Securities - Schedule of Fair Value and Amortized Cost of Available-for-sale and Held-to-maturity Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	$ 3,458,160	$ 2,541,107
Available-for-sale, Gross Unrealized Gains	6,825	384
Available-for-sale, Gross Unrealized Losses	(242,166)	(295,419)
Available-for-sale, Fair Value	3,222,819	2,246,072
Held-to-maturity, Amortized Cost	1,137,782	1,152,906
Held-to-maturity, Gross Unrealized Gains	324	164
Held-to-maturity, Gross Unrealized Losses	(131,996)	(146,253)
Held-to-maturity securities, Fair value	1,006,110	1,006,817
Total debt securities, Amortized Cost	4,595,942	3,694,013
Total debt securities, Gross Unrealized Gains	7,149	548
Total debt securities, Gross Unrealized Losses	(374,162)	(441,672)
Total securities, Fair Value	4,228,929	3,252,889
U.S. Treasury [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	195,488	146,113
Available-for-sale, Gross Unrealized Gains	59	63
Available-for-sale, Gross Unrealized Losses	(35)	(63)
Available-for-sale, Fair Value	195,512	146,113
U.S. Government Sponsored Entities and Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	230,822	224,944
Available-for-sale, Gross Unrealized Losses	(23,601)	(30,702)
Available-for-sale, Fair Value	207,247	194,242
Held-to-maturity, Amortized Cost	2,641	2,988
Held-to-maturity, Gross Unrealized Losses	(178)	(260)
Held-to-maturity securities, Fair value	2,463	2,728
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	2,655,694	1,850,284
Available-for-sale, Gross Unrealized Gains	6,145	245
Available-for-sale, Gross Unrealized Losses	(211,457)	(257,088)
Available-for-sale, Fair Value	2,450,382	1,593,441
Held-to-maturity, Amortized Cost	29,896	32,803
Held-to-maturity, Gross Unrealized Losses	(1,969)	(2,754)
Held-to-maturity securities, Fair value	27,927	30,049
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	155,071	235,873
Available-for-sale, Gross Unrealized Gains	154	51
Available-for-sale, Gross Unrealized Losses	(3,374)	(4,142)
Available-for-sale, Fair Value	151,851	231,782
Asset-Backed Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	72,546
Available-for-sale, Gross Unrealized Gains	31
Available-for-sale, Gross Unrealized Losses	(642)
Available-for-sale, Fair Value	71,935
Obligations of State and Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	84,806	1,098,957
Available-for-sale, Gross Unrealized Gains	61	164
Available-for-sale, Gross Unrealized Losses	(2,886)	(143,130)
Available-for-sale, Fair Value	81,981	955,991
Held-to-maturity, Amortized Cost	1,089,173	71,919
Held-to-maturity, Gross Unrealized Gains	281	25
Held-to-maturity, Gross Unrealized Losses	(129,817)	(3,324)
Held-to-maturity securities, Fair value	959,637	68,620
Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	63,733	11,974
Available-for-sale, Gross Unrealized Gains	349
Available-for-sale, Gross Unrealized Losses	(171)	(100)
Available-for-sale, Fair Value	63,911	11,874
Held-to-maturity, Amortized Cost	16,072	18,158
Held-to-maturity, Gross Unrealized Gains	43
Held-to-maturity, Gross Unrealized Losses	(32)	(109)
Held-to-maturity securities, Fair value	$ 16,083	$ 18,049