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Fair Value Measurements - Fair Value Inputs, Quantitative Information (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 USD ($) | Dec. 31, 2021 USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | $ 4,008.7 | $ 4,820.5
Minimum | Valuation, Market Approach [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Discount Rate for Level 3 Fair Value Disclosure | 0.00% |
Maximum [Member] | Valuation, Market Approach [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Discount Rate for Assets HFS Level 3 Fair Value | (37.00%) |
Weighted Average [Member] | Valuation, Market Approach [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Discount Rate for Level 3 Fair Value Disclosure | (9.00%) |
Discount Rate for Assets HFS Level 3 Fair Value | (4.00%) |
Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Collateral-dependent loans | $ (2.8) | 0.0
Other real estate owned | 0.0 | 0.0
Long-lived assets to be disposed of by sale | (0.2) | 0.0
Estimated Fair Value |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 4,008.7 | 4,820.5
Quoted Prices in Active Markets for Identical Assets (Level 1) | Estimated Fair Value |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 0.0 | 684.7
Significant Other Observable Inputs (Level 2) | Estimated Fair Value |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 4,008.7 | 4,135.8
Significant Unobservable Inputs (Level 3) | Estimated Fair Value |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 0.0 | 0.0
Significant Unobservable Inputs (Level 3) | Estimated Fair Value | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Collateral-dependent loans | $ (14.7) |
Measurement Input, Discount Rate [Member] | Minimum | Valuation, Market Approach [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Discount Rate for Assets HFS Level 3 Fair Value | 0.00% |
Measurement Input, Discount Rate [Member] | Maximum [Member] | Valuation, Market Approach [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Discount Rate for Level 3 Fair Value Disclosure | (18.00%) |
Other Debt Obligations [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | $ 0.2 |
Other Debt Obligations [Member] | Estimated Fair Value | Fair Value, Recurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 0.2 |
Other Debt Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 0.0 |
Other Debt Obligations [Member] | Significant Other Observable Inputs (Level 2) | Fair Value, Recurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 0.2 |
Other Debt Obligations [Member] | Significant Unobservable Inputs (Level 3) | Fair Value, Recurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 0.0 |
Loans And Leases Receivable, Impaired Loans [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Collateral-dependent loans | 0.0 | 0.0
Loans And Leases Receivable, Impaired Loans [Member] | Significant Other Observable Inputs (Level 2) | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Collateral-dependent loans | 0.0 | 0.0
Loans And Leases Receivable, Impaired Loans [Member] | Significant Unobservable Inputs (Level 3) | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Collateral-dependent loans | (14.7) |
Loans And Leases Receivable, Impaired Loans [Member] | Significant Unobservable Inputs (Level 3) | Estimated Fair Value | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Collateral-dependent loans | (14.7) | $ (11.7)
Loans And Leases Receivable, Impaired Loans [Member] | Measurement Input, Discount Rate [Member] | Significant Unobservable Inputs (Level 3) | Fair Value, Nonrecurring [Member] | Minimum | Valuation, Market Approach [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Servicing Asset, Measurement Input |  | 0.014
Loans And Leases Receivable, Impaired Loans [Member] | Measurement Input, Discount Rate [Member] | Significant Unobservable Inputs (Level 3) | Fair Value, Nonrecurring [Member] | Maximum [Member] | Valuation, Market Approach [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Servicing Asset, Measurement Input |  | 0.18
Loans And Leases Receivable, Impaired Loans [Member] | Measurement Input, Discount Rate [Member] | Significant Unobservable Inputs (Level 3) | Fair Value, Nonrecurring [Member] | Weighted Average [Member] | Valuation, Market Approach [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Servicing Asset, Measurement Input |  | 0.07
Loans And Leases Receivable, Other Real Estate Owned [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other real estate owned | 0.0 | $ 0.0
Loans And Leases Receivable, Other Real Estate Owned [Member] | Significant Other Observable Inputs (Level 2) | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other real estate owned | 0.0 | 0.0
Loans And Leases Receivable, Other Real Estate Owned [Member] | Significant Unobservable Inputs (Level 3) | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other real estate owned | (2.5) | (2.0)
Loans And Leases Receivable, Other Real Estate Owned [Member] | Significant Unobservable Inputs (Level 3) | Estimated Fair Value | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other real estate owned | (2.5) | (2.0)
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Long-lived assets to be disposed of by sale | 0.0 | 0.0
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Significant Other Observable Inputs (Level 2) | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Long-lived assets to be disposed of by sale | 0.0 | 0.0
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Significant Unobservable Inputs (Level 3) | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Long-lived assets to be disposed of by sale | (5.3) | (1.3)
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Significant Unobservable Inputs (Level 3) | Estimated Fair Value | Fair Value, Nonrecurring [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Long-lived assets to be disposed of by sale | $ (5.3) | $ (1.3)

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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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