XML 70 R59.htm IDEA: XBRL DOCUMENT
v3.26.1

DEFINED CONTRIBUTION PLAN (Details) - USD ($) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2026 | Jun. 30, 2025 | Jun. 30, 2026 | Jun. 30, 2025
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Defined Contribution Plan Employer Contribution of Eligible Compensation | $ 11,700,000 | $ 9,800,000 | $ 21,700,000 | $ 20,100,000
Employer matching contributions to employee ownership plan | 4,300,000 | 4,300,000 | 8,700,000 | 8,500,000
Total Defined Contribution Plan Expense | $ 16,000,000.0 | $ 14,100,000 | $ 30,400,000 | $ 28,600,000
Minimum |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation | 5.00% |  | 5.00% |
Maximum |  |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |  |
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation | 7.50% |  | 7.50% |

X
- Definition Contribution to an individual retirement account as a percentage of employee's eligible compensation. + References No definition available. + Details
Name: | oln_ContributionToIndividualRetirementAccountPercentageOfEmployeesEligibleCompensation
Namespace Prefix: | oln_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of employer contribution to a defined contribution plan based on employees' eligible compensation. + References No definition available. + Details
Name: | oln_DefinedContributionPlanEmployerContributionOfEligibleCompensation
Namespace Prefix: | oln_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Total Defined Contribution Plan Expense + References No definition available. + Details
Name: | oln_TotalDefinedContributionPlanExpense
Namespace Prefix: | oln_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 70 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480794/715-70-50-1 + Details
Name: | us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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 715 -SubTopic 70 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480794/715-70-50-1 + Details
Name: | us-gaap_DefinedContributionPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
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: |