Securities - Narrative (Details)	Mar. 31, 2024 USD ($) investment	Dec. 31, 2023 USD ($) investment	Dec. 31, 2009 USD ($)
Debt Securities, Available-for-sale [Line Items]
Carrying value of securities pledged to secure repurchase agreements, public and trust deposits and other by law	$ 380,442,000	$ 366,576,000
Allowance for credit losses for available-for-sale debt securities	0	0
Accrued interest receivable on available-for-sale debt securities	8,608,000	9,620,000
Original amount in non-controlling investment security in a single banking organization	353,000	$ 353,000	$ 1,350,000
Additional impairment on equity securities recognized through earnings	$ 0		$ 997,000
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Number of non-controlling investments in a single banking organization | investment	1	1