Summary of Significant Accounting Policies (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) Payment		Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
New Accounting Standards [Abstract]
Other liabilities	$ 28,705			$ 29,332
Equity, net of tax	644,450		$ 631,847	614,886	$ 605,518	$ 594,708	$ 564,150
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount	47,986	[1]		$ 35,096	34,811	34,998	35,908
% of portfolio				1.08%
Reserve for unfunded lending commitments				$ 274
Investments [Abstract]
Securities held-to-maturity	$ 0			517
Loans [Abstract]
Impact of difference in amortized cost basis versus consideration of loan balances on allowance for credit losses	1
Past due period after which loans must be well secured and in the process of collection to continue accruing interest	90 days
Period of current principal and interest payments for reclassifying nonaccrual loans as accruing loans	6 months
Allowance for Loan and Lease Losses [Abstract]
Number of delinquent monthly payments before loan charge off | Payment	5
Current value assessment period for past due loans secured against real estate	90 days
Threshold period past due for initiation of foreclosure proceedings	120 days
Minimum [Member]
Allowance for Loan and Lease Losses [Abstract]
Percentage exposure of capital	5.00%
Other Real Estate Owned [Abstract]
Typical frequency of periodic reviews	12 months
Maximum [Member]
Other Real Estate Owned [Abstract]
Typical frequency of periodic reviews	18 months
Frequency of periodic reviews in general	24 months
Commercial Loans [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 21,683
% of portfolio				1.30%
Residential Mortgage [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 5,501
% of portfolio				0.61%
Consumer Direct [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 1,711
% of portfolio				1.16%
Consumer Indirect [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 6,201
% of portfolio				1.18%
Commercial [Member]
Allowance for Loan and Lease Losses [Abstract]
Threshold period past due for individual evaluations	90 days
Commercial [Member] | 90+ Days Past Due [Member] | Minimum [Member]
Allowance for Loan and Lease Losses [Abstract]
Threshold outstanding loan balance for individual evaluations	$ 1,000
Commercial [Member] | Nonaccrual Status [Member] | Minimum [Member]
Allowance for Loan and Lease Losses [Abstract]
Threshold outstanding loan balance for individual evaluations	1,000
Threshold amount of outstanding loan balance for specific reserve to be created	1,000
Commercial [Member] | TDR [Member] | Minimum [Member]
Allowance for Loan and Lease Losses [Abstract]
Threshold outstanding loan balance for individual evaluations	1,000
Threshold amount of outstanding loan balance for specific reserve to be created	1,000
Commercial [Member] | Criticized [Member] | Minimum [Member]
Allowance for Loan and Lease Losses [Abstract]
Threshold outstanding loan balance for individual evaluations	1,000
Threshold amount of outstanding loan balance for specific reserve to be created	$ 1,000
Commercial [Member] | Unsecured Commercial Loan [Member]
Allowance for Loan and Lease Losses [Abstract]
Charge off threshold for loans considered uncollectible	90 days
Commercial [Member] | Residential Mortgage [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 14,025	14,375	15,098	14,531
Consumer [Member] | Consumer Direct [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				1,711	1,735	1,767	1,883
Consumer [Member] | Consumer Indirect [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				6,201	$ 6,059	$ 6,960	7,841
Consumer [Member] | Closed-End Consumer Loan [Member]
Allowance for Loan and Lease Losses [Abstract]
Charge off threshold for loans considered uncollectible	120 days
ASU 2016-13 [Member]
New Accounting Standards [Abstract]
Forecast period used in calculating the allowance for credit losses	12 months
Effect of adoption of ASU in allowance for credit losses	$ 3,000
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 38,137
% of portfolio				1.17%
Reserve for unfunded lending commitments				$ 386
ASU 2016-13 [Member] | Commercial Loans [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 21,680
% of portfolio				1.30%
ASU 2016-13 [Member] | Residential Mortgage [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 7,319
% of portfolio				0.81%
ASU 2016-13 [Member] | Consumer Direct [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 1,671
% of portfolio				1.13%
ASU 2016-13 [Member] | Consumer Indirect [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount				$ 7,467
% of portfolio				1.42%
Cumulative Effect, Period of Adoption, Adjustment [Member]
New Accounting Standards [Abstract]
Equity, net of tax				$ 612,520			$ 563,670
Cumulative Effect, Period of Adoption, Adjustment [Member] | ASU 2016-13 [Member]
New Accounting Standards [Abstract]
Other liabilities				112
Equity, net of tax				(2,366)
Cumulative Effect, Period of Adoption, Adjustment [Member] | ASU 2016-13 [Member] | Unfunded Commitment [Member]
New Accounting Standards [Abstract]
Other liabilities				112
Equity, net of tax				$ 84

[1] Effective January 1, 2020, the allowance for loan and lease losses became the allowance for credit losses with the implementation of ASU 2016-13, commonly referred to as CECL.