Investment Securities - Narrative (Detail) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2025 USD ($) position Investment	Jun. 30, 2025 USD ($) position Investment	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) Investment	Dec. 31, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items]
Carrying value of securities pledged to secure public deposits and other contractual obligations	$ 424,600	$ 424,600		$ 424,800
Pledging requirements for credit derivatives and SWAP agreements - securities			$ 0	$ 0
Number of investments in non federal issuer representing more than 10% of shareholder's equity | Investment	0	0		0
Maximum investment in any single non-federal issuer representing shareholders equity	10.00%	10.00%		10.00%
Fair value HTM in unrealized loss with no ACL	$ 111,929	$ 111,929		$ 115,007
Unrealized loss included in fair value of securities HTM in unrealized loss position for which an ACL has not been recorded	15,289	15,289		19,104
Fair value AFS in unrealized loss with no ACL	286,476	286,476		271,800
Unrealized loss included in fair value of securities AFS in unrealized loss position for which an ACL has not been recorded	34,882	34,882		39,575
Fair value of securities AFS in unrealized loss position for which an ACL has been recorded, net of allowance	10,300	10,300
Unrealized loss position included in fair value of securities AFS in unrealized loss position for which an ACL has been recorded	209	209
Allowance for credit losses	$ 17	$ 17		839
U.S. Government Corporations and Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Held-to-maturity, securities in unrealized loss positions, qualitative disclosure, number of positions | position	90	90
Debt securities, available-for-sale, unrealized loss position, number of positions | position	106	106
Collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Fair value AFS in unrealized loss with no ACL	$ 1,542	$ 1,542		1,685
Unrealized loss included in fair value of securities AFS in unrealized loss position for which an ACL has not been recorded	$ 99	$ 99		133
Debt securities, available-for-sale, unrealized loss position, number of positions | position	2	2
Allowance for credit losses	$ 0	$ 0		0
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Fair value AFS in unrealized loss with no ACL	57,973	57,973
Unrealized loss included in fair value of securities AFS in unrealized loss position for which an ACL has not been recorded	$ 3,940	$ 3,940
Debt securities, available-for-sale, unrealized loss position, number of positions | position	10	10
Allowance for credit losses	$ 17	$ 17	781	$ 839	$ 731
Number of securities | Investment	19	19
Allowance for credit losses, reversed	$ 719	$ 822	(49)
Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	1,200	1,200
Allowance for credit losses	$ 17	$ 17
Equity Securities | Other noninterest income
Debt Securities, Available-for-sale [Line Items]
Marketable Security, Realized Gain (Loss)			$ 42