XML 108 R80.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Note 4 - Loans and Allowance for Loan Losses (Details) - Activity for Troubled Debt Restructurings (USD $) | 12 Months Ended | 7 Months Ended | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Commercial and Industrial [Member] | Originated Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance | $ 1,656,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |  |
Ending Balance | 7,026,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember | 7,026,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |
Charge-Offs | (67,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |  |
Payments | (871,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |  |
Transfers to ORE | (21,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |  |
Net Additions/Deletions | 6,329,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |  |
Commercial and Industrial [Member] | Acquired Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |
Ending Balance | 1,439,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember | 1,439,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |
Charge-Offs |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |
Payments |  | (2,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |
Transfers to ORE |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |
Net Additions/Deletions |  | 1,441,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember |  |
Commercial and Industrial [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  |  | 2,720,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember | 4,553,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember
Ending Balance |  |  | 1,656,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember | 2,720,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember
Charge-Offs |  |  | (35,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember | (540,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember
Payments |  |  | (2,781,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember | (2,584,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember
Transfers to ORE |  |  | (74,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember | (96,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember
Net Additions/Deletions |  |  | 1,826,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember | 1,387,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialAndIndustrialMember
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Originated Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance | 4,501,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |  |
Ending Balance | 2,680,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | 2,680,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |
Charge-Offs | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |  |
Payments | (4,719,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |  |
Transfers to ORE | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |  |
Net Additions/Deletions | 2,898,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |  |
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Acquired Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |
Ending Balance | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |
Charge-Offs |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |
Payments |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |
Transfers to ORE |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |
Net Additions/Deletions |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember |  |
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  |  | 3,071,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | 5,100,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Ending Balance |  |  | 4,501,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | 3,071,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Charge-Offs |  |  | (725,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | (63,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Payments |  |  | (1,596,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | (2,013,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Transfers to ORE |  |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Net Additions/Deletions |  |  | 3,751,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember | 47,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Commercial Real Estate Owner Occupied Loan [Member] | Originated Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance | 1,816,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |  |
Ending Balance | 17,160,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember | 17,160,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |
Charge-Offs | (11,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |  |
Payments | (2,343,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |  |
Transfers to ORE | (48,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |  |
Net Additions/Deletions | 17,746,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |  |
Commercial Real Estate Owner Occupied Loan [Member] | Acquired Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |
Ending Balance | 1,569,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember | 1,569,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |
Charge-Offs |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |
Payments |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |
Transfers to ORE |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |
Net Additions/Deletions |  | 1,569,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember |  |
Commercial Real Estate Owner Occupied Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  |  | 4,116,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember | 6,183,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember
Ending Balance |  |  | 1,816,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember | 4,116,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember
Charge-Offs |  |  | (70,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember | (426,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember
Payments |  |  | (2,151,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember | (3,443,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember
Transfers to ORE |  |  | (363,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember | (65,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember
Net Additions/Deletions |  |  | 284,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember | 1,867,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateOwnerOccupiedLoanMember
Commercial Real Estate Non Owner Occupied Loan [Member] | Originated Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance | 22,311,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |  |
Ending Balance | 17,439,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember | 17,439,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |
Charge-Offs | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |  |
Payments | (5,190,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |  |
Transfers to ORE | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |  |
Net Additions/Deletions | 318,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |  |
Commercial Real Estate Non Owner Occupied Loan [Member] | Acquired Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |
Ending Balance | 64,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember | 64,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |
Charge-Offs |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |
Payments |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |
Transfers to ORE |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |
Net Additions/Deletions |  | 64,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember |  |
Commercial Real Estate Non Owner Occupied Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  |  | 37,671,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember | 12,036,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember
Ending Balance |  |  | 22,312,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember | 37,671,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember
Charge-Offs |  |  | (2,537,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember | (720,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember
Payments |  |  | (13,795,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember | (2,482,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember
Transfers to ORE |  |  | (1,153,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember | (1,045,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember
Net Additions/Deletions |  |  | 2,126,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember | 29,882,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember
Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Originated Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance | 2,620,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |  |
Ending Balance | 505,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember | 505,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |
Charge-Offs | (420,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |  |
Payments | (1,695,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |  |
Transfers to ORE | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |  |
Net Additions/Deletions | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |  |
Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Acquired Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |
Ending Balance | 381,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember | 381,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |
Charge-Offs |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |
Payments |  | (18,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |
Transfers to ORE |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |
Net Additions/Deletions |  | 399,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember |  |
Commercial Real Estate Multi Family and Residential Rental Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  |  | 3,027,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember | 12,626,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember
Ending Balance |  |  | 2,620,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember | 3,027,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember
Charge-Offs |  |  | (15,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember | (2,180,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember
Payments |  |  | (735,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember | (7,422,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember
Transfers to ORE |  |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember | (186,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember
Net Additions/Deletions |  |  | 343,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember | 189,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember
Retail Home Equity and Other [Member] | Originated Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |  |
Ending Balance | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |
Charge-Offs | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |  |
Payments | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |  |
Transfers to ORE | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |  |
Net Additions/Deletions | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |  |
Retail Home Equity and Other [Member] | Acquired Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |
Ending Balance | 26,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember | 26,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |
Charge-Offs |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |
Payments |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |
Transfers to ORE |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |
Net Additions/Deletions |  | 26,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember |  |
Retail Home Equity and Other [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  |  | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember
Ending Balance |  |  | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember
Charge-Offs |  |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember
Payments |  |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember
Transfers to ORE |  |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember
Net Additions/Deletions |  |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_RetailHomeEquityAndOtherMember
Retail 1-4 Family Mortgages [Member] | Originated Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance | 1,987,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |  |
Ending Balance | 1,967,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember | 1,967,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |
Charge-Offs | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |  |
Payments | (224,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |  |
Transfers to ORE | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |  |
Net Additions/Deletions | 204,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_OriginatedLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |  |
Retail 1-4 Family Mortgages [Member] | Acquired Loan [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  | 0 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |
Ending Balance | 178,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember | 178,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |
Charge-Offs |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |
Payments |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |
Transfers to ORE |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |
Net Additions/Deletions |  | 178,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancialInstrumentAxis = mbwm_AcquiredLoanMember / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember |  |
Retail 1-4 Family Mortgages [Member] |  |  |  |
Commercial Loan Portfolio: |  |  |  |
Beginning Balance |  |  | 155,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember | 164,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember
Ending Balance |  |  | 1,987,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember | 155,000 us-gaap_FinancingReceivableModificationsRecordedInvestment / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember
Charge-Offs |  |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember
Payments |  |  | (46,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember | (9,000)mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember
Transfers to ORE |  |  | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember | 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember
Net Additions/Deletions |  |  | $ 1,878,000 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember | $ 0 mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions / us-gaap_FinancingReceivableTroubledDebtRestructuringAxis = mbwm_Retail1To4FamilyMortgagesMember

X
- Details
Name: | mbwm_CommercialLoanPortfolioAbstract
Namespace Prefix: | mbwm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition A financing receivable which had its terms modified during the period and is now considered a troubled restructuring. + References No definition available. + Details
Name: | mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsAdditions
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Reflects the amount of the charge-off related to a troubled debt restructuring. + References No definition available. + Details
Name: | mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsChargeOffs
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow associated with a financing receivable classified as a troubled debt restructuring. + References No definition available. + Details
Name: | mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsPayments
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The transfer of a financing receivable classified as a troubled debt restructuring to other real estate. + References No definition available. + Details
Name: | mbwm_FinancingReceivableModifiedAsTroubledDebtRestructuringsTransferToOtherRealEstate
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554 + Details
Name: | us-gaap_FinancingReceivableModificationsRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=mbwm_CommercialAndIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=mbwm_CommercialRealEstateMultiFamilyAndResidentialRentalLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=mbwm_CommercialRealEstateNonOwnerOccupiedLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=mbwm_CommercialRealEstateOwnerOccupiedLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=mbwm_CommercialVacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=mbwm_Retail1To4FamilyMortgagesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableTroubledDebtRestructuringAxis=mbwm_RetailHomeEquityAndOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |