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Deposits (Details Textual) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2012
Deposits (Textual) [Abstract] |
Out-of-area certificates of deposit obtained through deposit brokers | $ 242.8
Out-of-area certificates of deposit obtained directly from depositors | $ 5.0

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- Details
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- Definition Out -of-area certificates of deposit obtained directly from depositors. + References No definition available. + Details
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Namespace Prefix: | mbwm_
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- Definition Out of area certificates of deposits obtained through brokers. + References No definition available. + Details
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Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
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Period Type: | instant