaction include (7,500) Restricted Shares, that will vest on 6/6/2010, only if the Reporting Owner is employed by AmericanWest Bancorporation (or its subsidiary, AmericanWest Bank) continuously throught the vesting date. Such restricted shares may vest sooner than the vesting date if the Reporting Person is terminated without good cause or terminates his or her employment for good reason (primarily material breach of contract by Issuer) as set forth in his or her employment agreement. Further, 20% of such restricted shares are subject to forfeiture each of the calendar years 2005 through 2010 that the Issuer's Return on Average Assets fails to meet a specified target.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>R. Blair Reynolds, Pursuant to Power of Attorney on File</signatureName>
        <signatureDate>2006-05-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2006-05-12
0000726990
AMERICANWEST BANCORPORATION
AWBC
0001329751
Kelleher Diane Lea
C/O AMERICANWEST BANCORPORATION
41 W. RIVERSIDE AVE. SUITE 400
SPOKANE
WA
99201
0
1
0
0
EVP/Chief Financial Officer
Common Stock
2006-05-12
4
P
0
1000
23.20
A
8500
D
The Amount of Securities Beneficially Owned Following the Reported Transaction include (7,500) Restricted Shares, that will vest on 6/6/2010, only if the Reporting Owner is employed by AmericanWest Bancorporation (or its subsidiary, AmericanWest Bank) continuously throught the vesting date. Such restricted shares may vest sooner than the vesting date if the Reporting Person is terminated without good cause or terminates his or her employment for good reason (primarily material breach of contract by Issuer) as set forth in his or her employment agreement. Further, 20% of such restricted shares are subject to forfeiture each of the calendar years 2005 through 2010 that the Issuer's Return on Average Assets fails to meet a specified target.
R. Blair Reynolds, Pursuant to Power of Attorney on File
2006-05-12