Investment Securities - Summary of Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, Amortized Cost, Held-to-maturity	$ 4,875
Due after one year through five years, Amortized Cost, Held-to-maturity	606,745
Due after five years through ten years, Amortized Cost, Held-to-maturity	737,884
Due after ten years, Amortized Cost, Held-to-maturity	1,062,804
Total Held-to-maturity, Debt Maturities, Amortized Cost Basis	2,412,308
Due in one year or less, Fair Value, Held-to-maturity	4,882
Due after one year through five years, Fair Value, Held-to-maturity	556,072
Due after five years through ten years, Fair Value, Held-to-maturity	659,288
Due after ten years, Fair Value, Held-to-maturity	913,941
Total, Held-to-maturity, Fair Value	2,134,183
Due in one year or less, Amortized Cost, Available-for-sale	26,014
Due after one year through five years, Amortized Cost, Available-for-sale	1,059,708
Due after five years through ten years, Amortized Cost, Available-for-sale	2,654,991
Due after ten years, Amortized Cost, Available-for-sale	231,724
Amortized Cost, Available-for-sale	3,972,437	$ 3,185,249
Due in one year or less, Fair Value, Available-for-sale	25,660
Due after one year through five years, Fair Value, Available-for-sale	995,539
Due after five years through ten years, Fair Value, Available-for-sale	2,403,349
Due after ten years, Fair Value, Available-for-sale	201,609
Total Available-for-sale Securities, Debt Maturities, Available-for-sale, Fair Value	$ 3,626,157	$ 3,183,923