Securities - Schedule of Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Amortized Cost And Fair Value Debt Securities [Abstract]
Total available-for-sale debt securities, Amortized Cost, Less than one year	$ 31,309
Total available-for-sale debt securities, Amortized Cost, 1-5 years	155,156
Total available-for-sale debt securities, Amortized Cost, 5-10 years	321,197
Total available-for-sale debt securities, Amortized Cost, Over 10 years	1,993,526
Available-for-sale, Amortized Cost	2,501,188	$ 2,874,776
Total held-to-maturity debt securities, Amortized Cost, Less than one year	19,747
Total held-to-maturity debt securities, Amortized Cost, 1-5 years	114,612
Total held-to-maturity debt securities, Amortized Cost, 5-10 years	482,666
Total held-to-maturity debt securities, Amortized Cost, Over 10 years	582,502
Held-to-maturity, Amortized Cost	1,199,527	1,248,629
Total debt securities, Amortized Cost	3,700,715
Total available-for-sale debt securities, Fair Value, Less than one year	30,868
Total available-for-sale debt securities, Fair Value, 1-5 years	151,367
Total available-for-sale debt securities, Fair Value, 5-10 years	304,927
Total available-for-sale debt securities, Fair Value, Over 10 years	1,707,167
Total available-for-sale debt securities, Fair Value	2,194,329	2,529,140
Total held-to-maturity debt securities, Fair Value, Less than one year	19,727
Total held-to-maturity debt securities, Fair Value, 1-5 years	113,565
Total held-to-maturity debt securities, Fair Value, 5-10 years	447,074
Total held-to-maturity debt securities, Fair Value, Over 10 years	488,793
Total held-to-maturity debt securities, Fair Value	1,069,159	1,084,390
Total debt securities, Fair Value	$ 3,263,488	$ 3,613,530