Loans, Impaired Financing Receivable (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	$ 30,255		$ 36,332
Unpaid Contractual Principal Balance With An Allowance Recorded	23,840		28,034
Unpaid Contractual Principal Balance, Total	54,095		64,366
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	25,601	51,159	29,820
Impaired Balance With An Allowance Recorded	21,988	19,204	26,278
Impaired Balance, Total	47,589	70,363	56,098
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	4,493	4,882	4,272
Related Allowance, Total	4,493	4,882	4,272
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	25,601	51,159	42,461
Average Recorded Investment With An Allowance Recorded	21,988	19,204	22,229
Average Recorded Investment, Total	47,589	70,363	64,690
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	118	383	627
Interest Income Recognized With An Allowance Recorded	133	38	621
Interest Income Recognized, Total	251	421	1,248
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	161	347	693
Interest Income Collected With An Allowance Recorded	145	51	571
Interest Income Collected, Total	306	398	1,264
Commercial [Member]
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	264		1,508
Unpaid Contractual Principal Balance With An Allowance Recorded	1,465		1,493
Unpaid Contractual Principal Balance, Total	1,729		3,001
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	122	1,679	1,042
Impaired Balance With An Allowance Recorded	1,465	310	1,493
Impaired Balance, Total	1,587	1,989	2,535
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	456	304	463
Related Allowance, Total	456	304	463
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	122	1,679	1,053
Average Recorded Investment With An Allowance Recorded	1,465	310	943
Average Recorded Investment, Total	1,587	1,989	1,996
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	3	25	27
Interest Income Recognized With An Allowance Recorded	20	2	92
Interest Income Recognized, Total	23	27	119
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	4	26	28
Interest Income Collected With An Allowance Recorded	17	5	88
Interest Income Collected, Total	21	31	116
Agricultural [Member]
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	39		39
Unpaid Contractual Principal Balance With An Allowance Recorded	0		0
Unpaid Contractual Principal Balance, Total	39		39
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	39	39	39
Impaired Balance With An Allowance Recorded	0	0	0
Impaired Balance, Total	39	39	39
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	0	0	0
Related Allowance, Total	0	0	0
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	39	39	58
Average Recorded Investment With An Allowance Recorded	0	0	0
Average Recorded Investment, Total	39	39	58
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	0	0	0
Interest Income Recognized With An Allowance Recorded	0	0	0
Interest Income Recognized, Total	0	0	0
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	0	0	0
Interest Income Collected With An Allowance Recorded	0	0	0
Interest Income Collected, Total	0	0	0
Commercial Construction [Member]
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	9,002		10,625
Unpaid Contractual Principal Balance With An Allowance Recorded	5,339		8,267
Unpaid Contractual Principal Balance, Total	14,341		18,892
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	4,962	12,463	6,415
Impaired Balance With An Allowance Recorded	4,690	10,942	7,618
Impaired Balance, Total	9,652	23,405	14,033
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	1,493	2,755	1,733
Related Allowance, Total	1,493	2,755	1,733
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	4,962	12,463	9,194
Average Recorded Investment With An Allowance Recorded	4,690	10,942	10,534
Average Recorded Investment, Total	9,652	23,405	19,728
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	4	1	27
Interest Income Recognized With An Allowance Recorded	0	(9)	0
Interest Income Recognized, Total	4	(8)	27
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	5	4	52
Interest Income Collected With An Allowance Recorded	1	0	0
Interest Income Collected, Total	6	4	52
Commercial Real Estate [Member]
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	15,405		16,566
Unpaid Contractual Principal Balance With An Allowance Recorded	10,077		12,759
Unpaid Contractual Principal Balance, Total	25,482		29,325
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	15,331	32,018	15,506
Impaired Balance With An Allowance Recorded	9,917	3,647	12,745
Impaired Balance, Total	25,248	35,665	28,251
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	1,426	1,023	1,236
Related Allowance, Total	1,426	1,023	1,236
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	15,331	32,018	26,482
Average Recorded Investment With An Allowance Recorded	9,917	3,647	6,399
Average Recorded Investment, Total	25,248	35,665	32,881
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	102	300	430
Interest Income Recognized With An Allowance Recorded	73	20	384
Interest Income Recognized, Total	175	320	814
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	129	296	421
Interest Income Collected With An Allowance Recorded	91	20	366
