STOCK-BASED COMPENSATION (Details 1) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-Based Payment Arrangement [Abstract]
Stock-based compensation	$ 5.8	$ 10.3	$ 20.0	$ 22.2
Mark-to-market adjustments	(2.0)	2.5	(10.5)	16.6
Total expense	$ 3.8	$ 12.8	$ 9.5	$ 38.8

Increase (decrease) to expense resulting from changes in the market value of underlying common stock in the liabilities associated with employee/director stock options, performance stock awards, restricted stock awards and deferred directors' compensation issued to employees and directors.

No definition available.

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