XML 22 R50.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings (USD $) | 3 Months Ended
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Mar. 31, 2015 | Mar. 31, 2014
Commercial: |  |
Loans modified, number of contracts |  | 3 us-gaap_FinancingReceivableModificationsNumberOfContracts2
Loans modified, pre-modification recorded principal balance |  | $ 368,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Loans modified, post-modification recorded principal balance |  | 337,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Commercial and Industrial [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 6 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_CommercialAndIndustrialMember | 1 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_CommercialAndIndustrialMember
Loans modified, pre-modification recorded principal balance | 568,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_CommercialAndIndustrialMember | 14,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_CommercialAndIndustrialMember
Loans modified, post-modification recorded principal balance | 593,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_CommercialAndIndustrialMember | 14,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_CommercialAndIndustrialMember
Commercial and Industrial [Member] | Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 1 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_CommercialAndIndustrialMember |
Loans modified, pre-modification recorded principal balance | 79,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_CommercialAndIndustrialMember |
Loans modified, post-modification recorded principal balance | 79,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_CommercialAndIndustrialMember |
Vacant Land and Land Development and Residential Construction Loan [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Vacant Land and Land Development and Residential Construction Loan [Member] | Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |
Real Estate Owner Occupied Loan [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateOwnerOccupiedLoanMember | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateOwnerOccupiedLoanMember
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateOwnerOccupiedLoanMember | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateOwnerOccupiedLoanMember
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateOwnerOccupiedLoanMember | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateOwnerOccupiedLoanMember
Real Estate Owner Occupied Loan [Member] | Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 2 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateOwnerOccupiedLoanMember |
Loans modified, pre-modification recorded principal balance | 50,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateOwnerOccupiedLoanMember |
Loans modified, post-modification recorded principal balance | 50,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateOwnerOccupiedLoanMember |
Real Estate Non Owner Occupied Loan [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateNonOwnerOccupiedLoanMember | 2 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateNonOwnerOccupiedLoanMember
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateNonOwnerOccupiedLoanMember | 354,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateNonOwnerOccupiedLoanMember
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateNonOwnerOccupiedLoanMember | 323,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateNonOwnerOccupiedLoanMember
Real Estate Non Owner Occupied Loan [Member] | Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateNonOwnerOccupiedLoanMember |
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateNonOwnerOccupiedLoanMember |
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateNonOwnerOccupiedLoanMember |
Real Estate Multi Family and Residential Rental Loan [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 6 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember |
Loans modified, pre-modification recorded principal balance | 568,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember |
Loans modified, post-modification recorded principal balance | 593,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember |
Real Estate Multi Family and Residential Rental Loan [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 3 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember |
Loans modified, pre-modification recorded principal balance | 129,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember |
Loans modified, post-modification recorded principal balance | 129,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember |
Real Estate Multi Family and Residential Rental Loan [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember
Real Estate Multi Family and Residential Rental Loan [Member] | Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember |
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember |
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember |
Home Equity and Other [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_HomeEquityAndOtherMember |
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_HomeEquityAndOtherMember |
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_HomeEquityAndOtherMember |
Home Equity and Other [Member] | Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_HomeEquityAndOtherMember |
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_HomeEquityAndOtherMember |
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_HomeEquityAndOtherMember |
Home Equity and Other [Member] |  |
Commercial: |  |
Loans modified, number of contracts |  | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_HomeEquityAndOtherMember
Loans modified, pre-modification recorded principal balance |  | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_HomeEquityAndOtherMember
Loans modified, post-modification recorded principal balance |  | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_HomeEquityAndOtherMember
1-4 Family Mortgages [Member] | Retail Loan [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = mbwm_RetailLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember |
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = mbwm_RetailLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember |
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = mbwm_RetailLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember |
1-4 Family Mortgages [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember |
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember |
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember |
1-4 Family Mortgages [Member] | Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember |
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember |
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember |
1-4 Family Mortgages [Member] |  |
Commercial: |  |
Loans modified, number of contracts |  | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember
Loans modified, pre-modification recorded principal balance |  | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember
Loans modified, post-modification recorded principal balance |  | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = mbwm_OneToFourFamilyMortgagesMember
Commercial Portfolio Segment [Member] | Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts |  | 3 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember
Loans modified, pre-modification recorded principal balance |  | 368,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember
Loans modified, post-modification recorded principal balance |  | 337,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember
Retail Loan [Member] | Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = mbwm_RetailLoanMember |
Loans modified, pre-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = mbwm_RetailLoanMember |
Loans modified, post-modification recorded principal balance | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivablePortfolioSegmentAxis = mbwm_RetailLoanMember |
Retail Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts |  | 0 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancingReceivablePortfolioSegmentAxis = mbwm_RetailLoanMember
Loans modified, pre-modification recorded principal balance |  | 0 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancingReceivablePortfolioSegmentAxis = mbwm_RetailLoanMember
Loans modified, post-modification recorded principal balance |  | 0 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancingReceivablePortfolioSegmentAxis = mbwm_RetailLoanMember
Originated Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 6 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember |
Loans modified, pre-modification recorded principal balance | 568,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember |
Loans modified, post-modification recorded principal balance | 593,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember |
Acquired Loan [Member] |  |
Commercial: |  |
Loans modified, number of contracts | 3 us-gaap_FinancingReceivableModificationsNumberOfContracts2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember |
Loans modified, pre-modification recorded principal balance | 129,000 us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember |
Loans modified, post-modification recorded principal balance | $ 129,000 us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2 / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember |

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