Quarterly report pursuant to Section 13 or 15(d)

Securities - Summary of Investment Securities Available for Sale (Detail)

v3.21.2
Securities - Summary of Investment Securities Available for Sale (Detail) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 914,649 $ 749,458
Gross Unrealized Gain 332 4,729
Gross Unrealized Loss (7,985) (406)
Estimated Fair Value 906,996 753,781
U.S. Treasury securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 4,948 9,997
Gross Unrealized Gain   135
Gross Unrealized Loss (3)  
Estimated Fair Value 4,945 10,132
Mortgage-backed securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 641,256 515,169
Gross Unrealized Gain 138 4,260
Gross Unrealized Loss (5,332) (188)
Estimated Fair Value 636,062 519,241
Collateralized mortgage obligations    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 100,244 133,632
Gross Unrealized Gain 190 186
Gross Unrealized Loss (551) (217)
Estimated Fair Value 99,883 133,601
Debt securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 99,015 90,660
Gross Unrealized Gain 4 148
Gross Unrealized Loss (583) (1)
Estimated Fair Value 98,436 90,807
Total U.S. government agency and sponsored agency obligations    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 840,515 739,461
Gross Unrealized Gain 332 4,594
Gross Unrealized Loss (6,466) (406)
Estimated Fair Value 834,381 $ 743,649
Municipal bonds-tax exempt    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 69,186  
Gross Unrealized Loss (1,516)  
Estimated Fair Value $ 67,670