XML 50 R40.htm IDEA: XBRL DOCUMENT
v3.19.1

Note 3 - Loans and Allowance for Loan Losses - Nonperforming Loans (Details) - USD ($) | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Originated Loan [Member] |  |
Loans past due 90 days or more still accruing interest | $ 0 | $ 0
Originated Loan [Member] | Commercial Portfolio Segment [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Originated Loan [Member] | Retail Portfolio Segment [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] | Retail Portfolio Segment [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Nonperforming Financial Instruments [Member] |  |
Total nonperforming originated loans | 4,138,000 | 4,141,000
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] |  |
Total nonperforming originated loans | 1,171,000 | 1,108,000
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |
Total nonperforming originated loans | 207,000 | 17,000
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member] |  |
Total nonperforming originated loans | 0 | 0
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member] |  |
Total nonperforming originated loans | 767,000 | 950,000
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member] |  |
Total nonperforming originated loans | 62,000 | 0
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member] |  |
Total nonperforming originated loans | 135,000 | 141,000
Nonperforming Financial Instruments [Member] | Retail Portfolio Segment [Member] |  |
Total nonperforming originated loans | 2,967,000 | 3,033,000
Nonperforming Financial Instruments [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member] |  |
Total nonperforming originated loans | 447,000 | 454,000
Nonperforming Financial Instruments [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member] |  |
Total nonperforming originated loans | 2,520,000 | 2,579,000
Nonperforming Financial Instruments [Member] | Originated Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Nonaccrual loans | 1,035,000 | 803,000
Total nonperforming originated loans | 1,035,000 | 803,000
Nonperforming Financial Instruments [Member] | Acquired Loan [Member] |  |
Loans past due 90 days or more still accruing interest | 0 | 0
Nonaccrual loans | 3,103,000 | 3,338,000
Total nonperforming originated loans | $ 3,103,000 | $ 3,338,000

X
- Definition Amount of financing receivables which are past due 90 days or more and still accruing interest and nonaccrual loans. + References No definition available. + Details
Name: | mbwm_FinancingReceivablePastDueNinetyDaysOrMoreAndStillAccruingInterestAndNonaccrualLoans
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of financing receivable 90 days or more past due and still accruing. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 80 -URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of financing receivable on nonaccrual status. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=mbwm_OriginatedLoanMember
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_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: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=mbwm_AcquiredLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentPerformanceStatusAxis=us-gaap_NonperformingFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |