XML 61 R51.htm IDEA: XBRL DOCUMENT
v3.23.3

Loans and Allowance for Credit Losses - Additional Information (Details) | 9 Months Ended |
--- | --- | ---
Sep. 30, 2023 USD ($) segment portfolio | Dec. 31, 2022 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items] |  |
Number of loan portfolios | portfolio | 4 |
Number of loan segments | segment | 7 |
Accrued interest receivable on loans | $ 162,800,000 | $ 137,700,000
Loan placed on nonaccrual when past due, number of days | 90 days |
Loan participations | $ 2,800,000,000 |
Loan participations sold | 1,200,000,000 |
Loan participations retained | 1,600,000,000 |
Unfunded commitments on TDRs | $ 0 |
Commercial real estate |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |
Percentage of risk-based capital (in percent) | 245.00% |
Regulatory guideline limit (in percent) | 300.00% |

X
- Definition Commercial real estate loans as a percentage of risk-based capital. + References No definition available. + Details
Name: | onb_CommercialRealEstateLoansAsPercentageOfRiskBasedCapital
Namespace Prefix: | onb_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The regulatory guideline limit for commercial real estate loans as a percentage of risk-based capital. + References No definition available. + Details
Name: | onb_CommercialRealEstateLoansAsPercentageOfRiskBasedCapitalRegulatoryGuideLineLimit
Namespace Prefix: | onb_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Maximum number of days past due before loan is placed on nonaccrual status. + References No definition available. + Details
Name: | onb_FinanceReceivablePastDuePeriodForNonaccrualStatus
Namespace Prefix: | onb_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Number Of Loan Portfolios + References No definition available. + Details
Name: | onb_FinancingReceivableNumberOfLoanPortfolios
Namespace Prefix: | onb_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Financing Receivable, Number Of Loan Segments + References No definition available. + Details
Name: | onb_FinancingReceivableNumberOfLoanSegments
Namespace Prefix: | onb_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of loan participations with other financial institutions. + References No definition available. + Details
Name: | onb_LoanParticipations
Namespace Prefix: | onb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of loan participations retained. + References No definition available. + Details
Name: | onb_LoanParticipationsRetained
Namespace Prefix: | onb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of loan participations sold to other financial institutions. + References No definition available. + Details
Name: | onb_LoanParticipationsSold
Namespace Prefix: | onb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, before allowance for credit loss, of accrued interest on financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org//1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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 Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479319/326-20-50-13 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph c -Publisher SEC + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of commitment to lend additional funds to debtor experiencing financial difficulty for which creditor has modified terms of financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 36 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-36 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 40 -Topic 310 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481746/310-40-50-1 + Details
Name: | us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |