Allowance for Credit Losses on Loans (Allowance for Loan Losses Rollforward Analysis) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jan. 01, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance, Beginning Balance	$ 41,879	$ 41,441	$ 44,106	$ 27,014
Adoption of Topic 326					$ 6,501
Charge-offs	(249)	(111)	(630)	(1,072)
Recoveries	81	15	186	45
Provision	0	1,300	(1,951)	10,157
Allowance, Ending Balance	41,711	42,645	41,711	42,645
Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance, Beginning Balance	21,450	20,283	22,065	14,741
Adoption of Topic 326					3,405
Charge-offs	0	0	0	(172)
Recoveries	0	0	0	0
Provision	(613)	1,474	(1,228)	3,783
Allowance, Ending Balance	20,837	21,757	20,837	21,757
Commercial & Industrial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance, Beginning Balance	11,717	11,278	12,228	3,921
Adoption of Topic 326					3,029
Charge-offs	2	(2)	(304)	(585)
Recoveries	0	2	3	11
Provision	(392)	(93)	(600)	4,809
Allowance, Ending Balance	11,327	11,185	11,327	11,185
Total Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance, Beginning Balance	33,167	31,561	34,293	18,662
Adoption of Topic 326					6,434
Charge-offs	2	(2)	(304)	(757)
Recoveries	0	2	3	11
Provision	(1,005)	1,381	(1,828)	8,592
Allowance, Ending Balance	32,164	32,942	32,164	32,942
Residential Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance, Beginning Balance	6,877	8,053	8,042	6,615
Adoption of Topic 326					221
Charge-offs	(57)	(99)	(107)	(99)
Recoveries	5	0	85	0
Provision	1,131	(35)	(64)	1,182
Allowance, Ending Balance	7,956	7,919	7,956	7,919
Home Equity
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance, Beginning Balance	1,340	1,394	1,300	1,390
Adoption of Topic 326					(106)
Charge-offs	(183)	0	(183)	(174)
Recoveries	73	4	79	11
Provision	(112)	(51)	(78)	226
Allowance, Ending Balance	1,118	1,347	1,118	1,347
Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance, Beginning Balance	495	433	471	347
Adoption of Topic 326					(48)
Charge-offs	(11)	(10)	(36)	(42)
Recoveries	3	9	19	23
Provision	(14)	5	19	157
Allowance, Ending Balance	473	437	473	437
Total Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance, Beginning Balance	1,835	1,827	1,771	1,737
Adoption of Topic 326					$ (154)
Charge-offs	(194)	(10)	(219)	(216)
Recoveries	76	13	98	34
Provision	(126)	(46)	(59)	383
Allowance, Ending Balance	$ 1,591	$ 1,784	$ 1,591	$ 1,784

Amount, after recovery, of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of increase in allowance for credit loss on financing receivable from recovery.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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