Fair Value Measurements (Details) - EBP 032 - USD ($)	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	$ 1,489,888,745	$ 1,344,344,557
EBP, Fair Value, Investment, NAV, Unfunded Commitment	$ 0
EBP, Fair Value, Investment, NAV, Redemption, Description	Investments may be redeemed on a daily basis and it is probable that the Plan will sell the investments for the NAV.
Fair Value Investment NAV Redemption Notice Period Applicable	no
Investment, Identifier [Axis]: Galliard Managed Income Fund D
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	$ 77,550,989	76,464,939
Investment, Identifier [Axis]: JPMCB Core Plus Bond
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	36,604,152	32,749,006
Investment, Identifier [Axis]: Northern Trust All Country World ex-US Investable Market Index
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	52,662,967	43,087,822
Investment, Identifier [Axis]: Northern Trust Extended Equity Market Index
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	18,147,027	16,451,996
Investment, Identifier [Axis]: Northern Trust S&P 500 Index
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	260,535,622	220,037,383
Investment, Identifier [Axis]: T. Rowe Price Age Based Funds
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	772,181,199	678,213,811
Mutual funds
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	165,884,532	167,466,925
Mutual funds \| Fair Value, Inputs, Level 1
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	165,884,532	167,466,925
Olin Corporation common stock
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	26,901,921	42,871,537
Olin Corporation common stock \| Fair Value, Inputs, Level 1
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	26,901,921	42,871,537
Self-directed brokerage investment
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	79,420,336	67,001,138
Self-directed brokerage investment \| Fair Value, Inputs, Level 1
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	79,420,336	67,001,138
Total categorized investments measured at fair value
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	272,206,789	277,339,600
Total categorized investments measured at fair value \| Fair Value, Inputs, Level 1
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	272,206,789	277,339,600
Collective trust funds with fair value measured at net asset value (1)
EBP, Investment, Fair Value and NAV [Line Items]
Investments, at fair value	$ 1,217,681,956	$ 1,067,004,957

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Description of information about redemption of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), that is measured at net asset value (NAV) per share as practical expedient for estimate of fair value. Includes, but is not limited, term, condition, circumstance in which otherwise redeemable investment might not be redeemable, and restriction on ability to sell investment at measurement date.

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Amount of unfunded commitment for investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), that is fair value measured at net asset value (NAV) per share as practical expedient.

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Fair value of investment, excluding plan interest in master trust, held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, derivative, investment measured at net asset value per share as practical expedient, and insurance contract not meeting fully-benefit responsive investment criteria.

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