Investment Securities - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Debt Securities, Held-to-maturity, Restricted	$ 118,900,000		$ 368,800,000
Debt Securities, Available-for-sale, Restricted	$ 406,600,000		626,700,000
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total	219
Other Investments and Securities, at Cost	$ 6,200,000		1,200,000
Federal Home Loan Bank Stock	40,200,000		25,200,000
Amortized Cost	877,909,000		898,702,000
Debt Securities, Available-for-Sale	$ 738,109,000		762,661,000
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	$ 883,000		$ 882,000
Corporate Debt Securities [Member]
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total	8		6
Amortized Cost	$ 30,417,000		$ 32,010,000
Debt Securities, Available-for-Sale	26,631,000		$ 29,204,000
Equity Securities [Member]
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount	$ 0	$ 0