Quarterly report pursuant to Section 13 or 15(d)

Securities - Summary of Debt Securities Available for Sale in an Unrealized Loss Position for Which an Allowance for Credit Losses Has Not Been Recorded (Detail)

v3.21.1
Securities - Summary of Debt Securities Available for Sale in an Unrealized Loss Position for Which an Allowance for Credit Losses Has Not Been Recorded (Detail)
$ in Thousands
Mar. 31, 2021
USD ($)
Security
Dec. 31, 2020
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (7,901) $ (406)
Available-for-Sale Within One Year, Estimated Fair Value $ 696,263 $ 178,681
Available-for-Sale Within One Year, Number of Securities | Security 114 32
Available-for-Sale, Gross Unrealized Loss $ (7,901) $ (406)
Available-for-Sale, Estimated Fair Value $ 696,263 $ 178,681
Available-for-Sale, Number of Securities | Security 114 32
Mortgage-backed securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (7,216) $ (188)
Available-for-Sale Within One Year, Estimated Fair Value $ 562,136 $ 76,023
Available-for-Sale Within One Year, Number of Securities | Security 87 10
Available-for-Sale, Gross Unrealized Loss $ (7,216) $ (188)
Available-for-Sale, Estimated Fair Value $ 562,136 $ 76,023
Available-for-Sale, Number of Securities | Security 87 10
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (210) $ (217)
Available-for-Sale Within One Year, Estimated Fair Value $ 78,602 $ 97,659
Available-for-Sale Within One Year, Number of Securities | Security 18 21
Available-for-Sale, Gross Unrealized Loss $ (210) $ (217)
Available-for-Sale, Estimated Fair Value $ 78,602 $ 97,659
Available-for-Sale, Number of Securities | Security 18 21
Debt securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (475) $ (1)
Available-for-Sale Within One Year, Estimated Fair Value $ 55,525 $ 4,999
Available-for-Sale Within One Year, Number of Securities | Security 9 1
Available-for-Sale, Gross Unrealized Loss $ (475) $ (1)
Available-for-Sale, Estimated Fair Value $ 55,525 $ 4,999
Available-for-Sale, Number of Securities | Security 9 1
Total U.S. government agency and sponsored agency obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (7,901) $ (406)
Available-for-Sale Within One Year, Estimated Fair Value $ 696,263 $ 178,681
Available-for-Sale Within One Year, Number of Securities | Security 114 32
Available-for-Sale, Gross Unrealized Loss $ (7,901) $ (406)
Available-for-Sale, Estimated Fair Value $ 696,263 $ 178,681
Available-for-Sale, Number of Securities | Security 114 32