$BMRC
Bank of Marin Bancorp Stock $bmrc

$bmrc Overview Financials Valuation SEC Filings Company Website

2023 Q1 Form 10-K Financial Statement

#000140347523000015 Filed on March 16, 2023

Income Statement

Concept	2023 Q1	2022 Q4	2022
Revenue	$34.35M	$34.20M	$130.0M
YoY Change	12.7%	9.46%	20.02%
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	$1.227M	$946.0K	$1.800M
YoY Change	47.48%	10.0%	5.88%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$4.448M	$831.0K	$2.549M
YoY Change	669.55%	35.78%	-25.07%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$12.88M	$17.65M	$63.51M
YoY Change	-9.27%	30.16%	41.49%
Income Tax	$3.438M	$4.766M	$16.92M
% Of Pretax Income	26.7%	27.01%	26.65%
Net Earnings	$9.440M	$12.88M	$46.59M
YoY Change	-9.79%	32.6%	40.2%
Net Earnings / Revenue	27.48%	37.66%	35.82%
Basic Earnings Per Share	$0.59	$0.81	$2.93
Diluted Earnings Per Share	$0.59	$805.0K	$2.917M
COMMON SHARES
Basic Shares Outstanding	16.06M shares	16.03M shares	15.92M shares
Diluted Shares Outstanding	16.00M shares	16.00M shares	15.97M shares

Balance Sheet

Concept	2023 Q1	2022 Q4	2022
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$37.99M	$45.42M
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	$31.54M	$32.96M	$32.96M
YoY Change	2.48%	5.63%	5.63%
Goodwill	$72.75M	$72.75M
YoY Change	0.0%	0.0%
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets			$43.86M
YoY Change			229.74%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$4.135B	$4.147B	$4.147B
YoY Change	-4.51%	-3.87%	-3.86%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$23.30M	$22.95M	$22.95M
YoY Change	1.57%	-21.95%	-21.95%
Accrued Expenses	$25.43M	$26.64M	$26.64M
YoY Change	0.32%	4.88%	4.88%
Deferred Revenue
YoY Change
Short-Term Debt
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$48.73M	$49.59M	$49.59M
YoY Change	0.92%	-9.52%	-9.52%
LONG-TERM LIABILITIES
Long-Term Debt	$402.0K	$439.0K	$439.0K
YoY Change	3.61%
Other Long-Term Liabilities
YoY Change
Total Long-Term Liabilities	$402.0K	$439.0K	$439.0K
YoY Change	3.61%
TOTAL LIABILITIES
Total Short-Term Liabilities	$48.73M	$49.59M	$49.59M
Total Long-Term Liabilities	$402.0K	$439.0K	$439.0K
Total Liabilities	$3.705B	$3.735B	$3.735B
YoY Change	-5.24%	-3.32%	-3.32%
SHAREHOLDERS EQUITY
Retained Earnings	$276.2M	$270.8M
YoY Change	12.05%	12.9%
Common Stock	$216.0M	$215.1M
YoY Change	1.3%	1.19%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$430.2M	$412.1M	$412.1M
YoY Change
Total Liabilities & Shareholders Equity	$4.135B	$4.147B	$4.147B
YoY Change	-4.51%	-3.87%	-3.86%

