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Business Segments - Financial Data for Continuing Operations for Company's Reportable Business Segments (Detail) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2020
Segment Reporting Information [Line Items]          
Total revenues $ 1,377.9 $ 1,270.6 $ 2,360.3 $ 2,228.9  
Earnings (Loss) from operations 307.5 306.4 406.8 364.2  
Assets employed 11,223.1   11,223.1   $ 10,580.8
Products and Services          
Segment Reporting Information [Line Items]          
Total revenues 1,295.3 1,189.5 2,217.2 2,080.5  
Building Materials Business          
Segment Reporting Information [Line Items]          
Total revenues 1,302.1 1,217.0 2,213.6 2,109.6  
Earnings (Loss) from operations 299.6 303.1 393.1 360.6  
Assets employed 10,506.3   10,506.3   9,698.0
Building Materials Business | Products and Services          
Segment Reporting Information [Line Items]          
Total revenues 1,225.3 1,140.6 2,082.0 1,971.7  
Operating Segments | Building Materials Business East Group          
Segment Reporting Information [Line Items]          
Total revenues 635.3 534.5 1,030.2 916.5  
Earnings (Loss) from operations 197.8 169.9 259.5 204.7  
Assets employed 5,110.4   5,110.4   4,342.5
Operating Segments | Building Materials Business East Group | Products and Services          
Segment Reporting Information [Line Items]          
Total revenues 596.5 499.7 969.1 857.6  
Operating Segments | Building Materials Business West Group          
Segment Reporting Information [Line Items]          
Total revenues 666.8 682.5 1,183.4 1,193.1  
Earnings (Loss) from operations 101.8 133.2 133.6 155.9  
Assets employed 5,395.9   5,395.9   5,355.5
Operating Segments | Building Materials Business West Group | Products and Services          
Segment Reporting Information [Line Items]          
Total revenues 628.8 640.9 1,112.9 1,114.1  
Operating Segments | Magnesia Specialties          
Segment Reporting Information [Line Items]          
Total revenues 75.8 53.6 146.7 119.3  
Earnings (Loss) from operations 23.1 13.2 46.7 34.9  
Assets employed 168.3   168.3   167.9
Operating Segments | Magnesia Specialties | Products and Services          
Segment Reporting Information [Line Items]          
Total revenues 70.0 48.9 135.2 108.8  
Operating Segments | Building Materials Business          
Segment Reporting Information [Line Items]          
Total revenues 1,302.1 1,217.0 2,213.6 2,109.6  
Corporate          
Segment Reporting Information [Line Items]          
Earnings (Loss) from operations (15.2) $ (9.9) (33.0) $ (31.3)  
Assets employed $ 548.5   $ 548.5   $ 714.9