$FBIZ
FIRST BUSINESS FINANCIAL SERVICES, INC. Stock $fbiz

$fbiz Overview Financials Valuation SEC Filings Company Website

2021 Q1 Form 10-Q Financial Statement

#000152195121000041 Filed on April 30, 2021

Income Statement

Concept	2021 Q1	2020 Q1
Revenue	$23.81M	$23.37M
YoY Change	1.86%	-8.98%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$960.0K	$810.0K
YoY Change	18.52%	24.62%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$2.943M	$6.322M
YoY Change	-53.45%	-20.23%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$12.80M	$4.136M
YoY Change	209.38%	-10.11%
Income Tax	$3.065M	$858.0K
% Of Pretax Income	23.95%	20.74%
Net Earnings	$9.731M	$3.278M
YoY Change	196.86%	-44.43%
Net Earnings / Revenue	40.88%	14.03%
Basic Earnings Per Share	$1.12	$0.38
Diluted Earnings Per Share	$1.12	$0.38
COMMON SHARES
Basic Shares Outstanding	8.429M shares	8.389M shares
Diluted Shares Outstanding	8.429M shares	8.389M shares

Balance Sheet

Concept	2021 Q1	2020 Q1
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$58.87M	$94.99M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$1.923M	$2.427M
YoY Change	-20.77%	-20.24%
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments	$15.30M	$13.10M
YoY Change	16.79%	589.47%
Other Assets	$7.200M	$5.200M
YoY Change	38.46%	62.5%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$2.621B	$2.196B
YoY Change	19.32%	9.51%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$9.400M	$17.30M
YoY Change	-45.66%	-21.36%
Accrued Expenses	$6.000M	$7.200M
YoY Change	-16.67%	-15.29%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$15.40M	$24.50M
YoY Change	-37.14%	-19.67%
LONG-TERM LIABILITIES
Long-Term Debt	$42.70M	$34.40M
YoY Change	24.13%	-0.29%
Other Long-Term Liabilities	$29.60M	$53.10M
YoY Change	-44.26%	539.76%
Total Long-Term Liabilities	$72.30M	$87.50M
YoY Change	-17.37%	104.44%
TOTAL LIABILITIES
Total Short-Term Liabilities	$15.40M	$24.50M
Total Long-Term Liabilities	$72.30M	$87.50M
Total Liabilities	$2.406B	$2.001B
YoY Change	20.27%	9.9%
SHAREHOLDERS EQUITY
Retained Earnings	$148.6M	$131.0M
YoY Change	13.47%	13.31%
Common Stock	$83.79M	$81.70M
YoY Change	2.56%	2.08%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$16.88M	$16.33M
YoY Change	3.37%	79.21%
Treasury Stock Shares	682.3K shares	655.3K shares
Shareholders Equity	$214.5M	$195.7M
YoY Change
Total Liabilities & Shareholders Equity	$2.621B	$2.196B
YoY Change	19.32%	9.51%

Cashflow Statement

Concept	2021 Q1	2020 Q1
OPERATING ACTIVITIES
Net Income	$9.731M	$3.278M
YoY Change	196.86%	-44.43%
Depreciation, Depletion And Amortization	$960.0K	$810.0K
YoY Change	18.52%	24.62%
Cash From Operating Activities	$6.829M	$1.227M
YoY Change	456.56%	-88.49%
INVESTING ACTIVITIES
Capital Expenditures	-$90.00K	-$90.00K
YoY Change	0.0%
Acquisitions
YoY Change
Other Investing Activities	-$79.40M	-$33.66M
YoY Change	135.89%	-39.36%
Cash From Investing Activities	-$79.49M	-$33.75M
YoY Change	135.55%	-39.2%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net	$326.0K	$1.447M
YoY Change	-77.47%	-2.1%
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	$74.63M	$60.40M
YoY Change	23.55%	312.76%
NET CHANGE
Cash From Operating Activities	$6.829M	$1.227M
Cash From Investing Activities	-$79.49M	-$33.75M
Cash From Financing Activities	$74.63M	$60.40M
Net Change In Cash	$1.965M	$27.88M
YoY Change	-92.95%	-192.3%
FREE CASH FLOW
Cash From Operating Activities	$6.829M	$1.227M
Capital Expenditures	-$90.00K	-$90.00K
Free Cash Flow	$6.919M	$1.317M
YoY Change	425.36%	-87.65%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2021Q1	dei	Entity Central Index Key EntityCentralIndexKey	0001521951
CY2021Q1	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2021Q1	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
CY2021Q1	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q1
CY2021Q1	dei	Amendment Flag AmendmentFlag	false
CY2021Q1	dei	Document Type DocumentType	10-Q
CY2021Q1	dei	Document Quarterly Report DocumentQuarterlyReport	true
CY2021Q1	dei	Document Period End Date DocumentPeriodEndDate	2021-03-31
CY2021Q1	dei	Document Transition Report DocumentTransitionReport	false
CY2021Q1	dei	Entity File Number EntityFileNumber	001-34095
CY2021Q1	dei	Entity Registrant Name EntityRegistrantName	FIRST BUSINESS FINANCIAL SERVICES, INC.
CY2021Q1	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	WI
CY2021Q1	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	39-1576570
CY2021Q1	dei	Entity Address Address Line1 EntityAddressAddressLine1	401 Charmany Drive
CY2021Q1	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	53719
CY2021Q1	dei	Entity Address City Or Town EntityAddressCityOrTown	Madison
CY2021Q1	dei	Entity Address State Or Province EntityAddressStateOrProvince	WI
CY2021Q1	dei	City Area Code CityAreaCode	608
CY2021Q1	dei	Local Phone Number LocalPhoneNumber	238-8008
CY2021Q1	dei	Security12b Title Security12bTitle	Common Stock, $0.01 par value
CY2021Q1	dei	Trading Symbol TradingSymbol	FBIZ
CY2021Q1	dei	Security Exchange Name SecurityExchangeName	NASDAQ
CY2021Q1	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2021Q1	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2021Q1	dei	Entity Filer Category EntityFilerCategory	Accelerated Filer
CY2021Q1	dei	Entity Small Business EntitySmallBusiness	true
CY2021Q1	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2021Q1	dei	Entity Shell Company EntityShellCompany	false
CY2021Q2	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	8568955	shares
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CY2021Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-2238000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	4501000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	0	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-4000	USD
CY2021Q1	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	8000	USD
CY2020Q1	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	10000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	2089000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-3625000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	-36000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	227000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-105000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	663000	USD
CY2021Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	9626000	USD
CY2020Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	3941000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	194156000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	3278000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	663000	USD
CY2020Q1	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	417000	USD
CY2020Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.165
CY2020Q1	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	1410000	USD
CY2020Q1	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	1447000	USD
CY2020Q1	us-gaap	Stockholders Equity StockholdersEquity	195657000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	206162000	USD
CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	9731000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-105000	USD
CY2021Q1	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	531000	USD
CY2021Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Employee Stock Purchase Program Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployeeStockPurchaseProgramRequisiteServicePeriodRecognition	39000	USD
CY2021Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.18
CY2021Q1	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	1541000	USD
CY2021Q1	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	326000	USD
CY2021Q1	us-gaap	Stockholders Equity StockholdersEquity	214491000	USD
CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	9731000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	3278000	USD
CY2021Q1	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-1242000	USD
CY2020Q1	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-26000	USD
CY2021Q1	fbiz	Impairmentof Tax Credit Investments ImpairmentofTaxCreditInvestments	0	USD
CY2020Q1	fbiz	Impairmentof Tax Credit Investments ImpairmentofTaxCreditInvestments	113000	USD
CY2021Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	-2068000	USD
CY2020Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3182000	USD
CY2021Q1	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	-130000	USD
CY2020Q1	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	25000	USD
CY2021Q1	fbiz	Derivative Credit Valuation Adjustment DerivativeCreditValuationAdjustment	-170000	USD
CY2020Q1	fbiz	Derivative Credit Valuation Adjustment DerivativeCreditValuationAdjustment	0	USD
CY2021Q1	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	956000	USD
CY2020Q1	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	806000	USD
CY2021Q1	us-gaap	Share Based Compensation ShareBasedCompensation	531000	USD
CY2020Q1	us-gaap	Share Based Compensation ShareBasedCompensation	417000	USD
CY2021Q1	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	0	USD
CY2020Q1	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-4000	USD
CY2021Q1	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	350000	USD
CY2020Q1	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	295000	USD
CY2021Q1	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	13674000	USD
CY2020Q1	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	15709000	USD
CY2021Q1	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	16871000	USD
CY2020Q1	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	14848000	USD
CY2021Q1	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	1078000	USD
CY2020Q1	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	265000	USD
CY2021Q1	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-3000	USD
CY2020Q1	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-102000	USD
CY2021Q1	us-gaap	Excess Tax Benefit From Share Based Compensation Operating Activities ExcessTaxBenefitFromShareBasedCompensationOperatingActivities	7000	USD
CY2020Q1	us-gaap	Excess Tax Benefit From Share Based Compensation Operating Activities ExcessTaxBenefitFromShareBasedCompensationOperatingActivities	-18000	USD
CY2021Q1	us-gaap	Operating Lease Payments OperatingLeasePayments	393000	USD
CY2020Q1	us-gaap	Operating Lease Payments OperatingLeasePayments	387000	USD
CY2021Q1	us-gaap	Proceeds From Lease Payments ProceedsFromLeasePayments	39000	USD
CY2020Q1	us-gaap	Proceeds From Lease Payments ProceedsFromLeasePayments	28000	USD
CY2021Q1	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	4979000	USD
CY2020Q1	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	40050000	USD
CY2021Q1	us-gaap	Increase Decrease In Accrued Liabilities And Other Operating Liabilities IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities	2789000	USD
CY2020Q1	us-gaap	Increase Decrease In Accrued Liabilities And Other Operating Liabilities IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities	35138000	USD
CY2021Q1	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	6829000	USD
CY2020Q1	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1227000	USD
CY2021Q1	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	17222000	USD
CY2020Q1	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	9458000	USD
CY2021Q1	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	1580000	USD
CY2020Q1	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	1910000	USD
CY2021Q1	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
CY2020Q1	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	839000	USD
CY2021Q1	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	9030000	USD
CY2020Q1	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	8286000	USD
CY2021Q1	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	0	USD
CY2020Q1	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	1148000	USD
CY2021Q1	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	86613000	USD
CY2020Q1	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	28719000	USD
CY2021Q1	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	60000	USD
CY2020Q1	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	0	USD
CY2021Q1	fbiz	Paymentsto Acquire Historic Development Entities PaymentstoAcquireHistoricDevelopmentEntities	0	USD
CY2020Q1	fbiz	Paymentsto Acquire Historic Development Entities PaymentstoAcquireHistoricDevelopmentEntities	259000	USD
CY2021Q1	fbiz	Distributionfromhistoricdevelopmententities Distributionfromhistoricdevelopmententities	49000	USD
CY2020Q1	fbiz	Distributionfromhistoricdevelopmententities Distributionfromhistoricdevelopmententities	30000	USD
CY2021Q1	fbiz	Payments To Acquire Low Income Housing Entities PaymentsToAcquireLowIncomeHousingEntities	1307000	USD
CY2020Q1	fbiz	Payments To Acquire Low Income Housing Entities PaymentsToAcquireLowIncomeHousingEntities	0	USD
CY2021Q1	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	3614000	USD
CY2020Q1	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	2040000	USD
CY2021Q1	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	2250000	USD
CY2020Q1	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	260000	USD
CY2021Q1	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	89000	USD
CY2020Q1	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	88000	USD
CY2021Q1	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	0	USD
CY2020Q1	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	8000000	USD
CY2021Q1	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-79492000	USD
CY2020Q1	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-33747000	USD
CY2021Q1	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	47202000	USD
CY2020Q1	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-30253000	USD
CY2021Q1	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	290300000	USD
CY2020Q1	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	260000000	USD
CY2021Q1	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	269000000	USD
CY2020Q1	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	166500000	USD
CY2021Q1	us-gaap	Proceeds From Repayments Of Notes Payable ProceedsFromRepaymentsOfNotesPayable	7954000	USD
CY2020Q1	us-gaap	Proceeds From Repayments Of Notes Payable ProceedsFromRepaymentsOfNotesPayable	14000	USD
CY2021Q1	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	1541000	USD
CY2020Q1	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	1410000	USD
CY2021Q1	fbiz	Proceeds From Issuance Of Common Stock Under The Employee Stock Purchase Plan ProceedsFromIssuanceOfCommonStockUnderTheEmployeeStockPurchasePlan	39000	USD
CY2020Q1	fbiz	Proceeds From Issuance Of Common Stock Under The Employee Stock Purchase Plan ProceedsFromIssuanceOfCommonStockUnderTheEmployeeStockPurchasePlan	0	USD
CY2021Q1	fbiz	Sba Paycheck Protection Program Interest Income Loans SBAPaycheckProtectionProgramInterestIncomeLoans	2200000	USD
CY2021Q1	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	326000	USD
CY2020Q1	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1447000	USD
CY2021Q1	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	74628000	USD
CY2020Q1	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	60404000	USD
CY2021Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	1965000	USD
CY2020Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	27884000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	56909000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	67102000	USD
CY2021Q1	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	58874000	USD
CY2020Q1	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	94986000	USD
CY2021Q1	us-gaap	Interest Paid Net InterestPaidNet	4856000	USD
CY2020Q1	us-gaap	Interest Paid Net InterestPaidNet	7250000	USD
CY2021Q1	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	32000	USD
CY2020Q1	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-8000	USD
CY2021Q1	us-gaap	Use Of Estimates UseOfEstimates	Management of the Corporation is required to make estimates and assumptions which affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements as well as reported amounts of revenues and expenses during the reporting period. Actual results could differ significantly from those estimates. Material estimates that could significantly change in the near-term include the value of securities and interest rate swaps, level of the allowance for loan and lease losses, lease residuals, property under operating leases, goodwill, level of the Small Business Administration (“SBA”) recourse reserve, and income taxes.
CY2021Q1	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	Certain amounts in prior periods may have been reclassified to conform to the current presentation.
CY2021Q1	fbiz	Numberof Short Term Loan Modifications NumberofShortTermLoanModifications	7
CY2021Q1	fbiz	Gross Loansand Leases Outstanding Short Term Modification GrossLoansandLeasesOutstandingShortTermModification	13000000.0	USD
CY2021Q1	fbiz	Gross Loansand Leases Outstanding Short Term Modification Percent6 Month Deferral Period GrossLoansandLeasesOutstandingShortTermModificationPercent6MonthDeferralPeriod	0.007
CY2020Q4	fbiz	Gross Loansand Leases Outstanding Short Term Modification GrossLoansandLeasesOutstandingShortTermModification	27000000.0	USD
CY2020Q4	fbiz	Gross Loansand Leases Outstanding Short Term Modification Percent6 Month Deferral Period GrossLoansandLeasesOutstandingShortTermModificationPercent6MonthDeferralPeriod	0.014
CY2021Q1	fbiz	Sba Paycheck Protection Program Loans Outstanding Gross Amount SBAPaycheckProtectionProgramLoansOutstandingGrossAmount	272700000	USD
CY2021Q1	fbiz	Sba Paycheck Protection Program Loan Leases Receiveable Deferred Income SBAPaycheckProtectionProgramLoanLeasesReceiveableDeferredIncome	5100000	USD
CY2021Q1	fbiz	Employee Stock Purchase Plan Number Of Shares Authorized For Grant EmployeeStockPurchasePlanNumberOfSharesAuthorizedForGrant	250000	shares
CY2021Q1	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	1775	shares
CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	9731000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	3278000	USD
CY2021Q1	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	251000	USD
CY2020Q1	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	78000	USD
CY2021Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	9480000	USD
CY2020Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	3200000	USD
CY2021Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8429149	shares
CY2020Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8388666	shares
CY2021Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.12
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.38
CY2021Q1	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	9480000	USD
CY2020Q1	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	3200000	USD
CY2021Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8429149	shares
CY2020Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8388666	shares
CY2021Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.12
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.38
CY2021Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	40953	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	176935	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	22.51
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	78775	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	25.82
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	56904	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	22.26
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	11002	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	22.86
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	187804	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	24.29
CY2021Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	85435	shares
CY2021Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	23.18
CY2021Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	25897	shares
CY2021Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	24.04
CY2021Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	1180	shares
CY2021Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	23.12
CY2021Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	246162	shares
CY2021Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	23.94
CY2021Q1	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	4700000	USD
CY2021Q1	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P2Y6M14D
CY2021Q1	fbiz	Employee Stock Purchase Plan Number Of Shares Available For Grant EmployeeStockPurchasePlanNumberOfSharesAvailableForGrant	244258	shares
CY2021Q1	us-gaap	Share Based Compensation ShareBasedCompensation	531000	USD
CY2020Q1	us-gaap	Share Based Compensation ShareBasedCompensation	417000	USD
CY2021Q1	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	171155000	USD
CY2021Q1	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	3272000	USD
CY2021Q1	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	1166000	USD
CY2021Q1	us-gaap	Available For Sale Securities AvailableForSaleSecurities	173261000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	179581000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	4476000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	132000	USD
CY2020Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	183925000	USD
CY2021Q1	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	24783000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	773000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	19000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	25537000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	26374000	USD
CY2020Q1	us-gaap	Other Than Temporary Impairment Losses Investments Availableforsale Securities OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities	0	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	974000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	15000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	27333000	USD
CY2021Q1	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	0	securities
CY2020Q1	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	1	securities
CY2021Q1	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	29700000	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	73700000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	0	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	0	USD
CY2021Q1	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	2663000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Next Rolling Twelve Months Fair Value HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	2672000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	8575000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	8770000	USD
CY2021Q1	fbiz	Heldtomaturity Securities Debt Maturities Rolling Years Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearsTwoThroughFiveAmortizedCost	11129000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Two Through Five Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	11306000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	41310000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	42045000	USD
CY2021Q1	fbiz	Heldtomaturity Securities Debt Maturities Rolling Years Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearsSixThroughTenAmortizedCost	8754000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Six Through Ten Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	9213000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	121270000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	122446000	USD
CY2021Q1	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	2237000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Debt Maturities Rolling After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue	2346000	USD
CY2021Q1	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	171155000	USD
CY2021Q1	us-gaap	Available For Sale Securities AvailableForSaleSecurities	173261000	USD
CY2021Q1	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	24783000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	25537000	USD
CY2021Q1	us-gaap	Availableforsale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions1 AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1	26	securities
CY2021Q1	us-gaap	Availableforsale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositionsGreaterThanOrEqualToOneYear	4	securities
CY2021Q1	us-gaap	Other Than Temporary Impairment Losses Investments Availableforsale Securities OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities	0	USD
CY2021Q1	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	40645000	USD
CY2021Q1	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	1089000	USD
CY2021Q1	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	14357000	USD
CY2021Q1	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	77000	USD
CY2021Q1	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	55002000	USD
CY2021Q1	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	1166000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	33543000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	98000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	4031000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	34000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	37574000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	132000	USD
CY2021Q1	us-gaap	Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions HeldToMaturitySecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions	3	securities
CY2021Q1	fbiz	Heldto Maturity Securities Securitiesin Unrealized Loss Positions Qualitative Disclosures Numberof Positions12monthsorgreater HeldtoMaturitySecuritiesSecuritiesinUnrealizedLossPositionsQualitativeDisclosuresNumberofPositions12monthsorgreater	2	securities
CY2021Q1	us-gaap	Other Than Temporary Impairment Losses Investments Heldtomaturity Securities OtherThanTemporaryImpairmentLossesInvestmentsHeldtomaturitySecurities	0	USD
CY2020Q1	us-gaap	Other Than Temporary Impairment Losses Investments Heldtomaturity Securities OtherThanTemporaryImpairmentLossesInvestmentsHeldtomaturitySecurities	0	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	5000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	0	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	484000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	19000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue	489000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	19000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2241400000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2150515000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	28982000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	28521000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	6288000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	4545000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	2206130000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	2117449000	USD
CY2021Q1	fbiz	Sba Paycheck Protection Program Loans Outstanding Gross Amount SBAPaycheckProtectionProgramLoansOutstandingGrossAmount	272700000	USD
CY2020Q4	fbiz	Sba Paycheck Protection Program Loans Outstanding Gross Amount SBAPaycheckProtectionProgramLoansOutstandingGrossAmount	228900000	USD
CY2021Q1	fbiz	Paycheck Protection Loans And Leases Receivable Deferred Income PaycheckProtectionLoansAndLeasesReceivableDeferredIncome	5100000	USD
CY2020Q4	fbiz	Paycheck Protection Loans And Leases Receivable Deferred Income PaycheckProtectionLoansAndLeasesReceivableDeferredIncome	3500000	USD
CY2021Q1	fbiz	Small Business Administration7a Loans SmallBusinessAdministration7aLoans	33870000	USD
CY2020Q4	fbiz	Small Business Administration7a Loans SmallBusinessAdministration7aLoans	36266000	USD
CY2021Q1	fbiz	Small Business Administration504 Loans SmallBusinessAdministration504Loans	30004000	USD
CY2020Q4	fbiz	Small Business Administration504 Loans SmallBusinessAdministration504Loans	26327000	USD
CY2021Q1	fbiz	Small Business Administration Express Loans SmallBusinessAdministrationExpressLoans	910000	USD
CY2020Q4	fbiz	Small Business Administration Express Loans SmallBusinessAdministrationExpressLoans	1251000	USD
CY2021Q1	fbiz	Small Business Administration Paycheck Protection Program Loans SmallBusinessAdministrationPaycheckProtectionProgramLoans	272664000	USD
CY2020Q4	fbiz	Small Business Administration Paycheck Protection Program Loans SmallBusinessAdministrationPaycheckProtectionProgramLoans	228870000	USD
CY2021Q1	fbiz	Small Business Administration Loans SmallBusinessAdministrationLoans	337448000	USD
CY2020Q4	fbiz	Small Business Administration Loans SmallBusinessAdministrationLoans	292714000	USD
CY2021Q1	fbiz	Sb Aloansintheparticipationsoldportfolioconsideredimpaired SBAloansintheparticipationsoldportfolioconsideredimpaired	8600000	USD
CY2020Q4	fbiz	Sb Aloansintheparticipationsoldportfolioconsideredimpaired SBAloansintheparticipationsoldportfolioconsideredimpaired	9300000	USD
CY2021Q1	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	10600000	USD
CY2020Q1	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	2700000	USD
CY2021Q1	fbiz	Totalamountofoutstanding Sb Aloanssold TotalamountofoutstandingSBAloanssold	82700000	USD
CY2020Q4	fbiz	Totalamountofoutstanding Sb Aloanssold TotalamountofoutstandingSBAloanssold	79500000	USD
CY2021Q1	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	5200000	USD
CY2020Q1	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	11900000	USD
CY2021Q1	fbiz	Gain Loss Recognizedon Participation Interestin Originated Loans GainLossRecognizedonParticipationInterestinOriginatedLoans	0	USD
CY2021Q1	fbiz	Total Amount Of Outstanding Loans Transferred To Third Parties As Loan Participations TotalAmountOfOutstandingLoansTransferredToThirdPartiesAsLoanParticipations	151300000	USD
CY2020Q4	fbiz	Total Amount Of Outstanding Loans Transferred To Third Parties As Loan Participations TotalAmountOfOutstandingLoansTransferredToThirdPartiesAsLoanParticipations	153600000	USD
CY2021Q1	fbiz	Total Amount Of Loan Participations Remaining On Corporations Balance Sheet TotalAmountOfLoanParticipationsRemainingOnCorporationsBalanceSheet	259900000	USD
CY2020Q4	fbiz	Total Amount Of Loan Participations Remaining On Corporations Balance Sheet TotalAmountOfLoanParticipationsRemainingOnCorporationsBalanceSheet	276500000	USD
CY2021Q1	fbiz	Loans In The Participation Sold Portfolio Considered Impaired Gross Amount LoansInTheParticipationSoldPortfolioConsideredImpairedGrossAmount	3000000.0	USD
CY2021Q1	fbiz	Loans In The Participation Sold Portfolio Considered Impaired Sold Amount LoansInTheParticipationSoldPortfolioConsideredImpairedSoldAmount	4200000	USD
CY2021Q1	fbiz	Loan Participations Purchased On Corporations Balance Sheet LoanParticipationsPurchasedOnCorporationsBalanceSheet	0	USD
CY2020Q4	fbiz	Loan Participations Purchased On Corporations Balance Sheet LoanParticipationsPurchasedOnCorporationsBalanceSheet	410000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2241400000	USD
CY2021Q1	fbiz	Category Rating As Percentage Of Total Loans And Leases CategoryRatingAsPercentageOfTotalLoansAndLeases	1.0000
CY2020Q4	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2150515000	USD
CY2020Q4	fbiz	Category Rating As Percentage Of Total Loans And Leases CategoryRatingAsPercentageOfTotalLoansAndLeases	1.0000
CY2021Q1	us-gaap	Financing Receivable Recorded Investment Past Due FinancingReceivableRecordedInvestmentPastDue	13217000	USD
CY2021Q1	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	2228183000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2241400000	USD
CY2021Q1	fbiz	Financing Receivable Recorded Investment30 To59 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment30To59DaysPastDuePercentOfPortfolio	0.0024
CY2021Q1	fbiz	Financing Receivable Recorded Investment60 To89 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment60To89DaysPastDuePercentOfPortfolio	0.0006
CY2021Q1	fbiz	Financing Receivable Recorded Investment Equal To Greater Than90 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDuePercentOfPortfolio	0.0029
CY2021Q1	fbiz	Financing Receivable Recorded Investment Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentPastDuePercentOfPortfolio	0.0059
CY2021Q1	fbiz	Financing Receivable Recorded Investment Current Percent Of Portfolio FinancingReceivableRecordedInvestmentCurrentPercentOfPortfolio	0.9941
CY2021Q1	fbiz	Financing Receivable Recorded Investment Gross Percent Of Portfolio FinancingReceivableRecordedInvestmentGrossPercentOfPortfolio	1.0000
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Past Due FinancingReceivableRecordedInvestmentPastDue	21572000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	2128943000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2150515000	USD
CY2020Q4	fbiz	Financing Receivable Recorded Investment30 To59 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment30To59DaysPastDuePercentOfPortfolio	0.0044
CY2020Q4	fbiz	Financing Receivable Recorded Investment60 To89 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment60To89DaysPastDuePercentOfPortfolio	0.0002
CY2020Q4	fbiz	Financing Receivable Recorded Investment Equal To Greater Than90 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDuePercentOfPortfolio	0.0054
CY2020Q4	fbiz	Financing Receivable Recorded Investment Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentPastDuePercentOfPortfolio	0.0100
CY2020Q4	fbiz	Financing Receivable Recorded Investment Current Percent Of Portfolio FinancingReceivableRecordedInvestmentCurrentPercentOfPortfolio	0.9900
CY2020Q4	fbiz	Financing Receivable Recorded Investment Gross Percent Of Portfolio FinancingReceivableRecordedInvestmentGrossPercentOfPortfolio	1.0000
CY2021Q1	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	18992000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	26617000	USD
CY2021Q1	us-gaap	Foreclosed Assets ForeclosedAssets	31000	USD
CY2020Q4	us-gaap	Foreclosed Assets ForeclosedAssets	34000	USD
CY2021Q1	fbiz	Total Nonperforming Assets TotalNonperformingAssets	19023000	USD
CY2020Q4	fbiz	Total Nonperforming Assets TotalNonperformingAssets	26651000	USD
CY2021Q1	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	59000	USD
CY2020Q4	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	46000	USD
CY2021Q1	fbiz	Impaired Assets ImpairedAssets	19082000	USD
CY2020Q4	fbiz	Impaired Assets ImpairedAssets	26697000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Ratio Of Nonperforming Loans To All Loans LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans	0.0085
CY2020Q4	us-gaap	Loans And Leases Receivable Ratio Of Nonperforming Loans To All Loans LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans	0.0124
CY2021Q1	fbiz	Ratio Of Total Nonperforming Assets To Gross Loans And Leases Plus Foreclosed Properties Net RatioOfTotalNonperformingAssetsToGrossLoansAndLeasesPlusForeclosedPropertiesNet	0.0085
CY2020Q4	fbiz	Ratio Of Total Nonperforming Assets To Gross Loans And Leases Plus Foreclosed Properties Net RatioOfTotalNonperformingAssetsToGrossLoansAndLeasesPlusForeclosedPropertiesNet	0.0124
CY2021Q1	fbiz	Ratio Of Total Nonperforming Assets To Total Assets RatioOfTotalNonperformingAssetsToTotalAssets	0.0073
CY2020Q4	fbiz	Ratio Of Total Nonperforming Assets To Total Assets RatioOfTotalNonperformingAssetsToTotalAssets	0.0104
CY2021Q1	fbiz	Ratio Of Allowance For Loan And Lease Losses To Total Gross Loans And Leases RatioOfAllowanceForLoanAndLeaseLossesToTotalGrossLoansAndLeases	0.0129
CY2020Q4	fbiz	Ratio Of Allowance For Loan And Lease Losses To Total Gross Loans And Leases RatioOfAllowanceForLoanAndLeaseLossesToTotalGrossLoansAndLeases	0.0133
CY2021Q1	fbiz	Ratio Of Allowance For Loan And Leases Losses To Non Accrual Loans And Leases RatioOfAllowanceForLoanAndLeasesLossesToNonAccrualLoansAndLeases	1.5260
CY2020Q4	fbiz	Ratio Of Allowance For Loan And Leases Losses To Non Accrual Loans And Leases RatioOfAllowanceForLoanAndLeasesLossesToNonAccrualLoansAndLeases	1.0715
CY2021Q1	fbiz	Non Accrual Troubled Debt Restructurings NonAccrualTroubledDebtRestructurings	4800000	USD
CY2020Q4	fbiz	Non Accrual Troubled Debt Restructurings NonAccrualTroubledDebtRestructurings	6500000	USD
CY2021Q1	fbiz	Specific Reserveson Troubled Debt Restructurings SpecificReservesonTroubledDebtRestructurings	765000	USD
CY2020Q4	fbiz	Specific Reserveson Troubled Debt Restructurings SpecificReservesonTroubledDebtRestructurings	760000	USD
CY2021Q1	fbiz	Unfunded Commitments Troubled Debt Restructurings UnfundedCommitmentsTroubledDebtRestructurings	0	USD
CY2020Q1	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	6	loans
CY2020Q1	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	1725000	USD
CY2020Q1	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	1712000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	10391000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	14783000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable With No Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment	14929000	USD
CY2021Q1	fbiz	Impaired Financing Receivable With No Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceForegoneInterestIncome	399000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable With No Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod	61000	USD
CY2021Q1	fbiz	Impaired Financing Receivable With No Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceNetForegoneInterestIncome	338000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	8660000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	9797000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	3487000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable With Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment	7162000	USD
CY2021Q1	fbiz	Impaired Financing Receivable With Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceForegoneInterestIncome	204000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable With Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod	7000	USD
CY2021Q1	fbiz	Impaired Financing Receivable With Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceNetForegoneInterestIncome	197000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	19051000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	24580000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	3487000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	22091000	USD
CY2021Q1	fbiz	Impaired Financing Receivable Foregone Interest Income ImpairedFinancingReceivableForegoneInterestIncome	603000	USD
CY2021Q1	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	68000	USD
CY2021Q1	fbiz	Impaired Financing Receivable Net Foregone Interest Income ImpairedFinancingReceivableNetForegoneInterestIncome	535000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	18966000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	29191000	USD
CY2020	us-gaap	Impaired Financing Receivable With No Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment	21709000	USD
CY2020	fbiz	Impaired Financing Receivable With No Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceForegoneInterestIncome	2082000	USD
CY2020	us-gaap	Impaired Financing Receivable With No Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod	636000	USD
CY2020	fbiz	Impaired Financing Receivable With No Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceNetForegoneInterestIncome	1446000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	7697000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	12103000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	3681000	USD
CY2020	us-gaap	Impaired Financing Receivable With Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment	5994000	USD
CY2020	fbiz	Impaired Financing Receivable With Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceForegoneInterestIncome	712000	USD
CY2020	us-gaap	Impaired Financing Receivable With Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod	0	USD
CY2020	fbiz	Impaired Financing Receivable With Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceNetForegoneInterestIncome	712000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	26663000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	41294000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	3681000	USD
CY2020	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	27703000	USD
CY2020	fbiz	Impaired Financing Receivable Foregone Interest Income ImpairedFinancingReceivableForegoneInterestIncome	2794000	USD
CY2020	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	636000	USD
CY2020	fbiz	Impaired Financing Receivable Net Foregone Interest Income ImpairedFinancingReceivableNetForegoneInterestIncome	2158000	USD
CY2021Q1	fbiz	Loans And Leases Receivable Difference Between Recorded Investment And Unpaid Principal Balance LoansAndLeasesReceivableDifferenceBetweenRecordedInvestmentAndUnpaidPrincipalBalance	5500000	USD
CY2020Q4	fbiz	Loans And Leases Receivable Difference Between Recorded Investment And Unpaid Principal Balance LoansAndLeasesReceivableDifferenceBetweenRecordedInvestmentAndUnpaidPrincipalBalance	14600000	USD
CY2021Q1	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	59000	USD
CY2020Q4	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	46000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	28521000	USD
CY2021Q1	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	144000	USD
CY2021Q1	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	2673000	USD
CY2021Q1	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	2529000	USD
CY2021Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	-2068000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	28982000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	19520000	USD
