Quarterly report pursuant to Section 13 or 15(d)

Related Parties - Additional Information (Detail)

v3.21.2
Related Parties - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended 12 Months Ended
Mar. 31, 2021
Jan. 01, 2021
Mar. 05, 2020
Jun. 13, 2019
Sep. 30, 2021
Jun. 30, 2021
Mar. 31, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Mar. 31, 2020
Jan. 01, 2020
Related Party Transaction [Line Items]                          
Equity Method Investment, Ownership Percentage         53.00%       53.00%        
Working capital true-up payment           $ 100,000              
Total invested capital         $ 47,087,000       $ 47,087,000   $ 47,216,000    
Expense related to business usage of the aircraft         100,000     $ 100,000 400,000 $ 300,000      
Non-recurring guarantee         10,000.0       10,000.0        
Ryan Re Services Agreement With Geneva Re And Nationwide [Member]                          
Related Party Transaction [Line Items]                          
Percentage of service fee arrived                         115.00%
Percentage of service fee, written off                     2.50%    
Revenue earned from Geneva Re         400,000     200,000 1,400,000 1,100,000      
Receivables due from Geneva Re         $ 3,200,000       $ 3,200,000   $ 3,000,000.0    
Geneva Ryan Holdings [Member]                          
Related Party Transaction [Line Items]                          
Non-controlling Interest, Ownership Percentage by Non-controlling Owners       53.00%                  
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage 53.00%                        
Ryan Specialty Group, LLC [Member]                          
Related Party Transaction [Line Items]                          
Total consideration transferred, net of cash acquired $ 48,400,000                        
Common stock, Par value       $ 1               $ 1  
Shares Issued, Price Per Share       $ 4.70                  
Derecognized the non-controlling interest             $ 3,700,000            
Recognized a deemed distribution             $ 44,600,000            
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage       47.00%                  
Geneva Re [Member]                          
Related Party Transaction [Line Items]                          
Equity Method Investment, Ownership Percentage         50.00%       50.00%        
Total invested capital         $ 47,000,000.0       $ 47,000,000.0        
Equity Method Investment, Aggregate Cost         50,000,000.0       50,000,000.0        
Capital contribution     $ 23,500,000                    
Related Party Transaction, Due from (to) Related Party         $ 400,000       $ 400,000   400,000    
JEM Underwriting Managers, LLC [Member]                          
Related Party Transaction [Line Items]                          
Total consideration transferred, net of cash acquired   $ 4,000,000.0                      
Ryan Re [Member]                          
Related Party Transaction [Line Items]                          
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage 53.00%                        
Ryan Investment Holdings [Member] | Ryan Specialty Group, LLC [Member]                          
Related Party Transaction [Line Items]                          
Non-controlling Interest, Ownership Percentage by Non-controlling Owners         47.00%       47.00%        
Total invested capital         $ 47,000.0       $ 47,000.0        
Michael O Halleran [Member] | Consulting Arrangement with Director [Member]                          
Related Party Transaction [Line Items]                          
Related party transaction         $ 100,000     $ 100,000 200,000 $ 200,000      
Immediate Family Member of Director [Member]                          
Related Party Transaction [Line Items]                          
Related party transaction                     300,000    
Base salary                 200,000   100,000    
Production bonus                 $ 100,000   $ 200,000