XML 83 R73.htm IDEA: XBRL DOCUMENT
v3.25.3

Note 12 - Fair Values - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Collateral dependent loans | $ 1,529 | $ 2,173
Fair Value, Inputs, Level 1 [Member] |  |
Collateral dependent loans | 0 | 0
Fair Value, Inputs, Level 2 [Member] |  |
Collateral dependent loans | 0 | 0
Fair Value, Inputs, Level 3 [Member] |  |
Collateral dependent loans | $ 1,529 | $ 2,173

X
- Definition The fair value disclosure of collateral dependent loans held by the company. + References No definition available. + Details
Name: | mbwm_CollateralDependentLoansFairValueDisclosure
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |