Additional payments to TDCC related to the supply of Ethylene at producer economics expected to occur in 2017.

No definition available.

Name:	olin_A2017SupplyContractPayment
Namespace Prefix:	olin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Additional payments to TDCC related to the supply of Ethylene at producer economics expected to occur in 2020.

+ References

No definition available.

+ Details

Name:	olin_A2020SupplyContractPayment
Namespace Prefix:	olin_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of amortization recognized in connection with the Ethylene Supply Agreement.

+ References

No definition available.

+ Details

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

- Definition

Amount of other assets acquired at the acquisition date in connection with the Ethylene Supply Agreement and expected to be realized.

+ References

No definition available.

+ Details

Name:	olin_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedEthyleneAsset
Namespace Prefix:	olin_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of upfront payments made upon the closing of the Transactions in order to receive ethylene at producer economics and for certain reservation fees for obtaining additional future ethylene supply at producer economics.

+ References

No definition available.

+ Details

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

- Definition

The cash outflow related to the arrangements for the long-term supply of low cost natural gas-based electricity.

+ References

No definition available.

+ Details

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

- Definition

Amount of other assets in connection with the Ethylene Supply Agreement and expected to be realized.

+ References

No definition available.

+ Details

Name:	olin_SupplyContracts
Namespace Prefix:	olin_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Noncurrent income tax, value-added tax, and other miscellaneous tax receivables

+ References

No definition available.

+ Details

Name:	olin_TaxRelatedReceivableNoncurrent
Namespace Prefix:	olin_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

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

- Definition

Amount, after accumulated amortization, of debt issuance costs classified as noncurrent. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DeferredFinanceCostsNoncurrentNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_EquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of the asset arising from a financial instrument or a contract used to hedge price changes in underlying assets, and which are expected to be converted into cash or otherwise disposed of after a year or beyond the normal operating cycle, if longer.

+ 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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_HedgingAssetsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Amount of other miscellaneous assets expected to be realized or consumed after one year or normal operating cycle, if longer.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherAssetsMiscellaneousNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of noncurrent assets classified as other.

+ References

+ Details

Name:	us-gaap_OtherAssetsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=olin_DCPBusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

OTHER ASSETS (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
OTHER ASSETS (Details) - USD ($) $ in Millions	Oct. 05, 2015	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Other Assets [Abstract]
Investments in non-consolidated affiliates		$ 27.7	$ 25.6	$ 27.7	$ 25.6	$ 26.7
Deferred debt issuance costs		2.8	2.9	2.8	2.9	2.6
Tax-Related Receivable, Noncurrent		16.0	18.2	16.0	18.2	17.5
Interest rate swaps		4.7	3.7	4.7	3.7	7.7
Supply Contracts		554.1	518.8	554.1	518.8	566.7
Other		20.3	19.4	20.3	19.4	23.2
Other assets		625.6	588.6	625.6	588.6	644.4
Business Combination, Separately Recognized Transactions [Line Items]
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Ethylene Asset	$ 416.1
2017 Supply Contract Payment				209.4
Payments under long-term supply contract				0.0	(85.0)	$ (175.7)
Amortization of Supply Contracts		$ 6.3	$ 4.4	12.6	$ 8.7
Minimum
Business Combination, Separately Recognized Transactions [Line Items]
2020 Supply Contract Payment				425.0
Maximum
Business Combination, Separately Recognized Transactions [Line Items]
2020 Supply Contract Payment				$ 465.0
DCP Business
Business Combination, Separately Recognized Transactions [Line Items]
Payments for Supply of Ethylene	$ 433.5