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Off-Balance Sheet Credit Risk (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2021 | Dec. 31, 2020
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
General settlement period of securities transactions | 2 days |
Fair value of securities accepted as collateral permitted to sell or repledge | $ 2,200.0 | $ 1,800.0
Fair value of collateral securities sold or repledged | 208.2 | 191.0
Outstanding commitments to originate loans | 840.4 | 889.0
Letters of credit outstanding | 26.3 | 31.8
Unfunded Commitment [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Expected credit losses | 21.4 |
Unused Lines Of Credit [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Unused lines of credit to commercial and consumer borrowers | $ 2,800.0 | $ 2,500.0
Standby Letters of Credit [Member] | Maximum [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Letters of credit, expiration period | 1 year |

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- Definition Expected credit losses for unfunded credit loss. + References No definition available. + Details
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- Definition General settlement period of securities transactions. + References No definition available. + Details
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- Definition Outstanding commitments to originate loans. + References No definition available. + Details
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- Definition Fair value as of the balance sheet date of customer securities accepted as collateral by the entity that it is permitted by contract or custom to sell or re-pledge to counterparties as collateral. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
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- Definition Fair value as of the balance sheet date of customer securities accepted as collateral by the entity that it has sold or re-pledged to counterparties as collateral. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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