XML 135 R117.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Note 19 - Subordinated Notes (Details Textual) - Subordinated Notes [Member] - USD ($) $ in Millions | Jan. 14, 2022 | Dec. 15, 2021 | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | --- | --- | ---
Subordinated Debt, Principal Amount | $ 15.0 | $ 75.0 |  |
Subordinated Borrowing, Interest Rate |  | 3.25% |  |
Subordinated Borrowing, Redemption Price, Percentage of Principal Amount |  | 100.00% |  |
Increase to Equity Capital From Issuance of Subordinated Long-term Debt | $ 15.0 | $ 70.0 |  |
Debt Issuance Costs, Gross |  |  | $ 1.0 | $ 1.4
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  | 2.12% |  |

X
- Definition The amount of proceeds that being injected and increase to equity capital from the issuance of subordinated long-term debt. + References No definition available. + Details
Name: | mbwm_ProceedsInjectedIncreaseToEquityCapitalFromIssuanceOfSubordinatedLongtermDebt
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Redemption price as a percentage of principal amount. + References No definition available. + Details
Name: | mbwm_SubordinatedBorrowingRedemptionPricePercentageOfPrincipalAmount
Namespace Prefix: | mbwm_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Principal amount of subordinated debt. + References No definition available. + Details
Name: | mbwm_SubordinatedDebtPrincipalAmount
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482925/835-30-45-3 + Details
Name: | us-gaap_DeferredFinanceCostsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Stated interest rate of the subordinated debt. + References No definition available. + Details
Name: | us-gaap_SubordinatedBorrowingInterestRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SubordinatedBorrowingAxis=mbwm_SubordinatedNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |