Securities - Summary of Amortized Cost and Estimated Fair Values of Debt Securities Available for Sale (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,631,891	$ 528,689
Gross Unrealized Gains	254	4,625
Gross Unrealized Losses	(93,924)	(1,791)
Estimated Fair Value	1,538,221	531,523
U.S. Treasuries [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,568,563	455,701
Gross Unrealized Gains		3,693
Gross Unrealized Losses	(90,699)	(1,766)
Estimated Fair Value	1,477,864	457,628
U.S. Federal Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,025	21,609
Gross Unrealized Gains	198	335
Gross Unrealized Losses	(1)	(2)
Estimated Fair Value	15,222	21,942
Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	18,449	28,897
Gross Unrealized Gains	21	400
Gross Unrealized Losses	(1,884)	(14)
Estimated Fair Value	16,586	29,283
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,320	6,128
Gross Unrealized Gains	35	194
Gross Unrealized Losses	(221)	(3)
Estimated Fair Value	8,134	6,319
Asset backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,371	13,354
Gross Unrealized Gains		3
Gross Unrealized Losses	(361)
Estimated Fair Value	13,010	13,357
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,163	3,000
Gross Unrealized Losses	(758)	(6)
Estimated Fair Value	$ 7,405	$ 2,994