v3.26.1
Investment Securities - Summary of Amortized Cost and Estimated Fair Value of Investment Securities (Detail) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Schedule of Investments [Line Items]    
Amortized cost $ 3,777,744 $ 2,982,228
Gross Unrealized Holding Gain, Available-for-sale 5,760 13,207
Gross Unrealized Holding Loss, Available-for-sale (325,740) (312,365)
Investment securities available-for-sale $ 3,457,764 $ 2,683,070
Total Percent, Available-for-sale 100.00% 100.00%
Amortized Cost, Held-to-maturity $ 2,218,529 $ 2,270,391
Gross Unrealized Holding Gain, Held-to-maturity 1,410 1,597
Gross Unrealized Holding Loss, Held-to-maturity (352,545) (346,496)
Fair Value, Held-to-maturity $ 1,867,394 $ 1,925,492
Total Percent, Held-to-maturity 100.00% 100.00%
Government Agency/GSE [Member]    
Schedule of Investments [Line Items]    
Amortized cost $ 45,635 $ 35,348
Gross Unrealized Holding Gain, Available-for-sale 0 17
Gross Unrealized Holding Loss, Available-for-sale (109) (81)
Investment securities available-for-sale $ 45,526 $ 35,284
Total Percent, Available-for-sale 1.32% 1.32%
Amortized Cost, Held-to-maturity $ 490,324 $ 498,513
Gross Unrealized Holding Gain, Held-to-maturity 0 0
Gross Unrealized Holding Loss, Held-to-maturity (84,755) (82,741)
Fair Value, Held-to-maturity $ 405,569 $ 415,772
Total Percent, Held-to-maturity 22.10% 21.96%
Mortgage-backed Securities [Member]    
Schedule of Investments [Line Items]    
Amortized cost $ 2,637,390 $ 2,089,155
Gross Unrealized Holding Gain, Available-for-sale 1,844 2,199
Gross Unrealized Holding Loss, Available-for-sale (213,835) (203,700)
Investment securities available-for-sale $ 2,425,399 $ 1,887,654
Total Percent, Available-for-sale 70.14% 70.35%
Amortized Cost, Held-to-maturity $ 533,852 $ 557,860
Gross Unrealized Holding Gain, Held-to-maturity 0 25
Gross Unrealized Holding Loss, Held-to-maturity (86,197) (84,512)
Fair Value, Held-to-maturity $ 447,655 $ 473,373
Total Percent, Held-to-maturity 24.06% 24.57%
CMO/REMIC [Member]    
Schedule of Investments [Line Items]    
Amortized cost $ 1,032,757 $ 800,896
Gross Unrealized Holding Gain, Available-for-sale 362 2,314
Gross Unrealized Holding Loss, Available-for-sale (111,171) (108,060)
Investment securities available-for-sale $ 921,948 $ 695,150
Total Percent, Available-for-sale 26.66% 25.91%
Amortized Cost, Held-to-maturity $ 736,006 $ 751,639
Gross Unrealized Holding Gain, Held-to-maturity 0 0
Gross Unrealized Holding Loss, Held-to-maturity (155,100) (152,417)
Fair Value, Held-to-maturity $ 580,906 $ 599,222
Total Percent, Held-to-maturity 33.18% 33.10%
Municipal Bonds [Member]    
Schedule of Investments [Line Items]    
Amortized cost $ 21,427 $ 21,787
Gross Unrealized Holding Gain, Available-for-sale 23 27
Gross Unrealized Holding Loss, Available-for-sale (625) (524)
Investment securities available-for-sale $ 20,825 $ 21,290
Total Percent, Available-for-sale 0.60% 0.79%
Amortized Cost, Held-to-maturity $ 439,548 $ 444,694
Gross Unrealized Holding Gain, Held-to-maturity 1,410 1,572
Gross Unrealized Holding Loss, Held-to-maturity (26,493) (26,826)
Fair Value, Held-to-maturity $ 414,465 $ 419,440
Total Percent, Held-to-maturity 19.81% 19.59%
Collateralized loan obligations    
Schedule of Investments [Line Items]    
Amortized cost $ 42,000 $ 42,000
Gross Unrealized Holding Gain, Available-for-sale 29 0
Gross Unrealized Holding Loss, Available-for-sale 0 0
Investment securities available-for-sale $ 42,029 $ 42,000
Total Percent, Available-for-sale 1.22% 1.57%
Other Securities [Member]    
Schedule of Investments [Line Items]    
Amortized cost $ 2,037 $ 1,692
Gross Unrealized Holding Gain, Available-for-sale 0 0
Gross Unrealized Holding Loss, Available-for-sale 0 0
Investment securities available-for-sale $ 2,037 $ 1,692
Total Percent, Available-for-sale 0.06% 0.06%
Amortized Cost, Held-to-maturity [1] $ 18,799 $ 17,685
Gross Unrealized Holding Gain, Held-to-maturity [1] 0 0
Gross Unrealized Holding Loss, Held-to-maturity [1] 0 0
Fair Value, Held-to-maturity [1] $ 18,799 $ 17,685
Total Percent, Held-to-maturity [1] 0.85% 0.78%
Unallocated Portfolio Layer Fair Value [Member]    
Schedule of Investments [Line Items]    
Basis Adjustment From Fair Value Hedge [2] $ (3,502) $ (8,650)
Gross Unrealized Holding Gain, Available-for-sale [2] 3,502 8,650
Gross Unrealized Holding Loss, Available-for-sale [2] 0 0
Investment securities available-for-sale [2] $ 0 $ 0
Total Percent, Available-for-sale [2] 0.00% 0.00%
[1] Represents Commercial Property Assessed Clean Energy (“C-PACE”) bonds.
[2] Represents the amount of portfolio layer method basis adjustments related to AFS mortgage-backed securities (“MBS”) securities hedged in a closed portfolio. Under GAAP, these basis adjustments are not allocated to individual securities, however the amounts impact the unrealized gains or losses of the hedged AFS securities. Refer to Note 11 for additional information.