Goodwill and other intangibles (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 159,595,000	$ 159,595,000	$ 159,595,000	$ 159,595,000	$ 159,595,000	$ 159,595,000	$ 159,595,000	$ 159,595,000
Other Intangible Assets, Net	4,986,000	6,316,000	4,986,000	6,316,000	5,320,000	5,975,000	6,657,000	7,462,000
Amortization of Intangible Assets	334,000	341,000	989,000	1,146,000
Finite-lived Intangible Assets Acquired	14,456,000		14,456,000			14,456,000
Indefinite-lived Intangible Assets Acquired	1,300,000		1,300,000			1,300,000
Finite-Lived Intangible Assets, Accumulated Amortization	10,770,000		10,770,000			9,781,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	334,000		334,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	1,215,000		1,215,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	1,042,000		1,042,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	887,000		887,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	754,000		754,000
Intangible Assets, Gross (Excluding Goodwill)	15,756,000		15,756,000			15,756,000
Intangible Assets, Net (Including Goodwill)	164,581,000	$ 165,911,000	164,581,000	$ 165,911,000	$ 164,915,000	165,570,000	$ 166,252,000	$ 167,057,000
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	9,470,000		9,470,000			8,481,000
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	$ 1,300,000		$ 1,300,000			$ 1,300,000