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Allowance for Loan Losses and Credit Quality of Loans, Average Recorded Investments on Loans Specifically Evaluated for Impairment and Interest Income Recognized (Details) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | $ 21,182 | $ 25,672
Interest income recognized | 222 | 206
Originated Loans [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 21,182 | 25,371
Interest income recognized | 222 | 206
Originated Loans [Member] | Commercial Loans [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 5,927 | 11,324
Interest income recognized | 37 | 57
Originated Loans [Member] | Commercial Loans [Member] | C&I [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 467 |
Interest income recognized | 0 |
Originated Loans [Member] | Commercial Loans [Member] | CRE [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 4,506 |
Interest income recognized | 32 |
Originated Loans [Member] | Commercial Loans [Member] | Commercial [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment |  | 2,926
Interest income recognized |  | 0
Originated Loans [Member] | Commercial Loans [Member] | Commercial Real Estate [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment |  | 5,995
Interest income recognized |  | 44
Originated Loans [Member] | Commercial Loans [Member] | Agricultural [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment |  | 173
Interest income recognized |  | 0
Originated Loans [Member] | Commercial Loans [Member] | Agricultural Real Estate [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment |  | 1,580
Interest income recognized |  | 11
Originated Loans [Member] | Commercial Loans [Member] | Business Banking [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 954 | 650
Interest income recognized | 5 | 2
Originated Loans [Member] | Consumer Loans [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 8,374 | 8,436
Interest income recognized | 112 | 110
Originated Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 184 |
Interest income recognized | 3 |
Originated Loans [Member] | Consumer Loans [Member] | Direct Lending [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 8,190 | 0
Interest income recognized | 109 | 0
Originated Loans [Member] | Consumer Loans [Member] | Indirect [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment |  | 5
Interest income recognized |  | 0
Originated Loans [Member] | Consumer Loans [Member] | Home Equity [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment |  | 8,431
Interest income recognized |  | 110
Originated Loans [Member] | Residential Real Estate Mortgages [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 6,881 | 5,611
Interest income recognized | 73 | 39
Acquired Loans [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 0 | 301
Interest income recognized | 0 | 0
Acquired Loans [Member] | Commercial Loans [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 0 | 301
Interest income recognized | 0 | 0
Acquired Loans [Member] | Commercial Loans [Member] | Commercial Real Estate [Member] |  |
Financing Receivable, Impaired [Line Items] |  |
Average recorded investment | 0 | 301
Interest income recognized | $ 0 | $ 0

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- Definition Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524 + Details
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