Investment Securities - Summary of Contractual Maturities of Investment Securities Classified as Available for Sale and Held to Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Available for Sale, Amortized Cost
Due in one year or less	$ 22,807
Due after one year through five years	264,511
Due after five years through ten years	155,023
Due after ten years	75,060
Total	517,401
Total	1,212,819
Available for Sale, Fair Value
Due in one year or less	22,778
Due after one year through five years	256,516
Due after five years through ten years	149,933
Due after ten years	72,435
Total	501,662
Total	1,170,938
Held to Maturity, Amortized Cost
Due in one year or less	63,878
Due after one year through five years	35,136
Due after five years through ten years	64,103
Due after ten years	392,081
Total	555,198
Amortized Cost	940,985
Held to Maturity, Fair Value
Due in one year or less	63,754
Due after one year through five years	34,352
Due after five years through ten years	59,765
Due after ten years	344,963
Total	502,834
Total	859,928	$ 815,211
Mortgage-backed and asset-backed securities
Available for Sale, Amortized Cost
Mortgage-backed and asset-backed securities	695,418
Available for Sale, Fair Value
Mortgage-backed and asset-backed securities	669,276
Held to Maturity, Amortized Cost
Mortgage-backed and asset-backed securities	385,787
Held to Maturity, Fair Value
Mortgage-backed and asset-backed securities	$ 357,094