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

$fbiz Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-Q Financial Statement

#000152195120000065 Filed on October 23, 2020

Income Statement

Concept	2020 Q4	2020 Q3	2019 Q3
Revenue	$25.77M	$22.28M	$25.44M
YoY Change	0.61%	-12.43%	7.96%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$960.0K	$870.0K	$810.0K
YoY Change	20.0%	7.41%	118.92%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$3.258M	$3.655M	$8.662M
YoY Change	-54.36%	-57.8%	33.9%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$7.338M	$5.436M	$6.503M
YoY Change	-1.08%	-16.41%	-3.87%
Income Tax	$1.254M	$1.143M	$1.418M
% Of Pretax Income	17.09%	21.03%	21.81%
Net Earnings	$6.084M	$4.293M	$5.085M
YoY Change	5.48%	-15.58%	-4.07%
Net Earnings / Revenue	23.61%	19.27%	19.99%
Basic Earnings Per Share	$0.71	$0.50	$0.59
Diluted Earnings Per Share	$0.71	$0.50	$0.59
COMMON SHARES
Basic Shares Outstanding	8.518M shares	8.404M shares	8.492M shares
Diluted Shares Outstanding		8.404M shares	8.492M shares

Balance Sheet

Concept	2020 Q4	2020 Q3	2019 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$56.91M	$51.73M	$60.96M
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	$1.998M	$2.130M	$2.740M
YoY Change	-21.86%	-22.26%	-15.61%
Goodwill	$10.70M
YoY Change	0.0%
Intangibles
YoY Change
Long-Term Investments	$14.30M	$13.50M	$13.00M
YoY Change	16.26%	3.85%	622.22%
Other Assets	$7.200M	$7.600M	$2.000M
YoY Change	33.33%	280.0%	-9.09%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$2.568B	$2.602B	$2.093B
YoY Change	22.47%	24.32%	10.48%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$15.60M	$79.40M	$19.30M
YoY Change	-7.69%	311.4%	26.97%
Accrued Expenses	$6.400M	$6.700M	$7.900M
YoY Change	-14.67%	-15.19%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$29.60M	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$22.00M	$86.10M	$27.20M
YoY Change	-9.84%	216.54%	78.95%
LONG-TERM LIABILITIES
Long-Term Debt	$34.70M	$34.50M	$34.40M
YoY Change	0.87%	0.29%	-0.29%
Other Long-Term Liabilities	$54.90M		$23.10M
YoY Change	200.0%		1825.0%
Total Long-Term Liabilities	$89.60M	$34.50M	$57.50M
YoY Change	70.02%	-40.0%	61.06%
TOTAL LIABILITIES
Total Short-Term Liabilities	$22.00M	$86.10M	$27.20M
Total Long-Term Liabilities	$89.60M	$34.50M	$57.50M
Total Liabilities	$2.362B	$2.401B	$1.902B
YoY Change	24.13%	26.24%	10.79%
SHAREHOLDERS EQUITY
Retained Earnings	$140.4M	$135.8M	$124.6M
YoY Change	8.77%	8.93%	15.98%
Common Stock	$83.22M	$82.71M	$80.83M
YoY Change	2.38%	2.33%	1.73%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$16.55M	$16.52M	$13.01M
YoY Change	11.24%	26.93%	76.38%
Treasury Stock Shares	667.5K shares	665.6K shares	520.9K shares
Shareholders Equity	$206.2M	$200.8M	$190.8M
YoY Change
Total Liabilities & Shareholders Equity	$2.568B	$2.602B	$2.093B
YoY Change	22.47%	24.32%	10.48%

Cashflow Statement

Concept	2020 Q4	2020 Q3	2019 Q3
OPERATING ACTIVITIES
Net Income	$6.084M	$4.293M	$5.085M
YoY Change	5.48%	-15.58%	-4.07%
Depreciation, Depletion And Amortization	$960.0K	$870.0K	$810.0K
YoY Change	20.0%	7.41%	118.92%
Cash From Operating Activities	$21.22M	$4.110M	$9.460M
YoY Change	157.84%	-56.55%	1.5%
INVESTING ACTIVITIES
Capital Expenditures	-$60.00K	-$60.00K	-$100.0K
YoY Change	-50.0%	-40.0%	-9.09%
Acquisitions
YoY Change
Other Investing Activities	$15.62M	-$122.6M	-$5.410M
YoY Change	-327.7%	2166.91%	1219.51%
Cash From Investing Activities	$15.55M	-$122.7M	-$5.510M
YoY Change	-322.78%	2126.86%	959.62%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-31.59M	127.9M	11.14M
YoY Change	-746.01%	1048.38%	-177.85%
NET CHANGE
Cash From Operating Activities	21.22M	4.110M	9.460M
Cash From Investing Activities	15.55M	-122.7M	-5.510M
Cash From Financing Activities	-31.59M	127.9M	11.14M
Net Change In Cash	5.180M	9.340M	15.09M
YoY Change	-15.64%	-38.1%	-373.87%
FREE CASH FLOW
Cash From Operating Activities	$21.22M	$4.110M	$9.460M
Capital Expenditures	-$60.00K	-$60.00K	-$100.0K
Free Cash Flow	$21.28M	$4.170M	$9.560M
YoY Change	154.85%	-56.38%	1.38%

