XML 14 R55.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Commitments and Off-Balance Sheet Risk (Details) (USD $) | Mar. 31, 2013 | Dec. 31, 2012
--- | --- | ---
Summary of contractual amounts of financial instruments with off-balance sheet risk |  |
Contractual amounts of financial instruments with off-balance sheet risk | $ 370,575,000 | $ 334,768,000
Commercial unused lines of credit [Member] |  |
Summary of contractual amounts of financial instruments with off-balance sheet risk |  |
Contractual amounts of financial instruments with off-balance sheet risk | 230,160,000 | 222,237,000
Unused lines of credit secured by 1 - 4 family residential properties [Member] |  |
Summary of contractual amounts of financial instruments with off-balance sheet risk |  |
Contractual amounts of financial instruments with off-balance sheet risk | 23,892,000 | 24,250,000
Credit card unused lines of credit [Member] |  |
Summary of contractual amounts of financial instruments with off-balance sheet risk |  |
Contractual amounts of financial instruments with off-balance sheet risk | 8,431,000 | 8,512,000
Other consumer unused lines of credit [Member] |  |
Summary of contractual amounts of financial instruments with off-balance sheet risk |  |
Contractual amounts of financial instruments with off-balance sheet risk | 3,752,000 | 4,613,000
Commitments to extent credit [Member] |  |
Summary of contractual amounts of financial instruments with off-balance sheet risk |  |
Contractual amounts of financial instruments with off-balance sheet risk | 94,000,000 | 64,565,000
Standby letters of credit [Member] |  |
Summary of contractual amounts of financial instruments with off-balance sheet risk |  |
Contractual amounts of financial instruments with off-balance sheet risk | $ 10,340,000 | $ 10,591,000

X
- Details
Name: | mbwm_CommitmentsAndOffBalanceSheetRiskAbstract
Namespace Prefix: | mbwm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The fair value of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + 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=7491637&loc=d3e13433-108611 + Details
Name: | us-gaap_FairValueDisclosureOffbalanceSheetRisksAmountLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant