Additional vesting percentage for each year of service, after the initial two years of service.

No definition available.

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- Definition

Initial vesting percentage after an employee completes two years of service.

+ References

No definition available.

+ Details

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Namespace Prefix:	oln_
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- Definition

Number of days employees are prohibited from trading out of the fund to which the transfer was made.

+ References

No definition available.

+ Details

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- Definition

Vesting percentage after an employee serves five years.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Term of service after which an employee becomes vested in the plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	oln_
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Period Type:	duration

- Definition

Contribution to an individual retirement account as a percentage of employee's eligible compensation.

+ References

No definition available.

+ Details

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Namespace Prefix:	oln_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of employer contribution to a defined contribution plan based on employees' eligible compensation.

+ References

No definition available.

+ Details

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Namespace Prefix:	oln_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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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Balance Type:	na
Period Type:	duration

- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

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CONTRIBUTING EMPLOYEE OWNERSHIP PLAN (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan Employer Contribution of Eligible Compensation		$ 30.6	$ 29.9	$ 28.6
Defined Contribution Plan Matching Expense		$ 3.7	$ 15.8	$ 14.9
Initial vesting period vested percentage		25.00%
Additional vesting percentage for each additional year of service		25.00%
Vesting percentage after five years		100.00%
Number of days an employee is prohibited from trading out of the fund to which the transfer was made		seven
Defined Contribution Plan, Discretionary Matching Contribution		$ 0.0
Minimum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation		5.00%
Vesting period (in years)		2 years
Maximum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation		7.50%
Vesting period (in years)		5 years
Maximum \| Subsequent Event
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	3.00%