CY2020Q1	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	131000	USD
CY2020Q1	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	177000	USD
CY2020Q1	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	46000	USD
CY2020Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3182000	USD
CY2020Q1	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	22748000	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	25495000	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	3487000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	28982000	USD
CY2021Q1	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	2222349000	USD
CY2021Q1	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	19051000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	2241400000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	24840000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	3681000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	28521000	USD
CY2020Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	2123852000	USD
CY2020Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	26663000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	2150515000	USD
CY2021Q1	us-gaap	Operating Lease Expense OperatingLeaseExpense	375000	USD
CY2020Q1	us-gaap	Operating Lease Expense OperatingLeaseExpense	372000	USD
CY2021Q1	us-gaap	Short Term Lease Cost ShortTermLeaseCost	39000	USD
CY2020Q1	us-gaap	Short Term Lease Cost ShortTermLeaseCost	74000	USD
CY2021Q1	us-gaap	Variable Lease Cost VariableLeaseCost	129000	USD
CY2020Q1	us-gaap	Variable Lease Cost VariableLeaseCost	127000	USD
CY2021Q1	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	39000	USD
CY2020Q1	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	28000	USD
CY2021Q1	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	504000	USD
CY2020Q1	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	545000	USD
CY2021Q1	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P5Y7M28D
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P5Y9M18D
CY2021Q1	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0306
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0303
CY2021Q1	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	1163000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	1373000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	1015000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	756000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	666000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	1641000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	6614000	USD
CY2021Q1	fbiz	Discountonoperatingleasecashflows Discountonoperatingleasecashflows	574000	USD
CY2021Q1	us-gaap	Operating Lease Liability OperatingLeaseLiability	6040000	USD
CY2021Q1	us-gaap	Interest Receivable InterestReceivable	7794000	USD
CY2020Q4	us-gaap	Interest Receivable InterestReceivable	8564000	USD
CY2021Q1	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	7234000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	7217000	USD
CY2021Q1	fbiz	Investmentin Historic Development Entities InvestmentinHistoricDevelopmentEntities	2307000	USD
CY2020Q4	fbiz	Investmentin Historic Development Entities InvestmentinHistoricDevelopmentEntities	2356000	USD
CY2021Q1	fbiz	Investment In Low Income Housing Development Entities InvestmentInLowIncomeHousingDevelopmentEntities	1307000	USD
CY2020Q4	fbiz	Investment In Low Income Housing Development Entities InvestmentInLowIncomeHousingDevelopmentEntities	0	USD
CY2021Q1	fbiz	Investmentin Community Development Entities InvestmentinCommunityDevelopmentEntities	5306000	USD
CY2020Q4	fbiz	Investmentin Community Development Entities InvestmentinCommunityDevelopmentEntities	5306000	USD
CY2021Q1	fbiz	Investmentin Limited Partnerships InvestmentinLimitedPartnerships	7361000	USD
CY2020Q4	fbiz	Investmentin Limited Partnerships InvestmentinLimitedPartnerships	6673000	USD
CY2021Q1	fbiz	Investmentin Trust Ii InvestmentinTrustII	315000	USD
CY2020Q4	fbiz	Investmentin Trust Ii InvestmentinTrustII	315000	USD
CY2021Q1	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	2947000	USD
CY2020Q4	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	2165000	USD
CY2021Q1	us-gaap	Other Assets Miscellaneous OtherAssetsMiscellaneous	3446000	USD
CY2020Q4	us-gaap	Other Assets Miscellaneous OtherAssetsMiscellaneous	6882000	USD
CY2021Q1	us-gaap	Other Assets OtherAssets	38017000	USD
CY2020Q4	us-gaap	Other Assets OtherAssets	39478000	USD
CY2021Q1	us-gaap	Deposits Deposits	1902718000	USD
CY2021Q1	fbiz	Deposits Weighted Average Interest Rate Duringthe Period DepositsWeightedAverageInterestRateDuringthePeriod	0.0022
CY2021Q1	fbiz	Average Balance Deposits AverageBalanceDeposits	1888859000	USD
CY2020Q4	us-gaap	Deposits Deposits	1855516000	USD
CY2020	fbiz	Average Balance Deposits AverageBalanceDeposits	1711092000	USD
CY2020	fbiz	Deposits Weighted Average Interest Rate Duringthe Period DepositsWeightedAverageInterestRateDuringthePeriod	0.0052
CY2021Q1	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	60465000	USD
CY2021Q1	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	24319000	USD
CY2021Q1	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	1796000	USD
CY2021Q1	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	369000	USD
CY2021Q1	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	360000	USD
CY2021Q1	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	1000	USD
CY2021Q1	us-gaap	Time Deposits TimeDeposits	87310000	USD
CY2021Q1	fbiz	Time Deposits250000or More TimeDeposits250000orMore	12900000	USD
CY2020Q4	fbiz	Time Deposits250000or More TimeDeposits250000orMore	28700000	USD
CY2021Q1	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	458482000	USD
CY2021Q1	fbiz	Borrowed Funds Average Balance BorrowedFundsAverageBalance	404029000	USD
CY2021Q1	us-gaap	Debt Instrument Interest Rate During Period DebtInstrumentInterestRateDuringPeriod	0.0191
CY2020Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	429229000	USD
CY2020	fbiz	Borrowed Funds Average Balance BorrowedFundsAverageBalance	429624000	USD
CY2020	us-gaap	Debt Instrument Interest Rate During Period DebtInstrumentInterestRateDuringPeriod	0.0191
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	171260000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	29000000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	37300000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	35500000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	20925000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	164497000	USD
CY2021Q1	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	458482000	USD
CY2021Q1	us-gaap	Line Of Credit Facility Commitment Fee Amount LineOfCreditFacilityCommitmentFeeAmount	3000	USD
CY2020Q1	us-gaap	Line Of Credit Facility Commitment Fee Amount LineOfCreditFacilityCommitmentFeeAmount	3000	USD
CY2021Q1	fbiz	Sba Loans Probabilityof Future Losses SBALoansProbabilityofFutureLosses	593000	USD
CY2020Q4	fbiz	Sba Recourse Reserve SBARecourseReserve	723000	USD
CY2019Q4	fbiz	Sba Recourse Reserve SBARecourseReserve	1345000	USD
CY2021Q1	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	-130000	USD
CY2020Q1	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	25000	USD
CY2021Q1	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	0	USD
CY2020Q1	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	-284000	USD
CY2021Q1	fbiz	Sba Recourse Reserve SBARecourseReserve	593000	USD
CY2020Q1	fbiz	Sba Recourse Reserve SBARecourseReserve	1086000	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2021Q1	fbiz	Fair Value Liabilities Level1to Level2 Transfers Amount1 FairValueLiabilitiesLevel1toLevel2TransfersAmount1	0	USD
CY2021Q1	fbiz	Fair Value Assets Level2to Level1 Transfers Amount1 FairValueAssetsLevel2toLevel1TransfersAmount1	0	USD
CY2021Q1	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3	0	USD
CY2020	fbiz	Fair Value Liabilities Level1to Level2 Transfers Amount1 FairValueLiabilitiesLevel1toLevel2TransfersAmount1	0	USD
CY2021Q1	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
CY2021Q1	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
CY2020	fbiz	Fair Value Assets Level1to Level2 Transfers Amount1 FairValueAssetsLevel1toLevel2TransfersAmount1	0	USD
CY2021Q1	fbiz	Fair Value Assets Level2to Level1 Transfers Amount1 FairValueAssetsLevel2toLevel1TransfersAmount1	0	USD
CY2021Q1	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	0	USD
CY2021Q1	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
CY2021Q1	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3	0	USD
CY2021Q1	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	0	USD
CY2020	fbiz	Fair Value Liabilities Level2to Level1 Transfers Amount1 FairValueLiabilitiesLevel2toLevel1TransfersAmount1	0	USD
CY2021Q1	fbiz	Fair Value Liabilities Level2to Level1 Transfers Amount1 FairValueLiabilitiesLevel2toLevel1TransfersAmount1	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	0	USD
CY2021Q1	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2021Q1	fbiz	Fair Value Assets Level1to Level2 Transfers Amount1 FairValueAssetsLevel1toLevel2TransfersAmount1	0	USD
CY2021Q1	fbiz	Fair Value Liabilities Level2to Level1 Transfers Amount1 FairValueLiabilitiesLevel2toLevel1TransfersAmount1	0	USD
CY2021Q1	fbiz	Fair Value Liabilities Level1to Level2 Transfers Amount1 FairValueLiabilitiesLevel1toLevel2TransfersAmount1	0	USD
CY2021Q1	fbiz	Fair Value Assets Level1to Level2 Transfers Amount1 FairValueAssetsLevel1toLevel2TransfersAmount1	0	USD
CY2020	fbiz	Fair Value Assets Level2to Level1 Transfers Amount1 FairValueAssetsLevel2toLevel1TransfersAmount1	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3	0	USD
CY2021Q1	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	58874000	USD
CY2021Q1	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	58874000	USD
CY2021Q1	us-gaap	Available For Sale Securities AvailableForSaleSecurities	173261000	USD
CY2021Q1	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	0	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	2100000	USD
CY2021Q1	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	0	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	173261000	USD
CY2021Q1	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	24783000	USD
CY2021Q1	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	25537000	USD
CY2021Q1	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	6576000	USD
CY2021Q1	us-gaap	Loans Held For Sale Fair Value Disclosure LoansHeldForSaleFairValueDisclosure	7167000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	2206130000	USD
CY2021Q1	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	2210391000	USD
CY2021Q1	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	14941000	USD
CY2021Q1	us-gaap	Interest Receivable InterestReceivable	7794000	USD
CY2021Q1	fbiz	Accrued Interest Receivable Fair Value Disclosure AccruedInterestReceivableFairValueDisclosure	7794000	USD
CY2021Q1	us-gaap	Deposits Deposits	1902718000	USD
CY2021Q1	us-gaap	Deposits Fair Value Disclosure DepositsFairValueDisclosure	1903873000	USD
CY2021Q1	fbiz	Federal Home Loan Bank And Other Borrowings FederalHomeLoanBankAndOtherBorrowings	448417000	USD
CY2021Q1	fbiz	Federal Home Loan Bank And Other Borrowings Fair Value Disclosure FederalHomeLoanBankAndOtherBorrowingsFairValueDisclosure	459775000	USD
CY2021Q1	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust	10065000	USD
CY2021Q1	us-gaap	Fair Value Liabilities Measured On Recurring Basis Subordinated Debt Obligations FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations	9990000	USD
CY2021Q1	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	969000	USD
CY2021Q1	us-gaap	Accrued Liabilities Fair Value Disclosure AccruedLiabilitiesFairValueDisclosure	969000	USD
CY2021Q1	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	134000	USD
CY2021Q1	fbiz	Standby Letters Of Credit Fair Value Disclosure StandbyLettersOfCreditFairValueDisclosure	134000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	56909000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	56909000	USD
CY2020Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	183925000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	183925000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	26374000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	27333000	USD
CY2020Q4	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	8695000	USD
CY2020Q4	us-gaap	Loans Held For Sale Fair Value Disclosure LoansHeldForSaleFairValueDisclosure	9478000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	2117449000	USD
CY2020Q4	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	2121107000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	13578000	USD
CY2020Q4	us-gaap	Interest Receivable InterestReceivable	8564000	USD
CY2020Q4	fbiz	Accrued Interest Receivable Fair Value Disclosure AccruedInterestReceivableFairValueDisclosure	8564000	USD
CY2020Q4	us-gaap	Deposits Deposits	1855516000	USD
CY2020Q4	us-gaap	Deposits Fair Value Disclosure DepositsFairValueDisclosure	1856910000	USD
CY2020Q4	fbiz	Federal Home Loan Bank And Other Borrowings FederalHomeLoanBankAndOtherBorrowings	419167000	USD
CY2020Q4	fbiz	Federal Home Loan Bank And Other Borrowings Fair Value Disclosure FederalHomeLoanBankAndOtherBorrowingsFairValueDisclosure	429347000	USD
CY2020Q4	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust	10062000	USD
CY2020Q4	us-gaap	Fair Value Liabilities Measured On Recurring Basis Subordinated Debt Obligations FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations	9986000	USD
CY2020Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	1578000	USD
CY2020Q4	us-gaap	Accrued Liabilities Fair Value Disclosure AccruedLiabilitiesFairValueDisclosure	1578000	USD
CY2020Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	75000	USD
CY2020Q4	fbiz	Standby Letters Of Credit Fair Value Disclosure StandbyLettersOfCreditFairValueDisclosure	75000	USD
CY2021Q1	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Asset At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue	26104000	USD
CY2021Q1	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Liability At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue	26104000	USD
CY2020Q4	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Asset At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue	49377000	USD
CY2020Q4	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Liability At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue	49377000	USD
CY2021Q1	fbiz	Effectiveportionofinterestratecashflowhedge Fair Valueincludedinaccumulatedothercomprehensiveincome EffectiveportionofinterestratecashflowhedgeFairValueincludedinaccumulatedothercomprehensiveincome	3461000	USD
CY2021Q1	us-gaap	Interest Rate Cash Flow Hedge Liability At Fair Value InterestRateCashFlowHedgeLiabilityAtFairValue	3461000	USD
CY2020Q4	fbiz	Effectiveportionofinterestratecashflowhedge Fair Valueincludedinaccumulatedothercomprehensiveincome EffectiveportionofinterestratecashflowhedgeFairValueincludedinaccumulatedothercomprehensiveincome	5550000	USD
CY2020Q4	us-gaap	Interest Rate Cash Flow Hedge Liability At Fair Value InterestRateCashFlowHedgeLiabilityAtFairValue	5550000	USD
CY2021Q1	us-gaap	Description Of Material Affects Of Noncompliance DescriptionOfMaterialAffectsOfNoncompliance	Failure to meet minimum capital requirements can result in certain mandatory, and possibly additional discretionary actions on the part of regulators, that if undertaken, could have a direct material effect on the Bank’s assets, liabilities, and certain off-balance sheet items as calculated under regulatory practices.
CY2021Q1	us-gaap	Capital Capital	267291000	USD
CY2021Q1	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1152
CY2021Q1	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	185682000	USD
CY2021Q1	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2021Q1	fbiz	Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	243708000	USD
CY2021Q1	fbiz	Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.1050
CY2021Q1	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	214510000	USD
CY2021Q1	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.0924
CY2021Q1	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	139262000	USD
CY2021Q1	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2021Q1	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	197288000	USD
CY2021Q1	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0850
CY2021Q1	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	204445000	USD
CY2021Q1	fbiz	Common Equity Tier One Capitalto Risk Weighted Assets CommonEquityTierOneCapitaltoRiskWeightedAssets	0.0881
CY2021Q1	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	104446000	USD
CY2021Q1	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacyto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0450
CY2021Q1	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	162472000	USD
CY2021Q1	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0700
CY2021Q1	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	214510000	USD
CY2021Q1	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.0837
CY2021Q1	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	102499000	USD
CY2021Q1	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2021Q1	fbiz	Tier One Leverage Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneLeverageCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	102499000	USD
CY2021Q1	fbiz	Tier One Leverage Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets TierOneLeverageCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0400
CY2020Q4	us-gaap	Capital Capital	258607000	USD
CY2020Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1125
CY2020Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	183965000	USD
CY2020Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2020Q4	fbiz	Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	241454000	USD
CY2020Q4	fbiz	Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.1050
CY2020Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	206104000	USD
CY2020Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.0896
CY2020Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	137974000	USD
CY2020Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2020Q4	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	195463000	USD
CY2020Q4	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0850
CY2020Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	196042000	USD
CY2020Q4	fbiz	Common Equity Tier One Capitalto Risk Weighted Assets CommonEquityTierOneCapitaltoRiskWeightedAssets	0.0853
CY2020Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	103480000	USD
CY2020Q4	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacyto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0450
CY2020Q4	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	160970000	USD
CY2020Q4	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0700
CY2020Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	206104000	USD
CY2020Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.0799
CY2020Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	103228000	USD
CY2020Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2020Q4	fbiz	Tier One Leverage Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneLeverageCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	103228000	USD
CY2020Q4	fbiz	Tier One Leverage Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets TierOneLeverageCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0400

Files In Submission

Name	View Source	Status
0001521951-21-000041-index-headers.html	Edgar Link	pending
0001521951-21-000041-index.html	Edgar Link	pending
0001521951-21-000041.txt	Edgar Link	pending
0001521951-21-000041-xbrl.zip	Edgar Link	pending
fbiz-20210331.htm	Edgar Link	pending
fbiz-20210331.xsd	Edgar Link	pending
fbiz-20210331_cal.xml	Edgar Link	unprocessable
fbiz-20210331_def.xml	Edgar Link	unprocessable
fbiz-20210331_htm.xml	Edgar Link	completed
fbiz-20210331_lab.xml	Edgar Link	unprocessable
fbiz-20210331_pre.xml	Edgar Link	unprocessable
fbiz20210331exhibit311.htm	Edgar Link	pending
fbiz20210331exhibit312.htm	Edgar Link	pending
fbiz20210331exhibit32.htm	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
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FIRST BUSINESS FINANCIAL SERVICES, INC. Stock $fbiz

2021 Q1 Form 10-Q Financial Statement

#000152195121000041 Filed on April 30, 2021

Income Statement

Balance Sheet

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Facts In Submission

Files In Submission

$FBIZ FIRST BUSINESS FINANCIAL SERVICES, INC. Stock $fbiz

2021 Q1 Form 10-Q Financial Statement

#000152195121000041 Filed on April 30, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$FBIZ
FIRST BUSINESS FINANCIAL SERVICES, INC. Stock $fbiz