Accounting Policies, New Accounting Standards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
New Accounting Standards [Abstract]
Other liabilities	$ 33,694		$ 29,332
Equity, net of tax	654,865		614,886		$ 564,150	$ 530,699
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount	$ 48,022	[1]	$ 35,096	[1]	$ 35,908
% of portfolio			1.08%
Reserve for unfunded lending commitments			$ 274
Commercial Loans [Member]
Allowance for loan and lease losses transitioned to allowance for credit losses [Abstract]
Amount			$ 21,683
% of portfolio			1.30%
Real Estate 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%
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] | Real Estate 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] | 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.