Note 7 - Federal Home Loan Bank Advances (Details) - Maturities of Currently Outstanding FHLB Advances (USD $)	Mar. 31, 2014
Maturities of Currently Outstanding FHLB Advances [Abstract]
2014	$ 0
2015	0
2016	0
2017	45,000,000
2018	$ 0

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Namespace Prefix:	mbwm_
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Amount of federal home loan bank advances maturing in the fifth fiscal year following the latest fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

+ Details

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- Definition

Amount of federal home loan bank advances maturing in the second fiscal year following the latest fiscal year.

+ References

+ Details

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- Definition

Amount of federal home loan bank advances maturing in the fourth fiscal year following the latest fiscal year.

+ References

+ Details

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- Definition

Amount of federal home loan bank advances maturing in the third fiscal year following the latest fiscal year.

+ References

+ Details

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- Definition

Amount of federal home loan bank advances maturing in the next fiscal year following the latest fiscal year.

+ References

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