XML 57 R47.htm IDEA: XBRL DOCUMENT
v3.21.2

Note 3 - Loans and Allowance for Loan Losses - Loans Modified As Troubled Debt Restructurings Within the Previous Twelve Months That Became Over 30 Days Past Due (Details) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2021 USD ($) | Jun. 30, 2020 USD ($) | Jun. 30, 2021 USD ($) | Jun. 30, 2020 USD ($)
Number of Contracts | 1 | 0 | 3 | 1
Recorded Principal Balance | $ 431,000 | $ 0 | $ 953,000 | $ 32,000
Commercial Portfolio Segment [Member] |  |  |  |
Number of Contracts | 1 | 0 | 3 | 0
Recorded Principal Balance | $ 431,000 | $ 0 | $ 953,000 | $ 0
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |
Number of Contracts | 0 | 0 | 2 | 0
Recorded Principal Balance | $ 0 | $ 0 | $ 522,000 | $ 0
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member] |  |  |  |
Number of Contracts | 0 | 0 | 0 | 0
Recorded Principal Balance | $ 0 | $ 0 | $ 0 | $ 0
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member] |  |  |  |
Number of Contracts | 1 | 0 | 1 | 0
Recorded Principal Balance | $ 431,000 | $ 0 | $ 431,000 | $ 0
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member] |  |  |  |
Number of Contracts | 0 | 0 | 0 | 0
Recorded Principal Balance | $ 0 | $ 0 | $ 0 | $ 0
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member] |  |  |  |
Number of Contracts | 0 | 0 | 0 | 0
Recorded Principal Balance | $ 0 | $ 0 | $ 0 | $ 0
Retail Portfolio Segment [Member] |  |  |  |
Number of Contracts | 0 | 0 | 0 | 1
Recorded Principal Balance | $ 0 | $ 0 | $ 0 | $ 32,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member] |  |  |  |
Number of Contracts | 0 | 0 | 0 | 0
Recorded Principal Balance | $ 0 | $ 0 | $ 0 | $ 0
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member] |  |  |  |
Number of Contracts | 0 | 0 | 0 | 1
Recorded Principal Balance | $ 0 | $ 0 | $ 0 | $ 32,000

X
- Definition Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953682-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953682-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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_HomeEquityAndOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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