XML 42 R32.htm IDEA: XBRL DOCUMENT
v3.25.1

Note 8 - Stock-based Compensation (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2025
Notes Tables |
Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] |
|  |  |  |  |  | Weighted |
|  |  |  |  |  | Average |
|  | Shares |  |  | Fair Value |
Nonvested at beginning of the period |  |  | 228,646 |  |  | $ | 35.84 |
Grants |  |  | 84,685 |  |  | $ | 50.34 |
Vested |  |  | (34,053 | ) |  |  | 34.79 |
Forfeited |  |  | (845 | ) |  |  | 34.42 |
Nonvested at end of the period |  |  | 278,433 |  |  | $ | 40.38 |
Corporate and Bank Board Members [Member] |
Notes Tables |
Disclosure of Share-Based Compensation Arrangements by Share-Based Payment Award [Table Text Block] |
|  |  |  |  |  | Total Cost |  |
Grant Year |  | Shares Granted |  |  | (in thousands) |  | Covered Period
2023 |  |  | 11,529 |  |  |  | 350 |  | June 1, 2023 - May 31, 2024
2024 |  |  | 11,316 |  |  |  | 423 |  | June 1, 2024 - May 31, 2025

X
- Definition Tabular disclosure of share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_DisclosureOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited during the year. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_TableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_TitleOfIndividualAxis=mbwm_CorporateAndBankBoardMembersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |