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

$fbiz Overview Financials Valuation SEC Filings Company Website

2021 Q2 Form 10-Q Financial Statement

#000152195121000066 Filed on July 30, 2021

Income Statement

Concept	2021 Q2	2020 Q2
Revenue	$24.60M	$22.76M
YoY Change	8.08%	-10.07%
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	$890.0K	$830.0K
YoY Change	7.23%	5.06%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$2.947M	$3.873M
YoY Change	-23.91%	-54.2%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$10.75M	$1.395M
YoY Change	670.39%	-76.66%
Income Tax	$2.512M	-$1.928M
% Of Pretax Income	23.37%	-138.21%
Net Earnings	$8.235M	$3.323M
YoY Change	147.82%	-49.44%
Net Earnings / Revenue	33.48%	14.6%
Basic Earnings Per Share	$0.95	$0.38
Diluted Earnings Per Share	$0.95	$0.38
COMMON SHARES
Basic Shares Outstanding	8.385M shares	8.392M shares
Diluted Shares Outstanding	8.385M shares	8.392M shares

Balance Sheet

Concept	2021 Q2	2020 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$390.0M	$42.39M
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	$1.747M	$2.266M
YoY Change	-22.9%	-20.94%
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments	$16.90M	$12.90M
YoY Change	31.01%	545.0%
Other Assets	$7.300M	$5.400M
YoY Change	35.19%	74.19%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$2.866B	$2.469B
YoY Change	16.07%	19.25%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$11.20M	$78.90M
YoY Change	-85.8%	310.94%
Accrued Expenses	$6.000M	$6.900M
YoY Change	-13.04%	-15.85%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$29.60M
YoY Change	-100.0%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$17.20M	$85.80M
YoY Change	-79.95%	213.14%
LONG-TERM LIABILITIES
Long-Term Debt	$42.40M	$34.50M
YoY Change	22.9%	0.0%
Other Long-Term Liabilities	$36.10M
YoY Change
Total Long-Term Liabilities	$78.50M	$34.50M
YoY Change	127.54%	-32.22%
TOTAL LIABILITIES
Total Short-Term Liabilities	$17.20M	$85.80M
Total Long-Term Liabilities	$78.50M	$34.50M
Total Liabilities	$2.644B	$2.271B
YoY Change	16.42%	20.72%
SHAREHOLDERS EQUITY
Retained Earnings	$155.3M	$132.9M
YoY Change	16.87%	9.96%
Common Stock	$84.44M	$82.21M
YoY Change	2.7%	2.2%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$17.52M	$16.35M
YoY Change	7.18%	44.13%
Treasury Stock Shares	705.8K shares	656.6K shares
Shareholders Equity	$221.5M	$197.6M
YoY Change
Total Liabilities & Shareholders Equity	$2.866B	$2.469B
YoY Change	16.07%	19.25%

Cashflow Statement

Concept	2021 Q2	2020 Q2
OPERATING ACTIVITIES
Net Income	$8.235M	$3.323M
YoY Change	147.82%	-49.44%
Depreciation, Depletion And Amortization	$890.0K	$830.0K
YoY Change	7.23%	5.06%
Cash From Operating Activities	$8.140M	$80.00K
YoY Change	10075.0%	-87.5%
INVESTING ACTIVITIES
Capital Expenditures	-$50.00K	-$50.00K
YoY Change	0.0%	400.0%
Acquisitions
YoY Change
Other Investing Activities	$95.47M	-$313.6M
YoY Change	-130.45%	393.87%
Cash From Investing Activities	$95.43M	-$313.6M
YoY Change	-130.43%	393.87%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	227.5M	260.9M
YoY Change	-12.8%	397.88%
NET CHANGE
Cash From Operating Activities	8.140M	80.00K
Cash From Investing Activities	95.43M	-313.6M
Cash From Financing Activities	227.5M	260.9M
Net Change In Cash	331.1M	-52.59M
YoY Change	-729.59%	403.25%
FREE CASH FLOW
Cash From Operating Activities	$8.140M	$80.00K
Capital Expenditures	-$50.00K	-$50.00K
Free Cash Flow	$8.190M	$130.0K
YoY Change	6200.0%	-80.0%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Entity Central Index Key EntityCentralIndexKey	0001521951
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q2
	dei	Amendment Flag AmendmentFlag	false
	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2021-06-30
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	001-34095
	dei	Entity Registrant Name EntityRegistrantName	FIRST BUSINESS FINANCIAL SERVICES, INC.
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	WI
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	39-1576570
	dei	Entity Address Address Line1 EntityAddressAddressLine1	401 Charmany Drive
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	53719
	dei	Entity Address City Or Town EntityAddressCityOrTown	Madison
	dei	Entity Address State Or Province EntityAddressStateOrProvince	WI
	dei	City Area Code CityAreaCode	608
	dei	Local Phone Number LocalPhoneNumber	238-8008
	dei	Security12b Title Security12bTitle	Common Stock, $0.01 par value
	dei	Trading Symbol TradingSymbol	FBIZ
	dei	Security Exchange Name SecurityExchangeName	NASDAQ
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Filer Category EntityFilerCategory	Accelerated Filer
	dei	Entity Small Business EntitySmallBusiness	true
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Shell Company EntityShellCompany	false
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	fbiz	Professional Fees Expense ProfessionalFeesExpense	1778000	USD
	fbiz	Professional Fees Expense ProfessionalFeesExpense	1678000	USD
CY2021Q2	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	798000	USD
CY2020Q2	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	710000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	1569000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	1386000	USD
CY2021Q2	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	511000	USD
CY2020Q2	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	352000	USD
	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	902000	USD
	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	813000	USD
CY2021Q2	us-gaap	Equipment Expense EquipmentExpense	261000	USD
CY2020Q2	us-gaap	Equipment Expense EquipmentExpense	304000	USD
	us-gaap	Equipment Expense EquipmentExpense	506000	USD
	us-gaap	Equipment Expense EquipmentExpense	595000	USD
CY2021Q2	fbiz	Computer Software Expense ComputerSoftwareExpense	1129000	USD
CY2020Q2	fbiz	Computer Software Expense ComputerSoftwareExpense	966000	USD
	fbiz	Computer Software Expense ComputerSoftwareExpense	2244000	USD
	fbiz	Computer Software Expense ComputerSoftwareExpense	1856000	USD
CY2021Q2	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	280000	USD
CY2020Q2	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	239000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	642000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	448000	USD
CY2021Q2	fbiz	Collateral Liquidation Costs CollateralLiquidationCosts	84000	USD
CY2020Q2	fbiz	Collateral Liquidation Costs CollateralLiquidationCosts	115000	USD
	fbiz	Collateral Liquidation Costs CollateralLiquidationCosts	178000	USD
	fbiz	Collateral Liquidation Costs CollateralLiquidationCosts	236000	USD
CY2021Q2	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	1000	USD
CY2020Q2	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-348000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-1000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-450000	USD
CY2021Q2	fbiz	Historic Rehabilitation Tax Credit Investment Impairment Recovery HistoricRehabilitationTaxCreditInvestmentImpairmentRecovery	0	USD
CY2020Q2	fbiz	Historic Rehabilitation Tax Credit Investment Impairment Recovery HistoricRehabilitationTaxCreditInvestmentImpairmentRecovery	1841000	USD
	fbiz	Historic Rehabilitation Tax Credit Investment Impairment Recovery HistoricRehabilitationTaxCreditInvestmentImpairmentRecovery	0	USD
	fbiz	Historic Rehabilitation Tax Credit Investment Impairment Recovery HistoricRehabilitationTaxCreditInvestmentImpairmentRecovery	1954000	USD
CY2021Q2	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	245000	USD
CY2020Q2	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	-30000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	115000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	-5000	USD
CY2021Q2	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2020Q2	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-744000	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-744000	USD
CY2021Q2	us-gaap	Other Noninterest Expense OtherNoninterestExpense	176000	USD
CY2020Q2	us-gaap	Other Noninterest Expense OtherNoninterestExpense	545000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	582000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	1359000	USD
CY2021Q2	us-gaap	Noninterest Expense NoninterestExpense	18184000	USD
CY2020Q2	us-gaap	Noninterest Expense NoninterestExpense	18343000	USD
	us-gaap	Noninterest Expense NoninterestExpense	35514000	USD
	us-gaap	Noninterest Expense NoninterestExpense	34488000	USD
CY2021Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	10747000	USD
CY2020Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	1395000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	23543000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	5531000	USD
CY2021Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2512000	USD
CY2020Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-1928000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	5577000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-1070000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	8235000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	3323000	USD
	us-gaap	Net Income Loss NetIncomeLoss	17966000	USD
	us-gaap	Net Income Loss NetIncomeLoss	6601000	USD
CY2021Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.95
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.38
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.08
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.77
CY2021Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.95
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.38
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.08
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.77
CY2021Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.18
CY2020Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.165
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.36
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.33
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	8235000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	3323000	USD
	us-gaap	Net Income Loss NetIncomeLoss	17966000	USD
	us-gaap	Net Income Loss NetIncomeLoss	6601000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	662000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-264000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-1576000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	4237000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	29000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	0	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	29000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-4000	USD
CY2021Q2	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	7000	USD
CY2020Q2	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	10000	USD
	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	15000	USD
	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	20000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-271000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-418000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	1818000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-4043000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	94000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	-171000	USD
	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	58000	USD
	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	56000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	275000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-501000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	170000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	162000	USD
CY2021Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	8510000	USD
CY2020Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	2822000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	18136000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	6763000	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
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	3323000	USD
CY2020Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-501000	USD
CY2020Q2	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	516000	USD
CY2020Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.165
CY2020Q2	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	1414000	USD
CY2020Q2	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	19000	USD
CY2020Q2	us-gaap	Stockholders Equity StockholdersEquity	197562000	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
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	8235000	USD
CY2021Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	275000	USD
CY2021Q2	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	607000	USD
CY2021Q2	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Employee Stock Purchase Program Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployeeStockPurchaseProgramRequisiteServicePeriodRecognition	42000	USD
CY2021Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.18
CY2021Q2	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	1556000	USD
CY2021Q2	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	642000	USD
CY2021Q2	us-gaap	Stockholders Equity StockholdersEquity	221452000	USD
	us-gaap	Net Income Loss NetIncomeLoss	17966000	USD
	us-gaap	Net Income Loss NetIncomeLoss	6601000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-1359000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-133000	USD
	fbiz	Impairmentof Tax Credit Investments ImpairmentofTaxCreditInvestments	0	USD
	fbiz	Impairmentof Tax Credit Investments ImpairmentofTaxCreditInvestments	1954000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	-3026000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8651000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	115000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	-5000	USD
	fbiz	Derivative Credit Valuation Adjustment DerivativeCreditValuationAdjustment	-376000	USD
	fbiz	Derivative Credit Valuation Adjustment DerivativeCreditValuationAdjustment	0	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	1845000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	1637000	USD
	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-56000	USD
	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	0	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	1138000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	933000	USD
	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	29000	USD
	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-4000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	699000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	672000	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	48137000	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	39931000	USD
	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	53054000	USD
	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	32303000	USD
	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	2281000	USD
	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	839000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-1000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-450000	USD
	us-gaap	Impairment Of Intangible Assets Finitelived ImpairmentOfIntangibleAssetsFinitelived	-78000	USD
	us-gaap	Impairment Of Intangible Assets Finitelived ImpairmentOfIntangibleAssetsFinitelived	0	USD
	us-gaap	Excess Tax Benefit From Share Based Compensation Operating Activities ExcessTaxBenefitFromShareBasedCompensationOperatingActivities	16000	USD
	us-gaap	Excess Tax Benefit From Share Based Compensation Operating Activities ExcessTaxBenefitFromShareBasedCompensationOperatingActivities	-19000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	788000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	775000	USD
	us-gaap	Proceeds From Lease Payments ProceedsFromLeasePayments	82000	USD
	us-gaap	Proceeds From Lease Payments ProceedsFromLeasePayments	56000	USD
	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	1152000	USD
	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	50989000	USD
	us-gaap	Increase Decrease In Accrued Liabilities And Other Operating Liabilities IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities	-1345000	USD
	us-gaap	Increase Decrease In Accrued Liabilities And Other Operating Liabilities IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities	42042000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	14971000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1306000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	31315000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	22457000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	3969000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	2844000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	14955000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	839000	USD
	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	35559000	USD
	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	17753000	USD
	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	0	USD
	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	1160000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-2444000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	343016000	USD
	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	60000	USD
	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	0	USD
	fbiz	Paymentsto Acquire Historic Development Entities PaymentstoAcquireHistoricDevelopmentEntities	0	USD
	fbiz	Paymentsto Acquire Historic Development Entities PaymentstoAcquireHistoricDevelopmentEntities	259000	USD
	fbiz	Distributionfromhistoricdevelopmententities Distributionfromhistoricdevelopmententities	57000	USD
	fbiz	Distributionfromhistoricdevelopmententities Distributionfromhistoricdevelopmententities	30000	USD
	fbiz	Payments To Acquire Low Income Housing Entities PaymentsToAcquireLowIncomeHousingEntities	1307000	USD
	fbiz	Payments To Acquire Low Income Housing Entities PaymentsToAcquireLowIncomeHousingEntities	0	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	6314000	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	6892000	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	6440000	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	1375000	USD
	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	135000	USD
	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	141000	USD
	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	12000	USD
	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	0	USD
	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	0	USD
	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	8000000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	15937000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-347356000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	305191000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	179996000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	510300000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	498500000	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	517000000	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	383243000	USD
	fbiz	Losson Early Extinguishmentof Debt Financing Activities LossonEarlyExtinguishmentofDebtFinancingActivities	0	USD
	fbiz	Losson Early Extinguishmentof Debt Financing Activities LossonEarlyExtinguishmentofDebtFinancingActivities	744000	USD
	fbiz	Proceedsfromthe Federal Paycheck Protection Program Lending Facility Investing Activities ProceedsfromtheFederalPaycheckProtectionProgramLendingFacilityInvestingActivities	0	USD
	fbiz	Proceedsfromthe Federal Paycheck Protection Program Lending Facility Investing Activities ProceedsfromtheFederalPaycheckProtectionProgramLendingFacilityInvestingActivities	29605000	USD
	us-gaap	Proceeds From Repayments Of Notes Payable ProceedsFromRepaymentsOfNotesPayable	7653000	USD
	us-gaap	Proceeds From Repayments Of Notes Payable ProceedsFromRepaymentsOfNotesPayable	27000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	3097000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	2824000	USD
	fbiz	Proceeds From Issuance Of Common Stock Under The Employee Stock Purchase Plan ProceedsFromIssuanceOfCommonStockUnderTheEmployeeStockPurchasePlan	81000	USD
	fbiz	Proceeds From Issuance Of Common Stock Under The Employee Stock Purchase Plan ProceedsFromIssuanceOfCommonStockUnderTheEmployeeStockPurchasePlan	0	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	968000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1466000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	302160000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	321339000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	333068000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-24711000	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
CY2021Q2	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	389977000	USD
CY2020Q2	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	42391000	USD
	us-gaap	Interest Paid Net InterestPaidNet	7469000	USD
	us-gaap	Interest Paid Net InterestPaidNet	11064000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	7658000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	1356000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	316000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	149000	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	80000	USD
	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.
	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	Certain amounts in prior periods may have been reclassified to conform to the current presentation.
CY2021Q2	fbiz	Numberof Short Term Loan Modifications NumberofShortTermLoanModifications	5
CY2021Q2	fbiz	Gross Loansand Leases Outstanding Short Term Modification GrossLoansandLeasesOutstandingShortTermModification	20500000	USD
CY2021Q2	fbiz	Gross Loansand Leases Outstanding Short Term Modification Percent6 Month Deferral Period GrossLoansandLeasesOutstandingShortTermModificationPercent6MonthDeferralPeriod	0.010
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
CY2021Q2	fbiz	Gross Loansand Leases Outstanding Short Term Modification GrossLoansandLeasesOutstandingShortTermModification	20500000	USD
CY2021Q2	fbiz	Sba Paycheck Protection Program Loans Outstanding Gross Amount SBAPaycheckProtectionProgramLoansOutstandingGrossAmount	123800000	USD
CY2021Q2	fbiz	Sba Paycheck Protection Program Loan Leases Receiveable Deferred Income SBAPaycheckProtectionProgramLoanLeasesReceiveableDeferredIncome	3100000	USD
CY2021Q2	fbiz	Sba Paycheck Protection Program Interest Income Loans SBAPaycheckProtectionProgramInterestIncomeLoans	2500000	USD
	fbiz	Sba Paycheck Protection Program Interest Income Loans SBAPaycheckProtectionProgramInterestIncomeLoans	4800000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	8235000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	3323000	USD
	us-gaap	Net Income Loss NetIncomeLoss	17966000	USD
	us-gaap	Net Income Loss NetIncomeLoss	6601000	USD
CY2021Q2	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	238000	USD
CY2020Q2	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	93000	USD
	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	493000	USD
	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	173000	USD
CY2021Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	7997000	USD
CY2020Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	3230000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	17473000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	6428000	USD
CY2021Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8385069	shares
CY2020Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8392197	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8381868	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8379696	shares
CY2021Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.95
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.38
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.08
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.77
CY2021Q2	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	7997000	USD
CY2020Q2	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	3230000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	17473000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	6428000	USD
CY2021Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8385069	shares
CY2020Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8392197	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8381868	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8379696	shares
CY2021Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.95
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.38
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.08
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.77
CY2021Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	219531	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
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	90055	shares
	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	23.39
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	34070	shares
	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	22.61
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	4379	shares
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	23.39
CY2021Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	239410	shares
CY2021Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	24.21
CY2021Q2	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	4100000	USD
	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P2Y4M24D
CY2021Q2	fbiz	Employee Stock Purchase Plan Number Of Shares Authorized For Grant EmployeeStockPurchasePlanNumberOfSharesAuthorizedForGrant	250000	shares
	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	3469	shares
CY2021Q2	fbiz	Employee Stock Purchase Plan Number Of Shares Available For Grant EmployeeStockPurchasePlanNumberOfSharesAvailableForGrant	242564	shares
CY2021Q2	us-gaap	Share Based Compensation ShareBasedCompensation	607000	USD
CY2020Q2	us-gaap	Share Based Compensation ShareBasedCompensation	516000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	1138000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	933000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	168480000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	3354000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	615000	USD
CY2021Q2	us-gaap	Available For Sale Securities AvailableForSaleSecurities	171219000	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
CY2021Q2	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	22382000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	741000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	10000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	23113000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	26374000	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
CY2021Q2	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	7	securities
	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	7	securities
CY2020Q2	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	0	securities
	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	1	securities
CY2021Q2	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	37000000.0	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	73700000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	1225000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	1251000	USD
CY2021Q2	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	3882000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities Next Rolling Twelve Months Fair Value HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	3909000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	7546000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	7707000	USD
CY2021Q2	fbiz	Heldtomaturity Securities Debt Maturities Rolling Years Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearsTwoThroughFiveAmortizedCost	8427000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Two Through Five Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	8570000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	42803000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	43827000	USD
CY2021Q2	fbiz	Heldtomaturity Securities Debt Maturities Rolling Years Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearsSixThroughTenAmortizedCost	8359000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Six Through Ten Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	8845000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	116906000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	118434000	USD
CY2021Q2	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	1714000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Debt Maturities Rolling After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue	1789000	USD
CY2021Q2	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	168480000	USD
CY2021Q2	us-gaap	Available For Sale Securities AvailableForSaleSecurities	171219000	USD
CY2021Q2	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	22382000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	23113000	USD
CY2021Q2	us-gaap	Availableforsale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions1 AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1	23	securities
CY2021Q2	us-gaap	Availableforsale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositionsGreaterThanOrEqualToOneYear	0	securities
	us-gaap	Other Than Temporary Impairment Losses Investments Availableforsale Securities OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities	0	USD
	us-gaap	Other Than Temporary Impairment Losses Investments Availableforsale Securities OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities	0	USD
CY2020Q2	us-gaap	Other Than Temporary Impairment Losses Investments Availableforsale Securities OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities	0	USD
CY2021Q2	us-gaap	Other Than Temporary Impairment Losses Investments Availableforsale Securities OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities	0	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	55089000	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	615000	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	0	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2150515000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	25675000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	28521000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	4338000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	4545000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	2117886000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	2117449000	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	0	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	55089000	USD
CY2021Q2	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	615000	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
CY2021Q2	us-gaap	Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions HeldToMaturitySecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions	2	securities
CY2021Q2	us-gaap	Other Than Temporary Impairment Losses Investments Heldtomaturity Securities OtherThanTemporaryImpairmentLossesInvestmentsHeldtomaturitySecurities	0	USD
	us-gaap	Other Than Temporary Impairment Losses Investments Heldtomaturity Securities OtherThanTemporaryImpairmentLossesInvestmentsHeldtomaturitySecurities	0	USD
	us-gaap	Other Than Temporary Impairment Losses Investments Heldtomaturity Securities OtherThanTemporaryImpairmentLossesInvestmentsHeldtomaturitySecurities	0	USD
CY2020Q2	us-gaap	Other Than Temporary Impairment Losses Investments Heldtomaturity Securities OtherThanTemporaryImpairmentLossesInvestmentsHeldtomaturitySecurities	0	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2147899000	USD
CY2020Q4	fbiz	Small Business Administration7a Loans SmallBusinessAdministration7aLoans	36266000	USD
CY2021Q2	fbiz	Sba Paycheck Protection Program Loans Outstanding Gross Amount SBAPaycheckProtectionProgramLoansOutstandingGrossAmount	123800000	USD
CY2020Q4	fbiz	Sba Paycheck Protection Program Loans Outstanding Gross Amount SBAPaycheckProtectionProgramLoansOutstandingGrossAmount	228900000	USD
CY2021Q2	fbiz	Paycheck Protection Loans And Leases Receivable Deferred Income PaycheckProtectionLoansAndLeasesReceivableDeferredIncome	3100000	USD
CY2020Q4	fbiz	Paycheck Protection Loans And Leases Receivable Deferred Income PaycheckProtectionLoansAndLeasesReceivableDeferredIncome	3500000	USD
CY2021Q2	fbiz	Small Business Administration7a Loans SmallBusinessAdministration7aLoans	28367000	USD
CY2021Q2	fbiz	Small Business Administration504 Loans SmallBusinessAdministration504Loans	33547000	USD
CY2020Q4	fbiz	Small Business Administration504 Loans SmallBusinessAdministration504Loans	26327000	USD
	fbiz	Gain Loss Recognizedon Participation Interestin Originated Loans GainLossRecognizedonParticipationInterestinOriginatedLoans	0	USD
CY2021Q2	fbiz	Small Business Administration Express Loans SmallBusinessAdministrationExpressLoans	765000	USD
CY2020Q4	fbiz	Small Business Administration Express Loans SmallBusinessAdministrationExpressLoans	1251000	USD
CY2021Q2	fbiz	Small Business Administration Paycheck Protection Program Loans SmallBusinessAdministrationPaycheckProtectionProgramLoans	123838000	USD
CY2020Q4	fbiz	Small Business Administration Paycheck Protection Program Loans SmallBusinessAdministrationPaycheckProtectionProgramLoans	228870000	USD
CY2021Q2	fbiz	Small Business Administration Loans SmallBusinessAdministrationLoans	186517000	USD
CY2020Q4	fbiz	Small Business Administration Loans SmallBusinessAdministrationLoans	292714000	USD
CY2021Q2	fbiz	Sb Aloansintheparticipationsoldportfolioconsideredimpaired SBAloansintheparticipationsoldportfolioconsideredimpaired	3400000	USD
CY2020Q4	fbiz	Sb Aloansintheparticipationsoldportfolioconsideredimpaired SBAloansintheparticipationsoldportfolioconsideredimpaired	9300000	USD
CY2021Q2	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	9000000.0	USD
CY2020Q2	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	6500000	USD
	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	19600000	USD
	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	9200000	USD
CY2021Q2	fbiz	Totalamountofoutstanding Sb Aloanssold TotalamountofoutstandingSBAloanssold	87800000	USD
CY2020Q4	fbiz	Totalamountofoutstanding Sb Aloanssold TotalamountofoutstandingSBAloanssold	79500000	USD
CY2021Q2	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	11800000	USD
CY2020Q2	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	10300000	USD
	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	16900000	USD
	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	22200000	USD
CY2021Q2	fbiz	Total Amount Of Outstanding Loans Transferred To Third Parties As Loan Participations TotalAmountOfOutstandingLoansTransferredToThirdPartiesAsLoanParticipations	157900000	USD
CY2020Q4	fbiz	Total Amount Of Outstanding Loans Transferred To Third Parties As Loan Participations TotalAmountOfOutstandingLoansTransferredToThirdPartiesAsLoanParticipations	153600000	USD
CY2021Q2	fbiz	Total Amount Of Loan Participations Remaining On Corporations Balance Sheet TotalAmountOfLoanParticipationsRemainingOnCorporationsBalanceSheet	269500000	USD
CY2020Q4	fbiz	Total Amount Of Loan Participations Remaining On Corporations Balance Sheet TotalAmountOfLoanParticipationsRemainingOnCorporationsBalanceSheet	276500000	USD
CY2021Q2	fbiz	Loans In The Participation Sold Portfolio Considered Impaired Gross Amount LoansInTheParticipationSoldPortfolioConsideredImpairedGrossAmount	3000000.0	USD
CY2021Q2	fbiz	Loans In The Participation Sold Portfolio Considered Impaired Sold Amount LoansInTheParticipationSoldPortfolioConsideredImpairedSoldAmount	4200000	USD
CY2021Q2	fbiz	Loan Participations Purchased On Corporations Balance Sheet LoanParticipationsPurchasedOnCorporationsBalanceSheet	0	USD
CY2020Q4	fbiz	Loan Participations Purchased On Corporations Balance Sheet LoanParticipationsPurchasedOnCorporationsBalanceSheet	410000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2147899000	USD
CY2021Q2	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
CY2021Q2	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2147899000	USD
CY2021Q2	fbiz	Financing Receivable Recorded Investment30 To59 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment30To59DaysPastDuePercentOfPortfolio	0.0003
CY2021Q2	fbiz	Financing Receivable Recorded Investment60 To89 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment60To89DaysPastDuePercentOfPortfolio	0.0001
CY2021Q2	fbiz	Financing Receivable Recorded Investment Equal To Greater Than90 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDuePercentOfPortfolio	0.0010
CY2021Q2	fbiz	Specific Reserveson Troubled Debt Restructurings SpecificReservesonTroubledDebtRestructurings	0	USD
CY2021Q2	fbiz	Financing Receivable Recorded Investment Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentPastDuePercentOfPortfolio	0.0014
CY2021Q2	fbiz	Financing Receivable Recorded Investment Current Percent Of Portfolio FinancingReceivableRecordedInvestmentCurrentPercentOfPortfolio	0.9986
CY2021Q2	fbiz	Financing Receivable Recorded Investment Gross Percent Of Portfolio FinancingReceivableRecordedInvestmentGrossPercentOfPortfolio	1.0000
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
CY2021Q2	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	11422000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	26617000	USD
CY2021Q2	us-gaap	Foreclosed Assets ForeclosedAssets	179000	USD
CY2020Q4	us-gaap	Foreclosed Assets ForeclosedAssets	34000	USD
CY2021Q2	fbiz	Total Nonperforming Assets TotalNonperformingAssets	11601000	USD
CY2020Q4	fbiz	Total Nonperforming Assets TotalNonperformingAssets	26651000	USD
CY2021Q2	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	56000	USD
CY2020Q4	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	46000	USD
CY2021Q2	fbiz	Impaired Assets ImpairedAssets	11657000	USD
CY2020Q4	fbiz	Impaired Assets ImpairedAssets	26697000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Ratio Of Nonperforming Loans To All Loans LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans	0.0053
CY2020Q4	us-gaap	Loans And Leases Receivable Ratio Of Nonperforming Loans To All Loans LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans	0.0124
CY2021Q2	fbiz	Ratio Of Total Nonperforming Assets To Gross Loans And Leases Plus Foreclosed Properties Net RatioOfTotalNonperformingAssetsToGrossLoansAndLeasesPlusForeclosedPropertiesNet	0.0054
CY2020Q4	fbiz	Ratio Of Total Nonperforming Assets To Gross Loans And Leases Plus Foreclosed Properties Net RatioOfTotalNonperformingAssetsToGrossLoansAndLeasesPlusForeclosedPropertiesNet	0.0124
CY2021Q2	fbiz	Ratio Of Total Nonperforming Assets To Total Assets RatioOfTotalNonperformingAssetsToTotalAssets	0.0040
CY2020Q4	fbiz	Ratio Of Total Nonperforming Assets To Total Assets RatioOfTotalNonperformingAssetsToTotalAssets	0.0104
CY2021Q2	fbiz	Ratio Of Allowance For Loan And Lease Losses To Total Gross Loans And Leases RatioOfAllowanceForLoanAndLeaseLossesToTotalGrossLoansAndLeases	0.0120
CY2020Q4	fbiz	Ratio Of Allowance For Loan And Lease Losses To Total Gross Loans And Leases RatioOfAllowanceForLoanAndLeaseLossesToTotalGrossLoansAndLeases	0.0133
CY2021Q2	fbiz	Ratio Of Allowance For Loan And Leases Losses To Non Accrual Loans And Leases RatioOfAllowanceForLoanAndLeasesLossesToNonAccrualLoansAndLeases	2.2479
CY2020Q4	fbiz	Ratio Of Allowance For Loan And Leases Losses To Non Accrual Loans And Leases RatioOfAllowanceForLoanAndLeasesLossesToNonAccrualLoansAndLeases	1.0715
CY2021Q2	fbiz	Non Accrual Troubled Debt Restructurings NonAccrualTroubledDebtRestructurings	523000	USD
CY2020Q4	fbiz	Non Accrual Troubled Debt Restructurings NonAccrualTroubledDebtRestructurings	6500000	USD
CY2020Q4	fbiz	Specific Reserveson Troubled Debt Restructurings SpecificReservesonTroubledDebtRestructurings	760000	USD
CY2021Q2	fbiz	Unfunded Commitments Troubled Debt Restructurings UnfundedCommitmentsTroubledDebtRestructurings	0	USD
CY2020Q2	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	1	loans
CY2020Q2	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	4986000	USD
CY2020Q2	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	4986000	USD
	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	5	loans
	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	6306000	USD
	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	6028000	USD
CY2021Q2	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	7948000	USD
CY2021Q2	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	11782000	USD
	us-gaap	Impaired Financing Receivable With No Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment	16730000	USD
	fbiz	Impaired Financing Receivable With No Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceForegoneInterestIncome	827000	USD
	us-gaap	Impaired Financing Receivable With No Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod	145000	USD
	fbiz	Impaired Financing Receivable With No Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceNetForegoneInterestIncome	682000	USD
CY2021Q2	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	3530000	USD
CY2021Q2	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	3560000	USD
CY2021Q2	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	2021000	USD
	us-gaap	Impaired Financing Receivable With Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment	2690000	USD
	fbiz	Impaired Financing Receivable With Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceForegoneInterestIncome	254000	USD
	us-gaap	Impaired Financing Receivable With Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod	8000	USD
	fbiz	Impaired Financing Receivable With Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceNetForegoneInterestIncome	246000	USD
CY2021Q2	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	11478000	USD
CY2021Q2	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	15342000	USD
CY2021Q2	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	2021000	USD
	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	19420000	USD
	fbiz	Impaired Financing Receivable Foregone Interest Income ImpairedFinancingReceivableForegoneInterestIncome	1081000	USD
	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	153000	USD
	fbiz	Impaired Financing Receivable Net Foregone Interest Income ImpairedFinancingReceivableNetForegoneInterestIncome	928000	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
CY2021Q2	fbiz	Loans And Leases Receivable Difference Between Recorded Investment And Unpaid Principal Balance LoansAndLeasesReceivableDifferenceBetweenRecordedInvestmentAndUnpaidPrincipalBalance	3900000	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
CY2020Q4	fbiz	Loans And Leases Receivable Difference Between Recorded Investment And Unpaid Principal Balance LoansAndLeasesReceivableDifferenceBetweenRecordedInvestmentAndUnpaidPrincipalBalance	14600000	USD
CY2021Q2	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	56000	USD
CY2020Q4	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	46000	USD
CY2021Q1	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	28982000	USD
CY2021Q2	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	2894000	USD
CY2021Q2	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	545000	USD
CY2021Q2	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	-2349000	USD
CY2021Q2	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	-958000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	25675000	USD
CY2020Q1	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	22748000	USD
CY2020Q2	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	5469000	USD
CY2020Q2	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	27464000	USD
CY2020Q2	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	817000	USD
CY2020Q2	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	64000	USD
CY2020Q2	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	-753000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	28521000	USD
	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	3038000	USD
	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	3218000	USD
	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	180000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	-3026000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	25675000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	19520000	USD
	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	948000	USD
	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	241000	USD
	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	-707000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8651000	USD
CY2020Q2	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	27464000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	23654000	USD
CY2021Q2	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	2021000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	25675000	USD
CY2021Q2	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	2136421000	USD
CY2021Q2	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	11479000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	2147900000	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
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	316000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	1585000	USD
CY2021Q2	fbiz	Investmentin Historic Development Entities InvestmentinHistoricDevelopmentEntities	2299000	USD
CY2021Q2	us-gaap	Operating Lease Expense OperatingLeaseExpense	374000	USD
CY2020Q2	us-gaap	Operating Lease Expense OperatingLeaseExpense	372000	USD
	us-gaap	Operating Lease Expense OperatingLeaseExpense	749000	USD
	us-gaap	Operating Lease Expense OperatingLeaseExpense	745000	USD
CY2021Q2	us-gaap	Short Term Lease Cost ShortTermLeaseCost	49000	USD
CY2020Q2	us-gaap	Short Term Lease Cost ShortTermLeaseCost	48000	USD
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	88000	USD
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	122000	USD
CY2021Q2	us-gaap	Variable Lease Cost VariableLeaseCost	111000	USD
CY2020Q2	us-gaap	Variable Lease Cost VariableLeaseCost	126000	USD
	us-gaap	Variable Lease Cost VariableLeaseCost	239000	USD
	us-gaap	Variable Lease Cost VariableLeaseCost	253000	USD
CY2021Q2	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	43000	USD
CY2020Q2	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	28000	USD
	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	82000	USD
	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	56000	USD
CY2021Q2	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	491000	USD
CY2020Q2	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	518000	USD
	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	994000	USD
	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	1064000	USD
CY2021Q2	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P5Y4M13D
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P5Y9M18D
CY2021Q2	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0294
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0303
CY2021Q2	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	795000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	7217000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	1059000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	790000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	666000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	1641000	USD
CY2021Q2	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	6536000	USD
CY2021Q2	fbiz	Discountonoperatingleasecashflows Discountonoperatingleasecashflows	531000	USD
CY2021Q2	us-gaap	Operating Lease Liability OperatingLeaseLiability	6005000	USD
CY2021Q2	us-gaap	Interest Receivable InterestReceivable	5857000	USD
CY2020Q4	us-gaap	Interest Receivable InterestReceivable	8564000	USD
CY2021Q2	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	7256000	USD
CY2020Q4	fbiz	Investmentin Historic Development Entities InvestmentinHistoricDevelopmentEntities	2356000	USD
CY2021Q2	fbiz	Investment In Low Income Housing Development Entities InvestmentInLowIncomeHousingDevelopmentEntities	1307000	USD
CY2020Q4	fbiz	Investment In Low Income Housing Development Entities InvestmentInLowIncomeHousingDevelopmentEntities	0	USD
CY2021Q2	fbiz	Investmentin Community Development Entities InvestmentinCommunityDevelopmentEntities	5306000	USD
CY2020Q4	fbiz	Investmentin Community Development Entities InvestmentinCommunityDevelopmentEntities	5306000	USD
CY2021Q2	fbiz	Investmentin Limited Partnerships InvestmentinLimitedPartnerships	7712000	USD
CY2020Q4	fbiz	Investmentin Limited Partnerships InvestmentinLimitedPartnerships	6673000	USD
CY2021Q2	fbiz	Investmentin Trust Ii InvestmentinTrustII	315000	USD
CY2020Q4	fbiz	Investmentin Trust Ii InvestmentinTrustII	315000	USD
CY2021Q2	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	2804000	USD
CY2020Q4	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	2165000	USD
CY2021Q2	us-gaap	Other Assets Miscellaneous OtherAssetsMiscellaneous	6999000	USD
CY2020Q4	us-gaap	Other Assets Miscellaneous OtherAssetsMiscellaneous	6882000	USD
CY2021Q2	us-gaap	Other Assets OtherAssets	39855000	USD
CY2020Q4	us-gaap	Other Assets OtherAssets	39478000	USD
CY2021Q2	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	245000	USD
CY2021Q2	us-gaap	Deposits Deposits	2160707000	USD
	fbiz	Average Balance Deposits AverageBalanceDeposits	1893441000	USD
	fbiz	Deposits Weighted Average Interest Rate Duringthe Period DepositsWeightedAverageInterestRateDuringthePeriod	0.0021
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
CY2021Q2	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	41925000	USD
CY2021Q2	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	29710000	USD
CY2021Q2	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	1948000	USD
CY2021Q2	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	369000	USD
CY2021Q2	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	321000	USD
CY2021Q2	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	356000	USD
CY2021Q2	us-gaap	Time Deposits TimeDeposits	74629000	USD
CY2021Q2	fbiz	Time Deposits250000or More TimeDeposits250000orMore	12400000	USD
CY2020Q4	fbiz	Time Deposits250000or More TimeDeposits250000orMore	28700000	USD
CY2021Q2	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	430182000	USD
	fbiz	Borrowed Funds Average Balance BorrowedFundsAverageBalance	426321000	USD
	us-gaap	Debt Instrument Interest Rate During Period DebtInstrumentInterestRateDuringPeriod	0.0184
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
CY2021Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	138275000	USD
CY2021Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	34000000	USD
CY2021Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	37300000	USD
CY2021Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	35500000	USD
CY2021Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	20596000	USD
CY2021Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	164511000	USD
CY2021Q2	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	430182000	USD
	us-gaap	Line Of Credit Facility Commitment Fee Amount LineOfCreditFacilityCommitmentFeeAmount	6600	USD
	us-gaap	Line Of Credit Facility Commitment Fee Amount LineOfCreditFacilityCommitmentFeeAmount	7000	USD
CY2021Q2	fbiz	Sba Loans Probabilityof Future Losses SBALoansProbabilityofFutureLosses	830000	USD
CY2021Q1	fbiz	Sba Recourse Reserve SBARecourseReserve	593000	USD
CY2020Q1	fbiz	Sba Recourse Reserve SBARecourseReserve	1086000	USD
CY2020Q4	fbiz	Sba Recourse Reserve SBARecourseReserve	723000	USD
CY2019Q4	fbiz	Sba Recourse Reserve SBARecourseReserve	1345000	USD
CY2020Q2	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	-30000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	115000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	-5000	USD
CY2021Q2	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	-8000	USD
CY2020Q2	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	-49000	USD
	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	-8000	USD
	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	-333000	USD
CY2021Q2	fbiz	Sba Recourse Reserve SBARecourseReserve	830000	USD
CY2020Q2	fbiz	Sba Recourse Reserve SBARecourseReserve	1007000	USD
CY2021Q2	fbiz	Sba Recourse Reserve SBARecourseReserve	830000	USD
CY2020Q2	fbiz	Sba Recourse Reserve SBARecourseReserve	1007000	USD
CY2020	fbiz	Fair Value Liabilities Level1to Level2 Transfers Amount1 FairValueLiabilitiesLevel1toLevel2TransfersAmount1	0	USD
CY2021Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3	0	USD
CY2021Q2	fbiz	Fair Value Assets Level1to Level2 Transfers Amount1 FairValueAssetsLevel1toLevel2TransfersAmount1	0	USD
CY2021Q2	fbiz	Fair Value Liabilities Level2to Level1 Transfers Amount1 FairValueLiabilitiesLevel2toLevel1TransfersAmount1	0	USD
CY2020	fbiz	Fair Value Assets Level1to Level2 Transfers Amount1 FairValueAssetsLevel1toLevel2TransfersAmount1	0	USD
CY2021Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	0	USD
CY2021Q2	fbiz	Fair Value Assets Level2to Level1 Transfers Amount1 FairValueAssetsLevel2toLevel1TransfersAmount1	0	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3	0	USD
CY2021Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
	fbiz	Fair Value Assets Level2to Level1 Transfers Amount1 FairValueAssetsLevel2toLevel1TransfersAmount1	0	USD
	fbiz	Fair Value Liabilities Level1to Level2 Transfers Amount1 FairValueLiabilitiesLevel1toLevel2TransfersAmount1	0	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	0	USD
	fbiz	Fair Value Liabilities Level2to Level1 Transfers Amount1 FairValueLiabilitiesLevel2toLevel1TransfersAmount1	0	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
CY2021Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
	fbiz	Fair Value Assets Level1to Level2 Transfers Amount1 FairValueAssetsLevel1toLevel2TransfersAmount1	0	USD
CY2021Q2	fbiz	Fair Value Liabilities Level1to Level2 Transfers Amount1 FairValueLiabilitiesLevel1toLevel2TransfersAmount1	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 Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2020	fbiz	Fair Value Liabilities Level2to Level1 Transfers Amount1 FairValueLiabilitiesLevel2toLevel1TransfersAmount1	0	USD
CY2021Q2	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	389977000	USD
CY2021Q2	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	389977000	USD
CY2021Q2	us-gaap	Available For Sale Securities AvailableForSaleSecurities	171219000	USD
CY2021Q2	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	171219000	USD
CY2021Q2	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	22382000	USD
CY2021Q2	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	23113000	USD
CY2021Q2	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	6059000	USD
CY2021Q2	us-gaap	Loans Held For Sale Fair Value Disclosure LoansHeldForSaleFairValueDisclosure	6604000	USD
CY2021Q2	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	2117886000	USD
CY2021Q2	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	2117775000	USD
CY2021Q2	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	13451000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	26374000	USD
CY2021Q2	us-gaap	Interest Receivable InterestReceivable	5857000	USD
CY2021Q2	fbiz	Accrued Interest Receivable Fair Value Disclosure AccruedInterestReceivableFairValueDisclosure	5857000	USD
CY2021Q2	us-gaap	Deposits Deposits	2160707000	USD
CY2021Q2	us-gaap	Deposits Fair Value Disclosure DepositsFairValueDisclosure	2161332000	USD
CY2021Q2	fbiz	Federal Home Loan Bank And Other Borrowings FederalHomeLoanBankAndOtherBorrowings	420113000	USD
CY2021Q2	fbiz	Federal Home Loan Bank And Other Borrowings Fair Value Disclosure FederalHomeLoanBankAndOtherBorrowingsFairValueDisclosure	428967000	USD
CY2021Q2	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust	10069000	USD
CY2021Q2	us-gaap	Fair Value Liabilities Measured On Recurring Basis Subordinated Debt Obligations FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations	9994000	USD
CY2021Q2	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	1303000	USD
CY2021Q2	us-gaap	Accrued Liabilities Fair Value Disclosure AccruedLiabilitiesFairValueDisclosure	1303000	USD
CY2021Q2	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	115000	USD
CY2021Q2	fbiz	Standby Letters Of Credit Fair Value Disclosure StandbyLettersOfCreditFairValueDisclosure	115000	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 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
CY2021Q2	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	0	USD
CY2021Q2	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-271000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	1800000	USD
CY2021Q2	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	0	USD
CY2021Q2	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Asset At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue	32377000	USD
CY2021Q2	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Liability At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue	32377000	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
CY2021Q2	us-gaap	Interest Rate Cash Flow Hedge Asset At Fair Value InterestRateCashFlowHedgeAssetAtFairValue	3732000	USD
CY2021Q2	us-gaap	Interest Rate Cash Flow Hedge Liability At Fair Value InterestRateCashFlowHedgeLiabilityAtFairValue	3732000	USD
CY2020Q4	us-gaap	Interest Rate Cash Flow Hedge Asset At Fair Value InterestRateCashFlowHedgeAssetAtFairValue	5550000	USD
CY2020Q4	us-gaap	Interest Rate Cash Flow Hedge Liability At Fair Value InterestRateCashFlowHedgeLiabilityAtFairValue	5550000	USD
	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.
CY2021Q2	us-gaap	Capital Capital	271536000	USD
CY2021Q2	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1122
CY2021Q2	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	193679000	USD
CY2021Q2	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2021Q2	fbiz	Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	254203000	USD
CY2021Q2	fbiz	Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.1050
CY2021Q2	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	221178000	USD
CY2021Q2	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	145259000	USD
CY2021Q2	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2021Q2	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.0914
CY2021Q2	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	205784000	USD
CY2021Q2	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0850
CY2021Q2	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	211109000	USD
CY2021Q2	fbiz	Common Equity Tier One Capitalto Risk Weighted Assets CommonEquityTierOneCapitaltoRiskWeightedAssets	0.0872
CY2021Q2	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	108944000	USD
CY2021Q2	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacyto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0450
CY2021Q2	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	169469000	USD
CY2021Q2	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0700
CY2021Q2	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	221178000	USD
CY2021Q2	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.0848
CY2021Q2	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	104310000	USD
CY2021Q2	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2021Q2	fbiz	Tier One Leverage Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneLeverageCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	104310000	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
CY2021Q2	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 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
0001521951-21-000066-index-headers.html	Edgar Link	pending
0001521951-21-000066-index.html	Edgar Link	pending
0001521951-21-000066.txt	Edgar Link	pending
0001521951-21-000066-xbrl.zip	Edgar Link	pending
fbiz-20210630.htm	Edgar Link	pending
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fbiz-20210630_pre.xml	Edgar Link	unprocessable
fbiz20210630exhibit311.htm	Edgar Link	pending
fbiz20210630exhibit312.htm	Edgar Link	pending
fbiz20210630exhibit32.htm	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
R1.htm	Edgar Link	pending
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$FBIZ
FIRST BUSINESS FINANCIAL SERVICES, INC. Stock $fbiz

2021 Q2 Form 10-Q Financial Statement

#000152195121000066 Filed on July 30, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

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

2021 Q2 Form 10-Q Financial Statement

#000152195121000066 Filed on July 30, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

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