Annual report pursuant to Section 13 and 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)

v2.4.1.9
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Segment
Branch
InterestRateSwap
Loan
Dec. 31, 2013
Dec. 31, 2012
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]      
Number of full service branch offices 26mcbc_NumberOfFullServiceBranchOffices    
Cash Flow Reporting [Abstract]      
Maturity days of short term securities included in cash and cash equivalent 90 days    
Securities [Abstract]      
OTTI charges $ 0us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax $ 0us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax $ 0us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax
Federal Home Loan Bank (FHLB) Stock [Abstract]      
FHLB stock impaired 0mcbc_FhlbStockImpaired 0mcbc_FhlbStockImpaired 0mcbc_FhlbStockImpaired
Loans Held-for-sale [Abstract]      
Net unrealized gain on loans held for sale 62,000us-gaap_IncreaseDecreaseInLoansHeldForSale 42,000us-gaap_IncreaseDecreaseInLoansHeldForSale  
Loans [Abstract]      
Delinquent period after which interest income is discontinued on mortgage and commercial loans 90 days    
Past due period to charge off consumer loans 120 days    
Allowance for Loan Losses [Abstract]      
Period for annualized historical loss experience used for commercial loans 18 months    
Period of historical loss experience applied to residential mortgage and consumer loan portfolios 12 months    
Threshold for commercial and commercial real estate loans evaluated for impairment 500,000mcbc_ThresholdForCommercialAndCommercialRealEstateLoansEvaluatedForImpairment    
Minimum internal risk grading of commercial and commercial real estate loans evaluated for impairment 6mcbc_MinimumInternalRiskGradingOfCommercialAndCommercialRealEstateLoansEvaluatedForImpairment    
Goodwill and Acquired Intangible Assets [Abstract]      
Goodwill 0us-gaap_Goodwill 0us-gaap_Goodwill  
Finite-Lived Intangible Assets [Line Items]      
Acquired intangible 0us-gaap_FinitelivedIntangibleAssetsAcquired1 0us-gaap_FinitelivedIntangibleAssetsAcquired1  
Mortgage Banking Derivatives [Abstract]      
Net fair value of mortgage banking derivatives (2,000)us-gaap_DerivativeAssets 51,000us-gaap_DerivativeAssets  
Derivatives [Abstract]      
Number of freestanding interest rate swaps 2us-gaap_DerivativeNumberOfInstrumentsHeld    
Notional amount of agreements 20,000,000invest_DerivativeNotionalAmount 20,000,000invest_DerivativeNotionalAmount  
Derivative asset fair value 140,000us-gaap_DerivativeFairValueOfDerivativeAsset 94,000us-gaap_DerivativeFairValueOfDerivativeAsset  
Trading liability fair value 140,000us-gaap_DerivativeAssetFairValueGrossLiability 94,000us-gaap_DerivativeAssetFairValueGrossLiability  
Restrictions on Cash [Abstract]      
Cash on hand or on deposit with the Federal Reserve Bank $ 5,016,000us-gaap_RestrictedCashAndCashEquivalents $ 4,417,000us-gaap_RestrictedCashAndCashEquivalents  
Stock Splits and Dividends [Abstract]      
Stock dividends, excess of threshold (in hundredths) 20.00%mcbc_StockDividendsThreshold    
Stock dividend threshold or less (in hundredths) 20.00%mcbc_StockDividendThresholdOrLess    
Segment Reporting [Abstract]      
Number of operating segments 1us-gaap_NumberOfOperatingSegments    
Minimum [Member]      
Finite-Lived Intangible Assets [Line Items]      
Estimated useful life of intangible assets 10 years    
Maximum [Member]      
Finite-Lived Intangible Assets [Line Items]      
Estimated useful life of intangible assets 16 years    
Building and Related Components [Member] | Minimum [Member]      
Property, Plant and Equipment [Line Items]      
Useful lives 5 years    
Building and Related Components [Member] | Maximum [Member]      
Property, Plant and Equipment [Line Items]      
Useful lives 40 years    
Furniture Fixture and Equipment [Member] | Minimum [Member]      
Property, Plant and Equipment [Line Items]      
Useful lives 3 years    
Furniture Fixture and Equipment [Member] | Maximum [Member]      
Property, Plant and Equipment [Line Items]      
Useful lives 15 years    
Commercial Real Estate [Member]      
Concentration Risk [Line Items]      
Concentration of credit risk (in hundredths) 44.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
   
Commercial and Industrial [Member]      
Concentration Risk [Line Items]      
Concentration of credit risk (in hundredths) 29.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
   
Residential Real Estate and Consumer Loans [Member]      
Concentration Risk [Line Items]      
Concentration of credit risk (in hundredths) 27.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByTypeAxis
= mcbc_ResidentialRealEstateAndConsumerLoansMember