Loans & Leases and Allowance for Credit Losses, Loan Portfolio Allocated by Management's Internal Risk Ratings (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	$ 1,363,030,000	$ 1,388,236,000	$ 1,226,695,000
Loans outstanding rated doubtful or loss	0	0	0
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	402,865,000	407,514,000	360,893,000
Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	326,112,000	328,264,000	318,823,000
Real Estate Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	55,751,000	41,092,000	32,681,000
Residential 1st Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	156,094,000	151,292,000	145,419,000
Home Equity Lines & Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	34,289,000	35,477,000	40,141,000
Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	209,228,000	256,414,000	181,725,000
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	155,802,000	150,398,000	142,115,000
Consumer & Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	4,721,000	5,052,000	4,898,000
Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	18,168,000	12,733,000	0
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	1,325,667,000	1,353,440,000	1,170,557,000
Pass [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	389,366,000	398,488,000	336,525,000
Pass [Member] | Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	326,112,000	325,926,000	308,475,000
Pass [Member] | Real Estate Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	54,120,000	39,460,000	26,472,000
Pass [Member] | Residential 1st Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	154,743,000	149,798,000	142,951,000
Pass [Member] | Home Equity Lines & Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	33,196,000	34,821,000	38,870,000
Pass [Member] | Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	208,308,000	255,443,000	177,245,000
Pass [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	137,125,000	132,008,000	135,375,000
Pass [Member] | Consumer & Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	4,529,000	4,763,000	4,644,000
Pass [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	18,168,000	12,733,000
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	33,295,000	29,038,000	33,926,000
Special Mention [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	13,126,000	7,979,000	15,273,000
Special Mention [Member] | Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	0	2,338,000	3,799,000
Special Mention [Member] | Real Estate Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	1,631,000	1,632,000	6,209,000
Special Mention [Member] | Residential 1st Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	767,000	774,000	1,376,000
Special Mention [Member] | Home Equity Lines & Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	0	0	0
Special Mention [Member] | Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	843,000	889,000	980,000
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	16,928,000	15,426,000	6,289,000
Special Mention [Member] | Consumer & Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	0	0	0
Special Mention [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	0	0
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	4,068,000	5,758,000	22,212,000
Substandard [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	373,000	1,047,000	9,095,000
Substandard [Member] | Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	0	0	6,549,000
Substandard [Member] | Real Estate Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	0	0	0
Substandard [Member] | Residential 1st Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	584,000	720,000	1,092,000
Substandard [Member] | Home Equity Lines & Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	1,093,000	656,000	1,271,000
Substandard [Member] | Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	77,000	82,000	3,500,000
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	1,749,000	2,964,000	451,000
Substandard [Member] | Consumer & Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	192,000	289,000	254,000
Substandard [Member] | Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans & lease	$ 0	$ 0