| Label | Element | Value |
|---|---|---|
| Partners' Capital Account, Unit-based Compensation | us-gaap_PartnersCapitalAccountUnitBasedCompensation | $ 105,922,000 |
| Adjustments to Additional Paid in Capital Initial Establishment of Deferred Tax Assets Net of Amounts Payable under Tax Receivable Agreement | mc_AdjustmentsToAdditionalPaidInCapitalInitialEstablishmentOfDeferredTaxAssetsNetOfAmountsPayableUnderTaxReceivableAgreement | 10,854,000 |
| Adjustments to Additional Paid in Capital Tax Benefit Related to Appreciation Units | mc_AdjustmentsToAdditionalPaidInCapitalTaxBenefitRelatedToAppreciationUnits | 4,308,000 |
| Adjustments to Additional Paid in Capital Increase in Deferred Tax Asset Related to Initial Public Offering | mc_AdjustmentsToAdditionalPaidInCapitalIncreaseInDeferredTaxAssetRelatedToInitialPublicOffering | 1,302,000 |
| Exchange Of Partnership Units To Common Stock In Connection With Secondary Offering Value | mc_ExchangeOfPartnershipUnitsToCommonStockInConnectionWithSecondaryOfferingValue | 20,711,000 |
| Adjustments to Additional Paid in Capital Distributions to Partners of Parent | mc_AdjustmentsToAdditionalPaidInCapitalDistributionsToPartnersOfParent | 139,429,000 |
| Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent | (2,638,000) |
| Dividends | us-gaap_Dividends | 76,233,000 |
| Equity Based Contributions to Joint Venture and Global Advisory Board | mc_EquityBasedContributionsToJointVentureAndGlobalAdvisoryBoard | 5,972,000 |
| Stockholders' Equity, Other | us-gaap_StockholdersEquityOther | 2,130,000 |
| Retained Earnings [Member] | ||
| Net Income (Loss), Including Portion Attributable to Noncontrolling Interest | us-gaap_ProfitLoss | (3,012,000) |
| Dividends | us-gaap_Dividends | 21,106,000 |
| Accumulated Other Comprehensive Income [Member] | ||
| Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent | (842,000) |
| Additional Paid In Capital [Member] | ||
| Partners' Capital Account, Unit-based Compensation | us-gaap_PartnersCapitalAccountUnitBasedCompensation | 39,156,000 |
| Adjustments to Additional Paid in Capital Initial Establishment of Deferred Tax Assets Net of Amounts Payable under Tax Receivable Agreement | mc_AdjustmentsToAdditionalPaidInCapitalInitialEstablishmentOfDeferredTaxAssetsNetOfAmountsPayableUnderTaxReceivableAgreement | 10,854,000 |
| Adjustments to Additional Paid in Capital Tax Benefit Related to Appreciation Units | mc_AdjustmentsToAdditionalPaidInCapitalTaxBenefitRelatedToAppreciationUnits | 4,308,000 |
| Adjustments to Additional Paid in Capital Increase in Deferred Tax Asset Related to Initial Public Offering | mc_AdjustmentsToAdditionalPaidInCapitalIncreaseInDeferredTaxAssetRelatedToInitialPublicOffering | 1,302,000 |
| Exchange Of Partnership Units To Common Stock In Connection With Secondary Offering Value | mc_ExchangeOfPartnershipUnitsToCommonStockInConnectionWithSecondaryOfferingValue | 33,723,000 |
| Adjustments to Additional Paid in Capital Distributions to Partners of Parent | mc_AdjustmentsToAdditionalPaidInCapitalDistributionsToPartnersOfParent | 139,429,000 |
| Dividends | us-gaap_Dividends | (3,115,000) |
| Equity Based Contributions to Joint Venture and Global Advisory Board | mc_EquityBasedContributionsToJointVentureAndGlobalAdvisoryBoard | 5,849,000 |
| Stock Issued During Period, Value, New Issues | us-gaap_StockIssuedDuringPeriodValueNewIssues | 162,032,000 |
| Stockholders' Equity, Other | us-gaap_StockholdersEquityOther | (112,000) |
| Noncontrolling Interest [Member] | ||
| Net Income (Loss), Including Portion Attributable to Noncontrolling Interest | us-gaap_ProfitLoss | 5,799,000 |
| Partners' Capital Account, Unit-based Compensation | us-gaap_PartnersCapitalAccountUnitBasedCompensation | 66,765,000 |
| Exchange Of Partnership Units To Common Stock In Connection With Secondary Offering Value | mc_ExchangeOfPartnershipUnitsToCommonStockInConnectionWithSecondaryOfferingValue | (13,012,000) |
| Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent | (1,796,000) |
| Dividends | us-gaap_Dividends | 58,242,000 |
| Equity Based Contributions to Joint Venture and Global Advisory Board | mc_EquityBasedContributionsToJointVentureAndGlobalAdvisoryBoard | 123,000 |
| Stockholders' Equity, Other | us-gaap_StockholdersEquityOther | $ 2,241,000 |
| Common Class A [Member] | ||
| Stockholders' Equity, Other Shares | us-gaap_StockholdersEquityOtherShares | 180 |
| Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures | us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation | 76,722 |
| Partners' Capital Account, Unit-based Compensation | us-gaap_PartnersCapitalAccountUnitBasedCompensation | $ 1,000 |
| Exchange Of Partnership Units To Common Stock In Connection With Secondary Offering Value | mc_ExchangeOfPartnershipUnitsToCommonStockInConnectionWithSecondaryOfferingValue | $ 45,000 |
| Common Class B [Member] | ||
| Stockholders' Equity, Other Shares | us-gaap_StockholdersEquityOtherShares | 29,703 |
| Exchange Of Partnership Units To Common Stock In Connection With Secondary Offering Value | mc_ExchangeOfPartnershipUnitsToCommonStockInConnectionWithSecondaryOfferingValue | $ (45,000) |
| Stockholders' Equity, Other | us-gaap_StockholdersEquityOther | $ 1,000 |