Business Segments - Financial Data for Continuing Operations for Company's Reportable Business Segments (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Oct. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Total revenues	$ 250.0	$ 1,230.8	$ 982.4
Earnings (Loss) from operations		59.9	99.3
Products and Services
Segment Reporting Information [Line Items]
Total revenues		1,147.8	921.9
Building Materials Business
Segment Reporting Information [Line Items]
Total revenues		1,153.8	911.5
Earnings (Loss) from operations		71.0	93.6
Building Materials Business | Products and Services
Segment Reporting Information [Line Items]
Total revenues		1,077.0	856.6
Operating Segments | Building Materials Business East Group
Segment Reporting Information [Line Items]
Total revenues		418.8	394.9
Earnings (Loss) from operations		28.0	61.7
Operating Segments | Building Materials Business East Group | Products and Services
Segment Reporting Information [Line Items]
Total revenues		394.6	372.5
Operating Segments | Building Materials Business West Group
Segment Reporting Information [Line Items]
Total revenues		735.0	516.6
Earnings (Loss) from operations		43.0	31.9
Operating Segments | Building Materials Business West Group | Products and Services
Segment Reporting Information [Line Items]
Total revenues		682.4	484.1
Operating Segments | Magnesia Specialties
Segment Reporting Information [Line Items]
Total revenues		77.0	70.9
Earnings (Loss) from operations		21.5	23.5
Operating Segments | Magnesia Specialties | Products and Services
Segment Reporting Information [Line Items]
Total revenues		70.8	65.3
Operating Segments | Building Materials Business
Segment Reporting Information [Line Items]
Total revenues		1,153.8	911.5
Corporate
Segment Reporting Information [Line Items]
Earnings (Loss) from operations		$ (32.6)	$ (17.8)