Loans & Leases and Allowance for Credit Losses, Aging Analysis of Loan Portfolio by the Time Past Due (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	$ 0	$ 0	$ 0
Nonaccrual	3,075	2,156	2,904
Total Past Due	4,063	3,159	3,330
Current	2,075,607	1,993,200	1,906,940
Total Loans & Leases	2,079,670	1,996,359	1,910,270
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5	809	230
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	983	194	196
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	998	19	696
Total Past Due	998	724	696
Current	626,116	602,926	558,047
Total Loans & Leases	627,114	603,650	558,743
Commercial Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	705	0
Commercial Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	322	0	0
Total Past Due	1,305	0	0
Current	438,667	424,034	432,610
Total Loans & Leases	439,972	424,034	432,610
Agricultural Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Agricultural Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	983	0	0
Real Estate Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	0	0	0
Current	175,045	151,974	161,762
Total Loans & Leases	175,045	151,974	161,762
Real Estate Construction [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Real Estate Construction [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Residential 1st Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	55	65	68
Total Past Due	55	356	338
Current	238,321	206,049	196,555
Total Loans & Leases	238,376	206,405	196,893
Residential 1st Mortgages [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	97	74
Residential 1st Mortgages [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	194	196
Home Equity Lines & Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	538	576
Total Past Due	0	538	726
Current	32,513	32,518	31,107
Total Loans & Leases	32,513	33,056	31,833
Home Equity Lines & Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	150
Home Equity Lines & Loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	243	0	8
Total Past Due	243	0	8
Current	274,461	293,966	249,775
Total Loans & Leases	274,704	293,966	249,783
Agricultural [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Agricultural [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	1,450	1,524	1,545
Total Past Due	1,450	1,524	1,545
Current	212,636	209,280	208,946
Total Loans & Leases	214,086	210,804	210,491
Commercial [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Commercial [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Consumer & Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	7	10	11
Total Past Due	12	17	17
Current	6,963	6,575	6,718
Total Loans & Leases	6,975	6,592	6,735
Consumer & Other [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5	7	6
Consumer & Other [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	0	0
Total Past Due	0	0	0
Current	70,885	65,878	61,420
Total Loans & Leases	70,885	65,878	61,420
Leases [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
Leases [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 0	$ 0	$ 0