Quarterly report pursuant to Section 13 or 15(d)

Investments in Marketable Securities - Additional Information (Detail)

v2.4.1.9
Investments in Marketable Securities - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]    
Available for sale securities continuous unrealized loss position for less than 12 months, amortized cost $ 727,000mmi_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsAmortizedCost $ 5,400,000mmi_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsAmortizedCost
Available for sale securities continuous unrealized loss position for less than 12 months, fair value 715,000us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue 5,400,000us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Available-for-sale-securities, Continuous unrealized loss position for 12 months or longer 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Available for sale securities gross realized gains 77,000us-gaap_AvailableForSaleSecuritiesGrossRealizedGains  
Available for sale securities gross realized loss 3,000us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses  
Other-than-temporary impairment $ 0us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities