Loans and Allowance for Credit Losses Allowance for Loan Losses by Portfolio Segment (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			$ 269,366,000
Loans charged off	$ (4,787,000)	$ (1,618,000)	(21,690,000)	$ (3,518,000)
Recoveries of loans previously charged off	2,816,000	5,367,000	5,715,000	8,321,000
Net loans (charged off) recovered	(1,971,000)	3,749,000	(15,975,000)	4,803,000
Provision for credit losses	10,718,000	1,110,000	34,051,000	(5,240,000)
Ending balance	287,442,000		287,442,000		$ 269,366,000
Loans - Excluding OBS Credit Exposure
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	278,695,000	243,705,000	269,366,000	249,001,000	249,001,000
Loans charged off	(4,787,000)	(1,618,000)	(21,690,000)	(3,518,000)
Recoveries of loans previously charged off	2,816,000	5,367,000	5,715,000	8,321,000
Net loans (charged off) recovered	(1,971,000)	3,749,000	(15,975,000)	4,803,000
Provision for credit losses	10,718,000	1,110,000	34,051,000	(5,240,000)
Ending balance	287,442,000	248,564,000	287,442,000	248,564,000	269,366,000
Loans - Excluding OBS Credit Exposure | Real estate - commercial mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	66,256,000	79,853,000	69,456,000	87,970,000	87,970,000
Loans charged off	(230,000)	0	(13,592,000)	(152,000)
Recoveries of loans previously charged off	29,000	3,536,000	815,000	3,648,000
Net loans (charged off) recovered	(201,000)	3,536,000	(12,777,000)	3,496,000
Provision for credit losses	6,247,000	(10,784,000)	15,623,000	(18,861,000)
Ending balance	72,302,000	72,605,000	72,302,000	72,605,000	69,456,000
Loans - Excluding OBS Credit Exposure | Commercial and Industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	77,126,000	66,511,000	70,116,000	67,056,000	67,056,000
Loans charged off	(2,017,000)	(201,000)	(2,629,000)	(428,000)
Recoveries of loans previously charged off	988,000	739,000	2,074,000	2,719,000
Net loans (charged off) recovered	(1,029,000)	538,000	(555,000)	2,291,000
Provision for credit losses	(908,000)	5,070,000	5,628,000	2,772,000
Ending balance	75,189,000	72,119,000	75,189,000	72,119,000	70,116,000
Loans - Excluding OBS Credit Exposure | Real estate – residential mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	86,209,000	55,892,000	83,250,000	54,236,000	54,236,000
Loans charged off	(62,000)	(66,000)	(62,000)	(66,000)
Recoveries of loans previously charged off	58,000	92,000	106,000	314,000
Net loans (charged off) recovered	(4,000)	26,000	44,000	248,000
Provision for credit losses	2,644,000	5,717,000	5,555,000	7,151,000
Ending balance	88,849,000	61,635,000	88,849,000	61,635,000	83,250,000
Loans - Excluding OBS Credit Exposure | Consumer and Home Equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	27,303,000	20,213,000	26,429,000	19,749,000	19,749,000
Loans charged off	(1,313,000)	(877,000)	(3,519,000)	(1,929,000)
Recoveries of loans previously charged off	959,000	762,000	1,620,000	1,216,000
Net loans (charged off) recovered	(354,000)	(115,000)	(1,899,000)	(713,000)
Provision for credit losses	2,033,000	2,982,000	4,452,000	4,044,000
Ending balance	28,982,000	23,080,000	28,982,000	23,080,000	26,429,000
Loans - Excluding OBS Credit Exposure | Real-estate - construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,646,000	13,303,000	10,743,000	12,941,000	12,941,000
Loans charged off	0	0	0	0
Recoveries of loans previously charged off	569,000	12,000	771,000	44,000
Net loans (charged off) recovered	569,000	12,000	771,000	44,000
Provision for credit losses	(1,071,000)	(2,687,000)	(370,000)	(2,357,000)
Ending balance	11,144,000	10,628,000	11,144,000	10,628,000	10,743,000
Loans - Excluding OBS Credit Exposure | Leases and other loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	10,155,000	7,933,000	9,372,000	7,049,000	7,049,000
Loans charged off	(1,165,000)	(474,000)	(1,888,000)	(943,000)
Recoveries of loans previously charged off	213,000	226,000	329,000	380,000
Net loans (charged off) recovered	(952,000)	(248,000)	(1,559,000)	(563,000)
Provision for credit losses	1,773,000	812,000	3,163,000	2,011,000
Ending balance	$ 10,976,000	$ 8,497,000	$ 10,976,000	$ 8,497,000	$ 9,372,000