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Derivatives and Hedging Activities - Pre-tax Gains and Losses on Derivative Contracts (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Derivative [Line Items] |  |  |
Amount of loss recognized in other comprehensive income (effective portion) |  |  | $ 1.1
Designated as Hedging Instrument |  |  |
Derivative [Line Items] |  |  |
Amount of loss recognized in other comprehensive income (effective portion) | $ 0.0 | $ 0.0 | 1.1
Reclassification adjustment for derivative net (gains) losses included in income | 0.0 | 0.0 | 1.1
Not Designated as Hedging Instrument |  |  |
Derivative [Line Items] |  |  |
Amount of gain recognized in other non-interest income | 0.0 | 0.3 |
Amount of net fee income recognized in other non-interest income | 2.5 | 1.3 |
Gain (Loss) on Fair Value Hedges Recognized in Earnings | $ 0.3 | $ (0.5) |
Not Designated as Hedging Instrument | Interest Rate Swap |  |  |
Derivative [Line Items] |  |  |
Amount of gain recognized in other non-interest income |  |  | 0.0
Amount of net fee income recognized in other non-interest income |  |  | 0.8
Amount of net gains (losses) recognized in mortgage banking revenues |  |  | $ (1.7)

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- Definition Fee Income on Derivatives + References No definition available. + Details
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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
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- Definition Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959 + Details
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