XML 57 R47.htm IDEA: XBRL DOCUMENT v3.25.3

Note 3 - Loans and Allowance for Loan Losses - Nonaccrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
With no related allowance recorded, principal balance	$ 1,478	$ 1,824
With related allowance recorded, principal balance	8,366	3,918
Related allowance	6,837	2,134
Total principal balance	9,844	5,742
Commercial Portfolio Segment [Member]
With no related allowance recorded, principal balance	60	657
With related allowance recorded, principal balance	6,981	2,110
Related allowance	6,564	1,732
Total principal balance	7,041	2,767
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
With no related allowance recorded, principal balance	60	615
With related allowance recorded, principal balance	1,449	2,110
Related allowance	1,032	1,732
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
With no related allowance recorded, principal balance	0	0
With related allowance recorded, principal balance	0	0
Related allowance	0	0
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
With no related allowance recorded, principal balance	0	42
With related allowance recorded, principal balance	0	0
Related allowance	0	0
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
With no related allowance recorded, principal balance	0	0
With related allowance recorded, principal balance	5,532	0
Related allowance	5,532	0
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
With no related allowance recorded, principal balance	0	0
With related allowance recorded, principal balance	0	0
Related allowance	0	0
Retail Portfolio Segment [Member]
With no related allowance recorded, principal balance	1,418	1,167
With related allowance recorded, principal balance	1,385	1,808
Related allowance	273	402
Total principal balance	2,803	2,975
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
With no related allowance recorded, principal balance	1,382	1,167
With related allowance recorded, principal balance	1,385	1,808
Related allowance	273	402
Retail Portfolio Segment [Member] | Other Consumer Loans [Member]
With no related allowance recorded, principal balance	36	0
With related allowance recorded, principal balance	0	0
Related allowance	$ 0	$ 0

X

- Definition

Allowance of nonaccrual financing receivable.

+ References

No definition available.

+ Details

Name:	mbwm_FinancingReceivableNonaccrualAllowance
Namespace Prefix:	mbwm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amortized cost of financing receivable on nonaccrual status with allowance for credit loss. Excludes net investment in lease.

+ References

No definition available.

+ Details

Name:	mbwm_FinancingReceivableNonaccrualWithAllowance
Namespace Prefix:	mbwm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amortized cost of financing receivable on nonaccrual status with no allowance for credit loss. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

+ Details

Name:	us-gaap_FinancingReceivableNonaccrualNoAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amortized cost of financing receivable on nonaccrual status. Excludes net investment in lease.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (3)
-Publisher SEC

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (2)
-Publisher SEC

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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_OneToFourFamilyMortgagesMember
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: