<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.4.0.6</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>373</ContextCount>
  <ElementCount>347</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>63</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001000 - Document - Document and Entity Information Document</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/DocumentAndEntityInformationDocument</Role>
      <ShortName>Document and Entity Information Document</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001000 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002500 - Statement - Balance Sheet Parenthetical (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/BalanceSheetParentheticalParentheticals</Role>
      <ShortName>Balance Sheet Parenthetical (Parentheticals)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1003000 - Statement - Consolidated Income Statements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/ConsolidatedIncomeStatements</Role>
      <ShortName>Consolidated Income Statements</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1004000 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/ConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1005000 - Statement - Consolidated Statements of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/ConsolidatedStatementsOfStockholdersEquity</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1006500 - Statement - Stockholders' Equity Parenthetical (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/StockholdersEquityParentheticalParentheticals</Role>
      <ShortName>Stockholders' Equity Parenthetical (Parentheticals)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>1007000 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - Basis of Presentation (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/BasisOfPresentationNotes</Role>
      <ShortName>Basis of Presentation (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2102100 - Disclosure - Critical Accounting Policies (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/CriticalAccountingPoliciesNotes</Role>
      <ShortName>Critical Accounting Policies (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2103100 - Disclosure - Securities Available for Sale (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/SecuritiesAvailableForSaleNotes</Role>
      <ShortName>Securities Available for Sale (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2104100 - Disclosure - Loans and Allowance for Loan Losses (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesNotes</Role>
      <ShortName>Loans and Allowance for Loan Losses (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2105100 - Disclosure - Fair Value Measurements (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/FairValueMeasurementsNotes</Role>
      <ShortName>Fair Value Measurements (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2106100 - Disclosure - Stock Compensation Plans (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/StockCompensationPlansNotes</Role>
      <ShortName>Stock Compensation Plans (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2108100 - Disclosure - Earnings (Loss) Per Common Share (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/EarningsLossPerCommonShareNotes</Role>
      <ShortName>Earnings (Loss) Per Common Share (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2109100 - Disclosure - Comprehensive Income (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/ComprehensiveIncomeNotes</Role>
      <ShortName>Comprehensive Income (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2110100 - Disclosure - Deferred Income Taxes (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/DeferredIncomeTaxesNotes</Role>
      <ShortName>Deferred Income Taxes (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2111100 - Disclosure - Commitments and Contingencies (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.westbankiowa.com/role/CommitmentsAndContingenciesNotes</Role>
      <ShortName>Commitments and Contingencies (Notes)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2202201 - Disclosure - Critical Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/CriticalAccountingPoliciesPolicies</Role>
      <ShortName>Critical Accounting Policies (Policies)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2303301 - Disclosure - Securities Available for Sale (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/SecuritiesAvailableForSaleTables</Role>
      <ShortName>Securities Available for Sale (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2304301 - Disclosure - Loans and Allowance for Loan Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesTables</Role>
      <ShortName>Loans and Allowance for Loan Losses (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2305301 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2306301 - Disclosure - Stock Compensation Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/StockCompensationPlansTables</Role>
      <ShortName>Stock Compensation Plans (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2308301 - Disclosure - Earnings Per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/EarningsPerCommonShareTables</Role>
      <ShortName>Earnings Per Common Share (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2309301 - Disclosure - Comprehensive Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/ComprehensiveIncomeTables</Role>
      <ShortName>Comprehensive Income (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2310301 - Disclosure - Deferred Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/DeferredIncomeTaxesTables</Role>
      <ShortName>Deferred Income Taxes (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2311301 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/CommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2401402 - Disclosure - Basis of Presentation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/BasisOfPresentationDetails</Role>
      <ShortName>Basis of Presentation (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2403402 - Disclosure - Securities Available for Sale Security Type (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/SecuritiesAvailableForSaleSecurityTypeDetails</Role>
      <ShortName>Securities Available for Sale Security Type (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2403403 - Disclosure - Securities Available for Sale Contractual Maturities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/SecuritiesAvailableForSaleContractualMaturitiesDetails</Role>
      <ShortName>Securities Available for Sale Contractual Maturities (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2403404 - Disclosure - Securities Available for Sale Detail of Sale of Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/SecuritiesAvailableForSaleDetailOfSaleOfSecuritiesDetails</Role>
      <ShortName>Securities Available for Sale Detail of Sale of Securities (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2403405 - Disclosure - Securities Available for Sale Gross Unrealized Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/SecuritiesAvailableForSaleGrossUnrealizedLossesDetails</Role>
      <ShortName>Securities Available for Sale Gross Unrealized Losses (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2403406 - Disclosure - Securities Available for Sale Rollforward of Credit-Related Losses Recognized in Earnings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/SecuritiesAvailableForSaleRollforwardOfCreditRelatedLossesRecognizedInEarningsDetails</Role>
      <ShortName>Securities Available for Sale Rollforward of Credit-Related Losses Recognized in Earnings (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2403407 - Disclosure - Securities Available for Sale Alesco TPS Narratives (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/SecuritiesAvailableForSaleAlescoTpsNarrativesDetails</Role>
      <ShortName>Securities Available for Sale Alesco TPS Narratives (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2403408 - Disclosure - Securities Available for Sale Other Narratives (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/SecuritiesAvailableForSaleOtherNarrativesDetails</Role>
      <ShortName>Securities Available for Sale Other Narratives (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2404402 - Disclosure - Loans and Allowance for Loan Losses Schedule of Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfLoansDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Loans (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2404403 - Disclosure - Loans and Allowance for Loan Losses Schedule of Nonperforming Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfNonperformingLoansDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Nonperforming Loans (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2404404 - Disclosure - Loans and Allowance for Loan Losses Schedule of Troubled Debt Restructurings by Type of Modification (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfTroubledDebtRestructuringsByTypeOfModificationDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Troubled Debt Restructurings by Type of Modification (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2404405 - Disclosure - Loans and Allowance for Loan Losses Schedule of Troubled Debt Restructured Loans that Subsequently Defaulted (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfTroubledDebtRestructuredLoansThatSubsequentlyDefaultedDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Troubled Debt Restructured Loans that Subsequently Defaulted (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2404406 - Disclosure - Loans and Allowance for Loan Losses Schedule of Impaired Loans With and Without an Allowance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfImpairedLoansWithAndWithoutAllowanceDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Impaired Loans With and Without an Allowance (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2404407 - Disclosure - Loans and Allowance for Loan Losses Schedule of Impaired Loans With and Without an Allowance 2 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfImpairedLoansWithAndWithoutAllowance2Details</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Impaired Loans With and Without an Allowance 2 (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2404408 - Disclosure - Loans and Allowance for Loan Losses Reconciliation of Nonaccrual Loans With Impaired Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesReconciliationOfNonaccrualLoansWithImpairedLoansDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Reconciliation of Nonaccrual Loans With Impaired Loans (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2404409 - Disclosure - Loans and Allowance for Loan Losses Schedule of Past Due Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfPastDueLoansDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Past Due Loans (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2404410 - Disclosure - Loans and Allowance for Loan Losses Schedule of Loans By Credit Quality Indicator (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfLoansByCreditQualityIndicatorDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Loans By Credit Quality Indicator (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2404411 - Disclosure - Loans and Allowance for Loan Losses Schedule of Allowance for Loan Loss Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfAllowanceForLoanLossActivityDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Allowance for Loan Loss Activity (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2404412 - Disclosure - Loans and Allowance for Loan Losses Schedule of Allowance for Loan Losses by Impairment Method (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfAllowanceForLoanLossesByImpairmentMethodDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Allowance for Loan Losses by Impairment Method (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2404413 - Disclosure - Loans and Allowance for Loan Losses Schedule of Loans by Impairment Method (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesScheduleOfLoansByImpairmentMethodDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Schedule of Loans by Impairment Method (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2404414 - Disclosure - Loans and Allowance for Loan Losses Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/LoansAndAllowanceForLoanLossesNarrativeDetails</Role>
      <ShortName>Loans and Allowance for Loan Losses Narrative (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>2405402 - Disclosure - Fair Value Measurements Recurring Basis by Level (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/FairValueMeasurementsRecurringBasisByLevelDetails</Role>
      <ShortName>Fair Value Measurements Recurring Basis by Level (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>2405403 - Disclosure - Fair Value Measurements Changes in Level 3 Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/FairValueMeasurementsChangesInLevel3SecuritiesDetails</Role>
      <ShortName>Fair Value Measurements Changes in Level 3 Securities (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>2405404 - Disclosure - Fair Value Measurements Nonrecurring Basis by Level (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/FairValueMeasurementsNonrecurringBasisByLevelDetails</Role>
      <ShortName>Fair Value Measurements Nonrecurring Basis by Level (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>2405405 - Disclosure - Fair Value Measurements Carrying Amounts and Fair Values (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/FairValueMeasurementsCarryingAmountsAndFairValuesDetails</Role>
      <ShortName>Fair Value Measurements Carrying Amounts and Fair Values (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>2405406 - Disclosure - Fair Value Measurements Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/FairValueMeasurementsNarrativeDetails</Role>
      <ShortName>Fair Value Measurements Narrative (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>2406402 - Disclosure - Stock Compensation Plans Nonvested Restrcited Stock Unit Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/StockCompensationPlansNonvestedRestrcitedStockUnitActivityDetails</Role>
      <ShortName>Stock Compensation Plans Nonvested Restrcited Stock Unit Activity (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>2406403 - Disclosure - Stock Compensation Plans Compensation Costs Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/StockCompensationPlansCompensationCostsNarrativeDetails</Role>
      <ShortName>Stock Compensation Plans Compensation Costs Narrative (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>2406404 - Disclosure - Stock Compensation Plans Other Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/StockCompensationPlansOtherNarrativeDetails</Role>
      <ShortName>Stock Compensation Plans Other Narrative (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>2408402 - Disclosure - Earnings Per Common Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/EarningsPerCommonShareDetails</Role>
      <ShortName>Earnings Per Common Share (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>2408403 - Disclosure - Earnings Per Common Share Preferred Stock Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/EarningsPerCommonSharePreferredStockNarrativeDetails</Role>
      <ShortName>Earnings Per Common Share Preferred Stock Narrative (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>2408404 - Disclosure - Earnings Per Common Share Other Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/EarningsPerCommonShareOtherNarrativeDetails</Role>
      <ShortName>Earnings Per Common Share Other Narrative (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>2409402 - Disclosure - Comprehensive Income Changes in Accumulated Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/ComprehensiveIncomeChangesInAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Comprehensive Income Changes in Accumulated Other Comprehensive Income (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>2409403 - Disclosure - Comprehensive Income Tax Effects Allocated to Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/ComprehensiveIncomeTaxEffectsAllocatedToOtherComprehensiveIncomeDetails</Role>
      <ShortName>Comprehensive Income Tax Effects Allocated to Other Comprehensive Income (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>2410402 - Disclosure - Deferred Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/DeferredIncomeTaxesDetails</Role>
      <ShortName>Deferred Income Taxes (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>2411402 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/CommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>2411403 - Disclosure - Commitments and Contingencies Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westbankiowa.com/role/CommitmentsAndContingenciesNarrativeDetails</Role>
      <ShortName>Commitments and Contingencies Narrative (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">Process Flow-Through: 1001000 - Statement - Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jun. 30, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2010'</Log>
    <Log type="Info">Process Flow-Through: 1002500 - Statement - Balance Sheet Parenthetical (Parentheticals)</Log>
    <Log type="Info">Process Flow-Through: 1003000 - Statement - Consolidated Income Statements</Log>
    <Log type="Info">Process Flow-Through: 1004000 - Statement - Consolidated Statements of Comprehensive Income</Log>
    <Log type="Info">Process Flow-Through: 1006500 - Statement - Stockholders' Equity Parenthetical (Parentheticals)</Log>
    <Log type="Info">Process Flow-Through: 1007000 - Statement - Consolidated Statements of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>wtba-20120630.xml</File>
    <File>wtba-20120630.xsd</File>
    <File>wtba-20120630_cal.xml</File>
    <File>wtba-20120630_def.xml</File>
    <File>wtba-20120630_lab.xml</File>
    <File>wtba-20120630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
