Investment Securities - Narrative (Detail)	6 Months Ended
	Jun. 30, 2024 USD ($) position Investment	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) Investment	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Carrying value of securities pledged to secure public deposits and other contractual obligations	$ 450,300,000		$ 464,000,000.0
Pledging requirements for credit derivatives and SWAP agreements - securities		$ 0	$ 0
Proceeds from sales	$ 0	0
Number of investments in non federal issuer representing more than 10% of shareholder's equity | Investment	0		0
Maximum investment in any single non-federal issuer representing shareholders equity	10.00%		10.00%
Fair value HTM in unrealized loss with no ACL	$ 120,592,000		$ 128,277,000
Unrealized loss included in fair value of securities HTM in unrealized loss position for which an ACL has not been recorded	19,520,000		17,500,000
Fair value AFS in unrealized loss with no ACL	258,814,000		258,855,000
Unrealized loss included in fair value of securities AFS in unrealized loss position for which an ACL has not been recorded	39,629,000		35,629,000
Fair value of securities AFS in unrealized loss position for which an ACL has been recorded, net of allowance	69,100,000
Unrealized loss position included in fair value of securities AFS in unrealized loss position for which an ACL has been recorded	7,500,000
Allowance for credit losses	781,000		731,000
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Proceeds from sale of equity securities	0	0
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Fair value AFS in unrealized loss with no ACL	984,000		780,000
Unrealized loss included in fair value of securities AFS in unrealized loss position for which an ACL has not been recorded	$ 1,000		1,000
Debt securities, available-for-sale, unrealized loss position, number of positions | position	2
Allowance for credit losses	$ 781,000	1,537,000	731,000	$ 1,140,000
Number of securities | Investment	35
Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	$ 1,100,000
Allowance for credit losses	$ 781,000
Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Number of securities | Investment	1
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	89
Debt securities, available-for-sale, unrealized loss position, number of positions | position	113
Collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Fair value AFS in unrealized loss with no ACL	$ 1,830,000		2,001,000
Unrealized loss included in fair value of securities AFS in unrealized loss position for which an ACL has not been recorded	$ 186,000		200,000
Debt securities, available-for-sale, unrealized loss position, number of positions | position	2
Allowance for credit losses	$ 0		$ 0
Other noninterest income | Equity Securities
Debt Securities, Available-for-sale [Line Items]
Net realized gain on investment securities	$ (42,000)	$ (114,000)