XML 60 R50.htm IDEA: XBRL DOCUMENT
v3.25.3

Note 3 - Loans and Allowance for Credit Losses - Financial Effect by Type of Modification (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Contractual Interest Rate Reduction [Member] |  |  |  |
Modified in period | $ 0 | $ 0 | $ 0 | $ 0
Contractual Interest Rate Reduction [Member] | Commercial Portfolio Segment [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Contractual Interest Rate Reduction [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Contractual Interest Rate Reduction [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Contractual Interest Rate Reduction [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Contractual Interest Rate Reduction [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Contractual Interest Rate Reduction [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Contractual Interest Rate Reduction [Member] | Retail Portfolio Segment [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Contractual Interest Rate Reduction [Member] | Retail Portfolio Segment [Member] | Loans Categorized as 1-4 Family Mortgages [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Contractual Interest Rate Reduction [Member] | Retail Portfolio Segment [Member] | Other Consumer Loans [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Extended Maturity [Member] |  |  |  |
Modified in period | 9,590 | 5,670 | 9,596 | 7,454
Extended Maturity [Member] | Commercial Portfolio Segment [Member] |  |  |  |
Modified in period | 9,590 | 5,670 | 9,596 | 7,454
Extended Maturity [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |
Modified in period | 9,590 | 5,670 | 9,596 | 7,454
Extended Maturity [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Extended Maturity [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Extended Maturity [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Extended Maturity [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Extended Maturity [Member] | Retail Portfolio Segment [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Extended Maturity [Member] | Retail Portfolio Segment [Member] | Loans Categorized as 1-4 Family Mortgages [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Extended Maturity [Member] | Retail Portfolio Segment [Member] | Other Consumer Loans [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] | Commercial Portfolio Segment [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] | Retail Portfolio Segment [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] | Retail Portfolio Segment [Member] | Loans Categorized as 1-4 Family Mortgages [Member] |  |  |  |
Modified in period | 0 | 0 | 0 | 0
Principal Forgiveness [Member] | Retail Portfolio Segment [Member] | Other Consumer Loans [Member] |  |  |  |
Modified in period | $ 0 | $ 0 | $ 0 | $ 0

X
- Definition Amortized cost of financing receivable modified during period for debtor experiencing financial difficulty. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 12A -Publisher FASB -URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 33 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-33 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-42 + Details
Name: | us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_ContractualInterestRateReductionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_RealEstateOwnerOccupiedLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_RealEstateNonOwnerOccupiedLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=mbwm_RetailPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_LoansCategorizedAs14FamilyMortgagesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_OtherConsumerLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_PrincipalForgivenessMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |