Loans and ALLL (Summary of information pertaining to TDRs) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) loan	Jun. 30, 2015 USD ($) loan	Jun. 30, 2016 USD ($) loan	Jun. 30, 2015 USD ($) loan
Financing Receivable, Modifications [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 20,720	$ 23,096	$ 21,201	$ 24,127
Impaired Financing Receivable, Interest Income, Accrual Method	$ 271	$ 320	$ 534	$ 635
Number of Loans | loan	3	11	6	18
Pre-Modification Recorded Investment	$ 201	$ 1,081	$ 229	$ 1,927
Post-Modification Recorded Investment	$ 201	$ 1,081	$ 229	$ 1,927
Commercial other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	1	0	5
Pre-Modification Recorded Investment	$ 0	$ 71	$ 0	$ 585
Post-Modification Recorded Investment	$ 0	$ 71	$ 0	$ 585
Agricultural other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	3	7	3	7
Pre-Modification Recorded Investment	$ 201	$ 770	$ 201	$ 770
Post-Modification Recorded Investment	201	770	201	770
Total residential real estate [Member]
Financing Receivable, Modifications [Line Items]
Impaired Financing Receivable, Average Recorded Investment	9,760	11,191	9,969	11,653
Impaired Financing Receivable, Interest Income, Accrual Method	$ 98	$ 115	$ 203	$ 241
Number of Loans | loan	0	3	2	6
Pre-Modification Recorded Investment	$ 0	$ 240	$ 26	$ 572
Post-Modification Recorded Investment	$ 0	$ 240	$ 26	$ 572
Residential real estate senior liens [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	2	2	4
Pre-Modification Recorded Investment	$ 0	$ 210	$ 26	$ 448
Post-Modification Recorded Investment	$ 0	$ 210	$ 26	$ 448
Residential real estate junior liens [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	1	0	1
Pre-Modification Recorded Investment	$ 0	$ 30	$ 0	$ 30
Post-Modification Recorded Investment	$ 0	$ 30	$ 0	$ 30
Residential real estate home equity lines of credit [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	0	1
Pre-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 94
Post-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 94
Consumer Unsecured Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	1	0
Pre-Modification Recorded Investment	$ 0	$ 0	$ 2	$ 0
Post-Modification Recorded Investment	0	0	2	0
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Impaired Financing Receivable, Average Recorded Investment	6,779	9,919	7,090	10,661
Impaired Financing Receivable, Interest Income, Accrual Method	117	177	223	342
Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Impaired Financing Receivable, Average Recorded Investment	4,148	1,940	4,108	1,761
Impaired Financing Receivable, Interest Income, Accrual Method	55	27	106	50
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Impaired Financing Receivable, Average Recorded Investment	33	46	34	52
Impaired Financing Receivable, Interest Income, Accrual Method	$ 1	$ 1	$ 2	$ 2
Below Market Interest Rate and Extension of Amortization Period [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	3	4	4	8
Pre-Modification Recorded Investment	$ 201	$ 286	$ 203	$ 899
Below Market Interest Rate and Extension of Amortization Period [Member] | Commercial other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	0	2
Pre-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 331
Below Market Interest Rate and Extension of Amortization Period [Member] | Agricultural other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	3	1	3	1
Pre-Modification Recorded Investment	$ 201	$ 46	$ 201	$ 46
Below Market Interest Rate and Extension of Amortization Period [Member] | Total residential real estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	3	0	5
Pre-Modification Recorded Investment	$ 0	$ 240	$ 0	$ 522
Below Market Interest Rate and Extension of Amortization Period [Member] | Residential real estate senior liens [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	2	0	3
Pre-Modification Recorded Investment	$ 0	$ 210	$ 0	$ 398
Below Market Interest Rate and Extension of Amortization Period [Member] | Residential real estate junior liens [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	1	0	1
Pre-Modification Recorded Investment	$ 0	$ 30	$ 0	$ 30
Below Market Interest Rate and Extension of Amortization Period [Member] | Residential real estate home equity lines of credit [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	0	1
Pre-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 94
Below Market Interest Rate and Extension of Amortization Period [Member] | Consumer Unsecured Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	1	0
Pre-Modification Recorded Investment	$ 0	$ 0	$ 2	$ 0
Interest Rate Below Market Reduction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	7	2	10
Pre-Modification Recorded Investment	$ 0	$ 795	$ 26	$ 1,028
Interest Rate Below Market Reduction [Member] | Commercial other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	1	0	3
Pre-Modification Recorded Investment	$ 0	$ 71	$ 0	$ 254
Interest Rate Below Market Reduction [Member] | Agricultural other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	6	0	6
Pre-Modification Recorded Investment	$ 0	$ 724	$ 0	$ 724
Interest Rate Below Market Reduction [Member] | Total residential real estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	2	1
Pre-Modification Recorded Investment	$ 0	$ 0	$ 26	$ 50
Interest Rate Below Market Reduction [Member] | Residential real estate senior liens [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	2	1
Pre-Modification Recorded Investment	$ 0	$ 0	$ 26	$ 50
Interest Rate Below Market Reduction [Member] | Residential real estate junior liens [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	0	0
Pre-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
Interest Rate Below Market Reduction [Member] | Residential real estate home equity lines of credit [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	0	0
Pre-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
Interest Rate Below Market Reduction [Member] | Consumer Unsecured Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	0	0	0
Pre-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0