Loans & Leases and Allowance for Credit Losses, Aging Analysis of Loan & Lease Portfolio by the Time Past Due (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	$ 0	$ 0	$ 0
Nonaccrual	498	0	0
Total Past Due	1,197	352	661
Current	3,110,734	2,672,675	2,616,461
Total Loans & Leases	3,111,931	2,673,027	2,617,122
30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	699	352	517
60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	144
Commercial Real Estate [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	0	0	0
Current	871,623	838,570	816,668
Total Loans & Leases	871,623	838,570	816,668
Commercial Real Estate [Member] | 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Commercial Real Estate [Member] | 60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Agricultural Real Estate [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	498	0	0
Total Past Due	498	0	0
Current	638,674	625,767	617,310
Total Loans & Leases	639,172	625,767	617,310
Agricultural Real Estate [Member] | 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Agricultural Real Estate [Member] | 60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Real Estate Construction [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	85	240	0
Current	186,538	115,404	98,662
Total Loans & Leases	186,623	115,644	98,662
Real Estate Construction [Member] | 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	85	240	0
Real Estate Construction [Member] | 60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Residential 1st Mortgages [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	0	0	0
Current	293,489	255,253	255,394
Total Loans & Leases	293,489	255,253	255,394
Residential 1st Mortgages [Member] | 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Residential 1st Mortgages [Member] | 60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Home Equity Lines and Loans [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	0	0	84
Current	35,875	39,270	39,406
Total Loans & Leases	35,875	39,270	39,490
Home Equity Lines and Loans [Member] | 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Home Equity Lines and Loans [Member] | 60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	84
Agricultural [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	0	0	250
Current	252,031	292,904	288,932
Total Loans & Leases	252,031	292,904	289,182
Agricultural [Member] | 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	250
Agricultural [Member] | 60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Commercial [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	547	77	258
Current	366,505	384,718	381,516
Total Loans & Leases	367,052	384,795	381,774
Commercial [Member] | 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	547	77	258
Commercial [Member] | 60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Consumer & Other [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	67	35	69
Current	359,630	15,387	16,802
Total Loans & Leases	359,697	15,422	16,871
Consumer & Other [Member] | 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	67	35	9
Consumer & Other [Member] | 60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	60
Leases [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	0	0	0
Current	106,369	105,402	101,771
Total Loans & Leases	106,369	105,402	101,771
Leases [Member] | 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	0	0
Leases [Member] | 60-89 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	$ 0	$ 0	$ 0