v3.26.1
Investment Securities - Summary of Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Investments, Debt and Equity Securities [Abstract]    
Due in one year or less, Amortized Cost, Available-for-sale $ 36,000  
Due in one year or less, Fair Value, Available-for-sale 35,938  
Due after one year through five years, Amortized Cost, Available-for-sale 28,905  
Due after one year through five years, Fair Value, Available-for-sale 32,164  
Due after five years through ten years, Amortized Cost, Available-for-sale 41,539  
Due after five years through ten years, Fair Value, Available-for-sale 40,581  
Due after ten years, Amortized Cost, Available-for-sale 3,671,300  
Due after ten years, Fair Value, Available-for-sale 3,349,081  
Amortized Cost, Available-for-sale 3,777,744 $ 2,982,228
Total Available-for-sale Securities, Debt Maturities, Available-for-sale, Fair Value 3,457,764 $ 2,683,070
Due in one year or less, Amortized Cost, Held-to-maturity 4,368  
Due after one year through five years, Amortized Cost, Held-to-maturity 130,367  
Due after five years through ten years, Amortized Cost, Held-to-maturity 328,226  
Due after ten years, Amortized Cost, Held-to-maturity 1,755,568  
Total Held-to-maturity, Debt Maturities, Amortized Cost Basis 2,218,529  
Due in one year or less, Fair Value, Held-to-maturity 4,361  
Due after one year through five years, Fair Value, Held-to-maturity 122,303  
Due after five years through ten years, Fair Value, Held-to-maturity 286,347  
Due after ten years, Fair Value, Held-to-maturity 1,454,383  
Total, Held-to-maturity, Fair Value $ 1,867,394