Interest Income Collected, Total	220	316	787
Residential Real Estate [Member]
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	2,726		4,450
Unpaid Contractual Principal Balance With An Allowance Recorded	6,959		5,515
Unpaid Contractual Principal Balance, Total	9,685		9,965
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	2,382	2,407	4,132
Impaired Balance With An Allowance Recorded	5,916	4,045	4,422
Impaired Balance, Total	8,298	6,452	8,554
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	1,118	788	840
Related Allowance, Total	1,118	788	840
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	2,382	2,407	3,096
Average Recorded Investment With An Allowance Recorded	5,916	4,045	4,288
Average Recorded Investment, Total	8,298	6,452	7,384
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	10	23	89
Interest Income Recognized With An Allowance Recorded	40	25	145
Interest Income Recognized, Total	50	48	234
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	18	18	123
Interest Income Collected With An Allowance Recorded	36	26	117
Interest Income Collected, Total	54	44	240
Farmland [Member]
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	2,590		2,829
Unpaid Contractual Principal Balance With An Allowance Recorded	0		0
Unpaid Contractual Principal Balance, Total	2,590		2,829
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	2,548	2,297	2,413
Impaired Balance With An Allowance Recorded	0	260	0
Impaired Balance, Total	2,548	2,557	2,413
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	0	12	0
Related Allowance, Total	0	12	0
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	2,548	2,297	2,326
Average Recorded Investment With An Allowance Recorded	0	260	65
Average Recorded Investment, Total	2,548	2,557	2,391
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	(1)	32	43
Interest Income Recognized With An Allowance Recorded	0	0	0
Interest Income Recognized, Total	(1)	32	43
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	3	0	55
Interest Income Collected With An Allowance Recorded	0	0	0
Interest Income Collected, Total	3	0	55
Consumer [Member]
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	229		297
Unpaid Contractual Principal Balance With An Allowance Recorded	0		0
Unpaid Contractual Principal Balance, Total	229		297
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	217	212	255
Impaired Balance With An Allowance Recorded	0	0	0
Impaired Balance, Total	217	212	255
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	0	0	0
Related Allowance, Total	0	0	0
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	217	212	228
Average Recorded Investment With An Allowance Recorded	0	0	0
Average Recorded Investment, Total	217	212	228
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	0	2	10
Interest Income Recognized With An Allowance Recorded	0	0	0
Interest Income Recognized, Total	0	2	10
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	2	3	13
Interest Income Collected With An Allowance Recorded	0	0	0
Interest Income Collected, Total	2	3	13
Other [Member]
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	0		18
Unpaid Contractual Principal Balance With An Allowance Recorded	0		0
Unpaid Contractual Principal Balance, Total	0		18
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	0	44	18
Impaired Balance With An Allowance Recorded	0	0	0
Impaired Balance, Total	0	44	18
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	0	0	0
Related Allowance, Total	0	0	0
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	0	44	24
Average Recorded Investment With An Allowance Recorded	0	0	0
Average Recorded Investment, Total	0	44	24
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	0	0	1
Interest Income Recognized With An Allowance Recorded	0	0	0
Interest Income Recognized, Total	0	0	1
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	0	0	1
Interest Income Collected With An Allowance Recorded	0	0	0
Interest Income Collected, Total	0	0	1
Residential Construction [Member]
Unpaid Contractual Principal Balance [Abstract]
Unpaid Contractual Principal Balance With No Related Allowance Recorded	0		0
Unpaid Contractual Principal Balance With An Allowance Recorded	0		0
Unpaid Contractual Principal Balance, Total	0		0
Impaired Balance [Abstract]
Impaired Balance With No Related Allowance Recorded	0	0	0
Impaired Balance With An Allowance Recorded	0	0	0
Impaired Balance, Total	0	0	0
Related Allowance [Abstract]
Related Allowance With No Related Allowance Recorded	0	0	0
Related Allowance With An Allowance Recorded	0	0	0
Related Allowance, Total	0	0	0
Average Recorded Investment [Abstract]
Average Recorded Investment With No Related Allowance Recorded	0	0	0
Average Recorded Investment With An Allowance Recorded	0	0	0
Average Recorded Investment, Total	0	0	0
Interest Income Recognized [Abstract]
Interest Income Recognized With No Related Allowance Recorded	0	0	0
Interest Income Recognized With An Allowance Recorded	0	0	0
Interest Income Recognized, Total	0	0	0
Interest Income Collected [Abstract]
Interest Income Collected With No Related Allowance Recorded	0	0	0
Interest Income Collected With An Allowance Recorded	0	0	0
Interest Income Collected, Total	$ 0	$ 0	$ 0