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Loans - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | $ 107.9 | $ 132.8 | $ 120.4
Recorded Investment With No Allowance | 51.4 | 57.9 | 56.3
Recorded Investment With Allowance | 31.8 | 46.8 | 35.7
Total Recorded Investment | 83.2 | 104.7 | 92.0
Related Allowance | 10.8 | 14.0 | 11.6
Average Recorded Investment | 94.0 | 101.1 | 80.4
Income Recognized | 0.5 | 0.6 | 1.0
Impaired Loans, interest lost on nonaccrual loans | 3.5 | 4.2 | 3.9
Commercial |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 45.6 | 57.0 | 58.2
Recorded Investment With No Allowance | 20.9 | 24.4 | 27.9
Recorded Investment With Allowance | 14.1 | 21.4 | 17.6
Total Recorded Investment | 35.0 | 45.8 | 45.5
Related Allowance | 3.9 | 2.8 | 3.4
Average Recorded Investment | 40.4 | 46.9 | 39.2
Income Recognized | 0.3 | 0.2 | 0.8
Land acquisition & development |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 10.0 | 12.1 | 15.5
Recorded Investment With No Allowance | 3.4 | 4.3 | 7.2
Recorded Investment With Allowance | 0.5 | 1.8 | 0.8
Total Recorded Investment | 3.9 | 6.1 | 8.0
Related Allowance | 0.0 | 0.8 | 0.3
Average Recorded Investment | 5.0 | 8.0 | 8.3
Income Recognized | 0.0 | 0.1 | 0.1
Residential |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 1.8 | 1.6 | 1.0
Recorded Investment With No Allowance | 1.7 | 0.2 | 0.3
Recorded Investment With Allowance | 0.0 | 0.6 | 0.0
Total Recorded Investment | 1.7 | 0.8 | 0.3
Related Allowance | 0.0 | 0.0 | 0.0
Average Recorded Investment | 1.3 | 0.8 | 0.3
Income Recognized | 0.0 | 0.0 | 0.0
Commercial |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 4.7 | 4.8 | 1.3
Recorded Investment With No Allowance | 0.4 | 3.9 | 0.3
Recorded Investment With Allowance | 3.5 | 0.7 | 0.7
Total Recorded Investment | 3.9 | 4.6 | 1.0
Related Allowance | 2.2 | 0.7 | 0.7
Average Recorded Investment | 4.2 | 2.9 | 1.9
Income Recognized | 0.0 | 0.0 | 0.0
Total construction loans |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 16.5 | 18.5 | 17.8
Recorded Investment With No Allowance | 5.5 | 8.4 | 7.8
Recorded Investment With Allowance | 4.0 | 3.1 | 1.5
Total Recorded Investment | 9.5 | 11.5 | 9.3
Related Allowance | 2.2 | 1.5 | 1.0
Average Recorded Investment | 10.5 | 11.7 | 10.5
Income Recognized | 0.0 | 0.1 | 0.1
Residential |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 11.5 | 8.2 | 7.1
Recorded Investment With No Allowance | 8.2 | 4.1 | 3.6
Recorded Investment With Allowance | 2.0 | 2.5 | 2.3
Total Recorded Investment | 10.2 | 6.6 | 5.9
Related Allowance | 0.1 | 0.3 | 0.4
Average Recorded Investment | 8.4 | 6.2 | 4.1
Income Recognized | 0.0 | 0.0 | 0.0
Agricultural |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 3.7 | 5.1 | 6.4
Recorded Investment With No Allowance | 3.6 | 4.5 | 5.6
Recorded Investment With Allowance | 0.0 | 0.2 | 0.2
Total Recorded Investment | 3.6 | 4.7 | 5.8
Related Allowance | 0.0 | 0.0 | 0.0
Average Recorded Investment | 4.2 | 4.4 | 7.2
Income Recognized | 0.0 | 0.0 | 0.0
Total real estate loans |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 77.3 | 88.8 | 89.5
Recorded Investment With No Allowance | 38.2 | 41.4 | 44.9
Recorded Investment With Allowance | 20.1 | 27.2 | 21.6
Total Recorded Investment | 58.3 | 68.6 | 66.5
Related Allowance | 6.2 | 4.6 | 4.8
Average Recorded Investment | 63.5 | 69.2 | 61.0
Income Recognized | 0.3 | 0.3 | 0.9
Commercial |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 29.5 | 40.3 | 29.6
Recorded Investment With No Allowance | 12.4 | 13.2 | 10.8
Recorded Investment With Allowance | 11.4 | 19.2 | 13.7
Total Recorded Investment | 23.8 | 32.4 | 24.5
Related Allowance | 4.4 | 9.3 | 6.5
Average Recorded Investment | 28.1 | 30.1 | 18.5
Income Recognized | 0.2 | 0.3 | 0.1
Agricultural |  |  |
Impaired Financing Receivable, Unpaid Principal Balance |  |  |
Unpaid Total Principal Balance | 1.1 | 3.7 | 1.3
Recorded Investment With No Allowance | 0.8 | 3.3 | 0.6
Recorded Investment With Allowance | 0.3 | 0.4 | 0.4
Total Recorded Investment | 1.1 | 3.7 | 1.0
Related Allowance | 0.2 | 0.1 | 0.3
Average Recorded Investment | 2.4 | 1.8 | 0.9
Income Recognized | $ 0.0 | $ 0.0 | $ 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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- Definition Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired. + 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)(3) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524 + Details
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