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, 2021	Dec. 31, 2020
Amortized Cost And Fair Value Debt Securities [Abstract]
Total available-for-sale debt securities, Amortized Cost, Less than one year	$ 10,376
Total available-for-sale debt securities, Amortized Cost, 1-5 years	158,861
Total available-for-sale debt securities, Amortized Cost, 5-10 years	427,966
Total available-for-sale debt securities, Amortized Cost, Over 10 years	2,422,492
Available-for-sale, Amortized Cost	3,019,695	$ 1,916,658
Total held-to-maturity debt securities, Amortized Cost, Less than one year	26,363
Total held-to-maturity debt securities, Amortized Cost, 1-5 years	117,290
Total held-to-maturity debt securities, Amortized Cost, 5-10 years	236,803
Total held-to-maturity debt securities, Amortized Cost, Over 10 years	624,367
Held-to-maturity, Amortized Cost	1,004,823	731,212
Total debt securities, Amortized Cost	4,024,518
Total available-for-sale debt securities, Fair Value, Less than one year	10,482
Total available-for-sale debt securities, Fair Value, 1-5 years	164,234
Total available-for-sale debt securities, Fair Value, 5-10 years	431,957
Total available-for-sale debt securities, Fair Value, Over 10 years	2,406,789
Total available-for-sale debt securities, Fair Value	3,013,462	1,978,136
Total held-to-maturity debt securities, Fair Value, Less than one year	26,779
Total held-to-maturity debt securities, Fair Value, 1-5 years	122,504
Total held-to-maturity debt securities, Fair Value, 5-10 years	246,396
Total held-to-maturity debt securities, Fair Value, Over 10 years	632,773
Total held-to-maturity debt securities, Fair Value	1,028,452	768,183
Total debt securities, Fair Value	$ 4,041,914	$ 2,746,319