Securities - Schedule of Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Amortized Cost And Fair Value Debt Securities [Abstract]
Total available-for-sale debt securities, Amortized Cost, Less than one year	$ 22,490
Total available-for-sale debt securities, Amortized Cost, 1-5 years	189,081
Total available-for-sale debt securities, Amortized Cost, 5-10 years	482,267
Total available-for-sale debt securities, Amortized Cost, Over 10 years	2,422,219
Available-for-sale, Amortized Cost	3,116,057	$ 3,019,695
Total held-to-maturity debt securities, Amortized Cost, Less than one year	30,679
Total held-to-maturity debt securities, Amortized Cost, 1-5 years	101,576
Total held-to-maturity debt securities, Amortized Cost, 5-10 years	314,256
Total held-to-maturity debt securities, Amortized Cost, Over 10 years	834,784
Held-to-maturity, Amortized Cost	1,281,295	1,004,823
Total debt securities, Amortized Cost	4,397,352
Total available-for-sale debt securities, Fair Value, Less than one year	22,433
Total available-for-sale debt securities, Fair Value, 1-5 years	187,159
Total available-for-sale debt securities, Fair Value, 5-10 years	469,762
Total available-for-sale debt securities, Fair Value, Over 10 years	2,205,297
Total available-for-sale debt securities, Fair Value	2,884,651	3,013,462
Total held-to-maturity debt securities, Fair Value, Less than one year	30,794
Total held-to-maturity debt securities, Fair Value, 1-5 years	101,882
Total held-to-maturity debt securities, Fair Value, 5-10 years	304,810
Total held-to-maturity debt securities, Fair Value, Over 10 years	716,108
Total held-to-maturity debt securities, Fair Value	1,153,594	1,028,452
Total debt securities, Fair Value	$ 4,038,245	$ 4,041,914