Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.2
Securities - Summary of Investment Securities Available for Sale (Detail) - USD ($)
$ in Thousands
Sep. 30, 2020
Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 721,183 $ 629,725
Gross Unrealized Gain 2,806 5,553
Gross Unrealized Loss (388) (801)
Estimated Fair Value 723,601 634,477
U.S. Treasury securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 19,993 34,947
Gross Unrealized Gain 202 259
Estimated Fair Value 20,195 35,206
Mortgage-backed securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 483,622 406,813
Gross Unrealized Gain 2,150 4,334
Gross Unrealized Loss (275) (347)
Estimated Fair Value 485,497 410,800
Collateralized mortgage obligations    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 131,908 164,232
Gross Unrealized Gain 317 792
Gross Unrealized Loss (112) (432)
Estimated Fair Value 132,113 164,592
Debt securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 85,660 23,733
Gross Unrealized Gain 137 168
Gross Unrealized Loss (1) (22)
Estimated Fair Value 85,796 23,879
Total U.S. government agency and sponsored agency obligations    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 701,190 594,778
Gross Unrealized Gain 2,604 5,294
Gross Unrealized Loss (388) (801)
Estimated Fair Value $ 703,406 $ 599,271