STOCK-BASED COMPENSATION (Details 1) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-Based Payment Arrangement [Abstract]
Stock-based compensation	$ 8.3	$ 9.6	$ 12.8	$ 14.2
Mark-to-market adjustments	(1.6)	(5.6)	(0.1)	(8.5)
Total expense	$ 6.7	$ 4.0	$ 12.7	$ 5.7

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