Loans and Allowance for Credit Losses Allowance for Loan Losses by Portfolio Segment (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			$ 269,366,000
Loans charged off	$ (7,279,000)	$ (3,724,000)	(28,969,000)	$ (7,242,000)
Recoveries of loans previously charged off	2,181,000	3,272,000	7,896,000	11,593,000
Net loans (charged off) recovered	(5,098,000)	(452,000)	(21,073,000)	4,351,000
Provision for credit losses	10,395,000	9,637,000	44,446,000	4,397,000
Ending balance	292,739,000		292,739,000		$ 269,366,000
Loans - Excluding OBS Credit Exposure
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	287,442,000	248,564,000	269,366,000	249,001,000	249,001,000
Loans charged off	(7,279,000)	(3,724,000)	(28,969,000)	(7,242,000)
Recoveries of loans previously charged off	2,181,000	3,272,000	7,896,000	11,593,000
Net loans (charged off) recovered	(5,098,000)	(452,000)	(21,073,000)	4,351,000
Provision for credit losses	10,395,000	9,637,000	44,446,000	4,397,000
Ending balance	292,739,000	266,838,000	292,739,000	266,838,000	269,366,000
CECL Day 1 Provision expense		7,954,000		7,954,000
Allowance for credit losses at acquisition		1,135,000		1,135,000
Loans - Excluding OBS Credit Exposure | Real estate - commercial mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	72,302,000	72,605,000	69,456,000	87,970,000	87,970,000
Loans charged off	(860,000)	(86,000)	(14,452,000)	(238,000)
Recoveries of loans previously charged off	101,000	29,000	916,000	3,677,000
Net loans (charged off) recovered	(759,000)	(57,000)	(13,536,000)	3,439,000
Provision for credit losses	2,403,000	11,144,000	18,026,000	(7,717,000)
Ending balance	73,946,000	88,850,000	73,946,000	88,850,000	69,456,000
CECL Day 1 Provision expense		4,107,000		4,107,000
Allowance for credit losses at acquisition		1,051,000		1,051,000
Loans - Excluding OBS Credit Exposure | Commercial and Industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	75,189,000	72,119,000	70,116,000	67,056,000	67,056,000
Loans charged off	(3,220,000)	(1,783,000)	(5,849,000)	(2,211,000)
Recoveries of loans previously charged off	620,000	2,213,000	2,694,000	4,932,000
Net loans (charged off) recovered	(2,600,000)	430,000	(3,155,000)	2,721,000
Provision for credit losses	9,766,000	(6,424,000)	15,394,000	(3,652,000)
Ending balance	82,355,000	66,125,000	82,355,000	66,125,000	70,116,000
CECL Day 1 Provision expense		0		0
Allowance for credit losses at acquisition		0		0
Loans - Excluding OBS Credit Exposure | Real estate – residential mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	88,849,000	61,635,000	83,250,000	54,236,000	54,236,000
Loans charged off	0	0	(62,000)	(66,000)
Recoveries of loans previously charged off	37,000	101,000	143,000	415,000
Net loans (charged off) recovered	37,000	101,000	81,000	349,000
Provision for credit losses	(2,685,000)	1,880,000	2,870,000	9,031,000
Ending balance	86,201,000	67,409,000	86,201,000	67,409,000	83,250,000
CECL Day 1 Provision expense		3,716,000		3,716,000
Allowance for credit losses at acquisition		77,000		77,000
Loans - Excluding OBS Credit Exposure | Consumer and Home Equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	28,982,000	23,080,000	26,429,000	19,749,000	19,749,000
Loans charged off	(1,803,000)	(1,172,000)	(5,322,000)	(3,101,000)
Recoveries of loans previously charged off	1,023,000	682,000	2,643,000	1,898,000
Net loans (charged off) recovered	(780,000)	(490,000)	(2,679,000)	(1,203,000)
Provision for credit losses	1,873,000	1,812,000	6,325,000	5,856,000
Ending balance	30,075,000	24,540,000	30,075,000	24,540,000	26,429,000
CECL Day 1 Provision expense		131,000		131,000
Allowance for credit losses at acquisition		7,000		7,000
Loans - Excluding OBS Credit Exposure | Real-estate - construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,144,000	10,628,000	10,743,000	12,941,000	12,941,000
Loans charged off	0	0	0	0
Recoveries of loans previously charged off	0	0	771,000	44,000
Net loans (charged off) recovered	0	0	771,000	44,000
Provision for credit losses	(2,873,000)	1,045,000	(3,243,000)	(1,312,000)
Ending balance	8,271,000	11,673,000	8,271,000	11,673,000	10,743,000
CECL Day 1 Provision expense		0		0
Allowance for credit losses at acquisition		0		0
Loans - Excluding OBS Credit Exposure | Leases and other loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	10,976,000	8,497,000	9,372,000	7,049,000	7,049,000
Loans charged off	(1,396,000)	(683,000)	(3,284,000)	(1,626,000)
Recoveries of loans previously charged off	400,000	247,000	729,000	627,000
Net loans (charged off) recovered	(996,000)	(436,000)	(2,555,000)	(999,000)
Provision for credit losses	1,911,000	180,000	5,074,000	2,191,000
Ending balance	$ 11,891,000	8,241,000	$ 11,891,000	8,241,000	$ 9,372,000
CECL Day 1 Provision expense		0		0
Allowance for credit losses at acquisition		$ 0		$ 0