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Loans and ALLL (Credit quality indicators for commercial and agricultural credit exposures) (Details) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Financing Receivable, Recorded Investment [Line Items] |  |
Total | $ 1,151,756 | $ 1,091,519
Total commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 691,623 | 634,759
Commercial real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 496,049 | 481,654
Commercial other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 171,710 | 141,024
Commercial Advances to Mortgage Brokers Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 23,864 | 12,081
Total agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 125,249 | 128,269
Agricultural real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 86,809 | 88,165
Agricultural other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 38,440 | 40,104
Commercial And Agricultural Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 816,872 | 763,028
1 - Excellent [Member] | Total commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 53 | 340
1 - Excellent [Member] | Commercial real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 23 | 24
1 - Excellent [Member] | Commercial other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 30 | 316
1 - Excellent [Member] | Commercial Advances to Mortgage Brokers Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
1 - Excellent [Member] | Total agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 34 | 34
1 - Excellent [Member] | Agricultural real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
1 - Excellent [Member] | Agricultural other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 34 | 34
1 - Excellent [Member] | Commercial And Agricultural Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 87 | 374
2 - High quality [Member] | Total commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 25,976 | 20,664
2 - High quality [Member] | Commercial real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 6,144 | 8,402
2 - High quality [Member] | Commercial other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 19,832 | 12,262
2 - High quality [Member] | Commercial Advances to Mortgage Brokers Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
2 - High quality [Member] | Total agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 3,547 | 3,933
2 - High quality [Member] | Agricultural real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 3,026 | 2,909
2 - High quality [Member] | Agricultural other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 521 | 1,024
2 - High quality [Member] | Commercial And Agricultural Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 29,523 | 24,597
3 - High satisfactory [Member] | Total commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 196,845 | 190,575
3 - High satisfactory [Member] | Commercial real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 117,355 | 131,826
3 - High satisfactory [Member] | Commercial other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 55,626 | 46,668
3 - High satisfactory [Member] | Commercial Advances to Mortgage Brokers Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 23,864 | 12,081
3 - High satisfactory [Member] | Total agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 26,788 | 29,939
3 - High satisfactory [Member] | Agricultural real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 19,751 | 21,072
3 - High satisfactory [Member] | Agricultural other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 7,037 | 8,867
3 - High satisfactory [Member] | Commercial And Agricultural Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 223,633 | 220,514
4 - Low satisfactory [Member] | Total commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 444,986 | 401,757
4 - Low satisfactory [Member] | Commercial real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 353,308 | 326,166
4 - Low satisfactory [Member] | Commercial other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 91,678 | 75,591
4 - Low satisfactory [Member] | Commercial Advances to Mortgage Brokers Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
4 - Low satisfactory [Member] | Total agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 63,251 | 66,302
4 - Low satisfactory [Member] | Agricultural real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 45,287 | 47,835
4 - Low satisfactory [Member] | Agricultural other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 17,964 | 18,467
4 - Low satisfactory [Member] | Commercial And Agricultural Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 508,237 | 468,059
5 - Special mention [Member] | Total commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 14,376 | 12,875
5 - Special mention [Member] | Commercial real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 12,205 | 8,986
5 - Special mention [Member] | Commercial other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 2,171 | 3,889
5 - Special mention [Member] | Commercial Advances to Mortgage Brokers Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
5 - Special mention [Member] | Total agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 15,215 | 19,039
5 - Special mention [Member] | Agricultural real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 9,970 | 10,493
5 - Special mention [Member] | Agricultural other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 5,245 | 8,546
5 - Special mention [Member] | Commercial And Agricultural Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 29,591 | 31,914
6 - Substandard [Member] | Total commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 7,441 | 7,819
6 - Substandard [Member] | Commercial real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 5,368 | 5,521
6 - Substandard [Member] | Commercial other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 2,073 | 2,298
6 - Substandard [Member] | Commercial Advances to Mortgage Brokers Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
6 - Substandard [Member] | Total agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 12,657 | 7,072
6 - Substandard [Member] | Agricultural real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 6,623 | 4,325
6 - Substandard [Member] | Agricultural other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 6,034 | 2,747
6 - Substandard [Member] | Commercial And Agricultural Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 20,098 | 14,891
7 - Vulnerable [Member] | Total commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 1,946 | 729
7 - Vulnerable [Member] | Commercial real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 1,646 | 729
7 - Vulnerable [Member] | Commercial other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 300 | 0
7 - Vulnerable [Member] | Commercial Advances to Mortgage Brokers Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
7 - Vulnerable [Member] | Total agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 3,757 | 1,950
7 - Vulnerable [Member] | Agricultural real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 2,152 | 1,531
7 - Vulnerable [Member] | Agricultural other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 1,605 | 419
7 - Vulnerable [Member] | Commercial And Agricultural Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 5,703 | 2,679
8 - Doubtful [Member] | Total commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
8 - Doubtful [Member] | Commercial real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
8 - Doubtful [Member] | Commercial other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
8 - Doubtful [Member] | Commercial Advances to Mortgage Brokers Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
8 - Doubtful [Member] | Total agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
8 - Doubtful [Member] | Agricultural real estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
8 - Doubtful [Member] | Agricultural other [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | 0 | 0
8 - Doubtful [Member] | Commercial And Agricultural Portfolio Segment [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Total | $ 0 | $ 0

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