v3.26.1
Revenues - Schedule of Disaggregated by Revenue (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Disaggregation Of Revenue [Line Items]        
Investment Income, Nonoperating $ 22 $ 35 $ 39 $ 53
Other income, net 0 1 4 2
Total revenues 1,676 1,285 3,577 2,689
Base Commission Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 1,122 878 2,393 1,836
Fee Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 392 268 771 533
Other Supplemental Commissions Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 37 41 149 141
Profit-Sharing Contingent Commission Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 85 45 182 88
Earned premium        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 18 17 39 36
Operating Segments        
Disaggregation Of Revenue [Line Items]        
Total revenues 1,668 1,260 3,559 2,654
Operating Segments | Retail        
Disaggregation Of Revenue [Line Items]        
Investment Income, Nonoperating 7 3 11 4
Other income, net 0 0 2 1
Total revenues 947 697 2,156 1,604
Operating Segments | Retail | Base Commission Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 657 483 1,502 1,099
Operating Segments | Retail | Fee Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 226 173 446 350
Operating Segments | Retail | Other Supplemental Commissions Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 31 31 139 128
Operating Segments | Retail | Profit-Sharing Contingent Commission Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 26 7 56 22
Operating Segments | Retail | Earned premium        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 0 0 0 0
Operating Segments | Specialty Distribution        
Disaggregation Of Revenue [Line Items]        
Investment Income, Nonoperating 7 7 12 13
Other income, net 0 1 0 1
Total revenues 721 563 1,403 1,050
Operating Segments | Specialty Distribution | Base Commission Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 465 395 891 737
Operating Segments | Specialty Distribution | Fee Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 166 95 325 184
Operating Segments | Specialty Distribution | Other Supplemental Commissions Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 6 10 10 13
Operating Segments | Specialty Distribution | Profit-Sharing Contingent Commission Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 59 38 126 66
Operating Segments | Specialty Distribution | Earned premium        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 18 17 39 36
Other        
Disaggregation Of Revenue [Line Items]        
Investment Income, Nonoperating 8 25 16 36
Other income, net 0 0 2 0
Total revenues 8 25 18 35
Other | Base Commission Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 0 0 0 0
Other | Fee Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 0 0 0 (1)
Other | Other Supplemental Commissions Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 0 0 0 0
Other | Profit-Sharing Contingent Commission Revenue        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other 0 0 0 0
Other | Earned premium        
Disaggregation Of Revenue [Line Items]        
Fees and Commissions, Other $ 0 $ 0 $ 0 $ 0