Annual report pursuant to Section 13 and 15(d)

Description of Business, Basis of Presentation and Recent Accounting Pronouncements - Additional Information (Detail)

v2.4.1.9
Description of Business, Basis of Presentation and Recent Accounting Pronouncements - Additional Information (Detail) (USD $)
 12 Months Ended 0 Months Ended
Dec. 31, 2014
Office
Dec. 31, 2013
Nov. 05, 2013
Nov. 30, 2013
Class of Stock [Line Items]        
Number of offices in the United States and Canada 78mmi_NumberOfOffices      
Contribution date Oct. 30, 2013      
Percentage of common stock distributed 80.00%mmi_PercentageOfCommonStockDistributed      
Reclassification from other assets long-term to current   $ 668,000us-gaap_PriorPeriodReclassificationAdjustment    
Maximum [Member]        
Class of Stock [Line Items]        
Commission's receivable settled period 10 days      
Customer Concentration Risk [Member] | Total revenues [Member] | Maximum [Member]        
Class of Stock [Line Items]        
Concentration of credit risk percentage 10.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember 		10.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember 		   
Customer Concentration Risk [Member] | Commissions receivable [Member] | Maximum [Member]        
Class of Stock [Line Items]        
Concentration of credit risk percentage 10.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= mmi_CommissionReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember 		10.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= mmi_CommissionReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember 		   
MMI [Member]        
Class of Stock [Line Items]        
Formation date 2013-06      
IPO [Member]        
Class of Stock [Line Items]        
Common stock sold during initial public offering     6,900,000us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_IPOMember 		 
Common stock sold and issued under IPO, price per share     $ 12.00us-gaap_SharePrice
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_IPOMember 		$ 12us-gaap_SharePrice
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_IPOMember
Description of IPO On November 5, 2013, MMI completed its Initial Public Offering (“IPO”) of 6,900,000 shares of common stock at a price to the public of $12.00 per share of which 4,173,413 shares were sold by the Company and 2,726,587 shares were sold by certain selling stockholders.      
IPO MMI [Member]        
Class of Stock [Line Items]        
Common stock sold during initial public offering     4,173,413us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_SubsidiarySaleOfStockAxis
= mmi_IpoMmiMember 		 
IPO Selling Stockholder [Member]        
Class of Stock [Line Items]        
Common stock sold during initial public offering     2,726,587us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_SubsidiarySaleOfStockAxis
= mmi_IpoSellingStockholderMember