Loans & Leases and Allowance for Credit Losses, Aging Analysis of Loan & Lease Portfolio by the Time Past Due (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	$ 0	$ 0	$ 0
Nonaccrual	549	0	0
Total Past Due	1,032	352	727
Current	2,669,077	2,672,675	2,563,241
Total Loans & Leases	2,670,109	2,673,027	2,563,968
30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	483	352	727
60-89 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]
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	861,311	838,570	815,366
Total Loans & Leases	861,311	838,570	815,366
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	0	0	0
Total Past Due	0	0	0
Current	594,154	625,767	603,601
Total Loans & Leases	594,154	625,767	603,601
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	0	240	0
Current	126,956	115,404	99,837
Total Loans & Leases	126,956	115,644	99,837
Real Estate Construction [Member] \| 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	0	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	707
Current	256,732	255,253	257,652
Total Loans & Leases	256,732	255,253	258,359
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	707
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 & 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	226	0	0
Current	40,521	39,270	40,072
Total Loans & Leases	40,747	39,270	40,072
Home Equity Lines & Loans [Member] \| 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	226	0	0
Home Equity Lines & Loans [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 [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
90 Days and Still Accruing	0	0	0
Nonaccrual	549	0	0
Total Past Due	549	0	0
Current	264,222	292,904	257,004
Total Loans & Leases	264,771	292,904	257,004
Agricultural [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 [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	250	77	0
Current	404,079	384,718	364,439
Total Loans & Leases	404,329	384,795	364,439
Commercial [Member] \| 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	250	77	0
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	7	35	20
Current	14,832	15,387	18,398
Total Loans & Leases	14,839	15,422	18,418
Consumer & Other [Member] \| 30-59 Days Past Due [Member]
Aging Analysis of Loan & Lease Portfolio by Time Past Due [Abstract]
Total Past Due	7	35	20
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	0
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	106,270	105,402	106,872
Total Loans & Leases	106,270	105,402	106,872
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

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Amount of financing receivable 90 days or more past due and still accruing.

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