Allowance for Credit Losses, Loan Portfolio Allocated by Management's Internal Credit Ratings (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	$ 1,996,359	$ 1,712,244
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	1,972,059	1,678,690
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	18,169	29,934
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	6,131	3,620
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	0	0
Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	0	0
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	603,650	491,903
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	595,011	483,146
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	7,917	8,651
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	722	106
Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	424,034	357,207
Agricultural Real Estate [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	424,034	357,207
Agricultural Real Estate [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	0	0
Agricultural Real Estate [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	0	0
Real Estate Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	151,974	96,519
Real Estate Construction [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	150,379	94,887
Real Estate Construction [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	1,595	1,632
Real Estate Construction [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	0	0
Residential 1st Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	206,405	171,880
Residential 1st Mortgages [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	205,135	170,462
Residential 1st Mortgages [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	413	744
Residential 1st Mortgages [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	857	674
Home Equity Lines and Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	33,056	33,017
Home Equity Lines and Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	32,419	32,054
Home Equity Lines and Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	75	85
Home Equity Lines and Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	562	878
Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	293,966	281,963
Agricultural [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	293,325	281,232
Agricultural [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	9	679
Agricultural [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	632	52
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	210,804	230,819
Commercial [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	199,467	211,036
Commercial [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	8,160	18,143
Commercial [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	3,177	1,640
Consumer & Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	6,592	4,719
Consumer & Other [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	6,411	4,449
Consumer & Other [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	0	0
Consumer & Other [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	181	270
Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	65,878	44,217
Leases [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	65,878	44,217
Leases [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	0	0
Leases [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & leases	$ 0	$ 0