Revenues and Gross Profit - Total Revenues and Gross Profit (Loss) by Product Line (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Product Information [Line Items]
Total Revenues	$ 1,820.8	$ 1,641.7	$ 3,174.9	$ 2,872.5
Gross profit (loss)	560.4	425.2	863.2	581.3
Interproduct Revenues
Product Information [Line Items]
Total Revenues	(121.1)	(102.4)	(208.6)	(191.5)
Corporate
Product Information [Line Items]
Gross profit (loss)	(3.4)	1.6	(1.4)	(6.4)
Building Materials Business
Product Information [Line Items]
Total Revenues	1,740.3	1,560.0	3,011.0	2,713.8
Building Materials Business | Operating Segments
Product Information [Line Items]
Total Revenues	1,740.3	1,560.0	3,011.0	2,713.8
Gross profit (loss)	536.1	399.1	811.9	537.5
Magnesia Specialties | Operating Segments
Product Information [Line Items]
Total Revenues	80.5	81.7	163.9	158.7
Gross profit (loss)	27.7	24.5	52.7	50.2
Aggregates | Building Materials Business | Operating Segments | Reportable Subsegments
Product Information [Line Items]
Total Revenues	1,151.4	1,057.6	2,063.3	1,814.2
Gross profit (loss)	370.9	307.3	608.9	410.0
Cement | Building Materials Business | Operating Segments | Reportable Subsegments
Product Information [Line Items]
Total Revenues	197.7	162.5	366.2	300.8
Gross profit (loss)	93.3	50.7	140.4	77.5
Ready Mixed Concrete | Building Materials Business | Operating Segments | Reportable Subsegments
Product Information [Line Items]
Total Revenues	271.4	226.6	491.3	517.8
Gross profit (loss)	35.4	14.6	46.6	36.6
Asphalt and Paving | Building Materials Business | Operating Segments | Reportable Subsegments
Product Information [Line Items]
Total Revenues	240.9	215.7	298.8	272.5
Gross profit (loss)	$ 36.5	$ 26.5	$ 16.0	$ 13.4