v3.25.2

Document And Entity Information	Jul. 22, 2025
Document Information [Line Items]
Entity, Registrant Name	Mercantile Bank Corporation
Document, Type	8-K/A
Document, Period End Date	Jul. 22, 2025
Entity, Incorporation, State or Country Code	MI
Entity, File Number	000-26719
Entity, Tax Identification Number	38-3360865
Entity, Address, Address Line One	310 Leonard Street NW
Entity, Address, City or Town	Grand Rapids
Entity, Address, State or Province	MI
Entity, Address, Postal Zip Code	49504
City Area Code	616
Local Phone Number	406-3000
Written Communications	true
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Title of 12(b) Security	Common Stock
Trading Symbol	MBWM
Security Exchange Name	NASDAQ
Entity, Emerging Growth Company	false
Amendment Description	Form 8-K/A date of report 07-22-25
Amendment Flag	true
Entity, Central Index Key	0001042729

Description of changes contained within amended document.

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Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

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Area code of city

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

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The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

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Address Line 1 such as Attn, Building Name, Street Name

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Name of the City or Town

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Code for the postal or zip code

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Name of the state or province.

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A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Indicate if registrant meets the emerging growth company criteria.

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-Subsection b-2

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Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

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Two-character EDGAR code representing the state or country of incorporation.

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The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

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The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

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Local phone number for entity.

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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

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Name of the Exchange on which a security is registered.

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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Trading symbol of an instrument as listed on an exchange.

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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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MERCANTILE BANK CORP 8-K/A