Cashflow Statement

Concept	2023 Q1	2022 Q4	2022
OPERATING ACTIVITIES
Net Income	$9.440M	$12.88M	$46.59M
YoY Change	-9.79%	32.6%	40.2%
Depreciation, Depletion And Amortization	$1.227M	$946.0K	$1.800M
YoY Change	47.48%	10.0%	5.88%
Cash From Operating Activities	$13.44M	$16.33M	$55.28M
YoY Change	17.12%	26.36%	22.15%
INVESTING ACTIVITIES
Capital Expenditures	$1.438M	$1.504M	$2.266M
YoY Change	1006.15%	-816.19%	-317.88%
Acquisitions
YoY Change
Other Investing Activities	$13.81M	$66.44M	-$215.8M
YoY Change	-105.84%	-120.66%	-36.45%
Cash From Investing Activities	$12.37M	$64.93M	-$218.1M
YoY Change	-105.23%	-120.18%	-35.98%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-$33.25M	-221.4M	-$139.4M
YoY Change	-168.7%	-408.73%	-131.49%
NET CHANGE
Cash From Operating Activities	$13.44M	16.33M	$55.28M
Cash From Investing Activities	$12.37M	64.93M	-$218.1M
Cash From Financing Activities	-$33.25M	-221.4M	-$139.4M
Net Change In Cash	-$7.431M	-140.1M	-$302.2M
YoY Change	-95.8%	-40.9%	-305.14%
FREE CASH FLOW
Cash From Operating Activities	$13.44M	$16.33M	$55.28M
Capital Expenditures	$1.438M	$1.504M	$2.266M
Free Cash Flow	$12.01M	$14.82M	$53.01M
YoY Change	5.79%	12.89%	14.51%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2021	us-gaap	Professional Fees ProfessionalFees	4974000	usd
CY2020	us-gaap	Professional Fees ProfessionalFees	2181000	usd
CY2022	bmrc	Depreciation Depletion And Amortization Nonproduction Excluding Amortization Of Intangible Assets DepreciationDepletionAndAmortizationNonproductionExcludingAmortizationOfIntangibleAssets	1840000	usd
CY2021	bmrc	Depreciation Depletion And Amortization Nonproduction Excluding Amortization Of Intangible Assets DepreciationDepletionAndAmortizationNonproductionExcludingAmortizationOfIntangibleAssets	1740000	usd
CY2020	bmrc	Depreciation Depletion And Amortization Nonproduction Excluding Amortization Of Intangible Assets DepreciationDepletionAndAmortizationNonproductionExcludingAmortizationOfIntangibleAssets	2149000	usd
CY2022	bmrc	Information Technology InformationTechnology	2197000	usd
CY2021	bmrc	Information Technology InformationTechnology	1550000	usd
CY2020	bmrc	Information Technology InformationTechnology	1050000	usd
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1489000	usd
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1135000	usd
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	853000	usd
CY2022	us-gaap	Noninterest Expense Directors Fees NoninterestExpenseDirectorsFees	1107000	usd
CY2021	us-gaap	Noninterest Expense Directors Fees NoninterestExpenseDirectorsFees	957000	usd
CY2020	us-gaap	Noninterest Expense Directors Fees NoninterestExpenseDirectorsFees	713000	usd
CY2022	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1179000	usd
CY2021	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	889000	usd
CY2020	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	474000	usd
CY2022	bmrc	Charitable Contributions Expense CharitableContributionsExpense	709000	usd
CY2021	bmrc	Charitable Contributions Expense CharitableContributionsExpense	587000	usd
CY2020	bmrc	Charitable Contributions Expense CharitableContributionsExpense	1034000	usd
CY2022	bmrc	Other Real Estate Owned Expense OtherRealEstateOwnedExpense	359000	usd
CY2021	bmrc	Other Real Estate Owned Expense OtherRealEstateOwnedExpense	5000	usd
CY2020	bmrc	Other Real Estate Owned Expense OtherRealEstateOwnedExpense	0	usd
CY2022	us-gaap	Other Noninterest Expense OtherNoninterestExpense	8572000	usd
CY2021	us-gaap	Other Noninterest Expense OtherNoninterestExpense	6426000	usd
CY2020	us-gaap	Other Noninterest Expense OtherNoninterestExpense	5484000	usd
CY2022	us-gaap	Noninterest Expense NoninterestExpense	75269000	usd
CY2021	us-gaap	Noninterest Expense NoninterestExpense	72638000	usd
CY2020	us-gaap	Noninterest Expense NoninterestExpense	58458000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	63509000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	44886000	usd
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	40587000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	16923000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11658000	usd
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	10345000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	46586000	usd
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.93
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.32
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.24
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.92
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.30
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.22
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	15921000	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	14340000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	13525000	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	15969000	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	14422000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	13617000	shares
CY2022	us-gaap	Net Income Loss NetIncomeLoss	46586000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	33228000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	30242000	usd
CY2022	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-88620000	usd
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-21281000	usd
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	11891000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-63000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-16000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	915000	usd
CY2022	bmrc	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Investment Transferred From Available For Sale To Held To Maturity Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForInvestmentTransferredFromAvailableForSaleToHeldToMaturityBeforeTax	14847000	usd
CY2021	bmrc	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Investment Transferred From Available For Sale To Held To Maturity Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForInvestmentTransferredFromAvailableForSaleToHeldToMaturityBeforeTax	0	usd
CY2020	bmrc	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Investment Transferred From Available For Sale To Held To Maturity Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForInvestmentTransferredFromAvailableForSaleToHeldToMaturityBeforeTax	0	usd
CY2022	bmrc	Amortization Of Net Unrealized Loss On Available For Sale Securities Transferred To Held To Maturity AmortizationOfNetUnrealizedLossOnAvailableForSaleSecuritiesTransferredToHeldToMaturity	1580000	usd
CY2021	bmrc	Amortization Of Net Unrealized Loss On Available For Sale Securities Transferred To Held To Maturity AmortizationOfNetUnrealizedLossOnAvailableForSaleSecuritiesTransferredToHeldToMaturity	493000	usd
CY2020	bmrc	Amortization Of Net Unrealized Loss On Available For Sale Securities Transferred To Held To Maturity AmortizationOfNetUnrealizedLossOnAvailableForSaleSecuritiesTransferredToHeldToMaturity	524000	usd
CY2022	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Before Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent	-101824000	usd
CY2021	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Before Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent	-20772000	usd
CY2020	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Before Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent	11500000	usd
CY2022	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	-30102000	usd
CY2021	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	-6147000	usd
CY2020	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	3402000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-14625000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	8098000	usd
CY2022	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-25136000	usd
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	18603000	usd
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	38340000	usd
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	336788000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	30242000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	8098000	usd
CY2020	bmrc	Stock Issued During Period Value Stock Options Exercised Net Of Shares Surrendered For Cashless Exercises And Tax Withholdings StockIssuedDuringPeriodValueStockOptionsExercisedNetOfSharesSurrenderedForCashlessExercisesAndTaxWithholdings	1304000	usd
CY2020	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	72000	usd
CY2020	us-gaap	Stock Issued During Period Value Employee Stock Ownership Plan StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan	1289000	usd
CY2020	us-gaap	Adjustments Related To Tax Withholding For Share Based Compensation AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation	73000	usd
CY2020	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Stock Options Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition	319000	usd
CY2020	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	884000	usd
CY2020	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.92
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	12506000	usd
CY2020	bmrc	Stock Issued During Period Value Nonemployee Director Stock Purchase Plans StockIssuedDuringPeriodValueNonemployeeDirectorStockPurchasePlans	43000	usd
CY2020	bmrc	Stock Issued In Payment Of Director Fees StockIssuedInPaymentOfDirectorFees	217000	usd
CY2020	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	7208000	usd
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	358253000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-14625000	usd
CY2021	bmrc	Stock Issued During Period Value Stock Options Exercised Net Of Shares Surrendered For Cashless Exercises And Tax Withholdings StockIssuedDuringPeriodValueStockOptionsExercisedNetOfSharesSurrenderedForCashlessExercisesAndTaxWithholdings	463000	usd
CY2021	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	90000	usd
CY2021	us-gaap	Stock Issued During Period Value Employee Stock Ownership Plan StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan	1330000	usd
CY2021	us-gaap	Adjustments Related To Tax Withholding For Share Based Compensation AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation	166000	usd
CY2021	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Stock Options Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition	491000	usd
CY2021	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	481000	usd
CY2021	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.94
CY2021	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	13107000	usd
CY2021	bmrc	Stock Issued During Period Value Nonemployee Director Stock Purchase Plans StockIssuedDuringPeriodValueNonemployeeDirectorStockPurchasePlans	34000	usd
CY2021	bmrc	Stock Issued In Payment Of Director Fees StockIssuedInPaymentOfDirectorFees	217000	usd
CY2021	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	124401000	usd
CY2021	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	40722000	usd
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	450368000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	46586000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-71722000	usd
CY2022	bmrc	Stock Issued During Period Value Stock Options Exercised Net Of Shares Surrendered For Cashless Exercises And Tax Withholdings StockIssuedDuringPeriodValueStockOptionsExercisedNetOfSharesSurrenderedForCashlessExercisesAndTaxWithholdings	821000	usd
CY2022	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	62000	usd
CY2022	us-gaap	Stock Issued During Period Value Employee Stock Ownership Plan StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan	1233000	usd
CY2022	us-gaap	Adjustments Related To Tax Withholding For Share Based Compensation AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation	40000	usd
CY2022	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Stock Options Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition	251000	usd
CY2022	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	712000	usd
CY2022	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.98
CY2022	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	15673000	usd
CY2022	bmrc	Stock Issued During Period Value Nonemployee Director Stock Purchase Plans StockIssuedDuringPeriodValueNonemployeeDirectorStockPurchasePlans	16000	usd
CY2022	bmrc	Stock Issued In Payment Of Director Fees StockIssuedInPaymentOfDirectorFees	355000	usd
CY2022	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	877000	usd
CY2022	bmrc	Provision For Reversal Of Losses On Off Balance Sheet Commitments ProvisionForReversalOfLossesOnOffBalanceSheetCommitments	-318000	usd
CY2021	bmrc	Provision For Reversal Of Losses On Off Balance Sheet Commitments ProvisionForReversalOfLossesOnOffBalanceSheetCommitments	-992000	usd
CY2020	bmrc	Provision For Reversal Of Losses On Off Balance Sheet Commitments ProvisionForReversalOfLossesOnOffBalanceSheetCommitments	1570000	usd
CY2022	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-345000	usd
CY2021	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	0	usd
CY2020	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	0	usd
CY2022	bmrc	Proceeds From Collection Of Finance Receivables Net ProceedsFromCollectionOfFinanceReceivablesNet	164019000	usd
CY2021	bmrc	Proceeds From Collection Of Finance Receivables Net ProceedsFromCollectionOfFinanceReceivablesNet	256856000	usd
CY2020	bmrc	Proceeds From Collection Of Finance Receivables Net ProceedsFromCollectionOfFinanceReceivablesNet	-249337000	usd
CY2022	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	4714000	usd
CY2021	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	1943000	usd
CY2020	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	941000	usd
CY2022	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	350000	usd
CY2021	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	2478000	usd
CY2020	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	0	usd
CY2022	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	2266000	usd
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	1044000	usd
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	981000	usd
CY2022	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	0	usd
CY2021	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	140577000	usd
CY2020	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	0	usd
CY2022	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	0	usd
CY2021	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	0	usd
CY2020	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	176000	usd
CY2022	us-gaap	Payments To Acquire Real Estate Held For Investment PaymentsToAcquireRealEstateHeldForInvestment	30000	usd
CY2021	us-gaap	Payments To Acquire Real Estate Held For Investment PaymentsToAcquireRealEstateHeldForInvestment	398000	usd
CY2020	us-gaap	Payments To Acquire Real Estate Held For Investment PaymentsToAcquireRealEstateHeldForInvestment	1355000	usd
CY2022	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-218097000	usd
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-340666000	usd
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-173443000	usd
CY2022	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-235202000	usd
CY2021	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	514279000	usd
CY2020	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	167760000	usd
CY2022	bmrc	Payments Of Proceeds From Fhl Bank Borrowings Financing Activities PaymentsOfProceedsFromFHLBankBorrowingsFinancingActivities	-112000000	usd
CY2021	bmrc	Payments Of Proceeds From Fhl Bank Borrowings Financing Activities PaymentsOfProceedsFromFHLBankBorrowingsFinancingActivities	13885000	usd
CY2020	bmrc	Payments Of Proceeds From Fhl Bank Borrowings Financing Activities PaymentsOfProceedsFromFHLBankBorrowingsFinancingActivities	0	usd
CY2022	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	131000	usd
CY2021	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	86000	usd
CY2020	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	172000	usd
CY2022	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	usd
CY2021	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	4126000	usd
CY2020	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	usd
CY2022	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	821000	usd
CY2021	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	463000	usd
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1304000	usd
CY2022	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	40000	usd
CY2021	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	166000	usd
CY2020	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	73000	usd
CY2022	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	15673000	usd
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	13107000	usd
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	12506000	usd
CY2022	us-gaap	Payments For Repurchase Of Equity PaymentsForRepurchaseOfEquity	1250000	usd
CY2021	us-gaap	Payments For Repurchase Of Equity PaymentsForRepurchaseOfEquity	40762000	usd
CY2020	us-gaap	Payments For Repurchase Of Equity PaymentsForRepurchaseOfEquity	6898000	usd
CY2022	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans	78000	usd
CY2021	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans	124000	usd
CY2020	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans	115000	usd
CY2022	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-139397000	usd
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	442734000	usd
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	149530000	usd
CY2022	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-302217000	usd
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	147321000	usd
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	16932000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	347641000	usd
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	200320000	usd
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	183388000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	45424000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	347641000	usd
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	200320000	usd
CY2022	us-gaap	Interest Paid Net InterestPaidNet	2560000	usd
CY2021	us-gaap	Interest Paid Net InterestPaidNet	2105000	usd
CY2020	us-gaap	Interest Paid Net InterestPaidNet	2948000	usd
CY2022	us-gaap	Income Taxes Paid IncomeTaxesPaid	14325000	usd
CY2021	us-gaap	Income Taxes Paid IncomeTaxesPaid	12350000	usd
CY2020	us-gaap	Income Taxes Paid IncomeTaxesPaid	13065000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-88620000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-21281000	usd
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	11891000	usd
CY2022	bmrc	Cumulative Effect Of Change In Accounting Principle CumulativeEffectOfChangeInAccountingPrinciple	0	usd
CY2021	bmrc	Cumulative Effect Of Change In Accounting Principle CumulativeEffectOfChangeInAccountingPrinciple	0	usd
CY2020	bmrc	Cumulative Effect Of Change In Accounting Principle CumulativeEffectOfChangeInAccountingPrinciple	-1216000	usd
CY2022	bmrc	Amortization Of Net Unrealized Loss On Available For Sale Securities Transferred To Held To Maturity AmortizationOfNetUnrealizedLossOnAvailableForSaleSecuritiesTransferredToHeldToMaturity	1580000	usd
CY2021	bmrc	Amortization Of Net Unrealized Loss On Available For Sale Securities Transferred To Held To Maturity AmortizationOfNetUnrealizedLossOnAvailableForSaleSecuritiesTransferredToHeldToMaturity	493000	usd
CY2020	bmrc	Amortization Of Net Unrealized Loss On Available For Sale Securities Transferred To Held To Maturity AmortizationOfNetUnrealizedLossOnAvailableForSaleSecuritiesTransferredToHeldToMaturity	524000	usd
CY2022	bmrc	Repurchase Of Stock Not Yet Settled RepurchaseOfStockNotYetSettled	0	usd
CY2021	bmrc	Repurchase Of Stock Not Yet Settled RepurchaseOfStockNotYetSettled	373000	usd
CY2020	bmrc	Repurchase Of Stock Not Yet Settled RepurchaseOfStockNotYetSettled	413000	usd
CY2022	bmrc	Availableforsale Securities Transferredto Heldtomaturity Securities AvailableforsaleSecuritiesTransferredtoHeldtomaturitySecurities	357482000	usd
CY2021	bmrc	Availableforsale Securities Transferredto Heldtomaturity Securities AvailableforsaleSecuritiesTransferredtoHeldtomaturitySecurities	0	usd
CY2020	bmrc	Availableforsale Securities Transferredto Heldtomaturity Securities AvailableforsaleSecuritiesTransferredtoHeldtomaturitySecurities	0	usd
CY2022	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	0	usd
CY2021	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	757844000	usd
CY2020	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	0	usd
CY2022	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	0	usd
CY2021	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	816558000	usd
CY2020	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	0	usd
CY2022Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	0	usd
CY2021Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	4395000	usd
CY2020Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	2700000	usd
CY2022Q4	bmrc	Number Of Retail Branches NumberOfRetailBranches	31	retailbranch
CY2022Q4	bmrc	Number Of Commercial Banking Offices NumberOfCommercialBankingOffices	8	commercialbankingoffice
CY2022Q4	bmrc	Number Of Counties NumberOfCounties	10	county
CY2022	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	Accounting Changes and Reclassifications - Certain items in prior financial statements have been reclassified to conform to the current presentation, including the reclassification of the provision for credit losses on unfunded commitments in the second quarter of 2021 from non-interest expense to a separate line item under the provision for credit losses on loans in the consolidated statements of comprehensive (loss) income.
CY2020Q3	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	22113000	usd
CY2020Q3	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1697000	usd
CY2022	us-gaap	Use Of Estimates UseOfEstimates	<span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Use of Estimates -</span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%"> </span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Significant accounting estimates reflected in the consolidated financial statements include the allowance for credit losses, income taxes, and fair value measurements (including fair values of acquired assets and assumed liabilities at acquisition dates) as discussed in the Notes herein.</span>
CY2022Q4	us-gaap	Financing Receivable Threshold Period Past Due Writeoff FinancingReceivableThresholdPeriodPastDueWriteoff	P90D
CY2022	bmrc	Loansand Leases Receivable Nonperforming Number Of Consecutive Payments Considered Sustained Repayment Performance LoansandLeasesReceivableNonperformingNumberOfConsecutivePaymentsConsideredSustainedRepaymentPerformance	6	payment
CY2022	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	usd
CY2020	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	usd
CY2022Q4	us-gaap	Financing Receivable Threshold Period Past Due Writeoff FinancingReceivableThresholdPeriodPastDueWriteoff	P90D
CY2022	bmrc	Threshold Period Past Due For Write Off Of Deposit Liabilities Reclassified As Loans Receivable ThresholdPeriodPastDueForWriteOffOfDepositLiabilitiesReclassifiedAsLoansReceivable	P60D
CY2021	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	usd
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	2867000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	342755000	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityAccruedInterestBeforeAllowanceForCreditLoss	3700000	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityAccruedInterestBeforeAllowanceForCreditLoss	1100000	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	0	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	0	usd
CY2022	us-gaap	Gains Losses On Sales Of Assets GainsLossesOnSalesOfAssets	0	usd
CY2021	us-gaap	Gains Losses On Sales Of Assets GainsLossesOnSalesOfAssets	0	usd
CY2020	us-gaap	Gains Losses On Sales Of Assets GainsLossesOnSalesOfAssets	0	usd
CY2022	us-gaap	Real Estate Owned Valuation Allowance Valuation Increase RealEstateOwnedValuationAllowanceValuationIncrease	345000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	70000	usd
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	15921000	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	14340000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	13525000	shares
CY2022	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	31000	shares
CY2021	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	62000	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	69000	shares
CY2022	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	17000	shares
CY2021	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	20000	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	23000	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	15969000	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	14422000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	13617000	shares
CY2022	us-gaap	Net Income Loss NetIncomeLoss	46586000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	33228000	usd
CY2020	us-gaap	Net Income Loss NetIncomeLoss	30242000	usd
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.93
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.32
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.24
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.92
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.30
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.22
CY2022	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	211000	shares
CY2021	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	97000	shares
CY2020	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	148000	shares
CY2022Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	127038000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Amortized Cost Before Other Than Temporary Impairment HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment	342222000	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	0	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	342222000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	3400000	usd
CY2022	us-gaap	Advertising Expense AdvertisingExpense	1100000	usd
CY2021	us-gaap	Advertising Expense AdvertisingExpense	908000	usd
CY2020	us-gaap	Advertising Expense AdvertisingExpense	769000	usd
CY2021Q1	bmrc	Number Of Interest Rate Swap Contract NumberOfInterestRateSwapContract	4	contract
CY2021Q1	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	12000000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Amortized Cost Before Other Than Temporary Impairment HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment	972207000	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	0	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	972207000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss	892605000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	34000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	90543000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	802096000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss	1169520000	usd
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	11074000	usd
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	13026000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	1167568000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	3200000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	3700000	usd
CY2022Q1	us-gaap	Debt Securities Available For Sale Transfer To Held To Maturity Allowance For Credit Loss Expense DebtSecuritiesAvailableForSaleTransferToHeldToMaturityAllowanceForCreditLossExpense	357500000	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss Maturity Allocated And Single Maturity Date Year One DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateYearOne	450000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue	446000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	1254000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	1239000	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss Maturity Allocated And Single Maturity Date Year One DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateYearOne	101000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue	103000	usd
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	10785000	usd
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	10841000	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss Maturity Allocated And Single Maturity Date After Year One Through Five DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYearOneThroughFive	87418000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	83663000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	335813000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	307843000	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss Maturity Allocated And Single Maturity Date After Year One Through Five DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYearOneThroughFive	25666000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	26559000	usd
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	219474000	usd
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	219957000	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss Maturity Allocated And Single Maturity Date After Year5 Through10 DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear5Through10	262072000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	222280000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	185997000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	166273000	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss Maturity Allocated And Single Maturity Date After Year5 Through10 DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear5Through10	182604000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	182303000	usd
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	299937000	usd
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	300187000	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss Maturity Allocated And Single Maturity Date After Year10 DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear10	622267000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	538850000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	369541000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	326741000	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss Maturity Allocated And Single Maturity Date After Year10 DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear10	133851000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	133790000	usd
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	639324000	usd
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	636583000	usd
CY2022Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	972207000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	845239000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss	892605000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	802096000	usd
CY2021Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	342222000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	342755000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss	1169520000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	1167568000	usd
CY2022	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	10664000	usd
CY2021	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	6632000	usd
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	33756000	usd
CY2022	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	17000	usd
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	1000	usd
CY2020	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	916000	usd
CY2022	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	80000	usd
CY2021	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	17000	usd
CY2020	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	1000	usd
CY2022Q4	us-gaap	Securities Loaned Fair Value Of Collateral SecuritiesLoanedFairValueOfCollateral	234226000	usd
CY2021Q4	us-gaap	Securities Loaned Fair Value Of Collateral SecuritiesLoanedFairValueOfCollateral	217849000	usd
CY2022Q4	bmrc	Marketable Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions MarketableSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions	407	security
CY2021Q4	bmrc	Marketable Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions MarketableSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions	10	security
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	359313000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	23733000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	459948000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	103305000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue	819261000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	127038000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	354695000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	33887000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	443274000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	56656000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	797969000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	90543000	usd
CY2022Q4	bmrc	Available For Sale Securities And Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	714008000	usd
CY2022Q4	bmrc	Availableforsale Securitiesand Heldtomaturity Securities Continuous Unrealized Loss Position Lessthan12 Months Accumulated Loss AvailableforsaleSecuritiesandHeldtomaturitySecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss	57620000	usd
CY2022Q4	bmrc	Available For Sale Securities And Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	903222000	usd
CY2022Q4	bmrc	Availableforsale Securitiesand Heldtomaturity Securities Continuous Unrealized Loss Position12 Monthsor Longer Accumulated Loss AvailableforsaleSecuritiesandHeldtomaturitySecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss	159961000	usd
CY2022Q4	bmrc	Available For Sale Securities And Held To Maturity Securities Continuous Unrealized Loss Position Fair Value Total AvailableForSaleSecuritiesAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValueTotal	1617230000	usd
CY2022Q4	bmrc	Availableforsale Securitiesand Heldtomaturity Securities Continuous Unrealized Loss Position Accumulated Loss AvailableforsaleSecuritiesandHeldtomaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	217581000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	201204000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	2867000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	0	usd
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	0	usd
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Fair Value HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue	201204000	usd
CY2021Q4	us-gaap	Held To Maturity Securities Continuous Unrealized Loss Position Accumulated Loss HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	2867000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	797781000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	12411000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	14173000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	615000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	811954000	usd
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	13026000	usd
CY2021Q4	bmrc	Available For Sale Securities And Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	998985000	usd
CY2021Q4	bmrc	Availableforsale Securitiesand Heldtomaturity Securities Continuous Unrealized Loss Position Lessthan12 Months Accumulated Loss AvailableforsaleSecuritiesandHeldtomaturitySecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss	15278000	usd
CY2021Q4	bmrc	Available For Sale Securities And Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	14173000	usd
CY2021Q4	bmrc	Availableforsale Securitiesand Heldtomaturity Securities Continuous Unrealized Loss Position12 Monthsor Longer Accumulated Loss AvailableforsaleSecuritiesandHeldtomaturitySecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss	615000	usd
CY2021Q4	bmrc	Available For Sale Securities And Held To Maturity Securities Continuous Unrealized Loss Position Fair Value Total AvailableForSaleSecuritiesAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValueTotal	1013158000	usd
CY2021Q4	bmrc	Availableforsale Securitiesand Heldtomaturity Securities Continuous Unrealized Loss Position Accumulated Loss AvailableforsaleSecuritiesandHeldtomaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	15893000	usd
CY2022Q4	bmrc	Marketable Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Longer Than12 Months MarketableSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositionsLongerThan12Months	232	security
CY2022Q4	bmrc	Marketable Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than12 Months MarketableSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositionsLessThan12Months	175	security
CY2022Q4	bmrc	Debt Securities Available For Sale Unrealized Loss Position Allowance For Credit Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAllowanceForCreditLoss	0	usd
CY2022Q4	bmrc	Federal Home Loan Bank Stock Par Value FederalHomeLoanBankStockParValue	100
CY2022Q4	us-gaap	Amortization Method Qualified Affordable Housing Project Investments AmortizationMethodQualifiedAffordableHousingProjectInvestments	2500000	usd
CY2021Q4	us-gaap	Amortization Method Qualified Affordable Housing Project Investments AmortizationMethodQualifiedAffordableHousingProjectInvestments	3000000	usd
CY2022	bmrc	Amortization Method Qualified Affordable Housing Project Investments Tax Credits AmortizationMethodQualifiedAffordableHousingProjectInvestmentsTaxCredits	634000	usd
CY2022	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	533000	usd
CY2022Q4	bmrc	Affordable Housing Program Unfunded Commitments AffordableHousingProgramUnfundedCommitments	386000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual FinancingReceivableExcludingAccruedInterestNonaccrual	8376000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual No Allowance FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance	8376000	usd
CY2021Q4	bmrc	Financing Receivable90 Days Or More Past Due Still Accruing Number Of Loans FinancingReceivable90DaysOrMorePastDueStillAccruingNumberOfLoans	0	loan
CY2022Q4	bmrc	Financing Receivable90 Days Or More Past Due Still Accruing Number Of Loans FinancingReceivable90DaysOrMorePastDueStillAccruingNumberOfLoans	0	loan
CY2022Q4	bmrc	Financing Receivable Nonaccrual Earning Interest On Cash Basis FinancingReceivableNonaccrualEarningInterestOnCashBasis	0	usd
CY2021Q4	bmrc	Financing Receivable Nonaccrual Earning Interest On Cash Basis FinancingReceivableNonaccrualEarningInterestOnCashBasis	0	usd
CY2021	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0	usd
CY2020	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0	usd
CY2022	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0	usd
CY2022	us-gaap	Financing Receivable Accrued Interest Writeoff FinancingReceivableAccruedInterestWriteoff	48000	usd
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	2092546000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	2255645000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	22983000	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	23023000	usd
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	2069563000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	2232622000	usd
CY2022Q4	bmrc	Financing Receivable Net Deferred Loan Origination Costs Fees FinancingReceivableNetDeferredLoanOriginationCostsFees	1800000	usd
CY2021Q4	bmrc	Financing Receivable Net Deferred Loan Origination Costs Fees FinancingReceivableNetDeferredLoanOriginationCostsFees	-901000	usd
CY2022Q4	bmrc	Certain Loans Acquired In Transfer Without Evidence Of Deteriorated Credit Unrecognized Purchase Discounts CertainLoansAcquiredInTransferWithoutEvidenceOfDeterioratedCreditUnrecognizedPurchaseDiscounts	2600000	usd
CY2021Q4	bmrc	Certain Loans Acquired In Transfer Without Evidence Of Deteriorated Credit Unrecognized Purchase Discounts CertainLoansAcquiredInTransferWithoutEvidenceOfDeterioratedCreditUnrecognizedPurchaseDiscounts	2500000	usd
CY2022Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	6100000	usd
CY2021Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	7100000	usd
CY2022	bmrc	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff	0	usd
CY2022	bmrc	Financing Receivable Excluding Accrued Interest Year Two Originated Fiscal Year Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff	0	usd
CY2022	bmrc	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff	9000	usd
CY2022	bmrc	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff	0	usd
CY2022	bmrc	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff	0	usd
CY2022	bmrc	Financing Receivable Excluding Accrued Interest Year Three Originated Five Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearThreeOriginatedFiveYearsBeforeCurrentFiscalYearWriteoff	18000	usd
CY2022	bmrc	Financing Receivable Excluding Accrued Interest Revolving Writeoff FinancingReceivableExcludingAccruedInterestRevolvingWriteoff	5000	usd
CY2022	bmrc	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossWriteoff	32000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear	461784000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Two Originated Fiscal Year Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear	385837000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear	310140000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear	242704000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear	131462000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Originated More Than Five Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear	539868000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Revolving FinancingReceivableExcludingAccruedInterestRevolving	183850000	usd
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	2255645000	usd
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual FinancingReceivableExcludingAccruedInterestNonaccrual	2432000	usd
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest Nonaccrual No Allowance FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance	2432000	usd
CY2021	us-gaap	Financing Receivable Accrued Interest Writeoff FinancingReceivableAccruedInterestWriteoff	0	usd
CY2022Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	3388000	usd
CY2021Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	9510000	usd
CY2022Q4	bmrc	Financing Receivable Modifications Recorded Investment Nonaccrual Status FinancingReceivableModificationsRecordedInvestmentNonaccrualStatus	1600000	usd
CY2021Q4	bmrc	Financing Receivable Modifications Recorded Investment Nonaccrual Status FinancingReceivableModificationsRecordedInvestmentNonaccrualStatus	7400000	usd
CY2020	bmrc	Financing Receivable Modifications Removal From Troubled Debt Restructuring Number Of Contracts FinancingReceivableModificationsRemovalFromTroubledDebtRestructuringNumberOfContracts	0	loan
CY2022	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	4
CY2022	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	2005000	usd
CY2022	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	2005000	usd
CY2022	bmrc	Financing Receivable Modifications Contracts Modified During Period Recorded Investment FinancingReceivableModificationsContractsModifiedDuringPeriodRecordedInvestment	1400000	usd
CY2021	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	2
CY2021	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	1221000	usd
CY2021	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	1221000	usd
CY2021	bmrc	Financing Receivable Modifications Contracts Modified During Period Recorded Investment FinancingReceivableModificationsContractsModifiedDuringPeriodRecordedInvestment	1021000	usd
CY2020	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	5
CY2020	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	2203000	usd
CY2020	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	2195000	usd
CY2020	bmrc	Financing Receivable Modifications Contracts Modified During Period Recorded Investment FinancingReceivableModificationsContractsModifiedDuringPeriodRecordedInvestment	2121000	usd
CY2020	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	usd
CY2021	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	usd
CY2022	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	23023000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	-63000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	32000	usd
CY2022	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Recovery FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery	55000	usd
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	22874000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	-1449000	usd
CY2021	us-gaap	Financing Receivable Allowance For Credit Loss Purchased With Credit Deterioration Increase FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease	1505000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	5000	usd
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Recovery FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery	98000	usd
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	23023000	usd
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	16677000	usd
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	5450000	usd
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	30000	usd
	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	16000	usd
CY2020Q3	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	22113000	usd
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	-856000	usd
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	1000	usd
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Recovery FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery	14000	usd
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	22874000	usd
CY2021Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	7942000	usd
CY2020Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	6423000	usd
CY2019Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	8333000	usd
CY2022	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	1525000	usd
CY2021	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	0	usd
CY2020	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	0	usd
CY2022	bmrc	Loans And Leases Receivable Related Parties Acquisition LoansAndLeasesReceivableRelatedPartiesAcquisition	0	usd
CY2021	bmrc	Loans And Leases Receivable Related Parties Acquisition LoansAndLeasesReceivableRelatedPartiesAcquisition	4037000	usd
CY2020	bmrc	Loans And Leases Receivable Related Parties Acquisition LoansAndLeasesReceivableRelatedPartiesAcquisition	0	usd
CY2022	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	364000	usd
CY2021	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	2518000	usd
CY2020	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	1910000	usd
CY2022	bmrc	Loans And Leases Receivable Reclassified Due To Change In Borrower Status LoansAndLeasesReceivableReclassifiedDueToChangeInBorrowerStatus	-2658000	usd
CY2021	bmrc	Loans And Leases Receivable Reclassified Due To Change In Borrower Status LoansAndLeasesReceivableReclassifiedDueToChangeInBorrowerStatus	0	usd
CY2020	bmrc	Loans And Leases Receivable Reclassified Due To Change In Borrower Status LoansAndLeasesReceivableReclassifiedDueToChangeInBorrowerStatus	0	usd
CY2022Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	6445000	usd
CY2021Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	7942000	usd
CY2020Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	6423000	usd
CY2022Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Before Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization	31880000	usd
CY2021Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Before Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization	29530000	usd
CY2022Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization	23746000	usd
CY2021Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization	21972000	usd
CY2022Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	8134000	usd
CY2021Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	7558000	usd
CY2022	us-gaap	Depreciation Depreciation	1800000	usd
CY2021	us-gaap	Depreciation Depreciation	1700000	usd
CY2020	us-gaap	Depreciation Depreciation	2100000	usd
CY2022	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	11505	shares
CY2022Q4	bmrc	Life Insurance Corporate Or Bank Owned Death Benefits LifeInsuranceCorporateOrBankOwnedDeathBenefits	131900000	usd
CY2022Q4	us-gaap	Life Insurance Corporate Or Bank Owned Amount LifeInsuranceCorporateOrBankOwnedAmount	67100000	usd
CY2021Q4	us-gaap	Life Insurance Corporate Or Bank Owned Amount LifeInsuranceCorporateOrBankOwnedAmount	61500000	usd
CY2022	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1200000	usd
CY2021	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	2200000	usd
CY2020	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	973000	usd
CY2022	bmrc	Proceeds In Excess Of Cash Surrender Values On Bank Owned Life Insurance ProceedsInExcessOfCashSurrenderValuesOnBankOwnedLifeInsurance	86000	usd
CY2021	bmrc	Proceeds In Excess Of Cash Surrender Values On Bank Owned Life Insurance ProceedsInExcessOfCashSurrenderValuesOnBankOwnedLifeInsurance	1100000	usd
CY2020	bmrc	Proceeds In Excess Of Cash Surrender Values On Bank Owned Life Insurance ProceedsInExcessOfCashSurrenderValuesOnBankOwnedLifeInsurance	0	usd
CY2022Q4	bmrc	Time Deposits Less Than Or Equal To250000 TimeDepositsLessThanOrEqualTo250000	74421000	usd
CY2021Q4	bmrc	Time Deposits Less Than Or Equal To250000 TimeDepositsLessThanOrEqualTo250000	96214000	usd
CY2022Q4	bmrc	Time Deposits250000 Or More TimeDeposits250000OrMore	44609000	usd
CY2021Q4	bmrc	Time Deposits250000 Or More TimeDeposits250000OrMore	54021000	usd
CY2022Q4	us-gaap	Time Deposits TimeDeposits	119030000	usd
CY2021Q4	us-gaap	Time Deposits TimeDeposits	150235000	usd
CY2022	us-gaap	Interest Expense Time Deposits InterestExpenseTimeDeposits	323000	usd
CY2021	us-gaap	Interest Expense Time Deposits InterestExpenseTimeDeposits	246000	usd
CY2020	us-gaap	Interest Expense Time Deposits InterestExpenseTimeDeposits	554000	usd
CY2022Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	87011000	usd
CY2022Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	11152000	usd
CY2022Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	8898000	usd
CY2022Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	8167000	usd
CY2022Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	3801000	usd
CY2022Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	1000	usd
CY2022Q4	us-gaap	Time Deposits TimeDeposits	119030000	usd
CY2022Q4	us-gaap	Held To Maturity Securities Restricted HeldToMaturitySecuritiesRestricted	231300000	usd
CY2021	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	27929	shares
CY2020	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	10001	shares
CY2022	bmrc	Adjustments Related To Tax Withholding And Exercise Of Options For Share Based Compensation AdjustmentsRelatedToTaxWithholdingAndExerciseOfOptionsForShareBasedCompensation	393000	usd
CY2021	bmrc	Adjustments Related To Tax Withholding And Exercise Of Options For Share Based Compensation AdjustmentsRelatedToTaxWithholdingAndExerciseOfOptionsForShareBasedCompensation	1085000	usd
CY2020	bmrc	Adjustments Related To Tax Withholding And Exercise Of Options For Share Based Compensation AdjustmentsRelatedToTaxWithholdingAndExerciseOfOptionsForShareBasedCompensation	398000	usd
CY2022Q4	bmrc	Time Deposits Certificate Of Deposit Account Registry Service Cdars TimeDepositsCertificateOfDepositAccountRegistryServiceCDARS	11031000	usd
CY2022Q4	bmrc	Time Deposits Certificate Of Deposit Account Registry Service Cdars One Way TimeDepositsCertificateOfDepositAccountRegistryServiceCDARSOneWay	2162000	usd
CY2021Q4	bmrc	Time Deposits Certificate Of Deposit Account Registry Service Cdars TimeDepositsCertificateOfDepositAccountRegistryServiceCDARS	21413000	usd
CY2021Q4	bmrc	Time Deposits Certificate Of Deposit Account Registry Service Cdars One Way TimeDepositsCertificateOfDepositAccountRegistryServiceCDARSOneWay	2160000	usd
CY2022Q4	bmrc	Deposits Money Market Deposits Insured Cash Sweep Ics DepositsMoneyMarketDepositsInsuredCashSweepICS	100749000	usd
CY2022Q4	bmrc	Deposits Money Market Deposits Insured Cash Sweep Ics One Way DepositsMoneyMarketDepositsInsuredCashSweepICSOneWay	0	usd
CY2021Q4	bmrc	Deposits Money Market Deposits Insured Cash Sweep Ics DepositsMoneyMarketDepositsInsuredCashSweepICS	0	usd
CY2021Q4	bmrc	Deposits Money Market Deposits Insured Cash Sweep Ics One Way DepositsMoneyMarketDepositsInsuredCashSweepICSOneWay	110900000	usd
CY2022Q4	bmrc	Deposits Money Market Deposits Demand Deposit Marketplace DepositsMoneyMarketDepositsDemandDepositMarketplace	62219000	usd
CY2022Q4	bmrc	Deposits Money Market Deposits Demand Deposit Marketplace One Way DepositsMoneyMarketDepositsDemandDepositMarketplaceOneWay	0	usd
CY2021Q4	bmrc	Deposits Money Market Deposits Demand Deposit Marketplace DepositsMoneyMarketDepositsDemandDepositMarketplace	52365000	usd
CY2021Q4	bmrc	Deposits Money Market Deposits Demand Deposit Marketplace One Way DepositsMoneyMarketDepositsDemandDepositMarketplaceOneWay	60000000	usd
CY2022Q4	bmrc	Total Networkdeposits Reciprocal TotalNetworkdepositsReciprocal	173999000	usd
CY2022Q4	bmrc	Total Networkdeposits One Way TotalNetworkdepositsOneWay	2162000	usd
CY2021Q4	bmrc	Total Networkdeposits Reciprocal TotalNetworkdepositsReciprocal	73778000	usd
CY2021Q4	bmrc	Total Networkdeposits One Way TotalNetworkdepositsOneWay	173060000	usd
CY2022Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	247000	usd
CY2021Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	346000	usd
CY2022Q4	us-gaap	Related Party Deposit Liabilities RelatedPartyDepositLiabilities	11200000	usd
CY2021Q4	us-gaap	Related Party Deposit Liabilities RelatedPartyDepositLiabilities	25300000	usd
CY2022Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	439000	usd
CY2022Q4	us-gaap	Federal Home Loan Bank Advances Fixed Rate FederalHomeLoanBankAdvancesFixedRate	0	usd
CY2022	bmrc	Federal Home Loan Bank Advances Average Balance Fixed Rate FederalHomeLoanBankAdvancesAverageBalanceFixedRate	0	usd
CY2022Q4	us-gaap	Federal Home Loan Bank Advances Weighted Average Interest Rate FederalHomeLoanBankAdvancesWeightedAverageInterestRate	0
CY2021Q4	us-gaap	Federal Home Loan Bank Advances Fixed Rate FederalHomeLoanBankAdvancesFixedRate	0	usd
CY2021	bmrc	Federal Home Loan Bank Advances Average Balance Fixed Rate FederalHomeLoanBankAdvancesAverageBalanceFixedRate	642000	usd
CY2021Q4	us-gaap	Federal Home Loan Bank Advances Weighted Average Interest Rate FederalHomeLoanBankAdvancesWeightedAverageInterestRate	0.0118
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Fixed Rate FederalHomeLoanBankAdvancesFixedRate	0	usd
CY2020	bmrc	Federal Home Loan Bank Advances Average Balance Fixed Rate FederalHomeLoanBankAdvancesAverageBalanceFixedRate	0	usd
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Weighted Average Interest Rate FederalHomeLoanBankAdvancesWeightedAverageInterestRate	0
CY2022	bmrc	Sharebased Compensation Arrangementsby Sharebased Payment Award Options Tax Withholding And Exercisesin Period Weighted Average Exercise Price SharebasedCompensationArrangementsbySharebasedPaymentAwardOptionsTaxWithholdingAndExercisesinPeriodWeightedAverageExercisePrice	34.13
CY2021	bmrc	Sharebased Compensation Arrangementsby Sharebased Payment Award Options Tax Withholding And Exercisesin Period Weighted Average Exercise Price SharebasedCompensationArrangementsbySharebasedPaymentAwardOptionsTaxWithholdingAndExercisesinPeriodWeightedAverageExercisePrice	38.85
CY2020	bmrc	Sharebased Compensation Arrangementsby Sharebased Payment Award Options Tax Withholding And Exercisesin Period Weighted Average Exercise Price SharebasedCompensationArrangementsbySharebasedPaymentAwardOptionsTaxWithholdingAndExercisesinPeriodWeightedAverageExercisePrice	39.83
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	417382	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	28.01
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	7112000	usd
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P5Y6M
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	44632	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	39.18
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	6.84
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	17222	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	40.31
CY2020	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	73208	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	22.26
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	1370000	usd
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	371584	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	29.92
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	2262000	usd
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P5Y1M13D
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber	315377	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice	28.05
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue	2254000	usd
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1	P4Y6M10D
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	371584	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	29.92
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	2262000	usd
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P5Y1M13D
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	55861	shares
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	36.39
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	8.84
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	2008	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	42.50
CY2021	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	60056	shares
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	23.01
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	885000	usd
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	365381	shares
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	31.97
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	2326000	usd
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P5Y6M25D
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber	315744	shares
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice	30.85
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue	2264000	usd
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1	P5Y1M24D
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	365381	shares
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	31.97
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	2326000	usd
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P5Y6M25D
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	39094	shares
CY2022	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	34.16
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	8.49
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	23760	shares
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	37.48
CY2022	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	51010	shares
CY2022	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	23.01
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	617000	usd
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	329705	shares
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	33.22
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	813000	usd
CY2022	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P5Y7M2D
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber	287228	shares
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice	32.81
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue	813000	usd
CY2022	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1	P5Y1M24D
CY2022	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	962000	usd
CY2021	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	972000	usd
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	1200000	usd
CY2022	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	257000	usd
CY2021	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	213000	usd
CY2020	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	341000	usd
CY2022Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	1400000	usd
CY2022	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P2Y1M6D
CY2022	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount	3000	usd
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount	87000	usd
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount	120000	usd
CY2022	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	15673000	usd
CY2021	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	13107000	usd
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	12506000	usd
CY2022	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.98
CY2021	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.94
CY2020	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.92
CY2022Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	270800000	usd
CY2022Q4	us-gaap	Stockholders Equity StockholdersEquity	412100000	usd
CY2022Q4	bmrc	Dividends Cash Dividend Amount Retained Earnings Available For Dividend Payments Under Restriction DividendsCashDividendAmountRetainedEarningsAvailableForDividendPaymentsUnderRestriction	20100000	usd
CY2022Q4	us-gaap	Cash Cash	4500000	usd
CY2021Q1	bmrc	Deferred Compensation Arrangementwith Individual Deferred Interest Earned Percent DeferredCompensationArrangementwithIndividualDeferredInterestEarnedPercent	0.0325
CY2022Q1	bmrc	Deferred Compensation Arrangementwith Individual Deferred Interest Earned Percent DeferredCompensationArrangementwithIndividualDeferredInterestEarnedPercent	0.0325
CY2021Q3	us-gaap	Deferred Compensation Arrangement With Individual Recorded Liability DeferredCompensationArrangementWithIndividualRecordedLiability	2900000	usd
CY2022Q4	us-gaap	Deferred Compensation Arrangement With Individual Recorded Liability DeferredCompensationArrangementWithIndividualRecordedLiability	7100000	usd
CY2021Q4	us-gaap	Deferred Compensation Arrangement With Individual Recorded Liability DeferredCompensationArrangementWithIndividualRecordedLiability	7900000	usd
CY2022	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent Of Match DefinedContributionPlanEmployerMatchingContributionPercentOfMatch	0.70
CY2022	bmrc	Defined Contribution Plan Employer Matching Contribution Maximum Amount DefinedContributionPlanEmployerMatchingContributionMaximumAmount	5000	usd
CY2022	bmrc	Defined Benefit Plan Percentage Of Salary Paid Upon Retirement DefinedBenefitPlanPercentageOfSalaryPaidUponRetirement	0.25
CY2022	bmrc	Defined Benefits Plan Period Before Ratable Vesting Begins DefinedBenefitsPlanPeriodBeforeRatableVestingBegins	P5Y
CY2022	bmrc	Defined Benefits Plan Period Before Ratable Vesting Begins DefinedBenefitsPlanPeriodBeforeRatableVestingBegins	P5Y
CY2022	bmrc	Defined Benefits Plan Age Ratable Vesting Ends DefinedBenefitsPlanAgeRatableVestingEnds	P65Y
CY2022Q4	us-gaap	Defined Benefit Plan Amounts Recognized In Balance Sheet DefinedBenefitPlanAmountsRecognizedInBalanceSheet	4700000	usd
CY2021Q4	us-gaap	Defined Benefit Plan Amounts Recognized In Balance Sheet DefinedBenefitPlanAmountsRecognizedInBalanceSheet	5300000	usd
CY2022	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	10670000	usd
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	6627000	usd
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	7108000	usd
CY2022	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	6687000	usd
CY2021	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	4815000	usd
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	4895000	usd
CY2022	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	17357000	usd
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	11442000	usd
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	12003000	usd
CY2022	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-441000	usd
CY2021	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	274000	usd
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-964000	usd
CY2022	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	7000	usd
CY2021	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-58000	usd
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-694000	usd
CY2022	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-434000	usd
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	216000	usd
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-1658000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	16923000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11658000	usd
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	10345000	usd
CY2022Q4	bmrc	Deferred Tax Assets Unrealized Losseson Availablefor Sale Securities Net DeferredTaxAssetsUnrealizedLossesonAvailableforSaleSecuritiesNet	29458000	usd
CY2021Q4	bmrc	Deferred Tax Assets Unrealized Losseson Availablefor Sale Securities Net DeferredTaxAssetsUnrealizedLossesonAvailableforSaleSecuritiesNet	0	usd
CY2022Q4	bmrc	Operating Lease And Finance Lease Liability OperatingLeaseAndFinanceLeaseLiability	8002000	usd
CY2021Q4	bmrc	Operating Lease And Finance Lease Liability OperatingLeaseAndFinanceLeaseLiability	7642000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	7229000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	7335000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	3481000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	3911000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	1751000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	1884000	usd
CY2022Q4	us-gaap	Deferred Tax Assets State Taxes DeferredTaxAssetsStateTaxes	1396000	usd
CY2021Q4	us-gaap	Deferred Tax Assets State Taxes DeferredTaxAssetsStateTaxes	930000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	1239000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	1406000	usd
CY2022Q4	bmrc	Deferred Tax Asset Fair Value Adjustment Loans Receivable DeferredTaxAssetFairValueAdjustmentLoansReceivable	905000	usd
CY2021Q4	bmrc	Deferred Tax Asset Fair Value Adjustment Loans Receivable DeferredTaxAssetFairValueAdjustmentLoansReceivable	894000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	697000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	599000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	236000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	188000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	194000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	144000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	54588000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	24933000	usd
CY2022Q4	bmrc	Operating Lease And Finance Lease Right Of Use Asset OperatingLeaseAndFinanceLeaseRightOfUseAsset	7465000	usd
CY2021Q4	bmrc	Operating Lease And Finance Lease Right Of Use Asset OperatingLeaseAndFinanceLeaseRightOfUseAsset	7098000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	1512000	usd
CY2021Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	1953000	usd
CY2022Q4	bmrc	Deferred Tax Liabilities Deferred Loan Origination Costs DeferredTaxLiabilitiesDeferredLoanOriginationCosts	1476000	usd
CY2021Q4	bmrc	Deferred Tax Liabilities Deferred Loan Origination Costs DeferredTaxLiabilitiesDeferredLoanOriginationCosts	1526000	usd
CY2022Q4	bmrc	Net Unrealized Gains On Securities Availablefor Sale NetUnrealizedGainsOnSecuritiesAvailableforSale	0	usd
CY2021Q4	bmrc	Net Unrealized Gains On Securities Availablefor Sale NetUnrealizedGainsOnSecuritiesAvailableforSale	745000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	279000	usd
CY2021Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	292000	usd
CY2022Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	10732000	usd
CY2021Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	11614000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	43856000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	13319000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	1200000	usd
CY2021Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	0	usd
CY2022Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	0	usd
CY2022Q4	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	616000	usd
CY2021Q4	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	499000	usd
CY2022Q4	bmrc	Finance Lease Right Of Use Asset Accumulated Depreciation FinanceLeaseRightOfUseAssetAccumulatedDepreciation	187000	usd
CY2021Q4	bmrc	Finance Lease Right Of Use Asset Accumulated Depreciation FinanceLeaseRightOfUseAssetAccumulatedDepreciation	93000	usd
CY2022Q4	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	429000	usd
CY2022	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2021	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2022	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.083
CY2021	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.084
CY2020	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.081
CY2022	bmrc	Effective Income Tax Rate Reconciliation Tax Exempt Income Interest On Municipal Securities And Loans EffectiveIncomeTaxRateReconciliationTaxExemptIncomeInterestOnMunicipalSecuritiesAndLoans	0.019
CY2021	bmrc	Effective Income Tax Rate Reconciliation Tax Exempt Income Interest On Municipal Securities And Loans EffectiveIncomeTaxRateReconciliationTaxExemptIncomeInterestOnMunicipalSecuritiesAndLoans	0.025
CY2020	bmrc	Effective Income Tax Rate Reconciliation Tax Exempt Income Interest On Municipal Securities And Loans EffectiveIncomeTaxRateReconciliationTaxExemptIncomeInterestOnMunicipalSecuritiesAndLoans	0.024
CY2022	bmrc	Effective Income Tax Rate Reconciliation Tax Exempt Income Earnings On Bank Owned Life Insurance EffectiveIncomeTaxRateReconciliationTaxExemptIncomeEarningsOnBankOwnedLifeInsurance	0.004
CY2021	bmrc	Effective Income Tax Rate Reconciliation Tax Exempt Income Earnings On Bank Owned Life Insurance EffectiveIncomeTaxRateReconciliationTaxExemptIncomeEarningsOnBankOwnedLifeInsurance	0.010
CY2020	bmrc	Effective Income Tax Rate Reconciliation Tax Exempt Income Earnings On Bank Owned Life Insurance EffectiveIncomeTaxRateReconciliationTaxExemptIncomeEarningsOnBankOwnedLifeInsurance	0.005
CY2022	bmrc	Effective Income Tax Rate Reconciliation Non Deductible Acquisition Related Expenses EffectiveIncomeTaxRateReconciliationNonDeductibleAcquisitionRelatedExpenses	0
CY2021	bmrc	Effective Income Tax Rate Reconciliation Non Deductible Acquisition Related Expenses EffectiveIncomeTaxRateReconciliationNonDeductibleAcquisitionRelatedExpenses	0.006
CY2020	bmrc	Effective Income Tax Rate Reconciliation Non Deductible Acquisition Related Expenses EffectiveIncomeTaxRateReconciliationNonDeductibleAcquisitionRelatedExpenses	0
CY2022	bmrc	Effective Income Tax Rate Reconciliation Non Deductible Executive Compensation EffectiveIncomeTaxRateReconciliationNonDeductibleExecutiveCompensation	0
CY2021	bmrc	Effective Income Tax Rate Reconciliation Non Deductible Executive Compensation EffectiveIncomeTaxRateReconciliationNonDeductibleExecutiveCompensation	0.004
CY2020	bmrc	Effective Income Tax Rate Reconciliation Non Deductible Executive Compensation EffectiveIncomeTaxRateReconciliationNonDeductibleExecutiveCompensation	0
CY2022	bmrc	Effective Income Tax Rate Reconciliation Tax Credit Affordable Housing EffectiveIncomeTaxRateReconciliationTaxCreditAffordableHousing	0.002
CY2021	bmrc	Effective Income Tax Rate Reconciliation Tax Credit Affordable Housing EffectiveIncomeTaxRateReconciliationTaxCreditAffordableHousing	0.004
CY2020	bmrc	Effective Income Tax Rate Reconciliation Tax Credit Affordable Housing EffectiveIncomeTaxRateReconciliationTaxCreditAffordableHousing	0.005
CY2022	bmrc	Effective Income Tax Rate Reconciliation Deduction Share Based Compensation And Excess Tax Benefits EffectiveIncomeTaxRateReconciliationDeductionShareBasedCompensationAndExcessTaxBenefits	0
CY2021	bmrc	Effective Income Tax Rate Reconciliation Deduction Share Based Compensation And Excess Tax Benefits EffectiveIncomeTaxRateReconciliationDeductionShareBasedCompensationAndExcessTaxBenefits	0.001
CY2020	bmrc	Effective Income Tax Rate Reconciliation Deduction Share Based Compensation And Excess Tax Benefits EffectiveIncomeTaxRateReconciliationDeductionShareBasedCompensationAndExcessTaxBenefits	0.002
CY2022	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.002
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.004
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
CY2022	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.266
CY2021	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.260
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.255
CY2022Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	24821000	usd
CY2021Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	23604000	usd
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	26639000	usd
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	25429000	usd
CY2021Q4	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	406000	usd
CY2022Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	439000	usd
CY2021Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	419000	usd
CY2022	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	6116000	usd
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	2376000	usd
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	18633000	usd
CY2022	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	151000	usd
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	444000	usd
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	18000	usd
CY2022	us-gaap	Operating Lease Cost OperatingLeaseCost	5356000	usd
CY2021	us-gaap	Operating Lease Cost OperatingLeaseCost	4823000	usd
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	4498000	usd
CY2022	us-gaap	Variable Lease Cost VariableLeaseCost	0	usd
CY2021	us-gaap	Variable Lease Cost VariableLeaseCost	0	usd
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	5000	usd
CY2022	bmrc	Operating Lease Cost Net OperatingLeaseCostNet	5356000	usd
CY2021	bmrc	Operating Lease Cost Net OperatingLeaseCostNet	4823000	usd
CY2020	bmrc	Operating Lease Cost Net OperatingLeaseCostNet	4503000	usd
CY2022	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	127000	usd
CY2021	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	96000	usd
CY2020	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	169000	usd
CY2022	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	3000	usd
CY2021	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	2000	usd
CY2020	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	3000	usd
CY2022	bmrc	Finance Lease Cost FinanceLeaseCost	130000	usd
CY2021	bmrc	Finance Lease Cost FinanceLeaseCost	98000	usd
CY2020	bmrc	Finance Lease Cost FinanceLeaseCost	172000	usd
CY2022	us-gaap	Lease Cost LeaseCost	5486000	usd
CY2021	us-gaap	Lease Cost LeaseCost	4921000	usd
CY2020	us-gaap	Lease Cost LeaseCost	4675000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	5343000	usd
CY2022Q4	us-gaap	Finance Lease Liability Payments Due Next Twelve Months FinanceLeaseLiabilityPaymentsDueNextTwelveMonths	154000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	4585000	usd
CY2022Q4	us-gaap	Finance Lease Liability Payments Due Year Two FinanceLeaseLiabilityPaymentsDueYearTwo	153000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	3875000	usd
CY2022Q4	us-gaap	Finance Lease Liability Payments Due Year Three FinanceLeaseLiabilityPaymentsDueYearThree	106000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	3129000	usd
CY2022Q4	us-gaap	Finance Lease Liability Payments Due Year Four FinanceLeaseLiabilityPaymentsDueYearFour	36000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	2845000	usd
CY2022Q4	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	5000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	9693000	usd
CY2022Q4	us-gaap	Finance Lease Liability Payments Due After Year Five FinanceLeaseLiabilityPaymentsDueAfterYearFive	0	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	29470000	usd
CY2022Q4	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	454000	usd
CY2022Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	2831000	usd
CY2022Q4	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	15000	usd
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	26639000	usd
CY2022Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	439000	usd
CY2022Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P7Y8M12D
CY2022Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P3Y1M6D
CY2022Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0226
CY2022Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.0186
CY2022Q4	us-gaap	Hedged Asset Fair Value Hedge HedgedAssetFairValueHedge	11319000	usd
CY2021Q4	us-gaap	Hedged Asset Fair Value Hedge HedgedAssetFairValueHedge	13976000	usd
CY2022Q4	us-gaap	Hedged Asset Fair Value Hedge Cumulative Increase Decrease HedgedAssetFairValueHedgeCumulativeIncreaseDecrease	-726000	usd
CY2021Q4	us-gaap	Hedged Asset Fair Value Hedge Cumulative Increase Decrease HedgedAssetFairValueHedgeCumulativeIncreaseDecrease	939000	usd
CY2022	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	93868000	usd
CY2021	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	91612000	usd
CY2020	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	84674000	usd
CY2022Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	602000	usd
CY2022Q4	us-gaap	Derivative Asset Fair Value Gross Liability DerivativeAssetFairValueGrossLiability	0	usd
CY2022Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Not Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral	602000	usd
CY2022Q4	us-gaap	Derivative Collateral Obligation To Return Securities DerivativeCollateralObligationToReturnSecurities	0	usd
CY2022Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	0	usd
CY2022Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	602000	usd
CY2021Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	0	usd
CY2021Q4	us-gaap	Derivative Asset Fair Value Gross Liability DerivativeAssetFairValueGrossLiability	0	usd
CY2021Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Not Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral	0	usd
CY2021Q4	us-gaap	Derivative Collateral Obligation To Return Securities DerivativeCollateralObligationToReturnSecurities	0	usd
CY2021Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	0	usd
CY2021Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	0	usd
CY2022Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	0	usd
CY2022Q4	us-gaap	Derivative Liability Fair Value Gross Asset DerivativeLiabilityFairValueGrossAsset	0	usd
CY2022Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Not Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral	0	usd
CY2022Q4	us-gaap	Derivative Collateral Right To Reclaim Securities DerivativeCollateralRightToReclaimSecurities	0	usd
CY2022Q4	us-gaap	Derivative Collateral Right To Reclaim Cash DerivativeCollateralRightToReclaimCash	0	usd
CY2022Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral	0	usd
CY2021Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	1085000	usd
CY2021Q4	us-gaap	Derivative Liability Fair Value Gross Asset DerivativeLiabilityFairValueGrossAsset	0	usd
CY2021Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Not Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral	1085000	usd
CY2021Q4	us-gaap	Derivative Collateral Right To Reclaim Securities DerivativeCollateralRightToReclaimSecurities	0	usd
CY2021Q4	us-gaap	Derivative Collateral Right To Reclaim Cash DerivativeCollateralRightToReclaimCash	1085000	usd
CY2021Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral	0	usd
CY2022	bmrc	Increase Decrease In Unfunded Loan Commitments IncreaseDecreaseInUnfundedLoanCommitments	-318000	usd
CY2021	bmrc	Increase Decrease In Unfunded Loan Commitments IncreaseDecreaseInUnfundedLoanCommitments	-993000	usd
CY2022	dei	Auditor Name AuditorName	Moss Adams LLP
CY2022	dei	Auditor Location AuditorLocation	Portland, OR
CY2022	dei	Auditor Firm AuditorFirmId	659

Files In Submission

Name	View Source	Status
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bmrc-20221231_cal.xml	Edgar Link	unprocessable
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$BMRC
Bank of Marin Bancorp Stock $bmrc

2023 Q1 Form 10-K Financial Statement

#000140347523000015 Filed on March 16, 2023

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BMRC Bank of Marin Bancorp Stock $bmrc

2023 Q1 Form 10-K Financial Statement

#000140347523000015 Filed on March 16, 2023

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BMRC
Bank of Marin Bancorp Stock $bmrc