v2.4.1.9
STOCKHOLDERS EQUITY (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
3 Months Ended 1 Months Ended
Mar. 31, 2015
Apr. 30, 2014
Nov. 30, 2014
Dec. 31, 2014
STOCKHOLDERS EQUITY        
Shares deemed to be repurchased for payment of tax liabilities 6,043us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation      
Average price per share of shares deemed repurchased for payment of tax liabilities (in dollars per share) $ 32.17mc_TreasuryStockAcquiredForTaxSettlementOfShareBasedCompensationAverageCostPerShare      
Treasury stock shares acquired $ 4,327us-gaap_TreasuryStockValueAcquiredCostMethod      
Group LP        
STOCKHOLDERS EQUITY        
Number of units held by noncontrolling interest holders 34,479,961mc_PartnersCapitalAccountUnitsHeldByNoncontrollingInterestHolders
/ dei_LegalEntityAxis
= mc_MoelisAndCompanyGroupLPMember
     
Noncontrolling interests (as a percent) 64.00%us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
/ dei_LegalEntityAxis
= mc_MoelisAndCompanyGroupLPMember
     
Maximum        
STOCKHOLDERS EQUITY        
Aggregate number of shares of Class B common stock that may be converted into Class A common stock 20,000mc_MaximumNumberOfSharesWhichMayBeConvertedToPubliclyTradedShares
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
     
Class A common stock        
STOCKHOLDERS EQUITY        
Aggregate stock issuance (in shares)   15,263,653mc_AggregateStockIssuance
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
   
Reorganization of equity structure (in shares)   7,699,851mc_ReorganizationOfEquityStructureShares
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
   
Common Stock issued in connection with settlement of appreciation rights issued in prior years (in shares)   88,802mc_StockIssuedDuringPeriodSharesSettlementOfAppreciationRights
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
   
Common stock, shares issued 19,793,132us-gaap_CommonStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
    19,770,893us-gaap_CommonStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
Common stock, shares outstanding 19,657,226us-gaap_CommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
    19,770,893us-gaap_CommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
Number of shares of common stock to be issued upon exchange of a partnership unit 1mc_NumberOfSharesIssuableUponExchangeOfEachUnit
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
1mc_NumberOfSharesIssuableUponExchangeOfEachUnit
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
   
Class A common stock | IPO        
STOCKHOLDERS EQUITY        
Common Stock issued (in shares)   7,475,000us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_IPOMember
   
Class A common stock | Secondary Offering        
STOCKHOLDERS EQUITY        
Common Stock issued (in shares)     6,325,000us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
/ us-gaap_SubsidiarySaleOfStockAxis
= mc_SecondaryOfferingMember
 
Issuance of Class A common stock and acquisition of Class A partnership units in connection with secondary offering (in shares)     4,511,058mc_ExchangeOfPartnershipUnitsToCommonStockInConnectionWithSecondaryOfferingShares
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
/ us-gaap_SubsidiarySaleOfStockAxis
= mc_SecondaryOfferingMember
 
Class A common stock | Group LP        
STOCKHOLDERS EQUITY        
Common stock, shares outstanding 19,657,226us-gaap_CommonStockSharesOutstanding
/ dei_LegalEntityAxis
= mc_MoelisAndCompanyGroupLPMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
     
Class A common stock | Share repurchase program authorized first quarter 2015        
STOCKHOLDERS EQUITY        
Treasury stock shares acquired (in shares) 129,863us-gaap_TreasuryStockSharesAcquired
/ us-gaap_ShareRepurchaseProgramAxis
= mc_ShareRepurchaseProgramAuthorizedFirstQuarter2015Member
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
     
Average cost per share of treasury stock acquired (in dollars per share) $ 31.82us-gaap_TreasuryStockAcquiredAverageCostPerShare
/ us-gaap_ShareRepurchaseProgramAxis
= mc_ShareRepurchaseProgramAuthorizedFirstQuarter2015Member
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
     
Class B common stock        
STOCKHOLDERS EQUITY        
Common Stock issued (in shares)   36,158,698us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
   
Common stock, shares issued 31,617,704us-gaap_CommonStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
    31,621,542us-gaap_CommonStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
Common stock, shares outstanding 31,617,704us-gaap_CommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
    31,621,542us-gaap_CommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
Ratio of subscription price to the initial public offering price of shares of common stock 0.00055mc_RatioOfSubscriptionPriceToInitialPublicOfferingPriceUsedAsBasisForDeterminationOfShareholderEconomicRights
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
     
Dividends payable ratio to outstanding shares of publicly traded common stock 0.00055mc_DividendsPayableRatioToOutstandingSharesOfPubliclyTradedCommonStock
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
     
Class B common stock | Maximum        
STOCKHOLDERS EQUITY        
Aggregate number of shares of Class B common stock that may be converted into Class A common stock 20,000mc_MaximumNumberOfSharesWhichMayBeConvertedToPubliclyTradedShares
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember