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Loans - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019 | Jun. 30, 2020 | Dec. 31, 2019 | Jun. 30, 2019 | Dec. 31, 2018
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance | $ 4.3 |  | $ 4.3 |  |  | $ 0.3 |  |
Impaired Financing Receivable, Related Allowance |  |  |  |  |  | 3.6 |  |
Provision charged to operating expense | (5.2) | $ (2.6) | (53.7) | $ (10.1) |  |  |  |
Accounts Receivable, Allowance for Credit Loss | 145.5 | $ 75.0 | 145.5 | $ 75.0 | $ 146.1 | 73.0 | $ 74.2 | $ 73.0
Collateral dependent borrowings | 16.0 |  | 16.0 |  |  |  |  |
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal) | 4.0 |  |  |  |  |  |  |
Balance of defaulted loans under trouble debt restructurings | 0.0 |  | 0.0 |  |  |  |  |
Agriculture Portfolio Segment [Member] |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Provision charged to operating expense | 0.0 |  |  |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss | 0.9 |  | 0.9 |  | 0.9 |  |  |
Total real estate loans |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Provision charged to operating expense | (3.2) |  | (21.3) |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss | 78.6 |  | 78.6 |  | 75.2 | 28.9 |  |
Collateral dependent borrowings | 0.7 |  | 0.7 |  |  |  |  |
Commercial |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Provision charged to operating expense | (1.1) |  | (23.8) |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss | 42.0 |  | 42.0 |  | 46.5 | 32.6 |  |
Collateral dependent borrowings | 15.2 |  | 15.2 |  |  |  |  |
Agricultural |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Provision charged to operating expense | 0.0 |  | 0.0 |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss | 0.9 |  | 0.9 |  | $ 0.9 | $ 1.6 |  |
Collateral dependent borrowings | 0.1 |  | 0.1 |  |  |  |  |
Business Assets Pledged as Collateral [Member] |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 10.0 |  | 10.0 |  |  |  |  |
Business Assets Pledged as Collateral [Member] | Total real estate loans |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 0.2 |  | 0.2 |  |  |  |  |
Business Assets Pledged as Collateral [Member] | Commercial |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 9.8 |  | 9.8 |  |  |  |  |
Business Assets Pledged as Collateral [Member] | Agricultural |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 0.0 |  | 0.0 |  |  |  |  |
Real Property Pledged as Collateral [Member] |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 5.6 |  | 5.6 |  |  |  |  |
Real Property Pledged as Collateral [Member] | Total real estate loans |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 0.5 |  | 0.5 |  |  |  |  |
Real Property Pledged as Collateral [Member] | Commercial |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 5.0 |  | 5.0 |  |  |  |  |
Real Property Pledged as Collateral [Member] | Agricultural |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 0.1 |  | 0.1 |  |  |  |  |
Other Property [Member] |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 0.4 |  | 0.4 |  |  |  |  |
Other Property [Member] | Total real estate loans |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 0.0 |  | 0.0 |  |  |  |  |
Other Property [Member] | Commercial |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | 0.4 |  | 0.4 |  |  |  |  |
Other Property [Member] | Agricultural |  |  |  |  |  |  |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |  |  |  |  |  |  |
Collateral dependent borrowings | $ 0.0 |  | $ 0.0 |  |  |  |  |

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- Definition Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524 + Details
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