Document And Entity Information - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Olin Corporation
Entity Central Index Key	0000074303
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding	167,000,370
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float		$ 5,008,796,298