v3.26.3
Debt Securities (Sales of Debt Securities) (Narrative) (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Debt Securities, Available-for-Sale [Line Items]        
Realized losses on sales of debt securities $ 2.1 $ 3.7 $ 7.8 $ 13.0
Realized gains on sales of debt securities 0.7 1.7 3.6 4.2
Proceeds from sales of debt securities $ 239.1 $ 240.4 $ 782.8 $ 747.4