XML 31 R62.htm IDEA: XBRL DOCUMENT
v3.2.0.727

Note 9 - Commitments and Off-balance Sheet Risk (Details) - USD ($) | 6 Months Ended |
--- | --- | ---
Jun. 30, 2015 | Dec. 31, 2014
Note 9 - Commitments and Off-balance Sheet Risk (Details) [Line Items] |  |
Reserve or Liability Balance for Financial Instruments with Off-balance Sheet Risk | $ 0 | $ 0
Interest Rate Swap [Member] |  |
Note 9 - Commitments and Off-balance Sheet Risk (Details) [Line Items] |  |
Derivative, Notional Amount | 15,000,000 |
Derivative, Fair Value, Net | $ (2,300,000) |
Minimum [Member] |  |
Note 9 - Commitments and Off-balance Sheet Risk (Details) [Line Items] |  |
Fees Accreted Into Income During Interest Rate Swap Agreements, Term | 4 years |
Maximum [Member] |  |
Note 9 - Commitments and Off-balance Sheet Risk (Details) [Line Items] |  |
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
Name: | invest_DerivativeNotionalAmount
Namespace Prefix: | invest_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period of time between issuance and maturity of interest rate swap agreements, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | mbwm_FeesAccretedIntoIncomeDuringInterestRateSwapAgreementsTerm
Namespace Prefix: | mbwm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | mbwm_Note9CommitmentsandOffbalanceSheetRiskDetailsLineItems
Namespace Prefix: | mbwm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amount for the reserve or liability for financial instruments with off-balance sheet risk. + References No definition available. + Details
Name: | mbwm_ReserveOrLiabilityBalanceForFinancialInstrumentsWithOffBalanceSheetRisk
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 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 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13433-108611 Reference 4: 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=49121117&loc=d3e13495-108611 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |