Quarterly report [Sections 13 or 15(d)]

Mergers and Acquisitions - Narrative (Details)

v3.25.2
Mergers and Acquisitions - Narrative (Details)
$ in Millions
3 Months Ended 6 Months Ended 12 Months Ended
May 16, 2025
USD ($)
May 01, 2025
USD ($)
Feb. 03, 2025
USD ($)
Nov. 04, 2024
USD ($)
managingGeneralUnderwriter
Oct. 01, 2024
USD ($)
Sep. 13, 2024
USD ($)
program
Sep. 01, 2024
USD ($)
Aug. 30, 2024
USD ($)
May 01, 2024
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2024
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2024
USD ($)
Dec. 31, 2024
USD ($)
Business Combination [Line Items]                            
Acquisition related costs                   $ 3.3 $ 1.2 $ 9.5 $ 1.6  
Acquiree's revenue since acquisition date                   41.7   55.4    
Estimated tax deductible goodwill                   14.4   14.4    
Increase (decrease) of income tax expense related to the common control reorganization                       (48.0) 59.4  
Increase in financing costs and interest expense                     16.9   65.4  
Increase of amortization expense on acquired intangible assets                     31.2   66.6  
Increase (decrease) in transaction costs                   (5.7)   (10.8) 13.1  
Decrease in tax expenses related to pro forma adjustments                     $ 6.9   $ 20.5  
2025 Acquisitions                            
Business Combination [Line Items]                            
Contingent consideration liabilities                   44.1   $ 44.1    
2025 Acquisitions | Minimum                            
Business Combination [Line Items]                            
Contingent consideration period                       2 years    
2025 Acquisitions | Maximum                            
Business Combination [Line Items]                            
Contingent consideration period                       5 years    
Velocity Risk Underwriters, LLC                            
Business Combination [Line Items]                            
Cash consideration for acquisition     $ 548.6                      
Contingent consideration liabilities     $ 19.6                      
Measurement period adjustment, contingent consideration                       $ 1.5    
USQRisk Holdings, LLC                            
Business Combination [Line Items]                            
Cash consideration for acquisition   $ 28.7                        
Contingent consideration liabilities   $ 23.8                        
360° Underwriting                            
Business Combination [Line Items]                            
Cash consideration for acquisition $ 28.2                          
Contingent consideration liabilities $ 0.6                          
Castel Underwriting Agencies Limited                            
Business Combination [Line Items]                            
Cash consideration for acquisition                 $ 247.6          
Measurement period adjustments, deferred tax liabilities                           $ 1.6
Measurement period adjustments, taxes payable                           0.9
Measurement period adjustments, working capital                           0.5
Measurement period adjustments increase (decrease), goodwill                           (2.0)
Contingently returnable consideration                 4.9          
Castel Underwriting Agencies Limited | Class A Common Stock                            
Business Combination [Line Items]                            
Equity consideration for acquisition                 $ 2.2          
US Assure Insurance Services of Florida, Inc.                            
Business Combination [Line Items]                            
Cash consideration for acquisition               $ 1,079.8            
Contingent consideration liabilities               $ 103.8            
Measurement period adjustments increase (decrease), goodwill                           5.2
Greenhill Underwriting Insurance Services, LLC                            
Business Combination [Line Items]                            
Cash consideration for acquisition             $ 11.7              
Measurement period adjustments, working capital                           0.4
Measurement period adjustments increase (decrease), goodwill                           0.3
Measurement period adjustments, intangibles                           $ 0.1
Ethos Property And Casualty Managing General Underwriters                            
Business Combination [Line Items]                            
Cash consideration for acquisition           $ 44.0                
Underwriting programs for insurance carriers (in programs) | program           8                
EverSports & Entertainment Insurance, Inc                            
Business Combination [Line Items]                            
Cash consideration for acquisition         $ 43.1                  
Measurement period adjustments, commissions and fees receivable, net                       1.6    
Innovisk Capital Partners                            
Business Combination [Line Items]                            
Cash consideration for acquisition       $ 426.8                    
Number of managing general underwriters | managingGeneralUnderwriter       7                    
Business Combinations, Aggregate Business Combinations                            
Business Combination [Line Items]                            
Contingent consideration obligation, maximum                   605.7   605.7    
Contingently returnable consideration, maximum                   $ 13.7   $ 13.7