DISCONTINUED OPERATIONS - Net Earnings (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS ATTRIBUTABLE TO OWENS CORNING, NET OF TAX	$ (2)	$ 1	$ (229)	$ (318)
Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Revenue	0	301	426	877
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	0	245	340	679
Disposal Group, Including Discontinued Operation, General and Administrative Expense	0	18	27	53
Disposal Group, Including Discontinued Operation, Loss from classification as held for sale	8	28	183	409
Disposal Group, Including Discontinued Operation, Other Expense (Income), Net	0	10	6	15
Total operating expenses	8	56	216	477
Disposal Group, Including Discontinued Operation, Interest Expense	0	2	0	4
Disposal Group, Including Discontinued Operation, Income Tax Expense (Benefit)	(6)	(3)	99	35
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS ATTRIBUTABLE TO OWENS CORNING, NET OF TAX	$ (2)	$ 1	$ (229)	$ (318)

Disposal Group, Including Discontinued Operation, Income Tax Expense (Benefit)

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Disposal Group, Including Discontinued Operation, Loss from classification as held for sale

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Disposal Group, Including Discontinued Operation, Other Expense (Income), Net

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Amount of costs of goods sold attributable to disposal group, including, but not limited to, discontinued operation.

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Amount of general and administrative expense attributable to disposal group, including, but not limited to, discontinued operation.

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Amount of interest expense attributable to disposal group, including, but not limited to, discontinued operation.

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Amount of revenue attributable to disposal group, including, but not limited to, discontinued operation.

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Amount after tax of income (loss) from a discontinued operation attributable to the parent. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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