Loans (Changes in the Allowance for Credit Losses) (Details) - USD ($) $ in Thousands		3 Months Ended
Dec. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance, prior to adoption of ASC 326	$ 30,482	$ 43,356
Impact of adopting ASC 326	9,594
Allowance for loan losses, Beginning balance		40,076	$ 33,914
Allowance for loan losses, Charge-offs		(12,032)	(3,452)
Allowance for loan losses, Recoveries		1,889	1,672
Allowance for loan losses, Provision (credit)		13,423	1,193
Allowance for loan losses, Ending balance	40,076	43,356	33,327
Allowance for loan losses, Individually Evaluated for impairment			183
Allowance for loan losses, Collectively Evaluated for impairment			33,144
Loans, Ending balance	3,179,465	3,195,175	3,066,996
Allowance for loan losses, Individually Evaluated for impairment			2,077
Allowance for loan losses, Collectively Evaluated for impairment			3,064,919
Commercial Business [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance, prior to adoption of ASC 326	11,358
Impact of adopting ASC 326	(246)
Allowance for loan losses, Beginning balance		11,112	14,312
Allowance for loan losses, Charge-offs		(8,241)	(130)
Allowance for loan losses, Recoveries		58	103
Allowance for loan losses, Provision (credit)		7,294	(2,118)
Allowance for loan losses, Ending balance	11,112	10,223	12,167
Allowance for loan losses, Individually Evaluated for impairment			181
Allowance for loan losses, Collectively Evaluated for impairment			11,986
Loans, Ending balance	571,222	587,903	552,834
Allowance for loan losses, Individually Evaluated for impairment			725
Allowance for loan losses, Collectively Evaluated for impairment			552,109
Commercial Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance, prior to adoption of ASC 326	5,681
Impact of adopting ASC 326	7,310
Allowance for loan losses, Beginning balance		12,991	5,219
Allowance for loan losses, Charge-offs		0	0
Allowance for loan losses, Recoveries		0	17
Allowance for loan losses, Provision (credit)		2,163	1,080
Allowance for loan losses, Ending balance	12,991	15,154	6,316
Allowance for loan losses, Individually Evaluated for impairment			2
Allowance for loan losses, Collectively Evaluated for impairment			6,314
Loans, Ending balance	1,108,315	1,109,344	995,183
Allowance for loan losses, Individually Evaluated for impairment			1,352
Allowance for loan losses, Collectively Evaluated for impairment			993,831
Residential Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance, prior to adoption of ASC 326	1,059
Impact of adopting ASC 326	3,290
Allowance for loan losses, Beginning balance		4,349	1,112
Allowance for loan losses, Charge-offs		(98)	(31)
Allowance for loan losses, Recoveries		10	6
Allowance for loan losses, Provision (credit)		1,909	178
Allowance for loan losses, Ending balance	4,349	6,170	1,265
Allowance for loan losses, Individually Evaluated for impairment			0
Allowance for loan losses, Collectively Evaluated for impairment			1,265
Loans, Ending balance	560,717	567,714	525,036
Allowance for loan losses, Individually Evaluated for impairment			0
Allowance for loan losses, Collectively Evaluated for impairment			525,036
Residential Real Estate Lines [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance, prior to adoption of ASC 326	118
Impact of adopting ASC 326	607
Allowance for loan losses, Beginning balance		725	210
Allowance for loan losses, Charge-offs		0	0
Allowance for loan losses, Recoveries		3	2
Allowance for loan losses, Provision (credit)		171	(39)
Allowance for loan losses, Ending balance	725	899	173
Allowance for loan losses, Individually Evaluated for impairment			0
Allowance for loan losses, Collectively Evaluated for impairment			173
Loans, Ending balance	101,048	98,996	105,592
Allowance for loan losses, Individually Evaluated for impairment			0
Allowance for loan losses, Collectively Evaluated for impairment			105,592
Consumer Indirect [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance, prior to adoption of ASC 326	11,852
Impact of adopting ASC 326	(1,234)
Allowance for loan losses, Beginning balance		10,618	12,572
Allowance for loan losses, Charge-offs		(3,424)	(2,982)
Allowance for loan losses, Recoveries		1,668	1,424
Allowance for loan losses, Provision (credit)		1,783	2,011
Allowance for loan losses, Ending balance	10,618	10,645	13,025
Allowance for loan losses, Individually Evaluated for impairment			0
Allowance for loan losses, Collectively Evaluated for impairment			13,025
Loans, Ending balance	822,179	815,969	872,410
Allowance for loan losses, Individually Evaluated for impairment			0
Allowance for loan losses, Collectively Evaluated for impairment			872,410
Other Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance, prior to adoption of ASC 326	414
Impact of adopting ASC 326	(133)
Allowance for loan losses, Beginning balance		281	489
Allowance for loan losses, Charge-offs		(269)	(309)
Allowance for loan losses, Recoveries		150	120
Allowance for loan losses, Provision (credit)		103	81
Allowance for loan losses, Ending balance	281	265	381
Allowance for loan losses, Individually Evaluated for impairment			0
Allowance for loan losses, Collectively Evaluated for impairment			381
Loans, Ending balance	$ 15,984	$ 15,249	15,941
Allowance for loan losses, Individually Evaluated for impairment			0
Allowance for loan losses, Collectively Evaluated for impairment			$ 15,941

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of credit loss expense (reversal of expense) for financing receivable from change in methodology.

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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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