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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			$ 293,404,000
Loans charged off	$ (13,144,000)	$ (7,279,000)	(38,103,000)	$ (28,969,000)
Recoveries of loans previously charged off	2,022,000	2,181,000	7,081,000	7,896,000
Net loans (charged off) recovered	(11,122,000)	(5,098,000)	(31,022,000)	(21,073,000)
Provision for credit losses	12,281,000	10,395,000	35,368,000	44,446,000
Ending balance	375,961,000		375,961,000		$ 293,404,000
Loans - Excluding OBS Credit Exposure
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	375,941,000	287,442,000	293,404,000	269,366,000	269,366,000
CECL Day 1 Provision(1)	0		23,444,000
Initial PCD allowance for credit losses	(1,139,000)
PCD Loans credit discount			54,767,000
Loans charged off	(13,144,000)	(7,279,000)	(38,103,000)	(28,969,000)
Recoveries of loans previously charged off	2,022,000	2,181,000	7,081,000	7,896,000
Net loans (charged off) recovered	(11,122,000)	(5,098,000)	(31,022,000)	(21,073,000)
Provision for credit losses	12,281,000	10,395,000	35,368,000	44,446,000
Ending balance	375,961,000	292,739,000	375,961,000	292,739,000	293,404,000
Loans - Excluding OBS Credit Exposure | Real estate - commercial mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	156,165,000	72,302,000	112,565,000	69,456,000	69,456,000
CECL Day 1 Provision(1)	0		6,108,000
Initial PCD allowance for credit losses	0
PCD Loans credit discount			32,157,000
Loans charged off	(2,723,000)	(860,000)	(10,602,000)	(14,452,000)
Recoveries of loans previously charged off	107,000	101,000	405,000	916,000
Net loans (charged off) recovered	(2,616,000)	(759,000)	(10,197,000)	(13,536,000)
Provision for credit losses	(10,255,000)	2,403,000	2,661,000	18,026,000
Ending balance	143,294,000	73,946,000	143,294,000	73,946,000	112,565,000
Loans - Excluding OBS Credit Exposure | Commercial and Industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	94,623,000	75,189,000	74,266,000	70,116,000	70,116,000
CECL Day 1 Provision(1)	0		1,484,000
Initial PCD allowance for credit losses	(1,139,000)
PCD Loans credit discount			19,730,000
Loans charged off	(6,256,000)	(3,220,000)	(16,843,000)	(5,849,000)
Recoveries of loans previously charged off	1,008,000	620,000	3,052,000	2,694,000
Net loans (charged off) recovered	(5,248,000)	(2,600,000)	(13,791,000)	(3,155,000)
Provision for credit losses	13,128,000	9,766,000	19,675,000	15,394,000
Ending balance	101,364,000	82,355,000	101,364,000	82,355,000	74,266,000
Loans - Excluding OBS Credit Exposure | Real estate - residential mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	89,714,000	88,849,000	73,286,000	83,250,000	83,250,000
CECL Day 1 Provision(1)	0		14,922,000
Initial PCD allowance for credit losses	0
PCD Loans credit discount			565,000
Loans charged off	(1,131,000)	0	(1,417,000)	(62,000)
Recoveries of loans previously charged off	130,000	37,000	368,000	143,000
Net loans (charged off) recovered	(1,001,000)	37,000	(1,049,000)	81,000
Provision for credit losses	1,614,000	(2,685,000)	2,603,000	2,870,000
Ending balance	90,327,000	86,201,000	90,327,000	86,201,000	73,286,000
Loans - Excluding OBS Credit Exposure | Consumer and Home Equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	17,533,000	28,982,000	17,604,000	26,429,000	26,429,000
CECL Day 1 Provision(1)	0		444,000
Initial PCD allowance for credit losses	0
PCD Loans credit discount			357,000
Loans charged off	(2,308,000)	(1,803,000)	(6,312,000)	(5,322,000)
Recoveries of loans previously charged off	545,000	1,023,000	2,382,000	2,643,000
Net loans (charged off) recovered	(1,763,000)	(780,000)	(3,930,000)	(2,679,000)
Provision for credit losses	1,357,000	1,873,000	2,652,000	6,325,000
Ending balance	17,127,000	30,075,000	17,127,000	30,075,000	17,604,000
Loans - Excluding OBS Credit Exposure | Real-estate - construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	14,610,000	11,144,000	12,295,000	10,743,000	10,743,000
CECL Day 1 Provision(1)	0		486,000
Initial PCD allowance for credit losses	0
PCD Loans credit discount			1,958,000
Loans charged off	0	0	0	0
Recoveries of loans previously charged off	103,000	0	336,000	771,000
Net loans (charged off) recovered	103,000	0	336,000	771,000
Provision for credit losses	6,284,000	(2,873,000)	5,922,000	(3,243,000)
Ending balance	20,997,000	8,271,000	20,997,000	8,271,000	12,295,000
Loans - Excluding OBS Credit Exposure | Leases and other loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,296,000	10,976,000	3,388,000	9,372,000	9,372,000
CECL Day 1 Provision(1)	0		0
Initial PCD allowance for credit losses	0
PCD Loans credit discount			0
Loans charged off	(726,000)	(1,396,000)	(2,929,000)	(3,284,000)
Recoveries of loans previously charged off	129,000	400,000	538,000	729,000
Net loans (charged off) recovered	(597,000)	(996,000)	(2,391,000)	(2,555,000)
Provision for credit losses	153,000	1,911,000	1,855,000	5,074,000
Ending balance	$ 2,852,000	$ 11,891,000	$ 2,852,000	$ 11,891,000	$ 3,388,000