XML 70 R53.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Significant Accounting Policies (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 USD ($) segment banking_center | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($)
Property, Plant and Equipment [Line Items] |  |  |
Number of locations | banking_center | 60 |  |
Number of segments | segment | 1 |  |
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] | Accrued interest receivable and other assets |  |
Other financial institutions, excluding FRBD and FHLB | $ 43,400 | $ 25,900 |
Other real estate owned | 3,600 | 3,900 |
Penalties and related interest | 0 | 0 | $ 0
Other investments | 23,100 | 22,200 |
Amortization of investments in tax credit funds | 1,749 | 1,842 | 1,659
Income tax credits and other income tax benefits | $ 2,000 | 2,300 | $ 2,400
Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, before Amortization, Statement of Income or Comprehensive Income [Extensible Enumeration] | Income tax expense |  |
Investment Program Proportional Amortization Method Elected Income Tax Credit And Other Income Tax Benefit Before Amortization Statement Of Cash Flows Extensible Enumeration Not Disclosed Flag | income tax expense |  |
Investments in tax credit entities | $ 8,800 | $ 7,600 |
Tax Credit Entity |  |  |
Property, Plant and Equipment [Line Items] |  |  |
General partner ownership interest | 0.10% |  |
Maximum | Furniture, fixtures and equipment |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Estimated useful lives | 15 years |  |
Maximum | Buildings and improvements |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Estimated useful lives | 50 years |  |
Minimum | Furniture, fixtures and equipment |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Estimated useful lives | 3 years |  |
Minimum | Buildings and improvements |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Estimated useful lives | 15 years |  |

X
- Definition Investment In Tax Credit Entities + References No definition available. + Details
Name: | obnk_InvestmentInTaxCreditEntities
Namespace Prefix: | obnk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, before Amortization, Statement of Cash Flows Extensible Enumeration Not Disclosed Flag + References No definition available. + Details
Name: | obnk_InvestmentProgramProportionalAmortizationMethodElectedIncomeTaxCreditAndOtherIncomeTaxBenefitBeforeAmortizationStatementOfCashFlowsExtensibleEnumerationNotDisclosedFlag
Namespace Prefix: | obnk_
Data Type: | xbrli:tokenItemType
Balance Type: | na
Period Type: | duration

X
- Definition Investments In Other Financial Institutions Excluding Federal Home Loan Bank Stock and Federal Reserve Bank Stock + References No definition available. + Details
Name: | obnk_InvestmentsInOtherFinancialInstitutionsExcludingFederalHomeLoanBankStockAndFederalReserveBankStock
Namespace Prefix: | obnk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, before amortization expense, of income tax credit and other tax benefit generated by investment under tax credit program elected to be accounted for using proportional amortization method. Includes, but is not limited to, investment under tax credit program not meeting condition for accounting under proportional amortization method. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 323 -SubTopic 740 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478156/323-740-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 323 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478156/740-323-50-1A + Details
Name: | us-gaap_AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of amortization expense for investment that generates income tax credit and other income tax benefit under tax credit program accounted for using proportional amortization method. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 740 -SubTopic 323 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478156/740-323-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 323 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478156/740-323-50-1A + Details
Name: | us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Indicates line item in statement of financial position that includes accrued interest, after allowance for credit loss, on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3A -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3A + Details
Name: | us-gaap_DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLossStatementOfFinancialPositionExtensibleList
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
Balance Type: | na
Period Type: | instant

X
- Definition The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 15 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482685/740-10-50-15 + Details
Name: | us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Indicates line item in statement of income or comprehensive income that includes income tax credit and other income tax benefit, before amortization expense, generated by investment under tax credit program elected to be accounted for using proportional amortization method. Includes, but is not limited to, investment under tax credit program not meeting condition for accounting under proportional amortization method. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 323 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478156/740-323-50-1A + Details
Name: | us-gaap_InvestmentProgramProportionalAmortizationMethodElectedIncomeTaxCreditAndOtherIncomeTaxBenefitBeforeAmortizationStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482987/272-10-50-3 + Details
Name: | us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 49 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482785/280-10-55-49 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-18 + Details
Name: | us-gaap_NumberOfOperatingSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of stores. + References No definition available. + Details
Name: | us-gaap_NumberOfStores
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of investments classified as other. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(12)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(3)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
Name: | us-gaap_OtherInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(10)(4)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_OtherRealEstate
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/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 7A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A + Details
Name: | us-gaap_PropertyPlantAndEquipmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | srt_OwnershipAxis=obnk_TaxCreditEntityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=obnk_FurnitureFixturesAndEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingAndBuildingImprovementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |