COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Legal action liabilities	$ 22.4	$ 22.1	$ 22.4	$ 21.2
Insurance Recoveries	52.0	$ 11.0
Reduction in Cost of Goods Sold Due to Insurance Recoveries	9.0
Reduction in Selling and Administration Due to Insurance Recoveries	0.9
Gain in Other Operating Income due to Insurance Recoveries	$ 42.3
Proceeds from Property Damage Portion of Insurance Recoveries			$ 24.0

The gain recorded in other operating income due to insurance recoveries for property damage and business interruption.

No definition available.

Name:	olin_GaininOtherOperatingIncomeduetoInsuranceRecoveries
Namespace Prefix:	olin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow from the property damage portion of the insurance recoveries within proceeds from disposition of property, plant and equipment and gains on disposition of property, plant and equipment.

+ References

No definition available.

+ Details

Name:	olin_ProceedsfromPropertyDamagePortionofInsuranceRecoveries
Namespace Prefix:	olin_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of reduction in cost of goods sold for the reimbursement of costs incurred and expensed in prior periods relating to insurance recoveries for property damage and business interruption.

+ References

No definition available.

+ Details

Name:	olin_ReductioninCostofGoodsSoldDuetoInsuranceRecoveries
Namespace Prefix:	olin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of reduction in selling and administration for the reimbursement of costs incurred and expensed in prior periods relating to insurance recoveries for property damage and business interruption.

+ References

No definition available.

+ Details

Name:	olin_ReductioninSellingandAdministrationDuetoInsuranceRecoveries
Namespace Prefix:	olin_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_CommitmentsAndContingenciesDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount recovered from insurance. These recoveries reduce costs and losses that are reported as a separate line item under operating expenses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

Name:	us-gaap_InsuranceRecoveries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

+ Details

Name:	us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant