Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 17, 2019
Entity Registrant Name	Moelis & Co
Entity Central Index Key	0001596967
Document Type	10-Q
Document Period End Date	Jun. 30, 2019
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
Entity Shell Company	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Trading Symbol	MC
Entity File Number	001-36418
Entity Tax Identification Number	464500216
Entity Address, Address Line One	399 Park Avenue
Entity Address, Address Line Two	5th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10022
City Area Code	212
Local Phone Number	883-3800
Class A Common Stock
Entity Common Stock, Shares Outstanding		49,206,713
Class B Common Stock
Entity Common Stock, Shares Outstanding		10,431,422