Segments - Financial Data for Continuing Operations for Company's Reportable Business Segments (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Assets employed	$ 18,070		$ 18,170
Total property additions, including the impact of acquisitions	336	$ 2,692
Property additions through business combinations	0	2,433
Reportable Segments
Segment Reporting Information [Line Items]
Assets employed	16,967		16,662
Total property additions, including the impact of acquisitions	325	2,684
Property additions through business combinations	0	2,433
Operating Segments | East Group
Segment Reporting Information [Line Items]
Assets employed	8,711		8,452
Total property additions, including the impact of acquisitions	192	2,063
Property additions through business combinations	0	1,961
Operating Segments | West Group
Segment Reporting Information [Line Items]
Assets employed	7,965		7,941
Total property additions, including the impact of acquisitions	117	605
Property additions through business combinations	0	472
Operating Segments | Magnesia Specialties
Segment Reporting Information [Line Items]
Assets employed	291		269
Total property additions, including the impact of acquisitions	16	16
Corporate
Segment Reporting Information [Line Items]
Assets employed	1,103		$ 1,508
Total property additions, including the impact of acquisitions	11	8
Property additions through business combinations	$ 0	$ 0