Loans & Leases and Allowance for Credit Losses, Aging Analysis of Loan Portfolio by the Time Past Due (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	$ 0	$ 0	$ 0
Nonaccrual	2,297	2,156	2,393
Total Past Due	2,998	3,159	3,220
Current	1,990,073	1,993,200	1,702,100
Total Loans & Leases	1,993,071	1,996,359	1,705,320
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	701	809	827
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	194	0
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	0	19	103
Total Past Due	696	724	822
Current	610,815	602,926	528,728
Total Loans & Leases	611,511	603,650	529,550
Commercial Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	696	705	719
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	163	0	0
Total Past Due	163	0	0
Current	432,118	424,034	351,866
Total Loans & Leases	432,281	424,034	351,866
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	0	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	166,455	151,974	101,616
Total Loans & Leases	166,455	151,974	101,616
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	62	65	74
Total Past Due	62	356	173
Current	212,143	206,049	182,258
Total Loans & Leases	212,205	206,405	182,431
Residential 1st Mortgages [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	97	99
Residential 1st Mortgages [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	194	0
Home Equity Lines & Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Still Accruing	0	0	0
Nonaccrual	564	538	616
Total Past Due	564	538	616
Current	31,075	32,518	31,108
Total Loans & Leases	31,639	33,056	31,724
Home Equity Lines & Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0	0
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	0	0	14
Total Past Due	0	0	14
Current	253,655	293,966	216,217
Total Loans & Leases	253,655	293,966	216,231
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	1,499	1,524	1,573
Total Past Due	1,499	1,524	1,573
Current	211,980	209,280	234,568
Total Loans & Leases	213,479	210,804	236,141
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	9	10	13
Total Past Due	14	17	22
Current	7,052	6,575	4,893
Total Loans & Leases	7,066	6,592	4,915
Consumer & Other [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5	7	9
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	64,780	65,878	50,846
Total Loans & Leases	64,780	65,878	50,846
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