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Loans and ALLL (Summary of information pertaining to impaired loans) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Outstanding Balance | $ 8,782 | $ 11,263
Impaired loans without a valuation allowance, Outstanding Balance | 19,409 | 19,836
Impaired loans, Outstanding Balance | 28,191 | 31,099
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 9,329 | 11,960
Impaired loans without a valuation allowance, Unpaid Principal Balance | 20,022 | 20,439
Impaired loans, Unpaid Principal Balance | 29,351 | 32,399
Impaired loans, Valuation Allowance | 1,114 | 1,938
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 10,198 | 13,973
Impaired loans without a valuation allowance, Average Outstanding Balance | 19,034 | 16,532
Impaired loans, Average Outstanding Balance | 29,232 | 30,505
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 330 | 406
Impaired loans without a valuation allowance, Interest Income Recognized | 572 | 986
Impaired loans, Interest Income Recognized | 902 | 1,392
Total commercial [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans, Outstanding Balance | 7,865 | 9,899
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans, Unpaid Principal Balance | 8,246 | 10,401
Impaired loans, Valuation Allowance | 15 | 443
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans, Average Outstanding Balance | 8,998 | 9,890
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans, Interest Income Recognized | 198 | 301
Commercial real estate [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Outstanding Balance | 517 | 3,969
Impaired loans without a valuation allowance, Outstanding Balance | 4,961 | 2,794
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 635 | 4,211
Impaired loans without a valuation allowance, Unpaid Principal Balance | 5,224 | 2,947
Impaired loans, Valuation Allowance | 15 | 437
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 2,044 | 4,589
Impaired loans without a valuation allowance, Average Outstanding Balance | 4,247 | 2,728
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 61 | 129
Impaired loans without a valuation allowance, Interest Income Recognized | 91 | 74
Commercial other [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Outstanding Balance | 0 | 12
Impaired loans without a valuation allowance, Outstanding Balance | 2,387 | 3,124
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 0 | 12
Impaired loans without a valuation allowance, Unpaid Principal Balance | 2,387 | 3,231
Impaired loans, Valuation Allowance | 0 | 6
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 10 | 1,040
Impaired loans without a valuation allowance, Average Outstanding Balance | 2,697 | 1,533
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 0 | 55
Impaired loans without a valuation allowance, Interest Income Recognized | 46 | 43
Total agricultural [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans, Outstanding Balance | 14,840 | 14,298
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans, Unpaid Principal Balance | 14,890 | 14,341
Impaired loans, Valuation Allowance | 26 | 132
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans, Average Outstanding Balance | 13,950 | 12,969
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans, Interest Income Recognized | 584 | 960
Agricultural real estate [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Outstanding Balance | 1,509 | 392
Impaired loans without a valuation allowance, Outstanding Balance | 8,372 | 7,618
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 1,509 | 392
Impaired loans without a valuation allowance, Unpaid Principal Balance | 8,422 | 7,618
Impaired loans, Valuation Allowance | 12 | 112
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 1,091 | 606
Impaired loans without a valuation allowance, Average Outstanding Balance | 7,404 | 7,559
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 100 | 50
Impaired loans without a valuation allowance, Interest Income Recognized | 171 | 585
Agricultural other [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Outstanding Balance | 1,355 | 44
Impaired loans without a valuation allowance, Outstanding Balance | 3,604 | 6,244
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 1,355 | 44
Impaired loans without a valuation allowance, Unpaid Principal Balance | 3,604 | 6,287
Impaired loans, Valuation Allowance | 14 | 20
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 832 | 168
Impaired loans without a valuation allowance, Average Outstanding Balance | 4,623 | 4,636
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 55 | 46
Impaired loans without a valuation allowance, Interest Income Recognized | 258 | 279
Total residential real estate [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans, Outstanding Balance | 5,486 | 6,893
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans, Unpaid Principal Balance | 6,215 | 7,648
Impaired loans, Valuation Allowance | 1,073 | 1,363
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans, Average Outstanding Balance | 6,279 | 7,634
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans, Interest Income Recognized | 120 | 131
Residential real estate senior liens [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Outstanding Balance | 5,401 | 6,834
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 5,830 | 7,289
Impaired loans, Valuation Allowance | 1,073 | 1,361
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 6,210 | 7,545
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 114 | 126
Residential real estate junior liens [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Outstanding Balance | 0 | 12
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans with a valuation allowance, Unpaid Principal Balance | 0 | 12
Impaired loans, Valuation Allowance | 0 | 2
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans with a valuation allowance, Average Outstanding Balance | 11 | 25
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans with a valuation allowance, Interest Income Recognized | 0 | 0
Residential real estate home equity lines of credit [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans without a valuation allowance, Outstanding Balance | 85 | 47
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans without a valuation allowance, Unpaid Principal Balance | 385 | 347
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans without a valuation allowance, Average Outstanding Balance | 58 | 64
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans without a valuation allowance, Interest Income Recognized | 6 | 5
Total consumer [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans, Outstanding Balance | 0 | 9
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans, Unpaid Principal Balance | 0 | 9
Impaired loans, Valuation Allowance | 0 | 0
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans, Average Outstanding Balance | 5 | 12
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans, Interest Income Recognized | 0 | 0
Consumer secured [Member] |  |
Impaired Financing Receivable, Recorded Investment [Abstract] |  |
Impaired loans without a valuation allowance, Outstanding Balance | 0 | 9
Impaired Financing Receivable, Unpaid Principal Balance [Abstract] |  |
Impaired loans without a valuation allowance, Unpaid Principal Balance | 0 | 9
Impaired Financing Receivable, Average Recorded Investment [Abstract] |  |
Impaired loans without a valuation allowance, Average Outstanding Balance | 5 | 12
Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] |  |
Impaired loans without a valuation allowance, Interest Income Recognized | $ 0 | $ 0

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