Quarterly report pursuant to Section 13 or 15(d)

Revenue from Contracts with Customers - Summary of Revenue from Contracts (Detail)

v3.23.3
Revenue from Contracts with Customers - Summary of Revenue from Contracts (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2023
Sep. 30, 2022
Sep. 30, 2023
Sep. 30, 2022
Disaggregation of Revenue [Line Items]        
Net commissions and fees $ 487,345 $ 407,551 $ 1,507,878 $ 1,284,459
Wholesale brokerage [Member]        
Disaggregation of Revenue [Line Items]        
Net commissions and fees 308,872 267,222 976,338 841,273
Binding authorities [Member]        
Disaggregation of Revenue [Line Items]        
Net commissions and fees 69,245 55,607 208,547 178,351
Underwriting management [Member]        
Disaggregation of Revenue [Line Items]        
Net commissions and fees $ 109,228 $ 84,722 $ 322,993 $ 264,835