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Note 14 - Commitments and Off-balance-sheet Risk (Details) (USD $) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013
Note 14 - Commitments and Off-balance-sheet Risk (Details) [Line Items] |  |
Reserve or Liability Balance for Financial Instruments with Off-balance Sheet Risk | $ 0 mbwm_ReserveOrLiabilityBalanceForFinancialInstrumentsWithOffBalanceSheetRisk | $ 0 mbwm_ReserveOrLiabilityBalanceForFinancialInstrumentsWithOffBalanceSheetRisk
Mortgage Loans on Real Estate, Minimum Interest Rate in Range | 4.00%us-gaap_MortgageLoansOnRealEstateMinimumInterestRateInRange |
Mortgage Loans on Real Estate, Maximum Interest Rate in Range | 7.00%us-gaap_MortgageLoansOnRealEstateMaximumInterestRateInRange |
Term Debt Secured by Real Estate Balloon Payment Period | 5 years |
Term Debt Secured by Non-Real Estate Collateral Maturity Period | 5 years |
Liabilities for Accreted Fee Collected from Customer | 100,000 mbwm_LiabilitiesForAccretedFeeCollectedFromCustomer | 100,000 mbwm_LiabilitiesForAccretedFeeCollectedFromCustomer
Amount of Federal Reserve Requirement | 8,400,000 mbwm_AmountOfFederalReserveRequirement | 1,500,000 mbwm_AmountOfFederalReserveRequirement
Interest Rate Swap [Member] |  |
Note 14 - Commitments and Off-balance-sheet Risk (Details) [Line Items] |  |
Derivative, Notional Amount | 15,400,000 invest_DerivativeNotionalAmount / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember |
Derivative, Fair Value, Net | $ (2,900,000)us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember |
Minimum [Member] |  |
Note 14 - Commitments and Off-balance-sheet Risk (Details) [Line Items] |  |
Amortization Period for Term Debt Secured by Real Estate | 10 years |
Interest Rates on Loans Secured by Non-Real Estate Collateral | 4.00%mbwm_InterestRatesOnLoansSecuredByNonRealEstateCollateral / us-gaap_RangeAxis = us-gaap_MinimumMember |
Fees Accreted Into Income During Interest Rate Swap Agreements Term | 4 years |
Maximum [Member] |  |
Note 14 - Commitments and Off-balance-sheet Risk (Details) [Line Items] |  |
Amortization Period for Term Debt Secured by Real Estate | 20 years |
Interest Rates on Loans Secured by Non-Real Estate Collateral | 7.50%mbwm_InterestRatesOnLoansSecuredByNonRealEstateCollateral / us-gaap_RangeAxis = us-gaap_MaximumMember |
Fees Accreted Into Income During Interest Rate Swap Agreements Term | 15 years |

X
- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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X
- Definition Amortization period for term debt secured by real estate. + References No definition available. + Details
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- Definition Amount of federal reserve requirement at period end that can be met with vault cash or deposits at a Federal Reserve Bank. + References No definition available. + Details
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- Definition The fees associated with an interest rate swap agreement that have been accreted. + References No definition available. + Details
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- Definition Interest rates on loans secured by non-real estate collateral. + References No definition available. + Details
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- Definition Liabilities for accreted fee collected from customer. + References No definition available. + Details
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- Details
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- Definition The carrying amount for the reserve or liability for financial instruments with off-balance sheet risk. + References No definition available. + Details
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- Definition Term debt secured by non-real estate collateral maturity period. + References No definition available. + Details
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- Definition Term debt secured by real estate balloon payment period. + References No definition available. + Details
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X
- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 + Details
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X
- Definition The highest stated interest rate within the mortgage loans included in the loan grouping. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule IV) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29.3) -URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 29 -Article 12 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph c -Subparagraph Schedule IV -Article 5 + Details
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- Definition The lowest stated interest rate within the mortgage loans included in the loan grouping. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule IV) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29.3) -URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 29 -Article 12 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph c -Subparagraph Schedule IV -Article 5 + Details
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