The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

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The aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale.

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The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

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Aggregate cash proceeds received from a combination of transactions that are classified as investing activities in which assets, which may include one or more investments, are sold to third-party buyers. This element can be used by entities to aggregate proceeds from all asset sales that are classified as investing activities.

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Indicates title and position of individual or name of group identified as chief operating decision maker (CODM) for segment reporting.

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Description of how chief operating decision maker (CODM) uses reported segment profit (loss) measure to assess performance and allocate resource.

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Segment Results (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Jun. 30, 2024	Sep. 30, 2025
Segment Reporting Information [Line Items]
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]				President and Chief Executive Officer [Member]
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description				Segment operating income (loss) is the measure of segment profit or loss reviewed by the CODM.
Mineral Fiber [Member]
Segment Reporting Information [Line Items]
Proceeds from Sale of Property, Plant, and Equipment	$ 1.0	$ 9.4
Gain on sale of properties	$ 0.9	4.6
Impairment loss		$ 4.9
Architectural Specialties [Member]
Segment Reporting Information [Line Items]
Gain on sale of properties			$ 0.0
Proceeds from the sale of assets			$ 2.1