Subsequent debt issuance amount based on transactions that occurred after the balance sheet date.

No definition available.

Name:	oln_SubsequentDebtIssuanceAmount
Namespace Prefix:	oln_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oln_SeniorTermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

DEBT Subsequent Event (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
DEBT Subsequent Event (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Jan. 19, 2018	Dec. 31, 2016
2030 Note Issuance
Subsequent Event [Line Items]
Subsequent Debt Issuance, Amount			$ 550.0
Interest rate			5.00%
Debt Repayment on $1,375.0 million Senior Term Loan Facility	$ 550.0
Senior Term Loan Facility
Subsequent Event [Line Items]
Interest rate		3.57%		2.77%
Debt Repayment on $1,375.0 million Senior Term Loan Facility		$ 1,282.5