v3.26.3
Segment Results (Narrative) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2025
Sep. 30, 2026
Segment Reporting [Line Items]    
Number Of Reportable Segments Not Disclosed Flag   true
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 [Line Items]    
Proceeds from Sale of Property, Plant, and Equipment $ 1.0  
Gain on sale of properties $ 0.9