Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 17, 2018
Entity Registrant Name	Moelis & Co
Entity Central Index Key	0001596967
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Class A Common Stock
Entity Common Stock, Shares Outstanding		45,740,441
Class B Common Stock
Entity Common Stock, Shares Outstanding		10,493,358