v3.19.1
Document and Entity Information - shares
3 Months Ended
Mar. 31, 2019
May 03, 2019
Entity Registrant Name Focus Financial Partners Inc.  
Entity Central Index Key 0001651052  
Document Type 10-Q  
Document Period End Date Mar. 31, 2019  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Ex Transition Period true  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q1  
Class A common stock    
Entity Common Stock, Shares Outstanding   46,692,832
Class B common stock    
Entity Common Stock, Shares Outstanding   22,568,831