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	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Allowance for Credit Losses [Roll Forward]
Beginning Balance	$ 38,940	$ 34,277	$ 35,401	$ 34,274	$ 34,274
Charge-Offs	(17)	(113)	(46)	(143)	(276)
Recoveries	64	126	3,032	159	228
Provision	50	0	650	0	1,175
Ending Balance	39,037	34,290	39,037	34,290	35,401
Ending Balance Individually Evaluated for Impairment	1,231	2,073	1,231	2,073	2,197
Ending Balance Collectively Evaluated for Impairment	37,806	32,217	37,806	32,217	33,204
Loans & Leases [Abstract]
Ending Balance	1,818,642	1,499,709	1,818,642	1,499,709	1,712,244
Ending Balance Individually Evaluated for Impairment	17,407	34,886	17,407	34,886	33,584
Ending Balance Collectively Evaluated for Impairment	1,801,235	1,464,823	1,801,235	1,464,823	1,678,660
Commercial Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	7,954	6,426	7,842	5,178	5,178
Charge-Offs	0	0	0	0	0
Recoveries	1	0	2,939	0	11
Provision	636	565	(2,190)	1,813	2,653
Ending Balance	8,591	6,991	8,591	6,991	7,842
Ending Balance Individually Evaluated for Impairment	61	218	61	218	377
Ending Balance Collectively Evaluated for Impairment	8,530	6,773	8,530	6,773	7,465
Loans & Leases [Abstract]
Ending Balance	570,173	428,529	570,173	428,529	491,903
Ending Balance Individually Evaluated for Impairment	4,163	21,719	4,163	21,719	20,066
Ending Balance Collectively Evaluated for Impairment	566,010	406,810	566,010	406,810	471,837
Agricultural Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	6,901	3,387	4,185	3,576	3,576
Charge-Offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision	371	290	3,087	101	609
Ending Balance	7,272	3,677	7,272	3,677	4,185
Ending Balance Individually Evaluated for Impairment	0	0	0	0	0
Ending Balance Collectively Evaluated for Impairment	7,272	3,677	7,272	3,677	4,185
Loans & Leases [Abstract]
Ending Balance	373,324	358,933	373,324	358,933	357,207
Ending Balance Individually Evaluated for Impairment	0	0	0	0	0
Ending Balance Collectively Evaluated for Impairment	373,324	358,933	373,324	358,933	357,207
Real Estate Construction [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	1,916	1,077	1,669	654	654
Charge-Offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision	261	213	508	636	1,015
Ending Balance	2,177	1,290	2,177	1,290	1,669
Ending Balance Individually Evaluated for Impairment	0	241	0	241	0
Ending Balance Collectively Evaluated for Impairment	2,177	1,049	2,177	1,049	1,669
Loans & Leases [Abstract]
Ending Balance	116,983	81,647	116,983	81,647	96,519
Ending Balance Individually Evaluated for Impairment	4,335	4,446	4,335	4,446	4,386
Ending Balance Collectively Evaluated for Impairment	112,648	77,201	112,648	77,201	92,133
Residential 1st Mortgages [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	673	1,100	1,022	1,108	1,108
Charge-Offs	0	(30)	0	(33)	(73)
Recoveries	2	0	2	0	0
Provision	56	24	(293)	19	(13)
Ending Balance	731	1,094	731	1,094	1,022
Ending Balance Individually Evaluated for Impairment	71	329	71	329	422
Ending Balance Collectively Evaluated for Impairment	660	765	660	765	600
Loans & Leases [Abstract]
Ending Balance	189,039	160,418	189,039	160,418	171,880
Ending Balance Individually Evaluated for Impairment	2,055	1,647	2,055	1,647	2,108
Ending Balance Collectively Evaluated for Impairment	186,984	158,771	186,984	158,771	169,772
Home Equity Lines and Loans [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	2,096	2,648	2,426	2,767	2,767
Charge-Offs	0	(65)	0	(65)	(70)
Recoveries	42	39	47	51	58
Provision	(65)	115	(400)	(16)	(329)
Ending Balance	2,073	2,737	2,073	2,737	2,426
Ending Balance Individually Evaluated for Impairment	49	315	49	315	329
Ending Balance Collectively Evaluated for Impairment	2,024	2,422	2,024	2,422	2,097
Loans & Leases [Abstract]
Ending Balance	31,327	34,453	31,327	34,453	33,017
Ending Balance Individually Evaluated for Impairment	1,541	1,597	1,541	1,597	1,643
Ending Balance Collectively Evaluated for Impairment	29,786	32,856	29,786	32,856	31,374
Agricultural [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	4,602	9,601	6,104	12,205	12,205
Charge-Offs	0	0	0	0	0
Recoveries	2	1	3	2	8
Provision	442	(1,311)	(1,061)	(3,916)	(6,109)
Ending Balance	5,046	8,291	5,046	8,291	6,104
Ending Balance Individually Evaluated for Impairment	129	118	129	118	114
Ending Balance Collectively Evaluated for Impairment	4,917	8,173	4,917	8,173	5,990
Loans & Leases [Abstract]
Ending Balance	225,795	228,745	225,795	228,745	281,963
Ending Balance Individually Evaluated for Impairment	454	534	454	534	461
Ending Balance Collectively Evaluated for Impairment	225,341	228,211	225,341	228,211	281,502
Commercial [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	8,941	6,426	8,195	5,697	5,697
Charge-Offs	0	0	(12)	0	(1)
Recoveries	2	72	4	77	86
Provision	(65)	879	691	1,603	2,413
Ending Balance	8,878	7,377	8,878	7,377	8,195
Ending Balance Individually Evaluated for Impairment	887	807	887	807	914
Ending Balance Collectively Evaluated for Impairment	7,991	6,570	7,991	6,570	7,281
Loans & Leases [Abstract]
Ending Balance	256,386	179,948	256,386	179,948	230,819
Ending Balance Individually Evaluated for Impairment	4,819	4,898	4,819	4,898	4,874
Ending Balance Collectively Evaluated for Impairment	251,567	175,050	251,567	175,050	225,945
Consumer & Other [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	212	171	218	176	176
Charge-Offs	(17)	(18)	(34)	(45)	(132)
Recoveries	15	14	37	29	65
Provision	7	26	(4)	33	109
Ending Balance	217	193	217	193	218
Ending Balance Individually Evaluated for Impairment	34	45	34	45	41
Ending Balance Collectively Evaluated for Impairment	183	148	183	148	177
Loans & Leases [Abstract]
Ending Balance	4,984	4,881	4,984	4,881	4,719
Ending Balance Individually Evaluated for Impairment	40	45	40	45	46
Ending Balance Collectively Evaluated for Impairment	4,944	4,836	4,944	4,836	4,673
Leases [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	2,499	921	2,211	639	639
Charge-Offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision	33	187	321	469	1,572
Ending Balance	2,532	1,108	2,532	1,108	2,211
Ending Balance Individually Evaluated for Impairment	0	0	0	0	0
Ending Balance Collectively Evaluated for Impairment	2,532	1,108	2,532	1,108	2,211
Loans & Leases [Abstract]
Ending Balance	50,631	22,155	50,631	22,155	44,217
Ending Balance Individually Evaluated for Impairment	0	0	0	0	0
Ending Balance Collectively Evaluated for Impairment	50,631	22,155	50,631	22,155	44,217
Unallocated [Member]
Allowance for Credit Losses [Roll Forward]
Beginning Balance	3,146	2,520	1,529	2,274	2,274
Charge-Offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision	(1,626)	(988)	(9)	(742)	(745)
Ending Balance	1,520	1,532	1,520	1,532	1,529
Ending Balance Individually Evaluated for Impairment	0	0	0	0	0
Ending Balance Collectively Evaluated for Impairment	1,520	1,532	1,520	1,532	1,529
Loans & Leases [Abstract]
Ending Balance	0	0	0	0	0
Ending Balance Individually Evaluated for Impairment	0	0	0	0	0
Ending Balance Collectively Evaluated for Impairment	0	0	0	0	0
Restructured Loans [Member]
Loans & Leases [Abstract]
Ending Balance Individually Evaluated for Impairment	$ 9,600	$ 28,100	$ 9,600	$ 28,100	$ 26,400