Quarterly report pursuant to Section 13 or 15(d)

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

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Description of Business, Basis of Presentation and Recent Accounting Pronouncements - Additional Information (Detail) (USD $)
9 Months Ended 3 Months Ended 9 Months Ended 0 Months Ended 9 Months Ended
Sep. 30, 2014
Office
Subsidiary
Sep. 30, 2014
Maximum [Member]
Total revenues [Member]
Customer Concentration Risk [Member]
Sep. 30, 2013
Maximum [Member]
Total revenues [Member]
Customer Concentration Risk [Member]
Sep. 30, 2014
Maximum [Member]
Total revenues [Member]
Customer Concentration Risk [Member]
Sep. 30, 2013
Maximum [Member]
Total revenues [Member]
Customer Concentration Risk [Member]
Sep. 30, 2014
MMI [Member]
Nov. 05, 2013
IPO [Member]
Sep. 30, 2014
IPO [Member]
Nov. 05, 2013
IPO [Member]
Class of Stock [Line Items]                  
Number of offices in the United States and Canada 78                
Number of wholly owned subsidiaries 2                
Formation date           2013-06      
Contribution date Oct. 30, 2013                
Percentage of common stock distributed 80.00%                
Common stock sold             6,900,000    
Common stock sold and issued under IPO, price per share                 $ 12.00
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.  
Concentration of credit risk percentage   10.00% 10.00% 10.00% 10.00%