Annual report pursuant to Section 13 and 15(d)

Selected Balance Sheet Data - Additional Information (Detail)

v2.4.1.9
Selected Balance Sheet Data - Additional Information (Detail) (USD $)
 0 Months Ended 12 Months Ended
Jan. 02, 2014
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Mar. 31, 2013
Schedule Of Accrued Expenses [Line Items]          
SARs frozen liability amount   $ 20,542,000mmi_StockAppreciationRightsLiability $ 19,970,000mmi_StockAppreciationRightsLiability   $ 20,000,000mmi_StockAppreciationRightsLiability
SARs liability frozen value date   Mar. 31, 2013      
SARs liability interest accrual commencement date   Jan. 01, 2014      
Interest expense   1,651,000us-gaap_InterestExpense 105,000us-gaap_InterestExpense 4,000us-gaap_InterestExpense  
Treasury note term     10 years    
Base spread on SARs liability variable rate 2.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1        
SARs liability interest accrual rate 5.03%mmi_StockAppreciationRightsLiabilityInterestAccrualRate        
Stock appreciation rights liability distribution   412,000mmi_DistributionRelatedToStockAppreciationRightsLiabilityForTaxesPayable      
Maximum payment deferral period for certain commissions payable   3 years      
Fair value of deferred compensation plan assets   110.00%mmi_DeferredCompensationPlanPercentage      
Net change in carrying value of investments held in rabbi trust   290,000mmi_RecognizedGainsLossesOfInvestmentsHeldInTrust 495,000mmi_RecognizedGainsLossesOfInvestmentsHeldInTrust 353,000mmi_RecognizedGainsLossesOfInvestmentsHeldInTrust  
Deferred Compensation Liability [Member]          
Schedule Of Accrued Expenses [Line Items]          
Net change in carrying value of deferred compensation obligation   313,000us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense
/ us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis
= mmi_DeferredCompensationLiabilityMember 		504,000us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense
/ us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis
= mmi_DeferredCompensationLiabilityMember 		353,000us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense
/ us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis
= mmi_DeferredCompensationLiabilityMember 		 
SARs [Member]          
Schedule Of Accrued Expenses [Line Items]          
Interest expense   984,000us-gaap_InterestExpense
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember 		     
Stock appreciation rights liability distribution   $ 412,000mmi_DistributionRelatedToStockAppreciationRightsLiabilityForTaxesPayable
/ us-gaap_AwardTypeAxis
= us-gaap_StockAppreciationRightsSARSMember