Securities - Amortized Cost and Estimated Fair Value of Securities - Securities Held-to-maturity (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Securities held-to-maturity:
Total	$ 604,205,000	$ 650,577,000
Gross Unrecognized Gains	384,000	285,000
Gross Unrecognized (Losses)	(73,056,000)	(86,735,000)
Estimated Fair Value	531,533,000	564,127,000
Allowance for credit loss current period	(12,000)	(12,000)
Agency mortgage-backed securities
Securities held-to-maturity:
Total	573,621,000	618,374,000
Gross Unrecognized Gains	381,000	282,000
Gross Unrecognized (Losses)	(72,377,000)	(86,011,000)
Estimated Fair Value	501,625,000	532,645,000
Municipals - exempt from Federal tax
Securities held-to-maturity:
Total	30,584,000	32,203,000
Gross Unrecognized Gains	3,000	3,000
Gross Unrecognized (Losses)	(679,000)	(724,000)
Estimated Fair Value	29,908,000	31,482,000
Allowance for credit loss current period	$ (12,000)	$ (12,000)