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	2020
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Amendment Flag AmendmentFlag	false
	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2020-09-30
	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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	us-gaap	Noninterest Income NoninterestIncome	16234000	USD
CY2020Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	11857000	USD
CY2019Q3	us-gaap	Labor And Related Expense LaborAndRelatedExpense	10324000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	33705000	USD
	us-gaap	Labor And Related Expense LaborAndRelatedExpense	30991000	USD
CY2020Q3	us-gaap	Occupancy Net OccupancyNet	570000	USD
CY2019Q3	us-gaap	Occupancy Net OccupancyNet	580000	USD
	us-gaap	Occupancy Net OccupancyNet	1696000	USD
	us-gaap	Occupancy Net OccupancyNet	1730000	USD
CY2020Q3	fbiz	Professional Fees Expense ProfessionalFeesExpense	943000	USD
CY2019Q3	fbiz	Professional Fees Expense ProfessionalFeesExpense	751000	USD
	fbiz	Professional Fees Expense ProfessionalFeesExpense	2621000	USD
	fbiz	Professional Fees Expense ProfessionalFeesExpense	2745000	USD
CY2020Q3	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	679000	USD
CY2019Q3	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	654000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	2066000	USD
	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	1923000	USD
CY2020Q3	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	356000	USD
CY2019Q3	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	548000	USD
	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	1169000	USD
	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	1611000	USD
CY2020Q3	us-gaap	Equipment Expense EquipmentExpense	310000	USD
CY2019Q3	us-gaap	Equipment Expense EquipmentExpense	277000	USD
	us-gaap	Equipment Expense EquipmentExpense	905000	USD
	us-gaap	Equipment Expense EquipmentExpense	938000	USD
CY2020Q3	fbiz	Computer Software Expense ComputerSoftwareExpense	1017000	USD
CY2019Q3	fbiz	Computer Software Expense ComputerSoftwareExpense	859000	USD
	fbiz	Computer Software Expense ComputerSoftwareExpense	2873000	USD
	fbiz	Computer Software Expense ComputerSoftwareExpense	2485000	USD
CY2020Q3	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	312000	USD
CY2019Q3	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	760000	USD
	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	595000	USD
CY2020Q3	fbiz	Collateral Liquidation Costs CollateralLiquidationCosts	45000	USD
CY2019Q3	fbiz	Collateral Liquidation Costs CollateralLiquidationCosts	110000	USD
	fbiz	Collateral Liquidation Costs CollateralLiquidationCosts	281000	USD
	fbiz	Collateral Liquidation Costs CollateralLiquidationCosts	108000	USD
CY2020Q3	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	121000	USD
CY2019Q3	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-262000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-329000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-241000	USD
CY2020Q3	fbiz	Historic Rehabilitation Tax Credit Investment Impairment Recovery HistoricRehabilitationTaxCreditInvestmentImpairmentRecovery	113000	USD
CY2019Q3	fbiz	Historic Rehabilitation Tax Credit Investment Impairment Recovery HistoricRehabilitationTaxCreditInvestmentImpairmentRecovery	-120000	USD
	fbiz	Historic Rehabilitation Tax Credit Investment Impairment Recovery HistoricRehabilitationTaxCreditInvestmentImpairmentRecovery	2066000	USD
	fbiz	Historic Rehabilitation Tax Credit Investment Impairment Recovery HistoricRehabilitationTaxCreditInvestmentImpairmentRecovery	3982000	USD
CY2020Q3	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	57000	USD
CY2019Q3	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	-427000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	53000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	167000	USD
CY2020Q3	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2019Q3	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-744000	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2020Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	620000	USD
CY2019Q3	us-gaap	Other Noninterest Expense OtherNoninterestExpense	897000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	1977000	USD
	us-gaap	Other Noninterest Expense OtherNoninterestExpense	2406000	USD
CY2020Q3	us-gaap	Noninterest Expense NoninterestExpense	16758000	USD
CY2019Q3	us-gaap	Noninterest Expense NoninterestExpense	14716000	USD
	us-gaap	Noninterest Expense NoninterestExpense	51245000	USD
	us-gaap	Noninterest Expense NoninterestExpense	49922000	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	5436000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	6503000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	10967000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	17081000	USD
CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1143000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1418000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	73000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-475000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	4293000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	5085000	USD
	us-gaap	Net Income Loss NetIncomeLoss	10894000	USD
	us-gaap	Net Income Loss NetIncomeLoss	17556000	USD
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.50
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.01
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.50
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.59
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.27
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.01
CY2020Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.165
CY2019Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.15
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.495
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.45
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	4293000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	5085000	USD
	us-gaap	Net Income Loss NetIncomeLoss	10894000	USD
	us-gaap	Net Income Loss NetIncomeLoss	17556000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-377000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	64000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	3860000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	3302000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	0	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-4000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-4000	USD
	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-5000	USD
CY2020Q3	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	10000	USD
CY2019Q3	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	14000	USD
	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	30000	USD
	fbiz	Other Comprehensive Income Loss Amortizationof Net Unrealized Losses Transferredto Heldto Maturityfrom Availablefor Salebeforetax OtherComprehensiveIncomeLossAmortizationofNetUnrealizedLossesTransferredtoHeldtoMaturityfromAvailableforSalebeforetax	42000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	389000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-846000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-3654000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-3310000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	6000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	-195000	USD
	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	62000	USD
	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	10000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	16000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-569000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	178000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	29000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	4309000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	4516000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	11072000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	17585000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	180707000	USD
CY2019Q1	us-gaap	Income Tax Effects Allocated Directly To Equity Cumulative Effect Of Change In Accounting Principle IncomeTaxEffectsAllocatedDirectlyToEquityCumulativeEffectOfChangeInAccountingPrinciple	687000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	5899000	USD
CY2019Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	279000	USD
CY2019Q1	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	318000	USD
CY2019Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.15
CY2019Q1	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	1312000	USD
CY2019Q1	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	1478000	USD
CY2019Q1	us-gaap	Stockholders Equity StockholdersEquity	185100000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	6572000	USD
CY2019Q2	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	319000	USD
CY2019Q2	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	410000	USD
CY2019Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.15
CY2019Q2	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	1315000	USD
CY2019Q2	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	2231000	USD
CY2019Q2	us-gaap	Stockholders Equity StockholdersEquity	188855000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-569000	USD
CY2019Q3	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	390000	USD
CY2019Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.15
CY2019Q3	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	1298000	USD
CY2019Q3	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	1671000	USD
CY2019Q3	us-gaap	Stockholders Equity StockholdersEquity	190792000	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
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	4293000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	16000	USD
CY2020Q3	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	499000	USD
CY2020Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.165
CY2020Q3	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	1415000	USD
CY2020Q3	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	170000	USD
CY2020Q3	us-gaap	Stockholders Equity StockholdersEquity	200785000	USD
	us-gaap	Net Income Loss NetIncomeLoss	10894000	USD
	us-gaap	Net Income Loss NetIncomeLoss	17556000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-2291000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	105000	USD
	fbiz	Impairmentof Tax Credit Investments ImpairmentofTaxCreditInvestments	2066000	USD
	fbiz	Impairmentof Tax Credit Investments ImpairmentofTaxCreditInvestments	3982000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	12487000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	613000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	53000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	167000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	2509000	USD
	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	2252000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	1432000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	1118000	USD
	fbiz	Gain On Sale Of State Tax Credit GainOnSaleOfStateTaxCredit	0	USD
	fbiz	Gain On Sale Of State Tax Credit GainOnSaleOfStateTaxCredit	206000	USD
	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-4000	USD
	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-5000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1037000	USD
	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	894000	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	56923000	USD
	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	39799000	USD
	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	48676000	USD
	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	43009000	USD
	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	1598000	USD
	us-gaap	Gain Loss On Sale Of Loans And Leases GainLossOnSaleOfLoansAndLeases	993000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-329000	USD
	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-241000	USD
	us-gaap	Valuation Allowance For Impairment Of Recognized Servicing Assets Period Increase Decrease ValuationAllowanceForImpairmentOfRecognizedServicingAssetsPeriodIncreaseDecrease	-3000	USD
	us-gaap	Valuation Allowance For Impairment Of Recognized Servicing Assets Period Increase Decrease ValuationAllowanceForImpairmentOfRecognizedServicingAssetsPeriodIncreaseDecrease	25000	USD
	us-gaap	Excess Tax Benefit From Share Based Compensation Operating Activities ExcessTaxBenefitFromShareBasedCompensationOperatingActivities	35000	USD
	us-gaap	Excess Tax Benefit From Share Based Compensation Operating Activities ExcessTaxBenefitFromShareBasedCompensationOperatingActivities	74000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	1166000	USD
	us-gaap	Operating Lease Payments OperatingLeasePayments	1143000	USD
	us-gaap	Proceeds From Lease Payments ProceedsFromLeasePayments	84000	USD
	us-gaap	Proceeds From Lease Payments ProceedsFromLeasePayments	0	USD
	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	52492000	USD
	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	24918000	USD
	us-gaap	Increase Decrease In Accrued Liabilities And Other Operating Liabilities IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities	42429000	USD
	us-gaap	Increase Decrease In Accrued Liabilities And Other Operating Liabilities IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities	19710000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	5418000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	20756000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	40353000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	21225000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	3759000	USD
	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	4282000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	839000	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	15249000	USD
	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	43751000	USD
	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	55608000	USD
	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	2057000	USD
	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	0	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	456933000	USD
	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	104229000	USD
	us-gaap	Payments To Acquire Limited Partnership Interests PaymentsToAcquireLimitedPartnershipInterests	750000	USD
	us-gaap	Payments To Acquire Limited Partnership Interests PaymentsToAcquireLimitedPartnershipInterests	1250000	USD
	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	0	USD
	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	1499000	USD
	fbiz	Paymentsto Acquire Historic Development Entities PaymentstoAcquireHistoricDevelopmentEntities	259000	USD
	fbiz	Paymentsto Acquire Historic Development Entities PaymentstoAcquireHistoricDevelopmentEntities	4505000	USD
	fbiz	Distributionfromhistoricdevelopmententities Distributionfromhistoricdevelopmententities	30000	USD
	fbiz	Distributionfromhistoricdevelopmententities Distributionfromhistoricdevelopmententities	0	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	13422000	USD
	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	4700000	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	6222000	USD
	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	3625000	USD
	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	204000	USD
	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	108000	USD
	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	8000000	USD
	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	0	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-470059000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-124520000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	290996000	USD
	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	53517000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	979200000	USD
	us-gaap	Proceeds From Federal Home Loan Bank Borrowings ProceedsFromFederalHomeLoanBankBorrowings	435000000	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	845444000	USD
	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	401000000	USD
	fbiz	Losson Early Extinguishmentof Debt Financing Activities LossonEarlyExtinguishmentofDebtFinancingActivities	744000	USD
	fbiz	Losson Early Extinguishmentof Debt Financing Activities LossonEarlyExtinguishmentofDebtFinancingActivities	0	USD
	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	USD
	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	15000000	USD
	us-gaap	Proceeds From Issuance Of Subordinated Long Term Debt ProceedsFromIssuanceOfSubordinatedLongTermDebt	0	USD
	us-gaap	Proceeds From Issuance Of Subordinated Long Term Debt ProceedsFromIssuanceOfSubordinatedLongTermDebt	15000000	USD
	fbiz	Proceedsfromthe Federal Paycheck Protection Program Lending Facility Investing Activities ProceedsfromtheFederalPaycheckProtectionProgramLendingFacilityInvestingActivities	29605000	USD
	fbiz	Proceedsfromthe Federal Paycheck Protection Program Lending Facility Investing Activities ProceedsfromtheFederalPaycheckProtectionProgramLendingFacilityInvestingActivities	0	USD
	us-gaap	Proceeds From Repayments Of Notes Payable ProceedsFromRepaymentsOfNotesPayable	41000	USD
	us-gaap	Proceeds From Repayments Of Notes Payable ProceedsFromRepaymentsOfNotesPayable	-36000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	4239000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	3925000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1636000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	5380000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	449267000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	78176000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-15374000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-25588000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	67102000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	86546000	USD
CY2020Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	51728000	USD
CY2019Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	60958000	USD
	us-gaap	Interest Paid Net InterestPaidNet	15223000	USD
	us-gaap	Interest Paid Net InterestPaidNet	25828000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	3436000	USD
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	1303000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	190000	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	80000	USD
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	596000	USD
	us-gaap	Use Of Estimates UseOfEstimates	Management of the Corporation is required to make estimates and assumptions that 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.
	fbiz	Increasein Loansand Leases Receivable Allowance IncreaseinLoansandLeasesReceivableAllowance	11300000	USD
	fbiz	Percent Increasein Loansand Leases Receivable Allowance PercentIncreaseinLoansandLeasesReceivableAllowance	0.579
	fbiz	Provision For Loan And Lease Losses Specific Reserves Increase Decrease During The Period ProvisionForLoanAndLeaseLossesSpecificReservesIncreaseDecreaseDuringThePeriod	5500000	USD
	fbiz	Financing Receivable Allowancefor Credit Losses Increasedueto Economic Conditions FinancingReceivableAllowanceforCreditLossesIncreaseduetoEconomicConditions	4700000	USD
CY2020Q3	fbiz	Numberof Short Term Loan Modifications NumberofShortTermLoanModifications	60
CY2020Q3	fbiz	Gross Loansand Leases Outstanding Short Term Modification GrossLoansandLeasesOutstandingShortTermModification	131500000	USD
CY2020Q3	fbiz	Gross Loansand Leases Outstanding Short Term Modification Percent6 Month Deferral Period GrossLoansandLeasesOutstandingShortTermModificationPercent6MonthDeferralPeriod	0.071
CY2020Q2	fbiz	Gross Loansand Leases Outstanding Short Term Modification GrossLoansandLeasesOutstandingShortTermModification	323200000	USD
CY2020Q2	fbiz	Gross Loansand Leases Outstanding Short Term Modification Percent6 Month Deferral Period GrossLoansandLeasesOutstandingShortTermModificationPercent6MonthDeferralPeriod	0.186
CY2020Q3	fbiz	Sba Paycheck Protection Program Loans Outstanding Gross Amount SBAPaycheckProtectionProgramLoansOutstandingGrossAmount	332300000	USD
CY2020Q3	fbiz	Sba Paycheck Protection Program Loan Leases Receiveable Deferred Income SBAPaycheckProtectionProgramLoanLeasesReceiveableDeferredIncome	6900000	USD
CY2020Q3	fbiz	Sba Paycheck Protection Program Interest Income Loans SBAPaycheckProtectionProgramInterestIncomeLoans	1100000	USD
	fbiz	Sba Paycheck Protection Program Interest Income Loans SBAPaycheckProtectionProgramInterestIncomeLoans	2000000.0	USD
	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2020Q3	us-gaap	Equity Fair Value Disclosure EquityFairValueDisclosure	289000000.0	USD
CY2020Q3	us-gaap	Reporting Unit Amount Of Fair Value In Excess Of Carrying Amount ReportingUnitAmountOfFairValueInExcessOfCarryingAmount	89400000	USD
CY2020Q3	us-gaap	Reporting Unit Percentage Of Fair Value In Excess Of Carrying Amount ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount	0.448
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	4293000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	5085000	USD
	us-gaap	Net Income Loss NetIncomeLoss	10894000	USD
	us-gaap	Net Income Loss NetIncomeLoss	17556000	USD
CY2020Q3	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	110000	USD
CY2019Q3	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	111000	USD
	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	284000	USD
	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	340000	USD
CY2020Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	4183000	USD
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8380676	shares
CY2019Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	4974000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	10610000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	17216000	USD
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8404084	shares
CY2019Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8492445	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8380676	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8546192	shares
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.50
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.01
CY2020Q3	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	4183000	USD
CY2019Q3	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	4974000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	10610000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	17216000	USD
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8404084	shares
CY2019Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8492445	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8546192	shares
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.50
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.59
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.27
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.01
CY2020Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	151899	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	131621	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	21.02
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	95265	shares
CY2019	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	23.64
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	48207	shares
CY2019	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	20.62
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	1744	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	23.67
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
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	75345	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	26.10
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	49978	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	22.27
	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	10714	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	22.89
CY2020Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	191588	shares
CY2020Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	24.30
CY2020Q3	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	3700000	USD
	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P2Y3M18D
CY2020Q3	us-gaap	Share Based Compensation ShareBasedCompensation	499000	USD
CY2019Q3	us-gaap	Share Based Compensation ShareBasedCompensation	390000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	1432000	USD
	us-gaap	Share Based Compensation ShareBasedCompensation	1118000	USD
CY2020Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	174596000	USD
CY2020Q3	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	4780000	USD
CY2020Q3	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	102000	USD
CY2020Q3	us-gaap	Available For Sale Securities AvailableForSaleSecurities	179274000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	172319000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	1331000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	517000	USD
CY2019Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	173133000	USD
CY2020Q3	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	28897000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	1088000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	21000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	29964000	USD
CY2019Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	32700000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	528000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	40000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	33188000	USD
CY2020Q3	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	0	securities
	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	1	securities
CY2019Q3	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	37000	securities
	fbiz	Numberofavailableforsalesecuritiessold Numberofavailableforsalesecuritiessold	46	securities
CY2020Q3	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	79800000	USD
CY2019Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	30300000	USD
CY2020Q3	fbiz	Pledged Financial Instruments Not Separately Reported Securities Pledged Fair Value PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledgedFairValue	129300000	USD
CY2019Q4	fbiz	Pledged Financial Instruments Not Separately Reported Securities Pledged Fair Value PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledgedFairValue	0	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	0	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	0	USD
CY2020Q3	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	2804000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Next Rolling Twelve Months Fair Value HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	2823000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	8148000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	8439000	USD
CY2020Q3	fbiz	Heldtomaturity Securities Debt Maturities Rolling Years Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearsTwoThroughFiveAmortizedCost	12085000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Two Through Five Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	12344000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	33651000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	35229000	USD
CY2020Q3	fbiz	Heldtomaturity Securities Debt Maturities Rolling Years Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearsSixThroughTenAmortizedCost	10872000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Six Through Ten Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	11513000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	132797000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	135606000	USD
CY2020Q3	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	3136000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Debt Maturities Rolling After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue	3284000	USD
CY2020Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	174596000	USD
CY2020Q3	us-gaap	Available For Sale Securities AvailableForSaleSecurities	179274000	USD
CY2020Q3	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	28897000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	29964000	USD
CY2020Q3	us-gaap	Availableforsale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions1 AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1	12	securities
CY2020Q3	us-gaap	Availableforsale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositionsGreaterThanOrEqualToOneYear	1	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
CY2019Q3	us-gaap	Other Than Temporary Impairment Losses Investments Availableforsale Securities OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities	0	USD
CY2020Q3	us-gaap	Other Than Temporary Impairment Losses Investments Availableforsale Securities OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities	0	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	30508000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	69000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	4086000	USD
CY2019Q4	us-gaap	Deposits Deposits	1530379000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	33000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	34594000	USD
CY2020Q3	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	102000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	48199000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	272000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	17078000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	245000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	65277000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	517000	USD
CY2020Q3	us-gaap	Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions HeldToMaturitySecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions	2	securities
CY2020Q3	fbiz	Heldto Maturity Securities Securitiesin Unrealized Loss Positions Qualitative Disclosures Numberof Positions12monthsorgreater HeldtoMaturitySecuritiesSecuritiesinUnrealizedLossPositionsQualitativeDisclosuresNumberofPositions12monthsorgreater	1	securities
CY2019Q3	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
CY2020Q3	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
CY2019Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	1863000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	13000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	4031000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	27000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue	5894000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	40000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2178056000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	1715376000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	30817000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	19520000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	7757000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	741000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	2139482000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	1695115000	USD
CY2020Q3	fbiz	Small Business Administration7a Loans SmallBusinessAdministration7aLoans	41380000	USD
CY2019Q4	fbiz	Small Business Administration7a Loans SmallBusinessAdministration7aLoans	40402000	USD
CY2020Q3	fbiz	Small Business Administration504 Loans SmallBusinessAdministration504Loans	24833000	USD
CY2019Q4	fbiz	Small Business Administration504 Loans SmallBusinessAdministration504Loans	20592000	USD
CY2020Q3	fbiz	Small Business Administration Express Loans SmallBusinessAdministrationExpressLoans	1591000	USD
CY2019Q4	fbiz	Small Business Administration Express Loans SmallBusinessAdministrationExpressLoans	1781000	USD
CY2020Q3	fbiz	Small Business Administration Paycheck Protection Program Loans SmallBusinessAdministrationPaycheckProtectionProgramLoans	332342000	USD
CY2019Q4	fbiz	Small Business Administration Paycheck Protection Program Loans SmallBusinessAdministrationPaycheckProtectionProgramLoans	0	USD
CY2020Q3	fbiz	Small Business Administration Loans SmallBusinessAdministrationLoans	400146000	USD
CY2019Q4	fbiz	Small Business Administration Loans SmallBusinessAdministrationLoans	62775000	USD
CY2020Q3	fbiz	Sb Aloansintheparticipationsoldportfolioconsideredimpaired SBAloansintheparticipationsoldportfolioconsideredimpaired	9600000	USD
CY2019Q4	fbiz	Sb Aloansintheparticipationsoldportfolioconsideredimpaired SBAloansintheparticipationsoldportfolioconsideredimpaired	12100000	USD
CY2020Q3	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	7900000	USD
CY2019Q3	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	4900000	USD
	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	17200000	USD
	fbiz	Guaranteed Portionof Sba Loans Soldto Third Parties Total GuaranteedPortionofSBALoansSoldtoThirdPartiesTotal	10500000	USD
CY2020Q3	fbiz	Totalamountofoutstanding Sb Aloanssold TotalamountofoutstandingSBAloanssold	75100000	USD
CY2019Q4	fbiz	Totalamountofoutstanding Sb Aloanssold TotalamountofoutstandingSBAloanssold	73800000	USD
CY2020Q3	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	7700000	USD
CY2019Q3	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	7500000	USD
	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	29900000	USD
	fbiz	Loans And Leases Transferred To Third Parties Total Principal Amount LoansAndLeasesTransferredToThirdPartiesTotalPrincipalAmount	31500000	USD
	fbiz	Gain Loss Recognizedon Participation Interestin Originated Loans GainLossRecognizedonParticipationInterestinOriginatedLoans	0	USD
CY2020Q3	fbiz	Total Amount Of Outstanding Loans Transferred To Third Parties As Loan Participations TotalAmountOfOutstandingLoansTransferredToThirdPartiesAsLoanParticipations	144100000	USD
CY2019Q4	fbiz	Total Amount Of Outstanding Loans Transferred To Third Parties As Loan Participations TotalAmountOfOutstandingLoansTransferredToThirdPartiesAsLoanParticipations	142800000	USD
CY2020Q3	fbiz	Total Amount Of Loan Participations Remaining On Corporations Balance Sheet TotalAmountOfLoanParticipationsRemainingOnCorporationsBalanceSheet	266700000	USD
CY2019Q4	fbiz	Total Amount Of Loan Participations Remaining On Corporations Balance Sheet TotalAmountOfLoanParticipationsRemainingOnCorporationsBalanceSheet	244600000	USD
CY2020Q3	fbiz	Loans In The Participation Sold Portfolio Considered Impaired Gross Amount LoansInTheParticipationSoldPortfolioConsideredImpairedGrossAmount	5800000	USD
CY2020Q3	fbiz	Loans In The Participation Sold Portfolio Considered Impaired Sold Amount LoansInTheParticipationSoldPortfolioConsideredImpairedSoldAmount	4200000	USD
CY2019Q4	fbiz	Loans In The Participation Sold Portfolio Considered Impaired Gross Amount LoansInTheParticipationSoldPortfolioConsideredImpairedGrossAmount	0	USD
CY2020Q3	fbiz	Loan Participations Purchased On Corporations Balance Sheet LoanParticipationsPurchasedOnCorporationsBalanceSheet	424000	USD
CY2019Q4	fbiz	Loan Participations Purchased On Corporations Balance Sheet LoanParticipationsPurchasedOnCorporationsBalanceSheet	492000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2178056000	USD
CY2020Q3	fbiz	Category Rating As Percentage Of Total Loans And Leases CategoryRatingAsPercentageOfTotalLoansAndLeases	1.0000
CY2019Q4	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	1715376000	USD
CY2019Q4	fbiz	Category Rating As Percentage Of Total Loans And Leases CategoryRatingAsPercentageOfTotalLoansAndLeases	1.0000
CY2020Q3	us-gaap	Financing Receivable Recorded Investment Past Due FinancingReceivableRecordedInvestmentPastDue	10372000	USD
CY2020Q3	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	2167684000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	2178056000	USD
CY2020Q3	fbiz	Financing Receivable Recorded Investment30 To59 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment30To59DaysPastDuePercentOfPortfolio	0.0007
CY2020Q3	fbiz	Financing Receivable Recorded Investment60 To89 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment60To89DaysPastDuePercentOfPortfolio	0.0006
CY2020Q3	fbiz	Financing Receivable Recorded Investment Equal To Greater Than90 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDuePercentOfPortfolio	0.0035
CY2020Q3	fbiz	Financing Receivable Recorded Investment Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentPastDuePercentOfPortfolio	0.0048
CY2020Q3	fbiz	Financing Receivable Recorded Investment Current Percent Of Portfolio FinancingReceivableRecordedInvestmentCurrentPercentOfPortfolio	0.9952
CY2020Q3	fbiz	Financing Receivable Recorded Investment Gross Percent Of Portfolio FinancingReceivableRecordedInvestmentGrossPercentOfPortfolio	1.0000
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Past Due FinancingReceivableRecordedInvestmentPastDue	15088000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	1700288000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Before Fees Gross LoansAndLeasesReceivableBeforeFeesGross	1715376000	USD
CY2019Q4	fbiz	Financing Receivable Recorded Investment30 To59 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment30To59DaysPastDuePercentOfPortfolio	0.0043
CY2019Q4	fbiz	Financing Receivable Recorded Investment60 To89 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestment60To89DaysPastDuePercentOfPortfolio	0.0024
CY2019Q4	fbiz	Financing Receivable Recorded Investment Equal To Greater Than90 Days Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDuePercentOfPortfolio	0.0021
CY2019Q4	fbiz	Financing Receivable Recorded Investment Past Due Percent Of Portfolio FinancingReceivableRecordedInvestmentPastDuePercentOfPortfolio	0.0088
CY2019Q4	fbiz	Financing Receivable Recorded Investment Current Percent Of Portfolio FinancingReceivableRecordedInvestmentCurrentPercentOfPortfolio	0.9912
CY2019Q4	fbiz	Financing Receivable Recorded Investment Gross Percent Of Portfolio FinancingReceivableRecordedInvestmentGrossPercentOfPortfolio	1.0000
CY2020Q3	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	36050000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	20613000	USD
CY2020Q3	us-gaap	Foreclosed Assets ForeclosedAssets	613000	USD
CY2019Q4	us-gaap	Foreclosed Assets ForeclosedAssets	2919000	USD
CY2020Q3	fbiz	Total Nonperforming Assets TotalNonperformingAssets	36663000	USD
CY2019Q4	fbiz	Total Nonperforming Assets TotalNonperformingAssets	23532000	USD
CY2020Q3	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	47000	USD
CY2019Q4	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	140000	USD
CY2020Q3	fbiz	Impaired Assets ImpairedAssets	36710000	USD
CY2019Q4	fbiz	Impaired Assets ImpairedAssets	23672000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Ratio Of Nonperforming Loans To All Loans LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans	0.0166
CY2019Q4	us-gaap	Loans And Leases Receivable Ratio Of Nonperforming Loans To All Loans LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans	0.0120
CY2020Q3	fbiz	Ratio Of Total Nonperforming Assets To Gross Loans And Leases Plus Foreclosed Properties Net RatioOfTotalNonperformingAssetsToGrossLoansAndLeasesPlusForeclosedPropertiesNet	0.0168
CY2019Q4	fbiz	Ratio Of Total Nonperforming Assets To Gross Loans And Leases Plus Foreclosed Properties Net RatioOfTotalNonperformingAssetsToGrossLoansAndLeasesPlusForeclosedPropertiesNet	0.0137
CY2020Q3	fbiz	Ratio Of Total Nonperforming Assets To Total Assets RatioOfTotalNonperformingAssetsToTotalAssets	0.0141
CY2019Q4	fbiz	Ratio Of Total Nonperforming Assets To Total Assets RatioOfTotalNonperformingAssetsToTotalAssets	0.0112
CY2020Q3	fbiz	Ratio Of Allowance For Loan And Lease Losses To Total Gross Loans And Leases RatioOfAllowanceForLoanAndLeaseLossesToTotalGrossLoansAndLeases	0.0141
CY2019Q4	fbiz	Ratio Of Allowance For Loan And Lease Losses To Total Gross Loans And Leases RatioOfAllowanceForLoanAndLeaseLossesToTotalGrossLoansAndLeases	0.0114
CY2020Q3	fbiz	Ratio Of Allowance For Loan And Leases Losses To Non Accrual Loans And Leases RatioOfAllowanceForLoanAndLeasesLossesToNonAccrualLoansAndLeases	0.8548
CY2019Q4	fbiz	Ratio Of Allowance For Loan And Leases Losses To Non Accrual Loans And Leases RatioOfAllowanceForLoanAndLeasesLossesToNonAccrualLoansAndLeases	0.9470
CY2020Q3	fbiz	Non Accrual Troubled Debt Restructurings NonAccrualTroubledDebtRestructurings	15400000	USD
CY2019Q4	fbiz	Non Accrual Troubled Debt Restructurings NonAccrualTroubledDebtRestructurings	15600000	USD
CY2020Q3	fbiz	Specific Reserveson Troubled Debt Restructurings SpecificReservesonTroubledDebtRestructurings	4400000	USD
CY2019Q4	fbiz	Specific Reserveson Troubled Debt Restructurings SpecificReservesonTroubledDebtRestructurings	2700000	USD
CY2020Q3	fbiz	Unfunded Commitments Troubled Debt Restructurings UnfundedCommitmentsTroubledDebtRestructurings	0	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	7312000	USD
CY2020Q3	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	0	loans
CY2020Q3	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	0	USD
CY2020Q3	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	0	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	5861000	USD
CY2019Q3	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	4	loans
CY2019Q3	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	6578000	USD
CY2019Q3	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	6545000	USD
	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	18	loans
	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	17186000	USD
	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	16764000	USD
CY2020Q3	us-gaap	Impaired Financing Receivable With No Related Allowance Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment	15557000	USD
CY2020Q3	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	23065000	USD
	us-gaap	Impaired Financing Receivable With No Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment	15564000	USD
	fbiz	Impaired Financing Receivable With No Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceForegoneInterestIncome	1043000	USD
	us-gaap	Impaired Financing Receivable With No Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod	467000	USD
	fbiz	Impaired Financing Receivable With No Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceNetForegoneInterestIncome	576000	USD
CY2020Q3	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	20540000	USD
CY2020Q3	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	23221000	USD
CY2020Q3	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	8898000	USD
	us-gaap	Impaired Financing Receivable With Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment	9335000	USD
	fbiz	Impaired Financing Receivable With Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceForegoneInterestIncome	1006000	USD
	us-gaap	Impaired Financing Receivable With Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod	0	USD
	fbiz	Impaired Financing Receivable With Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceNetForegoneInterestIncome	1006000	USD
CY2020Q3	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	36097000	USD
CY2020Q3	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	46286000	USD
CY2020Q3	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	8898000	USD
	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	24899000	USD
	fbiz	Impaired Financing Receivable Foregone Interest Income ImpairedFinancingReceivableForegoneInterestIncome	2049000	USD
	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	467000	USD
	fbiz	Impaired Financing Receivable Net Foregone Interest Income ImpairedFinancingReceivableNetForegoneInterestIncome	1582000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance	14050000	USD
CY2019	us-gaap	Impaired Financing Receivable With No Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment	20212000	USD
CY2019	fbiz	Impaired Financing Receivable With No Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceForegoneInterestIncome	1257000	USD
CY2019	us-gaap	Impaired Financing Receivable With No Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod	793000	USD
CY2019	fbiz	Impaired Financing Receivable With No Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithNoRelatedAllowanceNetForegoneInterestIncome	464000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With Related Allowance Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment	13441000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable With Related Allowance Unpaid Principal Balance ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance	16183000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	3365000	USD
CY2019	us-gaap	Impaired Financing Receivable With Related Allowance Average Recorded Investment ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment	3878000	USD
CY2019	fbiz	Impaired Financing Receivable With Related Allowance Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceForegoneInterestIncome	1436000	USD
CY2019	us-gaap	Impaired Financing Receivable With Related Allowance Interest Income Cash Basis Method ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod	0	USD
CY2019	fbiz	Impaired Financing Receivable With Related Allowance Net Foregone Interest Income ImpairedFinancingReceivableWithRelatedAllowanceNetForegoneInterestIncome	1436000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	20753000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	30233000	USD
CY2019Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	3365000	USD
CY2019	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	24090000	USD
CY2019	fbiz	Impaired Financing Receivable Foregone Interest Income ImpairedFinancingReceivableForegoneInterestIncome	2693000	USD
CY2019	us-gaap	Impaired Financing Receivable Interest Income Cash Basis Method ImpairedFinancingReceivableInterestIncomeCashBasisMethod	793000	USD
CY2019	fbiz	Impaired Financing Receivable Net Foregone Interest Income ImpairedFinancingReceivableNetForegoneInterestIncome	1900000	USD
CY2020Q3	fbiz	Loans And Leases Receivable Difference Between Recorded Investment And Unpaid Principal Balance LoansAndLeasesReceivableDifferenceBetweenRecordedInvestmentAndUnpaidPrincipalBalance	10200000	USD
CY2019Q4	fbiz	Loans And Leases Receivable Difference Between Recorded Investment And Unpaid Principal Balance LoansAndLeasesReceivableDifferenceBetweenRecordedInvestmentAndUnpaidPrincipalBalance	9500000	USD
CY2020Q3	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	47000	USD
CY2019Q4	fbiz	Financing Receivable Modifications Performing Troubled Debt Restructuring FinancingReceivableModificationsPerformingTroubledDebtRestructuring	140000	USD
CY2020Q2	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	27464000	USD
CY2020Q3	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	505000	USD
CY2020Q3	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	23000	USD
CY2020Q3	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	-482000	USD
CY2020Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	3835000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	30817000	USD
CY2019Q2	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	19819000	USD
CY2019Q3	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	1099000	USD
CY2019Q3	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	101000	USD
CY2019Q3	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	-998000	USD
CY2019Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	1349000	USD
CY2019Q3	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	20170000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	19520000	USD
	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	1454000	USD
	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	264000	USD
	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	-1190000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	12487000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	30817000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	20425000	USD
	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	1162000	USD
	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	294000	USD
	us-gaap	Allowance For Loan And Lease Losses Writeoffs Net AllowanceForLoanAndLeaseLossesWriteoffsNet	-868000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	613000	USD
CY2019Q3	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	20170000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	21919000	USD
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	8898000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	30817000	USD
CY2020Q3	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	2141959000	USD
CY2020Q3	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	36097000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	2178056000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	16155000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	3365000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	19520000	USD
CY2019Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	1694623000	USD
CY2019Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	20753000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	1715376000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	190000	USD
CY2020Q3	us-gaap	Operating Lease Expense OperatingLeaseExpense	373000	USD
CY2019Q3	us-gaap	Operating Lease Expense OperatingLeaseExpense	391000	USD
	us-gaap	Operating Lease Expense OperatingLeaseExpense	1116000	USD
	us-gaap	Operating Lease Expense OperatingLeaseExpense	1172000	USD
CY2020Q3	us-gaap	Short Term Lease Cost ShortTermLeaseCost	52000	USD
CY2019Q3	us-gaap	Short Term Lease Cost ShortTermLeaseCost	56000	USD
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	174000	USD
	us-gaap	Short Term Lease Cost ShortTermLeaseCost	197000	USD
CY2020Q3	us-gaap	Variable Lease Cost VariableLeaseCost	141000	USD
CY2019Q3	us-gaap	Variable Lease Cost VariableLeaseCost	129000	USD
	us-gaap	Variable Lease Cost VariableLeaseCost	394000	USD
	us-gaap	Variable Lease Cost VariableLeaseCost	366000	USD
CY2020Q3	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	28000	USD
CY2019Q3	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	0	USD
	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	84000	USD
	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	0	USD
CY2020Q3	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	538000	USD
CY2019Q3	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	576000	USD
	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	1600000	USD
	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	1735000	USD
CY2020Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P5Y11M12D
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P6Y6M21D
CY2020Q3	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0300
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0309
CY2020Q3	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	391000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	1557000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	1373000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	1015000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	756000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	2307000	USD
CY2020Q3	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	7399000	USD
CY2020Q3	fbiz	Discountonoperatingleasecashflows Discountonoperatingleasecashflows	671000	USD
CY2020Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	6728000	USD
CY2020Q3	us-gaap	Interest Receivable InterestReceivable	9938000	USD
CY2019Q4	us-gaap	Interest Receivable InterestReceivable	5760000	USD
CY2020Q3	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	7588000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	5353000	USD
CY2020Q3	fbiz	Investmentin Historic Development Entities InvestmentinHistoricDevelopmentEntities	2345000	USD
CY2019Q4	fbiz	Investmentin Historic Development Entities InvestmentinHistoricDevelopmentEntities	2216000	USD
CY2020Q3	fbiz	Investmentin Community Development Entities InvestmentinCommunityDevelopmentEntities	5189000	USD
CY2019Q4	fbiz	Investmentin Community Development Entities InvestmentinCommunityDevelopmentEntities	5571000	USD
CY2020Q3	fbiz	Investmentin Limited Partnerships InvestmentinLimitedPartnerships	5641000	USD
CY2019Q4	fbiz	Investmentin Limited Partnerships InvestmentinLimitedPartnerships	4476000	USD
CY2020Q3	fbiz	Investmentin Trust Ii InvestmentinTrustII	315000	USD
CY2019Q4	fbiz	Investmentin Trust Ii InvestmentinTrustII	315000	USD
CY2020Q3	us-gaap	Interest Rate Derivative Assets At Fair Value InterestRateDerivativeAssetsAtFairValue	58210000	USD
CY2019Q4	us-gaap	Interest Rate Derivative Assets At Fair Value InterestRateDerivativeAssetsAtFairValue	18346000	USD
CY2020Q3	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	2402000	USD
CY2019Q4	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	2285000	USD
CY2020Q3	us-gaap	Other Assets Miscellaneous OtherAssetsMiscellaneous	7930000	USD
CY2019Q4	us-gaap	Other Assets Miscellaneous OtherAssetsMiscellaneous	4184000	USD
CY2020Q3	us-gaap	Other Assets OtherAssets	99558000	USD
CY2019Q4	us-gaap	Other Assets OtherAssets	48506000	USD
CY2020Q3	us-gaap	Deposits Deposits	1821375000	USD
	fbiz	Average Balance Deposits AverageBalanceDeposits	1660372000	USD
	fbiz	Deposits Weighted Average Interest Rate Duringthe Period DepositsWeightedAverageInterestRateDuringthePeriod	0.0062
CY2019Q4	us-gaap	Deposits Deposits	1530379000	USD
CY2019	fbiz	Average Balance Deposits AverageBalanceDeposits	1496430000	USD
CY2019	fbiz	Deposits Weighted Average Interest Rate Duringthe Period DepositsWeightedAverageInterestRateDuringthePeriod	0.0153
CY2020Q3	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	493575000	USD
	fbiz	Borrowed Funds Average Balance BorrowedFundsAverageBalance	423135000	USD
	us-gaap	Debt Instrument Interest Rate During Period DebtInstrumentInterestRateDuringPeriod	0.0195
CY2019Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	329429000	USD
CY2019Q3	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	-427000	USD
CY2019	fbiz	Borrowed Funds Average Balance BorrowedFundsAverageBalance	321740000	USD
CY2019	us-gaap	Debt Instrument Interest Rate During Period DebtInstrumentInterestRateDuringPeriod	0.0287
CY2020Q3	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	493575000	USD
CY2019Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	329429000	USD
	us-gaap	Line Of Credit Facility Commitment Fee Amount LineOfCreditFacilityCommitmentFeeAmount	10000	USD
	us-gaap	Line Of Credit Facility Commitment Fee Amount LineOfCreditFacilityCommitmentFeeAmount	10000	USD
CY2020Q3	fbiz	Sba Loans Probabilityof Future Losses SBALoansProbabilityofFutureLosses	1100000	USD
CY2020Q2	fbiz	Sba Recourse Reserve SBARecourseReserve	1007000	USD
CY2019Q2	fbiz	Sba Recourse Reserve SBARecourseReserve	2068000	USD
CY2019Q4	fbiz	Sba Recourse Reserve SBARecourseReserve	1345000	USD
CY2018Q4	fbiz	Sba Recourse Reserve SBARecourseReserve	2956000	USD
CY2020Q3	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	57000	USD
CY2020Q3	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	-4000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	53000	USD
	fbiz	Sba Recourse Provision Benefit SBARecourseProvisionBenefit	167000	USD
CY2019Q3	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	2000	USD
	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	-338000	USD
	fbiz	Sba Loan Charge Offs Net SBALoanChargeOffsNet	-1480000	USD
CY2020Q3	fbiz	Sba Recourse Reserve SBARecourseReserve	1060000	USD
CY2019Q3	fbiz	Sba Recourse Reserve SBARecourseReserve	1643000	USD
CY2020Q3	fbiz	Sba Recourse Reserve SBARecourseReserve	1060000	USD
CY2019Q3	fbiz	Sba Recourse Reserve SBARecourseReserve	1643000	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 Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3	0	USD
	fbiz	Fair Value Liabilities Level1to Level2 Transfers Amount1 FairValueLiabilitiesLevel1toLevel2TransfersAmount1	0	USD
	fbiz	Fair Value Assets Level1to Level2 Transfers Amount1 FairValueAssetsLevel1toLevel2TransfersAmount1	0	USD
	fbiz	Fair Value Assets Level2to Level1 Transfers Amount1 FairValueAssetsLevel2toLevel1TransfersAmount1	0	USD
	fbiz	Fair Value Liabilities Level1to Level2 Transfers Amount1 FairValueLiabilitiesLevel1toLevel2TransfersAmount1	0	USD
CY2020Q3	fbiz	Fair Value Assets Level2to Level1 Transfers Amount1 FairValueAssetsLevel2toLevel1TransfersAmount1	0	USD
	fbiz	Fair Value Liabilities Level2to Level1 Transfers Amount1 FairValueLiabilitiesLevel2toLevel1TransfersAmount1	0	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	0	USD
	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
CY2020Q3	fbiz	Fair Value Liabilities Level2to Level1 Transfers Amount1 FairValueLiabilitiesLevel2toLevel1TransfersAmount1	0	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	0	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	0	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
	fbiz	Fair Value Liabilities Level2to Level1 Transfers Amount1 FairValueLiabilitiesLevel2toLevel1TransfersAmount1	0	USD
CY2020Q3	fbiz	Fair Value Liabilities Level1to Level2 Transfers Amount1 FairValueLiabilitiesLevel1toLevel2TransfersAmount1	0	USD
	fbiz	Fair Value Assets Level1to Level2 Transfers Amount1 FairValueAssetsLevel1toLevel2TransfersAmount1	0	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3	0	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2020Q3	fbiz	Fair Value Assets Level1to Level2 Transfers Amount1 FairValueAssetsLevel1toLevel2TransfersAmount1	0	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3	0	USD
CY2020Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	51728000	USD
CY2020Q3	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	51728000	USD
CY2020Q3	us-gaap	Available For Sale Securities AvailableForSaleSecurities	179274000	USD
CY2020Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	179274000	USD
CY2020Q3	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	28897000	USD
CY2020Q3	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	29964000	USD
CY2020Q3	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	15049000	USD
CY2020Q3	us-gaap	Loans Held For Sale Fair Value Disclosure LoansHeldForSaleFairValueDisclosure	16404000	USD
CY2020Q3	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	2139482000	USD
CY2020Q3	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	2136174000	USD
CY2020Q3	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	15153000	USD
CY2020Q3	us-gaap	Interest Receivable InterestReceivable	9938000	USD
CY2020Q3	fbiz	Accrued Interest Receivable Fair Value Disclosure AccruedInterestReceivableFairValueDisclosure	9938000	USD
CY2020Q3	us-gaap	Deposits Deposits	1821375000	USD
CY2020Q3	us-gaap	Deposits Fair Value Disclosure DepositsFairValueDisclosure	1823640000	USD
CY2020Q3	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust	10058000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	7953000	USD
CY2020Q3	fbiz	Federal Home Loan Bank And Other Borrowings FederalHomeLoanBankAndOtherBorrowings	483517000	USD
CY2020Q3	fbiz	Federal Home Loan Bank And Other Borrowings Fair Value Disclosure FederalHomeLoanBankAndOtherBorrowingsFairValueDisclosure	492911000	USD
CY2020Q3	us-gaap	Fair Value Liabilities Measured On Recurring Basis Subordinated Debt Obligations FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations	9982000	USD
CY2020Q3	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	1509000	USD
CY2020Q3	us-gaap	Accrued Liabilities Fair Value Disclosure AccruedLiabilitiesFairValueDisclosure	1509000	USD
CY2020Q3	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	51000	USD
CY2020Q3	fbiz	Standby Letters Of Credit Fair Value Disclosure StandbyLettersOfCreditFairValueDisclosure	51000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	67102000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	67102000	USD
CY2019Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	173133000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	173133000	USD
CY2019Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	32700000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	33188000	USD
CY2019Q4	us-gaap	Loans Receivable Held For Sale Amount LoansReceivableHeldForSaleAmount	5205000	USD
CY2019Q4	us-gaap	Loans Held For Sale Fair Value Disclosure LoansHeldForSaleFairValueDisclosure	5673000	USD
CY2019Q4	us-gaap	Interest Receivable InterestReceivable	5760000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	1695115000	USD
CY2019Q4	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	1706201000	USD
CY2019Q4	us-gaap	Deposits Fair Value Disclosure DepositsFairValueDisclosure	1532517000	USD
CY2019Q4	fbiz	Accrued Interest Receivable Fair Value Disclosure AccruedInterestReceivableFairValueDisclosure	5760000	USD
CY2019Q4	fbiz	Federal Home Loan Bank And Other Borrowings FederalHomeLoanBankAndOtherBorrowings	319382000	USD
CY2020Q3	fbiz	Common Equity Tier One Capitalto Risk Weighted Assets CommonEquityTierOneCapitaltoRiskWeightedAssets	0.0864
CY2020Q3	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	99410000	USD
CY2019Q4	fbiz	Federal Home Loan Bank And Other Borrowings Fair Value Disclosure FederalHomeLoanBankAndOtherBorrowingsFairValueDisclosure	319507000	USD
CY2019Q4	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust	10047000	USD
CY2019Q4	us-gaap	Fair Value Liabilities Measured On Recurring Basis Subordinated Debt Obligations FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations	9970000	USD
CY2019Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	2882000	USD
CY2019Q4	us-gaap	Accrued Liabilities Fair Value Disclosure AccruedLiabilitiesFairValueDisclosure	2282000	USD
CY2019Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	63000	USD
CY2019Q4	fbiz	Standby Letters Of Credit Fair Value Disclosure StandbyLettersOfCreditFairValueDisclosure	63000	USD
CY2020Q3	fbiz	Interest Rate Swaps Default InterestRateSwapsDefault	0	USD
CY2020Q3	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	0	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	389000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-3700000	USD
CY2020Q3	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	0	USD
CY2020Q3	fbiz	Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	231956000	USD
CY2020Q3	fbiz	Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.1050
CY2020Q3	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	200922000	USD
CY2020Q3	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.0909
CY2020Q3	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	132546000	USD
CY2020Q3	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2020Q3	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	187774000	USD
CY2020Q3	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0850
CY2020Q3	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	190864000	USD
CY2020Q3	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacyto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0450
CY2020Q3	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	154637000	USD
CY2020Q3	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0700
CY2020Q3	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	200922000	USD
CY2020Q3	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Asset At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue	58210000	USD
CY2020Q3	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Liability At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue	58210000	USD
CY2019Q4	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Asset At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue	18346000	USD
CY2019Q4	us-gaap	Interest Rate Derivative Instruments Not Designated As Hedging Instruments Liability At Fair Value InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue	18346000	USD
CY2020Q3	fbiz	Effectiveportionofinterestratecashflowhedge Fair Valueincludedinaccumulatedothercomprehensiveincome EffectiveportionofinterestratecashflowhedgeFairValueincludedinaccumulatedothercomprehensiveincome	6193000	USD
CY2020Q3	us-gaap	Interest Rate Cash Flow Hedge Liability At Fair Value InterestRateCashFlowHedgeLiabilityAtFairValue	6193000	USD
CY2019Q4	fbiz	Effectiveportionofinterestratecashflowhedge Fair Valueincludedinaccumulatedothercomprehensiveincome EffectiveportionofinterestratecashflowhedgeFairValueincludedinaccumulatedothercomprehensiveincome	2539000	USD
CY2019Q4	us-gaap	Interest Rate Cash Flow Hedge Liability At Fair Value InterestRateCashFlowHedgeLiabilityAtFairValue	2539000	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.
CY2020Q3	us-gaap	Capital Capital	252325000	USD
CY2020Q3	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1142
CY2020Q3	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	176728000	USD
CY2020Q3	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2019Q4	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0850
CY2019Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	184409000	USD
CY2019Q4	fbiz	Common Equity Tier One Capitalto Risk Weighted Assets CommonEquityTierOneCapitaltoRiskWeightedAssets	0.0927
CY2019Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	89541000	USD
CY2019Q4	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacyto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacytoRiskWeightedAssets	0.0450
CY2019Q4	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	139286000	USD
CY2019Q4	fbiz	Common Equity Tier One Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0700
CY2019Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	194456000	USD
CY2019Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.0927
CY2019Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	83950000	USD
CY2019Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2019Q4	fbiz	Tier One Leverage Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneLeverageCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	83950000	USD
CY2019Q4	fbiz	Tier One Leverage Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets TierOneLeverageCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0400
CY2020Q3	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.0804
CY2020Q3	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	99940000	USD
CY2020Q3	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2020Q3	fbiz	Tier One Leverage Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneLeverageCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	99940000	USD
CY2020Q3	fbiz	Tier One Leverage Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets TierOneLeverageCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.0400
CY2019Q4	us-gaap	Capital Capital	239029000	USD
CY2019Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1201
CY2019Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	159185000	USD
CY2019Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2019Q4	fbiz	Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer CapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	208930000	USD
CY2019Q4	fbiz	Capital Requiredfor Capital Adequacy Plus Conservation Bufferto Risk Weighted Assets CapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets	0.1050
CY2019Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	194456000	USD
CY2019Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.0977
CY2019Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	119388000	USD
CY2019Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2019Q4	fbiz	Tier One Risk Based Capital Requiredfor Capital Adequacy Plus Capital Conservation Buffer TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer	169134000	USD

Files In Submission

Name	View Source	Status
0001521951-20-000065-index-headers.html	Edgar Link	pending
0001521951-20-000065-index.html	Edgar Link	pending
0001521951-20-000065.txt	Edgar Link	pending
0001521951-20-000065-xbrl.zip	Edgar Link	pending
fbiz-20200930.htm	Edgar Link	pending
fbiz-20200930.xsd	Edgar Link	pending
fbiz-20200930_cal.xml	Edgar Link	unprocessable
fbiz-20200930_def.xml	Edgar Link	unprocessable
fbiz-20200930_htm.xml	Edgar Link	completed
fbiz-20200930_lab.xml	Edgar Link	unprocessable
fbiz-20200930_pre.xml	Edgar Link	unprocessable
fbiz20200930exhibit311.htm	Edgar Link	pending
fbiz20200930exhibit312.htm	Edgar Link	pending
fbiz20200930exhibit32.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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R82.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending

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FIRST BUSINESS FINANCIAL SERVICES, INC. Stock $fbiz

2020 Q4 Form 10-Q Financial Statement

#000152195120000065 Filed on October 23, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

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

2020 Q4 Form 10-Q Financial Statement

#000152195120000065 Filed on October 23, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

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