XML 128 R101.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Regulatory Matters - Additional Information (Detail) (USD $) | 0 Months Ended | 1 Months Ended | 12 Months Ended |  | 1 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | ---
Dec. 10, 2013 | Sep. 10, 2013 | Jun. 10, 2013 | Mar. 08, 2013 | Dec. 10, 2012 | Oct. 31, 2013 | Jul. 31, 2013 | Apr. 30, 2013 | Jan. 31, 2013 | Oct. 31, 2012 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2009 | Jan. 31, 2014 Subsequent Event [Member] | Dec. 31, 2013 Installment One FY Two Thousand Thirteen [Member] | Dec. 31, 2013 Installment Two FY Two Thousand Thirteen [Member] | Dec. 31, 2013 Installment Three FY Two Thousand Thirteen [Member] | Dec. 31, 2013 Installment Four FY Two Thousand Thirteen [Member] | Dec. 31, 2013 Installment Five Fy Two Thousand Thirteen [Member] | Dec. 31, 2013 Installment Six Fy Two Thousand Thirteen [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum amount of dividends distributed by bank to holding company without prior regulatory approval |  |  |  |  |  |  |  |  |  |  | $ 31,400,000 |  |  |  |  |  |  |  |  |
Cash dividend on common stock | $ 0.12 | $ 0.12 | $ 0.11 | $ 0.10 | $ 0.09 |  |  |  |  |  | $ 0.45 | $ 0.09 |  |  |  |  |  |  |  |
Cash dividend declared on common stock |  |  |  |  |  | $ 0.12 | $ 0.12 | $ 0.11 | $ 0.10 | $ 0.09 |  |  |  | $ 0.12 |  |  |  |  |  |
Dividend declared date |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Oct. 11, 2012 | Jan. 10, 2013 | Apr. 11, 2013 | Jul. 11, 2013 | Oct. 10, 2013 | Jan. 16, 2014
Dividend payable date |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Dec. 10, 2012 | Mar. 08, 2013 | Jun. 10, 2013 | Sep. 10, 2013 | Dec. 10, 2013 | Mar. 10, 2014
Dividend payable date of record |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Nov. 09, 2012 | Feb. 08, 2013 | May 10, 2013 | Aug. 09, 2013 | Nov. 08, 2013 | Feb. 10, 2014
Dividend suspended date |  |  |  |  |  |  |  |  |  |  | Apr. 01, 2010 |  |  |  |  |  |  |  |  |
Trust preferred securities |  |  |  |  |  |  |  |  |  |  | 32,000,000 | 32,000,000 |  |  |  |  |  |  |  |
Aggregate amount of restricted core elements allowed in Tier 1 capital |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |  |
Trusted preferred securities issued date |  |  |  |  |  |  |  |  |  |  | Before May 19, 2010 |  |  |  |  |  |  |  |  |
Maximum level of consolidated aggregate assets allowing for inclusion of trust preferred securities in Tier Capital under Dodd-Frank Act |  |  |  |  |  |  |  |  |  |  |  |  | $ 15,000,000,000 |  |  |  |  |  |  |

X
- Definition Common stock cash dividend suspension period. + References No definition available. + Details
Name: | mbwm_CommonStockCashDividendSuspensionPeriod
Namespace Prefix: | mbwm_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum level of consolidated aggregate assets allowing for inclusion of trust preferred securities in Tier 1 capital under Dodd-Frank Act. + References No definition available. + Details
Name: | mbwm_MaximumLevelOfConsolidatedAggregateAssetsAllowingForInclusionOfTrustPreferredSecuritiesInTierOneCapitalUnderDoddFrankAct
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Maximum restricted core element allowed in tier one capital percent. + References No definition available. + Details
Name: | mbwm_MaximumRestrictedCoreElementAllowedInTierOneCapitalPercent
Namespace Prefix: | mbwm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Trust preferred securities issuance end date to include such securities in Tier 1 Capital under Dodd-Frank Act + References No definition available. + Details
Name: | mbwm_TrustedPreferredSecuritiesIssuanceDate
Namespace Prefix: | mbwm_
Data Type: | us-types:dateStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Trust Preferred Securities Included In Tier One Capital + References No definition available. + Details
Name: | mbwm_TrustPreferredSecuritiesIncludedInTierOneCapital
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Aggregate dividends paid during the period for each share of common stock outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_CommonStockDividendsPerShareCashPaid
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the declared dividend will be paid, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586 + Details
Name: | us-gaap_DividendPayableDateToBePaidDayMonthAndYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the dividend to be paid was declared, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586 + Details
Name: | us-gaap_DividendsPayableDateDeclaredDayMonthAndYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_DividendsPayableDateOfRecordDayMonthAndYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of dividends that can be declared or paid without approval of regulatory agency. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(e)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph e -Article 4 + Details
Name: | us-gaap_StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithoutRegulatoryApproval
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant