Investment Securities - Amortized Cost and Fair Values of Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Available-for-Sale [Abstract]
Amortized Cost	$ 22,563
Estimated Fair Value	20,171	$ 20,821
Debt Securities, Held-to-Maturity, Maturity [Abstract]
Amortized Cost	685,728	717,773
Gross Unrealized Gains	68
Gross Unrealized Losses	(117,668)	(126,751)
Estimated Fair Value	568,128	591,084
Debt Securities, Available-for-Sale and Held-to-Maturity, after Allowance for Credit Loss [Abstract]
Total Amortized Cost	708,291	741,317
Total Gross Unrealized Gains	68	62
Total Gross Unrealized Losses	(120,060)	(129,474)
Total Estimated Fair Value	588,299	611,905
U.S. government-sponsored mortgage-backed securities
Available-for-Sale [Abstract]
Amortized Cost	22,563	23,544
Gross Unrealized Losses	(2,392)	(2,723)
Estimated Fair Value	$ 20,171	20,821
Debt Securities, Held-to-Maturity, Maturity [Abstract]
Amortized Cost		717,773
Gross Unrealized Gains		62
Estimated Fair Value		$ 591,084