Investments - Available for sale securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Investments
Available for sale securities, amortized cost	$ 371,236	$ 379,195
Available for sale securities, gross unrealized gains	572	86
Available for sale securities, gross unrealized losses	(29,930)	(39,804)
Available for sale securities	341,878	339,477
U.S. Treasuries
Investments
Available for sale securities, amortized cost	139,174	123,945
Available for sale securities, gross unrealized gains	464	55
Available for sale securities, gross unrealized losses	(5,846)	(8,542)
Available for sale securities	133,792	115,458
Mortgage-backed securities
Investments
Available for sale securities, amortized cost	47,970	52,374
Available for sale securities, gross unrealized gains	46	14
Available for sale securities, gross unrealized losses	(3,389)	(4,603)
Available for sale securities	44,627	47,785
Collateralized mortgage obligations
Investments
Available for sale securities, amortized cost	83,142	101,316
Available for sale securities, gross unrealized gains	62	17
Available for sale securities, gross unrealized losses	(4,429)	(6,327)
Available for sale securities	78,775	95,006
States and political subdivisions
Investments
Available for sale securities, amortized cost	100,950	101,560
Available for sale securities, gross unrealized losses	(16,266)	(20,332)
Available for sale securities	$ 84,684	$ 81,228