Investment Securities - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Debt Securities, Held-to-maturity, Restricted	$ 147,700,000		$ 98,100,000
Debt Securities, Available-for-sale, Restricted	$ 803,200,000		386,500,000
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total	218
Other Investments and Securities, at Cost	$ 6,200,000		6,200,000
Federal Home Loan Bank Stock	19,200,000		44,700,000
Amortized Cost	1,151,024,000		1,138,425,000
Debt Securities, Available-for-Sale	1,023,711,000		1,020,986,000
Sales
Gross Losses	0	$ 0
Gross Gains	$ 0	0
US Government-sponsored Enterprises Debt Securities [Member]
Percent of Unrealized Losses	96.00%
Amortized Cost	$ 1,000,000		1,000,000
Debt Securities, Available-for-Sale	$ 913,000		$ 915,000
Corporate Debt Securities [Member]
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total	13		8
Amortized Cost	$ 67,007,000		$ 51,886,000
Debt Securities, Available-for-Sale	62,937,000		$ 48,412,000
Equity Securities [Member]
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount	$ 0	$ 0