v3.26.3
Debt and Equity Securities - Schedule of Amortized Cost and Estimated Fair Value of Securities (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Amortized Cost    
Amortized Cost $ 4,343,134 $ 3,998,939
Fair Value    
Fair Value 4,095,855 3,951,455
Fair Value    
Fair Value 575,384 $ 654,832
Available-for-sale    
Amortized Cost    
Due within one year 0  
Due after one year through five years 10,452  
Due after five years through ten years 249,090  
Due after ten years 4,083,592  
Amortized Cost 4,343,134  
Fair Value    
Due within one year 0  
Due after one year through five years 10,119  
Due after five years through ten years 236,181  
Due after ten years 3,849,555  
Fair Value 4,095,855  
Held-to-maturity    
Amortized Cost    
Due within one year 0  
Due after one year through five years 0  
Due after five years through ten years 0  
Due after ten years 672,881  
Amortized Cost 672,881  
Fair Value    
Due within one year 0  
Due after one year through five years 0  
Due after five years through ten years 0  
Due after ten years 575,384  
Fair Value $ 575,384