Securities - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule of Trading Securities and Other Trading Assets [Line Items]
Proceeds from sales of securities available for sale		$ 19,153,000	$ 68,000
Gross realized gains from securities		139,000	0
Gross realized losses from securities		0	2,000
Accrued interest on securities available for sale		36,400,000		$ 31,600,000
Impairment on one corporate available-for-sale security	$ 125,000		4,925,000
ACL related to AFS Securities		0		0
Sales of securities held to maturity		0	0
Amortized cost of available for sale securities transferred to held to maturity					$ 4,100,000,000
Fair value of available for sale securities transferred to held to maturity					$ 3,800,000,000
Gain (loss) on transfer of securities		0
Unamortized unrealized loss		189,500
Accrued interest on securities held to maturity		26,900,000		27,200,000
Unrealized gain (loss) on trading securities		6,000	$ (1,000)
Securities sold not yet purchased		10,800,000		8,000,000
Collateral Pledged [Member] | U.S. Government and Other Public Deposit [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Pledged securities for deposits		$ 8,800,000,000		$ 10,100,000,000