Loans & Leases and Allowance for Credit Losses, Allocation of The Allowance For Credit Losses by Portfolio Segment and By Impairment Methodology (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Allowance for Credit Losses [Roll Forward]
Beginning Balance	$ 34,274	$ 34,217	$ 34,217
Charge-Offs	(30)	(35)	(891)
Recoveries	33	73	523
Provision	0	0	425
Ending Balance	34,277	34,255	34,274
Ending Balance Individually Evaluated for Impairment	2,104	3,201	1,616
Ending Balance Collectively Evaluated for Impairment	32,173	31,054	32,658
Loans [Abstract]
Ending Balance	1,363,030	1,226,695	1,388,236
Ending Balance Individually Evaluated for Impairment	36,010	40,185	35,616
Ending Balance Collectively Evaluated for Impairment	1,327,020	1,186,510	1,352,620
Commercial Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	5,178	6,464	6,464
Charge-Offs	0	0	(6)
Recoveries	0	0	0
Provision	1,248	207	(1,280)
Ending Balance	6,426	6,671	5,178
Ending Balance Individually Evaluated for Impairment	245	1,191	0
Ending Balance Collectively Evaluated for Impairment	6,181	5,480	5,178
Loans [Abstract]
Ending Balance	402,865	360,893	407,514
Ending Balance Individually Evaluated for Impairment	22,046	22,719	22,176
Ending Balance Collectively Evaluated for Impairment	380,819	338,174	385,338
Agricultural Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	3,576	2,877	2,877
Charge-Offs	0	0	(575)
Recoveries	0	0	0
Provision	(189)	918	1,274
Ending Balance	3,387	3,795	3,576
Ending Balance Individually Evaluated for Impairment	0	263	0
Ending Balance Collectively Evaluated for Impairment	3,387	3,532	3,576
Loans [Abstract]
Ending Balance	326,112	318,823	328,264
Ending Balance Individually Evaluated for Impairment	0	5,335	0
Ending Balance Collectively Evaluated for Impairment	326,112	313,488	328,264
Real Estate Construction [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	654	986	986
Charge-Offs	0	0	0
Recoveries	0	0	0
Provision	423	(17)	(332)
Ending Balance	1,077	969	654
Ending Balance Individually Evaluated for Impairment	226	232	0
Ending Balance Collectively Evaluated for Impairment	851	737	654
Loans [Abstract]
Ending Balance	55,751	32,681	41,092
Ending Balance Individually Evaluated for Impairment	4,473	4,577	4,500
Ending Balance Collectively Evaluated for Impairment	51,278	28,104	36,592
Residential 1st Mortgages [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	1,108	1,219	1,219
Charge-Offs	(3)	(16)	(16)
Recoveries	0	0	0
Provision	(5)	57	(95)
Ending Balance	1,100	1,260	1,108
Ending Balance Individually Evaluated for Impairment	340	29	414
Ending Balance Collectively Evaluated for Impairment	760	1,231	694
Loans [Abstract]
Ending Balance	156,094	145,419	151,292
Ending Balance Individually Evaluated for Impairment	1,701	1,950	2,072
Ending Balance Collectively Evaluated for Impairment	154,393	143,469	149,220
Home Equity Lines and Loans [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	2,767	3,235	3,235
Charge-Offs	0	(1)	(91)
Recoveries	12	2	115
Provision	(131)	(27)	(492)
Ending Balance	2,648	3,209	2,767
Ending Balance Individually Evaluated for Impairment	313	186	209
Ending Balance Collectively Evaluated for Impairment	2,335	3,023	2,558
Loans [Abstract]
Ending Balance	34,289	40,141	35,477
Ending Balance Individually Evaluated for Impairment	2,055	1,007	1,045
Ending Balance Collectively Evaluated for Impairment	32,234	39,134	34,432
Agricultural [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	12,205	10,437	10,437
Charge-Offs	0	0	(23)
Recoveries	1	13	42
Provision	(2,605)	(1,038)	1,749
Ending Balance	9,601	9,412	12,205
Ending Balance Individually Evaluated for Impairment	118	1,028	122
Ending Balance Collectively Evaluated for Impairment	9,483	8,384	12,083
Loans [Abstract]
Ending Balance	209,228	181,725	256,414
Ending Balance Individually Evaluated for Impairment	587	3,961	522
Ending Balance Collectively Evaluated for Impairment	208,641	177,764	255,892
Commercial [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	5,697	7,963	7,963
Charge-Offs	0	0	(60)
Recoveries	5	47	312
Provision	724	(44)	(2,518)
Ending Balance	6,426	7,966	5,697
Ending Balance Individually Evaluated for Impairment	814	214	820
Ending Balance Collectively Evaluated for Impairment	5,612	7,752	4,877
Loans [Abstract]
Ending Balance	155,802	142,115	150,398
Ending Balance Individually Evaluated for Impairment	5,100	578	5,250
Ending Balance Collectively Evaluated for Impairment	150,702	141,537	145,148
Consumer & Other [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	176	182	182
Charge-Offs	(27)	(18)	(120)
Recoveries	15	11	54
Provision	7	(12)	60
Ending Balance	171	163	176
Ending Balance Individually Evaluated for Impairment	48	58	51
Ending Balance Collectively Evaluated for Impairment	123	105	125
Loans [Abstract]
Ending Balance	4,721	4,898	5,052
Ending Balance Individually Evaluated for Impairment	48	58	51
Ending Balance Collectively Evaluated for Impairment	4,673	4,840	5,001
Leases [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	639	0	0
Charge-Offs	0	0	0
Recoveries	0	0	0
Provision	282	0	639
Ending Balance	921	0	639
Ending Balance Individually Evaluated for Impairment	0	0	0
Ending Balance Collectively Evaluated for Impairment	921	0	639
Loans [Abstract]
Ending Balance	18,168	0	12,733
Ending Balance Individually Evaluated for Impairment	0	0	0
Ending Balance Collectively Evaluated for Impairment	18,168	0	12,733
Unallocated [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	2,274	854	854
Charge-Offs	0	0	0
Recoveries	0	0	0
Provision	246	(44)	1,420
Ending Balance	2,520	810	2,274
Ending Balance Individually Evaluated for Impairment	0	0	0
Ending Balance Collectively Evaluated for Impairment	2,520	810	2,274
Loans [Abstract]
Ending Balance	0	0	0
Ending Balance Individually Evaluated for Impairment	0	0	0
Ending Balance Collectively Evaluated for Impairment	0	0	0
Restructured loans [Member]
Loans [Abstract]
Ending Balance Individually Evaluated for Impairment	$ 28,900	$ 29,300	$ 28,400