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Financial Guarantees (Details) - USD ($) | 6 Months Ended |
--- | --- | ---
Jun. 30, 2022 | Dec. 31, 2021
Financial Guarantees [Line Items] |  |
Term of standby letters of credit (up to) | 1 year |
Notional amount of standby letters of credit | $ 223,000,000 | $ 75,700,000
Carrying value of letters of credit | 500,000 | $ 500,000
Interest Rate Swap |  |
Financial Guarantees [Line Items] |  |
Notional amount | $ 230,500,000 |

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- Definition Carrying value of standby letters of credit financial instruments. + References No definition available. + Details
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Balance Type: | credit
Period Type: | instant

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- Definition Financial guarantees. + References No definition available. + Details
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- Definition Amount of agreement to extend credit in the form of a standby letter of credit. + References No definition available. + Details
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Namespace Prefix: | onb_
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Period Type: | instant

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- Definition Length of time that standby letters of credit are effective. + References No definition available. + Details
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- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5579245-113959 + Details
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- Details
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