$BMRC
Bank of Marin Bancorp Stock $bmrc

$bmrc Overview Financials Valuation SEC Filings Company Website

2021 Form 10-K Financial Statement

#000140347522000015 Filed on March 15, 2022

Income Statement

Concept	2021	2020 Q4	2020
Revenue	$108.4M		$99.64M
YoY Change	8.75%		-0.8%
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	$1.700M	$770.0K	$2.100M
YoY Change	-19.05%	2.67%	-4.55%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$3.402M		$2.979M
YoY Change	14.2%		-37.38%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$44.89M	$11.10M	$40.59M
YoY Change	10.59%	-10.41%	-11.56%
Income Tax	$11.66M	$2.990M	$10.35M
% Of Pretax Income	25.97%	26.94%	25.49%
Net Earnings	$33.23M	$8.120M	$30.24M
YoY Change	9.87%	-10.57%	-11.68%
Net Earnings / Revenue	30.67%		30.35%
Basic Earnings Per Share	$2.32		$2.24
Diluted Earnings Per Share	$2.30	$596.2K	$2.22
COMMON SHARES
Basic Shares Outstanding	14.34M shares	13.62M shares	13.53M shares
Diluted Shares Outstanding	14.42M shares		13.62M shares

Balance Sheet

Concept	2021	2020 Q4	2020
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents		$200.3M
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	$31.20M	$30.50M	$30.50M
YoY Change	2.3%	402.47%	78.36%
Goodwill		$30.14M
YoY Change		0.0%
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets	$13.30M		$6.900M
YoY Change	92.75%		-15.85%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$4.314B	$2.900B	$2.912B
YoY Change	48.16%	7.12%	7.56%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$29.40M	$19.50M	$19.50M
YoY Change	50.77%	12.72%	12.72%
Accrued Expenses	$25.40M	$27.10M	$27.10M
YoY Change	-6.27%	115.08%	115.08%
Deferred Revenue
YoY Change
Short-Term Debt
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$54.80M	$46.60M	$46.60M
YoY Change	17.6%	55.85%	55.85%
LONG-TERM LIABILITIES
Long-Term Debt	$0.00	$2.800M	$2.800M
YoY Change	-100.0%	-3.45%	-3.45%
Other Long-Term Liabilities
YoY Change
Total Long-Term Liabilities	$0.00	$2.800M	$2.800M
YoY Change	-100.0%	-31.71%	-31.71%
TOTAL LIABILITIES
Total Short-Term Liabilities	$54.80M	$46.60M	$46.60M
Total Long-Term Liabilities	$0.00	$2.800M	$2.800M
Total Liabilities	$3.864B	$2.554B	$2.554B
YoY Change	51.3%	7.73%	7.73%
SHAREHOLDERS EQUITY
Retained Earnings		$219.7M
YoY Change		8.13%
Common Stock		$125.9M
YoY Change		-2.44%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$450.4M	$358.3M	$358.3M
YoY Change
Total Liabilities & Shareholders Equity	$4.314B	$2.912B	$2.912B
YoY Change	48.16%	7.56%	7.56%

Cashflow Statement

Concept	2021	2020 Q4	2020
OPERATING ACTIVITIES
Net Income	$33.23M	$8.120M	$30.24M
YoY Change	9.87%	-10.57%	-11.68%
Depreciation, Depletion And Amortization	$1.700M	$770.0K	$2.100M
YoY Change	-19.05%	2.67%	-4.55%
Cash From Operating Activities	$45.25M	$9.530M	$40.85M
YoY Change	10.79%	-2.06%	-0.21%
INVESTING ACTIVITIES
Capital Expenditures	-$1.040M	-$210.0K	-$980.0K
YoY Change	6.12%	75.0%	81.48%
Acquisitions
YoY Change
Other Investing Activities	-$339.6M	$49.15M	-$172.5M
YoY Change	96.93%	-142.33%	753.34%
Cash From Investing Activities	-$340.7M	$48.94M	-$173.4M
YoY Change	96.41%	-142.11%	735.71%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	$442.7M	-71.73M	$149.5M
YoY Change	196.08%	-166.79%	15.93%
NET CHANGE
Cash From Operating Activities	$45.25M	9.530M	$40.85M
Cash From Investing Activities	-$340.7M	48.94M	-$173.4M
Cash From Financing Activities	$442.7M	-71.73M	$149.5M
Net Change In Cash	$147.3M	-13.26M	$16.93M
YoY Change	770.07%	-1573.33%	-88.65%
FREE CASH FLOW
Cash From Operating Activities	$45.25M	$9.530M	$40.85M
Capital Expenditures	-$1.040M	-$210.0K	-$980.0K
Free Cash Flow	$46.29M	$9.740M	$41.83M
YoY Change	10.68%	-1.12%	0.85%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2021	dei	Entity Central Index Key EntityCentralIndexKey	0001403475
CY2021	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
CY2021	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2021	dei	Amendment Flag AmendmentFlag	false
CY2019	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	http://fasb.org/us-gaap/2021-01-31#AccountingStandardsUpdate201613Member
	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	http://fasb.org/us-gaap/2021-01-31#AccountingStandardsUpdate201613Member
	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	http://fasb.org/us-gaap/2021-01-31#AccountingStandardsUpdate201613Member
CY2021	bmrc	Dividends Cash Dividend Period Restricted Payment Amount Is Determined DividendsCashDividendPeriodRestrictedPaymentAmountIsDetermined	P3Y
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset Statement Of Financial Position Extensible List FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2021-01-31#PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
CY2021Q4	us-gaap	Finance Lease Right Of Use Asset Statement Of Financial Position Extensible List FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2021-01-31#PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
CY2021	dei	Document Type DocumentType	10-K
CY2021	dei	Document Annual Report DocumentAnnualReport	true
CY2021	dei	Document Period End Date DocumentPeriodEndDate	2021-12-31
CY2021	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2021	dei	Document Transition Report DocumentTransitionReport	false
CY2021	dei	Entity File Number EntityFileNumber	001-33572
CY2021	dei	Entity Registrant Name EntityRegistrantName	Bank of Marin Bancorp
CY2021	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	CA
CY2021	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	20-8859754
CY2021	dei	Entity Address Address Line1 EntityAddressAddressLine1	504 Redwood Blvd.
CY2021	dei	Entity Address Address Line2 EntityAddressAddressLine2	Suite 100
CY2021	dei	Entity Address City Or Town EntityAddressCityOrTown	Novato
CY2021	dei	Entity Address State Or Province EntityAddressStateOrProvince	CA
CY2021	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	94947
CY2021	dei	City Area Code CityAreaCode	415
CY2021	dei	Local Phone Number LocalPhoneNumber	763-4520
CY2021	dei	Security12g Title Security12gTitle	Common Stock, No Par Value, and attached Share Purchase Rights
CY2021	dei	Trading Symbol TradingSymbol	BMRC
CY2021	dei	Security Exchange Name SecurityExchangeName	NASDAQ
CY2021	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	No
CY2021	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2021	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2021	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2021	dei	Entity Filer Category EntityFilerCategory	Accelerated Filer
CY2021	dei	Entity Small Business EntitySmallBusiness	false
CY2021	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
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CY2021	dei	Entity Shell Company EntityShellCompany	false
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CY2019	us-gaap	Noninterest Income NoninterestIncome	9084000	USD
CY2021	us-gaap	Labor And Related Expense LaborAndRelatedExpense	41939000	USD
CY2020	us-gaap	Labor And Related Expense LaborAndRelatedExpense	34393000	USD
CY2019	us-gaap	Labor And Related Expense LaborAndRelatedExpense	34253000	USD
CY2021	bmrc	Occupancy And Equipment OccupancyAndEquipment	7302000	USD
CY2020	bmrc	Occupancy And Equipment OccupancyAndEquipment	6943000	USD
CY2019	bmrc	Occupancy And Equipment OccupancyAndEquipment	6143000	USD
CY2021	bmrc	Data Processing DataProcessing	5139000	USD
CY2020	bmrc	Data Processing DataProcessing	3184000	USD
CY2019	bmrc	Data Processing DataProcessing	3717000	USD
CY2021	us-gaap	Professional Fees ProfessionalFees	4974000	USD
CY2020	us-gaap	Professional Fees ProfessionalFees	2181000	USD
CY2019	us-gaap	Professional Fees ProfessionalFees	2132000	USD
CY2021	us-gaap	Depreciation Depreciation	1740000	USD
CY2020	us-gaap	Depreciation Depreciation	2149000	USD
CY2019	us-gaap	Depreciation Depreciation	2228000	USD
CY2021	bmrc	Information Technology InformationTechnology	1550000	USD
CY2020	bmrc	Information Technology InformationTechnology	1050000	USD
CY2019	bmrc	Information Technology InformationTechnology	1065000	USD
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1135000	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	853000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	887000	USD
CY2021	us-gaap	Noninterest Expense Directors Fees NoninterestExpenseDirectorsFees	957000	USD
CY2020	us-gaap	Noninterest Expense Directors Fees NoninterestExpenseDirectorsFees	713000	USD
CY2019	us-gaap	Noninterest Expense Directors Fees NoninterestExpenseDirectorsFees	735000	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
CY2020	bmrc	Charitable Contributions Expense CharitableContributionsExpense	1034000	USD
CY2019	bmrc	Charitable Contributions Expense CharitableContributionsExpense	508000	USD
CY2021	us-gaap	Other Noninterest Expense OtherNoninterestExpense	6426000	USD
CY2020	us-gaap	Other Noninterest Expense OtherNoninterestExpense	5484000	USD
CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	5812000	USD
CY2021	us-gaap	Noninterest Expense NoninterestExpense	72638000	USD
CY2020	us-gaap	Noninterest Expense NoninterestExpense	58458000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	57841000	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
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	45894000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11658000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	10345000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11653000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	33228000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	30242000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	34241000	USD
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.32
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.24
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.51
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.30
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.22
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.48
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
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	13620000	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
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	13794000	shares
CY2021	us-gaap	Net Income Loss NetIncomeLoss	33228000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	30242000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	34241000	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
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	11839000	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
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	55000	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
CY2019	bmrc	Amortization Of Net Unrealized Loss On Available For Sale Securities Transferred To Held To Maturity AmortizationOfNetUnrealizedLossOnAvailableForSaleSecuritiesTransferredToHeldToMaturity	445000	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
CY2019	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Before Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent	12229000	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
CY2019	us-gaap	Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent	3624000	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
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	8605000	USD
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	18603000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	38340000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	42846000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	316407000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	34241000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	8605000	USD
CY2019	bmrc	Stock Issued During Period Value Stock Options Exercised Net Of Shares Surrendered For Cashless Exercises And Tax Withholdings StockIssuedDuringPeriodValueStockOptionsExercisedNetOfSharesSurrenderedForCashlessExercisesAndTaxWithholdings	669000	USD
CY2019	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	54000	USD
CY2019	us-gaap	Stock Issued During Period Value Employee Stock Ownership Plan StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan	1245000	USD
CY2019	us-gaap	Adjustments Related To Tax Withholding For Share Based Compensation AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation	220000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Stock Options Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition	495000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	1017000	USD
CY2019	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.80
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	10958000	USD
CY2019	bmrc	Stock Issued During Period Value Nonemployee Director Stock Purchase Plans StockIssuedDuringPeriodValueNonemployeeDirectorStockPurchasePlans	24000	USD
CY2019	bmrc	Stock Issued In Payment Of Director Fees StockIssuedInPaymentOfDirectorFees	231000	USD
CY2019	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	15022000	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	Net Income Loss NetIncomeLoss	33228000	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 Acquisitions StockIssuedDuringPeriodValueAcquisitions	124401000	USD
CY2021	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	40722000	USD
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	450368000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	33228000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	30242000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	34241000	USD
CY2021	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	-1449000	USD
CY2020	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	4594000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	900000	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
CY2019	bmrc	Provision For Reversal Of Losses On Off Balance Sheet Commitments ProvisionForReversalOfLossesOnOffBalanceSheetCommitments	129000	USD
CY2021	bmrc	Noncash Contribution Expense To Employee Stock Ownership Plan NoncashContributionExpenseToEmployeeStockOwnershipPlan	1330000	USD
CY2020	bmrc	Noncash Contribution Expense To Employee Stock Ownership Plan NoncashContributionExpenseToEmployeeStockOwnershipPlan	1289000	USD
CY2019	bmrc	Noncash Contribution Expense To Employee Stock Ownership Plan NoncashContributionExpenseToEmployeeStockOwnershipPlan	1245000	USD
CY2021	bmrc	Compensation Expense Common Stock For Director Fees CompensationExpenseCommonStockForDirectorFees	347000	USD
CY2020	bmrc	Compensation Expense Common Stock For Director Fees CompensationExpenseCommonStockForDirectorFees	301000	USD
CY2019	bmrc	Compensation Expense Common Stock For Director Fees CompensationExpenseCommonStockForDirectorFees	301000	USD
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	972000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	1203000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	1512000	USD
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1135000	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	853000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	887000	USD
CY2021	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-5799000	USD
CY2020	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-1354000	USD
CY2019	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-1633000	USD
CY2021	bmrc	Accretion Of Discount On Acquired Loans AccretionOfDiscountOnAcquiredLoans	571000	USD
CY2020	bmrc	Accretion Of Discount On Acquired Loans AccretionOfDiscountOnAcquiredLoans	165000	USD
CY2019	bmrc	Accretion Of Discount On Acquired Loans AccretionOfDiscountOnAcquiredLoans	353000	USD
CY2021	us-gaap	Amortization Of Debt Discount Premium AmortizationOfDebtDiscountPremium	1347000	USD
CY2020	us-gaap	Amortization Of Debt Discount Premium AmortizationOfDebtDiscountPremium	69000	USD
CY2019	us-gaap	Amortization Of Debt Discount Premium AmortizationOfDebtDiscountPremium	68000	USD
CY2021	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	3155000	USD
CY2020	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	-5040000	USD
CY2019	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	348000	USD
CY2021	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	-16000	USD
CY2020	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	915000	USD
CY2019	us-gaap	Gain Loss On Sale Of Investments GainLossOnSaleOfInvestments	55000	USD
CY2021	us-gaap	Depreciation Depreciation	1740000	USD
CY2020	us-gaap	Depreciation Depreciation	2149000	USD
CY2019	us-gaap	Depreciation Depreciation	2228000	USD
CY2021	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	2194000	USD
CY2020	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	973000	USD
CY2019	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1196000	USD
CY2021	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-5554000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	5135000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	329000	USD
CY2021	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	2146000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-631000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	70000	USD
CY2021	us-gaap	Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities	12025000	USD
CY2020	us-gaap	Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities	10603000	USD
CY2019	us-gaap	Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities	6692000	USD
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	45253000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	40845000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	40933000	USD
CY2021	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	305329000	USD
CY2020	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	0	USD
CY2019	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	3549000	USD
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	620236000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	97544000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	110934000	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
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	66081000	USD
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	71682000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	28144000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	23005000	USD
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	110059000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	114991000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	86044000	USD
CY2021	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-256856000	USD
CY2020	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	249337000	USD
CY2019	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	77827000	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
CY2019	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	2997000	USD
CY2021	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	2478000	USD
CY2020	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	0	USD
CY2019	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	1533000	USD
CY2021	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	1044000	USD
CY2020	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	981000	USD
CY2019	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	542000	USD
CY2021	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	140577000	USD
CY2020	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	0	USD
CY2019	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	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
CY2019	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	616000	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
CY2019	us-gaap	Payments To Acquire Real Estate Held For Investment PaymentsToAcquireRealEstateHeldForInvestment	952000	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
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-20754000	USD
CY2021	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	514279000	USD
CY2020	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	167760000	USD
CY2019	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	161649000	USD
CY2021	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	463000	USD
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1304000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	669000	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
CY2019	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	220000	USD
CY2021	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	13885000	USD
CY2020	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	0	USD
CY2019	us-gaap	Repayments Of Federal Home Loan Bank Borrowings RepaymentsOfFederalHomeLoanBankBorrowings	7000000	USD
CY2021	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	4126000	USD
CY2020	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	USD
CY2019	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	USD
CY2021	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	86000	USD
CY2020	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	172000	USD
CY2019	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	168000	USD
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	13107000	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	12506000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	10958000	USD
CY2021	us-gaap	Payments For Repurchase Of Equity PaymentsForRepurchaseOfEquity	40762000	USD
CY2020	us-gaap	Payments For Repurchase Of Equity PaymentsForRepurchaseOfEquity	6898000	USD
CY2019	us-gaap	Payments For Repurchase Of Equity PaymentsForRepurchaseOfEquity	15062000	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
CY2019	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans	78000	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
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	128988000	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
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	149167000	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
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	34221000	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
CY2021	us-gaap	Interest Paid Net InterestPaidNet	2105000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	2948000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	4659000	USD
CY2021	us-gaap	Income Taxes Paid IncomeTaxesPaid	12350000	USD
CY2020	us-gaap	Income Taxes Paid IncomeTaxesPaid	13065000	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	12738000	USD
CY2021	bmrc	Increase Decrease In Unrealized Gain Loss On Available For Sale Securities Net Of Tax IncreaseDecreaseInUnrealizedGainLossOnAvailableForSaleSecuritiesNetOfTax	-21281000	USD
CY2020	bmrc	Increase Decrease In Unrealized Gain Loss On Available For Sale Securities Net Of Tax IncreaseDecreaseInUnrealizedGainLossOnAvailableForSaleSecuritiesNetOfTax	11891000	USD
CY2019	bmrc	Increase Decrease In Unrealized Gain Loss On Available For Sale Securities Net Of Tax IncreaseDecreaseInUnrealizedGainLossOnAvailableForSaleSecuritiesNetOfTax	11839000	USD
CY2021	bmrc	Stock Issued In Payment Of Director Fees And To Esop StockIssuedInPaymentOfDirectorFeesAndToESOP	1330000	USD
CY2020	bmrc	Stock Issued In Payment Of Director Fees And To Esop StockIssuedInPaymentOfDirectorFeesAndToESOP	1289000	USD
CY2019	bmrc	Stock Issued In Payment Of Director Fees And To Esop StockIssuedInPaymentOfDirectorFeesAndToESOP	1245000	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
CY2019	bmrc	Cumulative Effect Of Change In Accounting Principle CumulativeEffectOfChangeInAccountingPrinciple	0	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
CY2019	bmrc	Amortization Of Net Unrealized Loss On Available For Sale Securities Transferred To Held To Maturity AmortizationOfNetUnrealizedLossOnAvailableForSaleSecuritiesTransferredToHeldToMaturity	445000	USD
CY2021	bmrc	Repurchase Of Stock Not Yet Settled RepurchaseOfStockNotYetSettled	373000	USD
CY2020	bmrc	Repurchase Of Stock Not Yet Settled RepurchaseOfStockNotYetSettled	413000	USD
CY2019	bmrc	Repurchase Of Stock Not Yet Settled RepurchaseOfStockNotYetSettled	103000	USD
CY2021	bmrc	Stock Issued In Payment Of Director Fees StockIssuedInPaymentOfDirectorFees	217000	USD
CY2020	bmrc	Stock Issued In Payment Of Director Fees StockIssuedInPaymentOfDirectorFees	217000	USD
CY2019	bmrc	Stock Issued In Payment Of Director Fees StockIssuedInPaymentOfDirectorFees	231000	USD
CY2021	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	757844000	USD
CY2020	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	0	USD
CY2019	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	0	USD
CY2021	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	816558000	USD
CY2020	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	0	USD
CY2019	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	0	USD
CY2021Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	4395000	USD
CY2020Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	2700000	USD
CY2019Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	6516000	USD
CY2021Q4	bmrc	Number Of Retail Branches NumberOfRetailBranches	31	retailBranch
CY2021Q4	bmrc	Number Of Commercial Banking Offices NumberOfCommercialBankingOffices	8	commercialBankingOffice
CY2021Q4	bmrc	Number Of Counties NumberOfCounties	10	county
CY2021	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.
CY2021Q3	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	22113000	USD
CY2021Q3	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1697000	USD
CY2021	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>
CY2021Q4	us-gaap	Financing Receivable Threshold Period Past Due Writeoff FinancingReceivableThresholdPeriodPastDueWriteoff	P90D
CY2021	bmrc	Loansand Leases Receivable Nonperforming Number Of Consecutive Payments Considered Sustained Repayment Performance LoansandLeasesReceivableNonperformingNumberOfConsecutivePaymentsConsideredSustainedRepaymentPerformance	6	payment
CY2021Q4	us-gaap	Financing Receivable Threshold Period Past Due Writeoff FinancingReceivableThresholdPeriodPastDueWriteoff	P90D
CY2021	bmrc	Threshold Period Past Due For Write Off Of Deposit Liabilities Reclassified As Loans Receivable ThresholdPeriodPastDueForWriteOffOfDepositLiabilitiesReclassifiedAsLoansReceivable	P60D
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Policy For Uncollectible Amounts FinancingReceivableAllowanceForCreditLossesPolicyForUncollectibleAmounts	<div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Allowance for Credit Losses on Loans ("ACL")</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%">is a valuation account that is deducted from the amortized cost basis at the balance sheet date to present the net amount of loans expected to be collected. Amortized cost does not include accrued interest, which management elected to exclude from the estimate of expected credit losses (refer to the </span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Past-Due and Non-Accrual Loan Policy</span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> section above). Management estimates the allowance quarterly using relevant available information, from internal and external sources, relating to past events, current conditions, and reasonable and supportable forecasts. Credit loss experience provides the basis for the estimation of expected credit losses. </span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The ACL model utilizes a discounted cash flow ("DCF") method to measure the expected credit losses on loans collectively evaluated that are sub-segmented by loan pools with similar credit risk characteristics, which are generally comprised of federal regulatory reporting codes (i.e., Call codes). Pooled segments include the following:</span></div><div style="text-align:justify"><span><br/></span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Loans secured by real estate:</span></div><div style="padding-left:36pt;text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">- 1-4 family residential construction loans</span></div><div style="padding-left:36pt;text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">- Other construction loans and all land development and other land loans</span></div><div style="padding-left:36pt;text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">- Secured by farmland (including residential and other improvements)</span></div><div style="padding-left:36pt;text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">- Revolving, open-end loans secured by 1-4 family residential properties and extended under lines</span></div><div style="padding-left:36pt;text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">of credit</span></div><div style="padding-left:36pt;text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">- Closed-end loans secured by 1-4 family residential properties, secured by first liens</span></div><div style="padding-left:36pt;text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">- Closed-end loans secured by 1-4 family residential properties, secured by junior liens</span></div><div style="padding-left:36pt;text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">- Secured by multifamily (5 or more) residential properties</span></div><div style="padding-left:36pt;text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">- Commercial real estate loans secured by owner-occupied non-farm nonresidential properties</span></div><div style="padding-left:36pt;text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">- Commercial real estate loans secured by other non-farm nonresidential properties</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Loans to finance agricultural production and other loans to farmers</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Commercial and industrial loans</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Loans to individuals for household, family and other personal expenditures (i.e., consumer loans)</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Municipal entities</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Non-profit organizations</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Other loans (overdraft credit lines)</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The DCF method incorporates assumptions for probability of default ("PD"), loss given default ("LGD"), and prepayments and curtailments over the contractual terms of the loans. Under the DCF method, the ACL reflects the difference between the amortized cost basis and the present value of the expected cash flows using the loan's effective rate. We elected to report the change in present values from one reporting period to the next due to the passage of time and changes in the estimate of future expected cash flows through the provision for credit losses, rather than though interest income. </span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In determining the PD for each pooled segment, the Bank utilized regression analyses to identify certain economic drivers that were considered highly correlated to historical Bank or peer loan default experience. As a result, management chose the California unemployment rate as the primary economic forecast driver for all segments, except for municipal loans. In addition, the annual percentage change in the California gross domestic product was used in the commercial and industrial loan segment. For municipal loans, the ACL model utilized a constant default rate obtained from a nationally recognized default rate st</span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">udy, which is updated annually. In the third quarter of 2021, we eliminated the use of the </span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">annual percentage change in California retail sales in the owner-occupied and investor-owned commercial real estate segments as we determined that it was not highly correlated to peer loan default experience when we performed our annual validation of our peer group and regression analyses. The change in methodology did not have a material impact on the ACL. </span><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">A third party provides LGD estimates for each segment based on a banking industry Frye-Jacobs Risk Index approach. </span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The ACL model incorporates a one-year reasonable and supportable forecast of economic factors, updated quarterly, which is based on Moody's Analytics' Baseline Forecast. For periods beyond the forecast horizon the economic factors revert to historical averages on a straight-line basis over a one-year period.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Expected credit losses are estimated over the contractual term of the loans, adjusted for expected prepayments and curtailments, when appropriate. The pooled loans' contractual loan terms exclude extensions, renewals, and modifications unless one or more of the following applies: 1) management has a reasonable expectation at the reporting date that a troubled debt restructuring will be executed with an individual borrower, 2) the extension or renewal options are included in the original or modified contract, or 3) an existing troubled debt restructuring is within six months of maturity.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Loans that do not share the same risk characteristics as pooled loans are evaluated individually for credit loss and generally include all non-accrual loans, collateral dependent loans, and certain troubled debt restructured loans and loans graded substandard or worse as determined by management.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Management considers whether adjustments to the quantitative portion of the ACL are needed for differences in segment-specific risk characteristics or to reflect the extent to which it expects current conditions and reasonable and supportable forecasts of economic conditions to differ from the conditions that existed during the historical period included in the development of PD and LGD. </span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Qualitative internal and external risk factors include, but are not limited to, the following:</span></div><div style="margin-top:6pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Changes in the nature and volume of the loan portfolio</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Changes in the volume and severity of past due loans, the volume of non-accruals loans, and the volume and severity of adversely classified or graded loans</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">The existence and effect of individual loan and loan segment concentrations</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Changes in lending policies and procedures, including changes in underwriting standards and collection, charge-off, and recovery practices not considered elsewhere</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Changes in the experience, ability, and depth of lending management and other relevant staff</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Changes in the quality of our systematic loan review processes</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Changes in economic and business conditions, and developments that affect the collectability of the portfolio</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">Changes in the value of underlying collateral, where applicable</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">The effect of other external factors such as legal and regulatory requirements on the level of estimated credit losses in the portfolio</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">The effect of acquisitions of other loan portfolios on our infrastructure, including risk associated with entering new geographic areas as a result of such acquisitions</span></div><div style="padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;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%;padding-left:14.5pt">The presence of specialized lending segments in the portfolio</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">While we believe we use the best information available to determine the allowance for credit losses, our results of operations could be significantly affected if circumstances differ substantially from the assumptions used in determining the allowance. Our ACL model is sensitive to changes in unemployment rate forecasts and certain other assumptions that could result in material fluctuations in the allowance for credit losses and adversely affect our financial condition and results of operations.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">For further information regarding the allowance for loan losses, see Note 3, Loans and Allowance for Loan Losses.</span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> </span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">We use a risk rating system to evaluate asset quality, and to identify and monitor credit risk in individual loans, and in the loan portfolio. Our definitions of “Special Mention” risk graded loans, or worse, are consistent with those used by the Federal Deposit Insurance Corporation ("FDIC"). Our internally assigned grades are as follows:</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> </span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Pass and Watch</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%"> Loans to borrowers of acceptable or better credit quality. Borrowers in this category demonstrate fundamentally sound financial positions, repayment capacity, credit history and management expertise. Loans in this category must have an identifiable and stable source of repayment and meet the Bank’s policy regarding debt-service-coverage ratios. These borrowers are capable of sustaining normal economic, market or operational setbacks without significant financial consequences. Negative external industry factors are generally not present. The loan may be secured, unsecured or supported by non-real estate collateral for which the value is more difficult to determine and/or marketability is more uncertain. This category also includes “Watch” loans, where </span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">the primary source of repayment has been delayed. “Watch” is intended to be a transitional grade, with either an upgrade or downgrade within a reasonable period.</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> </span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Special Mention</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%">Potential weaknesses that deserve close attention. If left uncorrected, those potential weaknesses may result in deterioration of the payment prospects for the asset. Special Mention assets do not present sufficient risk to warrant adverse classification.</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> </span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Substandard </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%">Inadequately protected by either the current sound worth and paying capacity of the obligor or the collateral pledged, if any. A Substandard asset has a well-defined weakness or weaknesses that jeopardize(s) the liquidation of the debt. Substandard assets are characterized by the distinct possibility that we will sustain some loss if such weaknesses or deficiencies are not corrected. Well-defined weaknesses include adverse trends or developments of the borrower’s financial condition, managerial weaknesses and/or significant collateral deficiencies.</span></div><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> </span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Doubtful</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%">Critical weaknesses that make collection or liquidation in full improbable. There may be specific pending events that work to strengthen the asset; however, the amount or timing of the loss may not be determinable. Pending events generally occur within one year of the asset being classified as Doubtful. Examples include: merger, acquisition, or liquidation; capital injection; guarantee; perfecting liens on additional collateral; and refinancing. Such loans are placed on non-accrual status and usually are collateral-dependent.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%">We regularly review our credits for accuracy of risk grades whenever we receive new information. Borrowers are generally required to submit financial information at regular intervals. Typically, commercial borrowers with lines of credit are required to submit financial information with reporting intervals ranging from monthly to annually depending on credit size, risk and complexity. In addition, investor commercial real estate borrowers with loans exceeding a certain dollar threshold are usually required to submit rent rolls or property income statements annually. We monitor construction loans monthly. We review home equity and other consumer loans based on delinquency. We also review loans graded “Watch” or worse, regardless of loan type, no less than quarterly.</span></div>
CY2019	us-gaap	Gains Losses On Sales Of Assets GainsLossesOnSalesOfAssets	0	USD
CY2020	us-gaap	Gains Losses On Sales Of Assets GainsLossesOnSalesOfAssets	0	USD
CY2021	us-gaap	Gains Losses On Sales Of Assets GainsLossesOnSalesOfAssets	0	USD
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
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	13620000	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
CY2019	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	148000	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
CY2019	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	26000	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
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	13794000	shares
CY2021	us-gaap	Net Income Loss NetIncomeLoss	33228000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	30242000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	34241000	USD
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.32
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.24
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.51
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.30
