v3.26.1
Current Expected Credit Losses (CECL) - Current Expected Credit Losses (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Financing Receivable, Allowance for Credit Loss [Roll Forward]    
Beginning balance $ 24.2 $ 27.2
Current-period provision for expected credit losses (0.1) 1.1
Ending balance 24.1 28.3
Accrued commissions and other receivables, net    
Financing Receivable, Allowance for Credit Loss [Roll Forward]    
Beginning balance 6.2 6.2
Current-period provision for expected credit losses 0.1 0.0
Ending balance 6.3 6.2
Receivables from broker-dealers, clearing organizations, customers and related broker-dealers    
Financing Receivable, Allowance for Credit Loss [Roll Forward]    
Beginning balance 18.0 21.0
Current-period provision for expected credit losses (0.2) 1.1
Ending balance $ 17.8 $ 22.1