v3.26.1
Investment Securities - Summary of Continuous Unrealized Loss Position of Securities (Detail) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Schedule of Investments [Line Items]    
Fair Value, Less Than 12 Months, Available-for-sale $ 767,815 $ 38,498
Gross Unrealized Holding Losses, Less Than 12 Months, Available-for-sale (6,015) (152)
Fair Value, 12 Months or Longer, Available-for-sale 1,810,006 1,949,268
Gross Unrealized Holding Losses, 12 Months or Longer, Available-for-sale (319,725) (312,213)
Fair Value, Available-for-sale 2,577,821 1,987,766
Gross Unrealized Holding Losses, Available-for-sale (325,740) (312,365)
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value 29,966 3,690
Gross Unrealized Holding Loss, Less than 12 Months, Held-to-maturity (60) (11)
Fair Value, 12 Months or Longer, Held-to-maturity 1,731,555 1,791,972
Gross Unrealized Holding Losses, 12 Months or Longer, Held-to-maturity (352,485) (346,485)
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value 1,761,521 1,795,662
Gross Unrealized Holding Losses, Held-to-maturity (352,545) (346,496)
CMO/REMIC [Member]    
Schedule of Investments [Line Items]    
Fair Value, Less Than 12 Months, Available-for-sale 247,003 0
Gross Unrealized Holding Losses, Less Than 12 Months, Available-for-sale (1,082) 0
Fair Value, 12 Months or Longer, Available-for-sale 332,202 344,865
Gross Unrealized Holding Losses, 12 Months or Longer, Available-for-sale (110,089) (108,060)
Fair Value, Available-for-sale 579,205 344,865
Gross Unrealized Holding Losses, Available-for-sale (111,171) (108,060)
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value 0 0
Gross Unrealized Holding Loss, Less than 12 Months, Held-to-maturity 0 0
Fair Value, 12 Months or Longer, Held-to-maturity 580,906 599,222
Gross Unrealized Holding Losses, 12 Months or Longer, Held-to-maturity (155,100) (152,417)
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value 580,906 599,222
Gross Unrealized Holding Losses, Held-to-maturity (155,100) (152,417)
Government Agency/GSE [Member]    
Schedule of Investments [Line Items]    
Fair Value, Less Than 12 Months, Available-for-sale 44,970 5,919
Gross Unrealized Holding Losses, Less Than 12 Months, Available-for-sale (109) (81)
Fair Value, 12 Months or Longer, Available-for-sale 0 0
Gross Unrealized Holding Losses, 12 Months or Longer, Available-for-sale 0 0
Fair Value, Available-for-sale 44,970 5,919
Gross Unrealized Holding Losses, Available-for-sale (109) (81)
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value 0 0
Gross Unrealized Holding Loss, Less than 12 Months, Held-to-maturity 0 0
Fair Value, 12 Months or Longer, Held-to-maturity 405,569 415,772
Gross Unrealized Holding Losses, 12 Months or Longer, Held-to-maturity (84,755) (82,741)
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value 405,569 415,772
Gross Unrealized Holding Losses, Held-to-maturity (84,755) (82,741)
Mortgage-backed Securities [Member]    
Schedule of Investments [Line Items]    
Fair Value, Less Than 12 Months, Available-for-sale 474,856 32,579
Gross Unrealized Holding Losses, Less Than 12 Months, Available-for-sale (4,810) (71)
Fair Value, 12 Months or Longer, Available-for-sale 1,460,674 1,586,803
Gross Unrealized Holding Losses, 12 Months or Longer, Available-for-sale (209,025) (203,629)
Fair Value, Available-for-sale 1,935,530 1,619,382
Gross Unrealized Holding Losses, Available-for-sale (213,835) (203,700)
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value 16,310 0
Gross Unrealized Holding Loss, Less than 12 Months, Held-to-maturity (36) 0
Fair Value, 12 Months or Longer, Held-to-maturity 431,210 455,255
Gross Unrealized Holding Losses, 12 Months or Longer, Held-to-maturity (86,161) (84,512)
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value 447,520 455,255
Gross Unrealized Holding Losses, Held-to-maturity (86,197) (84,512)
Municipal Bonds [Member]    
Schedule of Investments [Line Items]    
Fair Value, Less Than 12 Months, Available-for-sale 986 0
Gross Unrealized Holding Losses, Less Than 12 Months, Available-for-sale (14) 0
Fair Value, 12 Months or Longer, Available-for-sale 17,130 17,600
Gross Unrealized Holding Losses, 12 Months or Longer, Available-for-sale (611) (524)
Fair Value, Available-for-sale 18,116 17,600
Gross Unrealized Holding Losses, Available-for-sale (625) (524)
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value 13,656 3,690
Gross Unrealized Holding Loss, Less than 12 Months, Held-to-maturity (24) (11)
Fair Value, 12 Months or Longer, Held-to-maturity 313,870 321,723
Gross Unrealized Holding Losses, 12 Months or Longer, Held-to-maturity (26,469) (26,815)
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Fair Value 327,526 325,413
Gross Unrealized Holding Losses, Held-to-maturity $ (26,493) $ (26,826)