Securities - Schedule of Fair Value and Amortized Cost of Available-for-sale and Held-to-maturity Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	$ 2,420,781	$ 2,501,188
Available-for-sale, Gross Unrealized Gains	101	225
Available-for-sale, Gross Unrealized Losses	(318,759)	(307,084)
Available-for-sale, Fair Value	2,102,123	2,194,329
Held-to-maturity, Amortized Cost	1,179,684	1,199,527
Held-to-maturity, Gross Unrealized Gains	105	852
Held-to-maturity, Gross Unrealized Losses	(151,357)	(131,220)
Held-to-maturity securities, Fair value	1,028,432	1,069,159
Total debt securities, Amortized Cost	3,600,465	3,700,715
Total debt securities, Gross Unrealized Gains	206	1,077
Total debt securities, Gross Unrealized Losses	(470,116)	(438,304)
Total securities, Fair Value	3,130,555	3,263,488
U.S. Treasury [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	49,099
Available-for-sale, Gross Unrealized Gains	4
Available-for-sale, Fair Value	49,103
U.S. Government Sponsored Entities and Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	231,912	238,676
Available-for-sale, Gross Unrealized Losses	(32,654)	(30,310)
Available-for-sale, Fair Value	199,258	208,366
Held-to-maturity, Amortized Cost	3,300	3,587
Held-to-maturity, Gross Unrealized Losses	(321)	(313)
Held-to-maturity securities, Fair value	2,979	3,274
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	1,791,043	1,897,511
Available-for-sale, Gross Unrealized Gains	51	47
Available-for-sale, Gross Unrealized Losses	(277,066)	(267,874)
Available-for-sale, Fair Value	1,514,028	1,629,684
Held-to-maturity, Amortized Cost	35,776	38,893
Held-to-maturity, Gross Unrealized Losses	(3,150)	(3,017)
Held-to-maturity securities, Fair value	32,626	35,876
Commercial Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	261,150	274,220
Available-for-sale, Gross Unrealized Gains	40	11
Available-for-sale, Gross Unrealized Losses	(5,000)	(5,924)
Available-for-sale, Fair Value	256,190	268,307
Obligations of State and Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	75,609	78,819
Available-for-sale, Gross Unrealized Gains	6	167
Available-for-sale, Gross Unrealized Losses	(3,859)	(2,861)
Available-for-sale, Fair Value	71,756	76,125
Held-to-maturity, Amortized Cost	1,122,395	1,136,779
Held-to-maturity, Gross Unrealized Gains	105	852
Held-to-maturity, Gross Unrealized Losses	(147,546)	(127,518)
Held-to-maturity securities, Fair value	974,954	1,010,113
Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	11,968	11,962
Available-for-sale, Gross Unrealized Losses	(180)	(115)
Available-for-sale, Fair Value	11,788	11,847
Held-to-maturity, Amortized Cost	18,213	20,268
Held-to-maturity, Gross Unrealized Losses	(340)	(372)
Held-to-maturity securities, Fair value	$ 17,873	$ 19,896

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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