Loans and ALLL (Summary of information pertaining to impaired loans) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Outstanding Balance	$ 15,319		$ 15,319		$ 16,141
Impaired loans without a valuation allowance, Outstanding Balance	5,087		5,087		6,197
Impaired loans, Outstanding Balance	20,406		20,406		22,338
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans with a valuation allowance, Unpaid Principal Balance	16,224		16,224		17,048
Impaired loans without a valuation allowance, Unpaid Principal Balance	5,551		5,551		6,649
Impaired loans, Unpaid Principal Balance	21,775		21,775		23,697
Impaired loans, Valuation Allowance	2,602		2,602		2,820
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Average Outstanding Balance	15,621	$ 18,712	15,825	$ 19,335
Impaired loans without a valuation allowance, Average Outstanding Balance	5,099	4,384	5,376	4,792
Impaired loans, Average Outstanding Balance	20,720	23,096	21,201	24,127
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans with a valuation allowance, Interest Income Recognized	183	213	369	436
Impaired loans without a valuation allowance, Interest Income Recognized	88	107	165	199
Impaired loans, Interest Income Recognized	271	320	534	635
Total commercial [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans, Outstanding Balance	6,714		6,714		7,969
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans, Unpaid Principal Balance	6,997		6,997		8,232
Impaired loans, Valuation Allowance	811		811		829
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans, Average Outstanding Balance	6,779	9,919	7,090	10,661
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans, Interest Income Recognized	117	177	223	342
Commercial real estate [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Outstanding Balance	5,729		5,729		5,659
Impaired loans without a valuation allowance, Outstanding Balance	820		820		2,122
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans with a valuation allowance, Unpaid Principal Balance	5,848		5,848		5,777
Impaired loans without a valuation allowance, Unpaid Principal Balance	973		973		2,256
Impaired loans, Valuation Allowance	801		801		818
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Average Outstanding Balance	5,793	7,052	5,773	7,163
Impaired loans without a valuation allowance, Average Outstanding Balance	814	2,230	1,139	2,818
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans with a valuation allowance, Interest Income Recognized	85	92	169	183
Impaired loans without a valuation allowance, Interest Income Recognized	28	74	47	135
Commercial other [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Outstanding Balance	93		93		8
Impaired loans without a valuation allowance, Outstanding Balance	72		72		180
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans with a valuation allowance, Unpaid Principal Balance	93		93		8
Impaired loans without a valuation allowance, Unpaid Principal Balance	83		83		191
Impaired loans, Valuation Allowance	10		10		11
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Average Outstanding Balance	95	569	74	581
Impaired loans without a valuation allowance, Average Outstanding Balance	77	68	104	99
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans with a valuation allowance, Interest Income Recognized	2	9	3	19
Impaired loans without a valuation allowance, Interest Income Recognized	2	2	4	5
Total agricultural [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans, Outstanding Balance	4,229		4,229		4,068
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans, Unpaid Principal Balance	4,229		4,229		4,068
Impaired loans, Valuation Allowance	15		15		2
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans, Average Outstanding Balance	4,148	1,940	4,108	1,761
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans, Interest Income Recognized	55	27	106	50
Agricultural real estate [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Outstanding Balance	181		181		0
Impaired loans without a valuation allowance, Outstanding Balance	3,362		3,362		3,549
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans with a valuation allowance, Unpaid Principal Balance	181		181		0
Impaired loans without a valuation allowance, Unpaid Principal Balance	3,362		3,362		3,549
Impaired loans, Valuation Allowance	15		15		0
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Average Outstanding Balance	91	44	46	44
Impaired loans without a valuation allowance, Average Outstanding Balance	3,454	1,545	3,501	1,513
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans with a valuation allowance, Interest Income Recognized	2	0	2	1
Impaired loans without a valuation allowance, Interest Income Recognized	43	20	88	41
Agricultural other [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Outstanding Balance	0		0		335
Impaired loans without a valuation allowance, Outstanding Balance	686		686		184
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans with a valuation allowance, Unpaid Principal Balance	0		0		335
Impaired loans without a valuation allowance, Unpaid Principal Balance	686		686		184
Impaired loans, Valuation Allowance	0		0		2
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Average Outstanding Balance	0	0	84	0
Impaired loans without a valuation allowance, Average Outstanding Balance	603	351	477	204
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans with a valuation allowance, Interest Income Recognized	0	0	0	0
Impaired loans without a valuation allowance, Interest Income Recognized	10	7	16	8
Total residential real estate [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans, Outstanding Balance	9,431		9,431		10,266
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans, Unpaid Principal Balance	10,517		10,517		11,362
Impaired loans, Valuation Allowance	1,776		1,776		1,989
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans, Average Outstanding Balance	9,760	11,191	9,969	11,653
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans, Interest Income Recognized	98	115	203	241
Residential real estate senior liens [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Outstanding Balance	9,183		9,183		9,996
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans with a valuation allowance, Unpaid Principal Balance	9,959		9,959		10,765
Impaired loans, Valuation Allowance	1,750		1,750		1,959
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Average Outstanding Balance	9,508	10,805	9,711	11,208
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans with a valuation allowance, Interest Income Recognized	93	99	193	217
Residential real estate junior liens [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Outstanding Balance	133		133		143
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans with a valuation allowance, Unpaid Principal Balance	143		143		163
Impaired loans, Valuation Allowance	26		26		30
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Average Outstanding Balance	134	196	137	227
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans with a valuation allowance, Interest Income Recognized	1	12	2	14
Residential real estate home equity lines of credit [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Outstanding Balance	0		0		0
Impaired loans without a valuation allowance, Outstanding Balance	115		115		127
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans with a valuation allowance, Unpaid Principal Balance	0		0		0
Impaired loans without a valuation allowance, Unpaid Principal Balance	415		415		434
Impaired loans, Valuation Allowance	0		0		0
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Average Outstanding Balance	0	0	0	63
Impaired loans without a valuation allowance, Average Outstanding Balance	118	190	121	155
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans with a valuation allowance, Interest Income Recognized	0	0	0	0
Impaired loans without a valuation allowance, Interest Income Recognized	4	4	8	10
Total Consumer [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans, Outstanding Balance	32		32		35
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans, Unpaid Principal Balance	32		32		35
Impaired loans, Valuation Allowance	0		0		0
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans, Average Outstanding Balance	33	46	34	52
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans, Interest Income Recognized	1	1	2	2
Consumer secured [Member]
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Outstanding Balance	0		0		0
Impaired loans without a valuation allowance, Outstanding Balance	32		32		35
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired loans with a valuation allowance, Unpaid Principal Balance	0		0		0
Impaired loans without a valuation allowance, Unpaid Principal Balance	32		32		35
Impaired loans, Valuation Allowance	0		0		$ 0
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired loans with a valuation allowance, Average Outstanding Balance	0	46	0	49
Impaired loans without a valuation allowance, Average Outstanding Balance	33	0	34	3
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract]
Impaired loans with a valuation allowance, Interest Income Recognized	0	1	0	2
Impaired loans without a valuation allowance, Interest Income Recognized	$ 1	$ 0	$ 2	$ 0