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.22
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.48
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
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	35000	shares
CY2021	us-gaap	Advertising Expense AdvertisingExpense	908000	USD
CY2020	us-gaap	Advertising Expense AdvertisingExpense	769000	USD
CY2019	us-gaap	Advertising Expense AdvertisingExpense	775000	USD
CY2021Q1	bmrc	Number Of Interest Rate Swap Contract NumberOfInterestRateSwapContract	4	contract
CY2021Q1	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	13000000	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
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
CY2020Q4	us-gaap	Held To Maturity Securities Amortized Cost Before Other Than Temporary Impairment HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment	109036000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	0	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	109036000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	6149000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	0	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	115185000	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 Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	0	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
CY2020Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss	373038000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	19393000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	80000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	392351000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount	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
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount	246000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue	250000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount	49127000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	51102000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	11530000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	11687000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount	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
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount	7550000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	7961000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	59028000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	62397000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount	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
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount	52113000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	55872000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	144908000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	154089000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount	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
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	157572000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	164178000	USD
CY2021Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	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 Before Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss	1169520000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	1167568000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	109036000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	115185000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss	373038000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	392351000	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
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	66081000	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
CY2019	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	214000	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
CY2019	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	159000	USD
CY2021Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	217849000	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Securities Pledged PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged	132431000	USD
CY2021Q4	bmrc	Marketable Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions MarketableSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions	217	security
CY2020Q4	bmrc	Marketable Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions MarketableSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions	10	security
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 Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	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
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	9918000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	25000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	1790000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	55000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	11708000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	80000	USD
CY2020Q4	bmrc	Available For Sale Securities And Held To Maturity Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	9918000	USD
CY2020Q4	bmrc	Availableforsale Securitiesand Heldtomaturity Securities Continuous Unrealized Loss Position Lessthan12 Months Accumulated Loss AvailableforsaleSecuritiesandHeldtomaturitySecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss	25000	USD
CY2020Q4	bmrc	Available For Sale Securities And Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	1790000	USD
CY2020Q4	bmrc	Availableforsale Securitiesand Heldtomaturity Securities Continuous Unrealized Loss Position12 Monthsor Longer Accumulated Loss AvailableforsaleSecuritiesandHeldtomaturitySecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss	55000	USD
CY2020Q4	bmrc	Available For Sale Securities And Held To Maturity Securities Continuous Unrealized Loss Position Fair Value Total AvailableForSaleSecuritiesAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValueTotal	11708000	USD
CY2020Q4	bmrc	Availableforsale Securitiesand Heldtomaturity Securities Continuous Unrealized Loss Position Accumulated Loss AvailableforsaleSecuritiesandHeldtomaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	80000	USD
CY2021Q4	bmrc	Marketable Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Longer Than12 Months MarketableSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositionsLongerThan12Months	9	security
CY2021Q4	bmrc	Marketable Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than12 Months MarketableSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositionsLessThan12Months	208	security
CY2021Q4	bmrc	Debt Securities Available For Sale Unrealized Loss Position Allowance For Credit Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAllowanceForCreditLoss	0	USD
CY2021Q4	bmrc	Federal Home Loan Bank Stock Par Value FederalHomeLoanBankStockParValue	100
CY2021Q4	us-gaap	Amortization Method Qualified Affordable Housing Project Investments AmortizationMethodQualifiedAffordableHousingProjectInvestments	3000000	USD
CY2020Q4	us-gaap	Amortization Method Qualified Affordable Housing Project Investments AmortizationMethodQualifiedAffordableHousingProjectInvestments	3500000	USD
CY2021	bmrc	Amortization Method Qualified Affordable Housing Project Investments Tax Credits AmortizationMethodQualifiedAffordableHousingProjectInvestmentsTaxCredits	645000	USD
CY2021	us-gaap	Amortization Method Qualified Affordable Housing Project Investments Amortization AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization	542000	USD
CY2021Q4	bmrc	Affordable Housing Program Unfunded Commitments AffordableHousingProgramUnfundedCommitments	422000	USD
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	2255645000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	2088556000	USD
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	23023000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	22874000	USD
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	2232622000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	2065682000	USD
CY2021Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	-901000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	-4100000	USD
CY2021Q4	bmrc	Certain Loans Acquired In Transfer Without Evidence Of Deteriorated Credit Unrecognized Purchase Discounts CertainLoansAcquiredInTransferWithoutEvidenceOfDeterioratedCreditUnrecognizedPurchaseDiscounts	2500000	USD
CY2020Q4	bmrc	Certain Loans Acquired In Transfer Without Evidence Of Deteriorated Credit Unrecognized Purchase Discounts CertainLoansAcquiredInTransferWithoutEvidenceOfDeterioratedCreditUnrecognizedPurchaseDiscounts	815000	USD
CY2021Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	7100000	USD
CY2020Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	8800000	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
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear	578922000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Two Originated Fiscal Year Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear	275977000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear	275069000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear	180349000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear	138246000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Originated More Than Five Years Before Current Fiscal Year FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear	428702000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Revolving FinancingReceivableExcludingAccruedInterestRevolving	211291000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	2088556000	USD
CY2021Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	8376000	USD
CY2021Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	8376000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	9233000	USD
CY2020Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	9233000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	0	USD
CY2021Q4	bmrc	Financing Receivable Nonaccrual Earning Interest On Cash Basis FinancingReceivableNonaccrualEarningInterestOnCashBasis	0	USD
CY2020Q4	bmrc	Financing Receivable Nonaccrual Earning Interest On Cash Basis FinancingReceivableNonaccrualEarningInterestOnCashBasis	0	USD
CY2019	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0	USD
CY2020	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0	USD
CY2021	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0	USD
CY2021	us-gaap	Financing Receivable Accrued Interest Writeoff FinancingReceivableAccruedInterestWriteoff	0	USD
CY2020	us-gaap	Financing Receivable Accrued Interest Writeoff FinancingReceivableAccruedInterestWriteoff	36000	USD
CY2021Q4	bmrc	Weighted Average Ratio Of Loans Value To Collateral Dependent Loans Value WeightedAverageRatioOfLoansValueToCollateralDependentLoansValue	0.67
CY2020Q4	bmrc	Weighted Average Ratio Of Loans Value To Collateral Dependent Loans Value WeightedAverageRatioOfLoansValueToCollateralDependentLoansValue	0.56
CY2021Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	9510000	USD
CY2020Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	12506000	USD
CY2021Q4	bmrc	Financing Receivable Modifications Recorded Investment Nonaccrual Status FinancingReceivableModificationsRecordedInvestmentNonaccrualStatus	7400000	USD
CY2020Q4	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
CY2019	bmrc	Financing Receivable Modifications Removal From Troubled Debt Restructuring Number Of Contracts FinancingReceivableModificationsRemovalFromTroubledDebtRestructuringNumberOfContracts	1	loan
	bmrc	Loan Modifications Under Cares Act During Period LoanModificationsUnderCARESActDuringPeriod	269	loan
	bmrc	Loans And Leases Receivable Net Of Deferred Income Modified Under Cares Act During Period LoansAndLeasesReceivableNetOfDeferredIncomeModifiedUnderCARESActDuringPeriod	402900000	USD
CY2020Q4	bmrc	Loan Modifications Under Cares Act Additional Relief Number Of Borrowing Relationships LoanModificationsUnderCARESActAdditionalReliefNumberOfBorrowingRelationships	21	borrowingRelationship
CY2020Q4	bmrc	Loan Modifications Under Cares Act Additional Relief LoanModificationsUnderCARESActAdditionalRelief	29	loan
CY2020Q4	bmrc	Loans And Leases Receivable Net Of Deferred Income Modified Under Cares Act Additional Relief LoansAndLeasesReceivableNetOfDeferredIncomeModifiedUnderCARESActAdditionalRelief	71000000	USD
CY2021Q4	bmrc	Loan Modifications Under Cares Act Additional Relief Number Of Borrowing Relationships LoanModificationsUnderCARESActAdditionalReliefNumberOfBorrowingRelationships	2	borrowingRelationship
CY2021Q4	bmrc	Loan Modifications Under Cares Act Additional Relief LoanModificationsUnderCARESActAdditionalRelief	3	loan
CY2021Q4	bmrc	Loans And Leases Receivable Net Of Deferred Income Modified Under Cares Act Additional Relief LoansAndLeasesReceivableNetOfDeferredIncomeModifiedUnderCARESActAdditionalRelief	23600000	USD
CY2021	bmrc	Loans And Leases Receivable Net Of Deferred Income Modified Under Cares Act Weighted Average Loan To Value Ratio LoansAndLeasesReceivableNetOfDeferredIncomeModifiedUnderCARESActWeightedAverageLoanToValueRatio	0.44
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	loanProductionOffice
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
CY2019	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
CY2020	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
CY2021Q3	bmrc	Financing Receivable Not Purchased With Credit Deterioration Unpaid Principal Balance FinancingReceivableNotPurchasedWithCreditDeteriorationUnpaidPrincipalBalance	92029000	USD
CY2021Q3	us-gaap	Financing Receivable Purchased With Credit Deterioration Discount Premium FinancingReceivablePurchasedWithCreditDeteriorationDiscountPremium	1662000	USD
CY2021Q3	bmrc	Financing Receivable Purchased With Credit Deterioration Amortized Cost FinancingReceivablePurchasedWithCreditDeteriorationAmortizedCost	90367000	USD
CY2021Q3	us-gaap	Financing Receivable Purchased With Credit Deterioration Allowance For Credit Loss At Acquisition Date FinancingReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate	1505000	USD
CY2021Q3	us-gaap	Financing Receivable Purchased With Credit Deterioration Amount At Purchase Price FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice	88862000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	22874000	USD
CY2021	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-1449000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Loss Purchased With Credit Deterioration Increase FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease	1505000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	5000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	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	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	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	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-856000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	1000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	14000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	22874000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	15821000	USD
CY2019	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	900000	USD
CY2019	us-gaap	Allowance For Loan And Lease Losses Write Offs AllowanceForLoanAndLeaseLossesWriteOffs	78000	USD
CY2019	us-gaap	Allowance For Loan And Lease Loss Recovery Of Bad Debts AllowanceForLoanAndLeaseLossRecoveryOfBadDebts	34000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	16677000	USD
CY2021Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Loans Receivable Pledged For Federal Home Loan Bank Debt PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedForFederalHomeLoanBankDebt	1330000000	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Loans Receivable Pledged For Federal Home Loan Bank Debt PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedForFederalHomeLoanBankDebt	1165000000	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
CY2018Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	10635000	USD
CY2021	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	4037000	USD
CY2020	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	0	USD
CY2019	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	0	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
CY2019	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	2320000	USD
CY2021	bmrc	Loans And Leases Receivable Reclassified As Unrelated Party Loan LoansAndLeasesReceivableReclassifiedAsUnrelatedPartyLoan	0	USD
CY2020	bmrc	Loans And Leases Receivable Reclassified As Unrelated Party Loan LoansAndLeasesReceivableReclassifiedAsUnrelatedPartyLoan	0	USD
CY2019	bmrc	Loans And Leases Receivable Reclassified As Unrelated Party Loan LoansAndLeasesReceivableReclassifiedAsUnrelatedPartyLoan	18000	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
CY2021Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Before Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization	29530000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Before Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization	25750000	USD
CY2021Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization	21972000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization	20831000	USD
CY2021Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	7558000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	4919000	USD
CY2021	us-gaap	Depreciation Depreciation	1700000	USD
CY2020	us-gaap	Depreciation Depreciation	2100000	USD
CY2019	us-gaap	Depreciation Depreciation	2200000	USD
CY2021Q4	bmrc	Life Insurance Corporate Or Bank Owned Death Benefits LifeInsuranceCorporateOrBankOwnedDeathBenefits	122900000	USD
CY2021Q4	us-gaap	Life Insurance Corporate Or Bank Owned Amount LifeInsuranceCorporateOrBankOwnedAmount	61500000	USD
CY2020Q4	us-gaap	Life Insurance Corporate Or Bank Owned Amount LifeInsuranceCorporateOrBankOwnedAmount	43600000	USD
CY2021	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	2200000	USD
CY2020	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	973000	USD
CY2019	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	1200000	USD
CY2021	bmrc	Proceeds In Excess Of Cash Surrender Values On Bank Owned Life Insurance ProceedsInExcessOfCashSurrenderValuesOnBankOwnedLifeInsurance	1100000	USD
CY2019	bmrc	Proceeds In Excess Of Cash Surrender Values On Bank Owned Life Insurance ProceedsInExcessOfCashSurrenderValuesOnBankOwnedLifeInsurance	562000	USD
CY2020	bmrc	Proceeds In Excess Of Cash Surrender Values On Bank Owned Life Insurance ProceedsInExcessOfCashSurrenderValuesOnBankOwnedLifeInsurance	0	USD
CY2021Q4	bmrc	Time Deposits Less Than Or Equal To250000 TimeDepositsLessThanOrEqualTo250000	96214000	USD
CY2020Q4	bmrc	Time Deposits Less Than Or Equal To250000 TimeDepositsLessThanOrEqualTo250000	66789000	USD
CY2021Q4	bmrc	Time Deposits250000 Or More TimeDeposits250000OrMore	54021000	USD
CY2020Q4	bmrc	Time Deposits250000 Or More TimeDeposits250000OrMore	30644000	USD
CY2021Q4	us-gaap	Time Deposits TimeDeposits	150235000	USD
CY2020Q4	us-gaap	Time Deposits TimeDeposits	97433000	USD
CY2021	us-gaap	Interest Expense Time Deposits InterestExpenseTimeDeposits	246000	USD
CY2020	us-gaap	Interest Expense Time Deposits InterestExpenseTimeDeposits	554000	USD
CY2019	us-gaap	Interest Expense Time Deposits InterestExpenseTimeDeposits	595000	USD
CY2021Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	109785000	USD
CY2021Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	15963000	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
CY2021Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	8187000	USD
CY2021Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	8357000	USD
CY2021Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	7943000	USD
CY2021Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	0	USD
CY2021Q4	us-gaap	Time Deposits TimeDeposits	150235000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Restricted HeldToMaturitySecuritiesRestricted	213900000	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
CY2020Q4	bmrc	Time Deposits Certificate Of Deposit Account Registry Service Cdars TimeDepositsCertificateOfDepositAccountRegistryServiceCDARS	7622000	USD
CY2020Q4	bmrc	Time Deposits Certificate Of Deposit Account Registry Service Cdars One Way TimeDepositsCertificateOfDepositAccountRegistryServiceCDARSOneWay	2434000	USD
CY2020Q4	bmrc	Deposits Money Market Deposits Insured Cash Sweep Ics DepositsMoneyMarketDepositsInsuredCashSweepICS	0	USD
CY2021Q4	us-gaap	Federal Home Loan Bank Advances Weighted Average Interest Rate FederalHomeLoanBankAdvancesWeightedAverageInterestRate	0.0118
CY2020Q4	bmrc	Deposits Money Market Deposits Insured Cash Sweep Ics One Way DepositsMoneyMarketDepositsInsuredCashSweepICSOneWay	110929000	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
CY2020Q4	bmrc	Deposits Money Market Deposits Demand Deposit Marketplace DepositsMoneyMarketDepositsDemandDepositMarketplace	30544000	USD
CY2020Q4	bmrc	Deposits Money Market Deposits Demand Deposit Marketplace One Way DepositsMoneyMarketDepositsDemandDepositMarketplaceOneWay	60000000	USD
CY2021Q4	bmrc	Total Networkdeposits Reciprocal TotalNetworkdepositsReciprocal	73778000	USD
CY2021Q4	bmrc	Total Networkdeposits One Way TotalNetworkdepositsOneWay	173060000	USD
CY2020Q4	bmrc	Total Networkdeposits Reciprocal TotalNetworkdepositsReciprocal	38166000	USD
CY2020Q4	bmrc	Total Networkdeposits One Way TotalNetworkdepositsOneWay	173363000	USD
CY2021Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	346000	USD
CY2020Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	219000	USD
CY2021Q4	us-gaap	Related Party Deposit Liabilities RelatedPartyDepositLiabilities	25300000	USD
CY2020Q4	us-gaap	Related Party Deposit Liabilities RelatedPartyDepositLiabilities	28100000	USD
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
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
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Fixed Rate FederalHomeLoanBankAdvancesFixedRate	0	USD
CY2019	bmrc	Federal Home Loan Bank Advances Average Balance Fixed Rate FederalHomeLoanBankAdvancesAverageBalanceFixedRate	0	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Advances Weighted Average Interest Rate FederalHomeLoanBankAdvancesWeightedAverageInterestRate	0
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
CY2019	us-gaap	Shares Paid For Tax Withholding For Share Based Compensation SharesPaidForTaxWithholdingForShareBasedCompensation	7795	shares
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
CY2019	bmrc	Adjustments Related To Tax Withholding And Exercise Of Options For Share Based Compensation AdjustmentsRelatedToTaxWithholdingAndExerciseOfOptionsForShareBasedCompensation	326000	USD
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
CY2019	bmrc	Sharebased Compensation Arrangementsby Sharebased Payment Award Options Tax Withholding And Exercisesin Period Weighted Average Exercise Price SharebasedCompensationArrangementsbySharebasedPaymentAwardOptionsTaxWithholdingAndExercisesinPeriodWeightedAverageExercisePrice	41.84
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	425700	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	25.01
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	6910000	USD
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P5Y10M6D
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	53370	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	44.01
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	9.37
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	13580	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	38.88
CY2019	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	48108	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	16.11
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	1247000	USD
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
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber	333870	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice	25.34
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue	6581000	USD
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1	P4Y9M3D
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
CY2021	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	972000	USD
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	1200000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	1500000	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
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	389000	USD
CY2021Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	652000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P2Y3M18D
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
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount	145000	USD
CY2021	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	13107000	USD
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	12506000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	10958000	USD
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
CY2019	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.80
CY2021Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	239900000	USD
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	450400000	USD
CY2021Q4	bmrc	Dividends Cash Dividend Amount Retained Earnings Available For Dividend Payments Under Restriction DividendsCashDividendAmountRetainedEarningsAvailableForDividendPaymentsUnderRestriction	6200000	USD
CY2021Q4	us-gaap	Cash Cash	6700000	USD
CY2017Q3	bmrc	Shareholder Rights Plan Percentage Of Share Ownership Defining Acquiring Person ShareholderRightsPlanPercentageOfShareOwnershipDefiningAcquiringPerson	0.10
CY2021Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	5000000	shares
CY2021Q4	us-gaap	Preferred Stock No Par Value PreferredStockNoParValue	0
CY2018Q2	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	25000000	USD
CY2020Q1	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	25000000	USD
CY2021Q3	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	25000000	USD
CY2021Q4	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	57000000	USD
CY2021	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	1117666	shares
CY2021Q3	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	25000000	USD
CY2021	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	40700000	USD
CY2021Q1	bmrc	Deferred Compensation Arrangementwith Individual Deferred Interest Earned Percent DeferredCompensationArrangementwithIndividualDeferredInterestEarnedPercent	0.0325
CY2020Q1	bmrc	Deferred Compensation Arrangementwith Individual Deferred Interest Earned Percent DeferredCompensationArrangementwithIndividualDeferredInterestEarnedPercent	0.0475
CY2021Q3	us-gaap	Deferred Compensation Arrangement With Individual Recorded Liability DeferredCompensationArrangementWithIndividualRecordedLiability	2900000	USD
CY2021Q4	us-gaap	Deferred Compensation Arrangement With Individual Recorded Liability DeferredCompensationArrangementWithIndividualRecordedLiability	7700000	USD
CY2020Q4	us-gaap	Deferred Compensation Arrangement With Individual Recorded Liability DeferredCompensationArrangementWithIndividualRecordedLiability	4700000	USD
CY2021	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent Of Match DefinedContributionPlanEmployerMatchingContributionPercentOfMatch	0.70
CY2021	bmrc	Defined Contribution Plan Employer Matching Contribution Maximum Amount DefinedContributionPlanEmployerMatchingContributionMaximumAmount	5000	USD
CY2021	bmrc	Defined Benefit Plan Percentage Of Salary Paid Upon Retirement DefinedBenefitPlanPercentageOfSalaryPaidUponRetirement	0.25
CY2021	bmrc	Defined Benefits Plan Period Before Ratable Vesting Begins DefinedBenefitsPlanPeriodBeforeRatableVestingBegins	P5Y
CY2021	bmrc	Defined Benefits Plan Period Before Ratable Vesting Begins DefinedBenefitsPlanPeriodBeforeRatableVestingBegins	P5Y
CY2021	bmrc	Defined Benefits Plan Age Ratable Vesting Ends DefinedBenefitsPlanAgeRatableVestingEnds	P65Y
CY2021Q3	us-gaap	Defined Benefit Plan Amounts Recognized In Balance Sheet DefinedBenefitPlanAmountsRecognizedInBalanceSheet	-1700000	USD
CY2021Q4	us-gaap	Defined Benefit Plan Amounts Recognized In Balance Sheet DefinedBenefitPlanAmountsRecognizedInBalanceSheet	-5300000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Amounts Recognized In Balance Sheet DefinedBenefitPlanAmountsRecognizedInBalanceSheet	-3200000	USD
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	6627000	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	7108000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	7838000	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
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	5183000	USD
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	11442000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	12003000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	13021000	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
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-907000	USD
CY2021	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-58000	USD
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CY2020Q4	bmrc	Finance Lease Right Of Use Asset Gross FinanceLeaseRightOfUseAssetGross	365000	USD
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CY2020Q4	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	58000	USD
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CY2021Q4	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	0	USD
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$BMRC
Bank of Marin Bancorp Stock $bmrc

2021 Form 10-K Financial Statement

#000140347522000015 Filed on March 15, 2022

Income Statement

Balance Sheet

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$BMRC Bank of Marin Bancorp Stock $bmrc

2021 Form 10-K Financial Statement

#000140347522000015 Filed on March 15, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BMRC
Bank of Marin Bancorp Stock $bmrc