Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Components of Stock-Based Compensation Included in Consolidated Statements of Net and Comprehensive Income (Detail)

v2.4.1.9
Stock-Based Compensation - Components of Stock-Based Compensation Included in Consolidated Statements of Net and Comprehensive Income (Detail) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended 10 Months Ended 12 Months Ended
Dec. 31, 2013
Oct. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock based compensation in connection with IPO $ 30,900mmi_StockbasedCompensationInConnectionWithInitialPublicOffering $ 30,886mmi_StockbasedCompensationInConnectionWithInitialPublicOffering   $ 30,886mmi_StockbasedCompensationInConnectionWithInitialPublicOffering  
Share-based compensation expense - Independent contractors     3,892us-gaap_IssuanceOfStockAndWarrantsForServicesOrClaims 168us-gaap_IssuanceOfStockAndWarrantsForServicesOrClaims  
Allocated share-based compensation expense     5,034us-gaap_AllocatedShareBasedCompensationExpense 35,841us-gaap_AllocatedShareBasedCompensationExpense 7,448us-gaap_AllocatedShareBasedCompensationExpense
Restricted stock and SARs (prior to IPO) [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Allocated share-based compensation expense       4,679us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= mmi_RestrictedStockAndStockAppreciationRightsPriorToInitialPublicOfferingMember 		7,448us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= mmi_RestrictedStockAndStockAppreciationRightsPriorToInitialPublicOfferingMember
Employee Stock Purchase Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Allocated share-based compensation expense     128us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= mmi_EmployeeStockPurchasePlanMember 		   
Restricted Stock [Member] | Non-employee directors [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Allocated share-based compensation expense     197us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_TitleOfIndividualAxis
= mmi_NonEmployeeDirectorMember 		20us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_TitleOfIndividualAxis
= mmi_NonEmployeeDirectorMember 		 
Restricted Stock Units (RSUs) [Member] | Employees [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Allocated share-based compensation expense     $ 817us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_EmployeeStockMember 		$ 88us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_EmployeeStockMember