v3.26.1
Securities - Schedule of Unrealized Losses on Investment Securities (Detail)
$ in Thousands
Jun. 30, 2026
USD ($)
Security
Dec. 31, 2025
USD ($)
Security
Net Unrealized Gains And Losses On Investments [Line Items]    
Less than 12 months, Fair Value $ 1,130,478 $ 327,278
Less than 12 months, Unrealized Losses $ (10,436) $ (1,833)
Less than 12 months, Number of Securities | Security 231 89
12 months or more, Fair Value $ 1,482,093 $ 1,574,675
12 months or more, Unrealized Losses $ (207,019) $ (199,984)
12 months or more, Number of Securities | Security 444 525
Fair Value, Total $ 2,612,571 $ 1,901,953
Unrealized Losses, Total $ (217,455) $ (201,817)
Number of Securities Total | Security 675 614
U.S. Treasury [Member]    
Net Unrealized Gains And Losses On Investments [Line Items]    
Less than 12 months, Fair Value $ 195,956 $ 0
Less than 12 months, Unrealized Losses $ (205) $ 0
Less than 12 months, Number of Securities | Security 4 0
12 months or more, Fair Value $ 0 $ 0
12 months or more, Unrealized Losses   $ 0
12 months or more, Number of Securities | Security 0 0
Fair Value, Total $ 195,956 $ 0
Unrealized Losses, Total $ (205) $ 0
Number of Securities Total | Security 4 0
U.S. Government Sponsored Entities and Agencies [Member]    
Net Unrealized Gains And Losses On Investments [Line Items]    
Less than 12 months, Fair Value $ 19,249 $ 8,252
Less than 12 months, Unrealized Losses $ (249) $ (109)
Less than 12 months, Number of Securities | Security 5 3
12 months or more, Fair Value $ 180,242 $ 189,841
12 months or more, Unrealized Losses $ (20,541) $ (20,514)
12 months or more, Number of Securities | Security 41 42
Fair Value, Total $ 199,491 $ 198,093
Unrealized Losses, Total $ (20,790) $ (20,623)
Number of Securities Total | Security 46 45
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member]    
Net Unrealized Gains And Losses On Investments [Line Items]    
Less than 12 months, Fair Value $ 836,528 $ 245,766
Less than 12 months, Unrealized Losses $ (9,663) $ (1,340)
Less than 12 months, Number of Securities | Security 179 59
12 months or more, Fair Value $ 1,222,630 $ 1,307,219
12 months or more, Unrealized Losses $ (181,775) $ (174,969)
12 months or more, Number of Securities | Security 356 430
Fair Value, Total $ 2,059,158 $ 1,552,985
Unrealized Losses, Total $ (191,438) $ (176,309)
Number of Securities Total | Security 535 489
Commercial Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member]    
Net Unrealized Gains And Losses On Investments [Line Items]    
Less than 12 months, Fair Value $ 10,967 $ 0
Less than 12 months, Unrealized Losses $ (75) $ 0
Less than 12 months, Number of Securities | Security 2 0
12 months or more, Fair Value $ 39,490 $ 48,325
12 months or more, Unrealized Losses $ (2,537) $ (2,661)
12 months or more, Number of Securities | Security 16 18
Fair Value, Total $ 50,457 $ 48,325
Unrealized Losses, Total $ (2,612) $ (2,661)
Number of Securities Total | Security 18 18
Asset-Backed Securities [Member]    
Net Unrealized Gains And Losses On Investments [Line Items]    
Less than 12 months, Fair Value $ 43,998 $ 4,168
Less than 12 months, Unrealized Losses $ (121) $ (124)
Less than 12 months, Number of Securities | Security 9 8
12 months or more, Fair Value $ 11,635 $ 23,806
12 months or more, Unrealized Losses $ (98) $ (1,838)
12 months or more, Number of Securities | Security 3 33
Fair Value, Total $ 55,633 $ 27,974
Unrealized Losses, Total $ (219) $ (1,962)
Number of Securities Total | Security 12 41
Obligations of State and Political Subdivisions [Member]    
Net Unrealized Gains And Losses On Investments [Line Items]    
Less than 12 months, Fair Value $ 17,340 $ 58,042
Less than 12 months, Unrealized Losses $ (73) $ (205)
Less than 12 months, Number of Securities | Security 26 11
12 months or more, Fair Value $ 20,630 $ 0
12 months or more, Unrealized Losses $ (2,042) $ 0
12 months or more, Number of Securities | Security 26 0
Fair Value, Total $ 37,970 $ 58,042
Unrealized Losses, Total $ (2,115) $ (205)
Number of Securities Total | Security 52 11
Corporate Debt Securities [Member]    
Net Unrealized Gains And Losses On Investments [Line Items]    
Less than 12 months, Fair Value $ 6,440 $ 11,050
Less than 12 months, Unrealized Losses $ (50) $ (55)
Less than 12 months, Number of Securities | Security 6 8
12 months or more, Fair Value $ 7,466 $ 5,484
12 months or more, Unrealized Losses $ (26) $ (2)
12 months or more, Number of Securities | Security 2 2
Fair Value, Total $ 13,906 $ 16,534
Unrealized Losses, Total $ (76) $ (57)
Number of Securities Total | Security 8 10