Segments - Schedule of Consolidated Earnings from Continuing Operations Before Income Tax Expense (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Segment Revenues	$ 1,811	$ 1,764	$ 3,164	$ 3,015
Labor and benefits expense	223	214	421	412
Raw materials expense	138	157	220	241
Depreciation, depletion and amortization expense	158	134	302	250
Energy expense	83	85	155	158
External freight expense	101	98	179	170
Other costs of revenues	564	559	1,008	994
Selling, general and administrative expenses	109	117	239	236
Acquisition, divestiture and integration expenses	2	21	4	41
Other operating (income) expense, net	(25)	(19)	(16)	(1,306)
Segment Earnings (Loss) from Operations	458	398	652	1,819
Interest expense	57	40	114	80
Other nonoperating income, net	(10)	(14)	(20)	(46)
Earnings before income tax expense	411	372	558	1,785
Operating Segments | East Group
Segment Reporting Information [Line Items]
Segment Revenues	868	823	1,466	1,349
Labor and benefits expense	108	103	200	192
Raw materials expense	21	23	22	23
Depreciation, depletion and amortization expense	80	65	152	114
Energy expense	38	40	69	71
External freight expense	32	32	51	52
Other costs of revenues	285	277	475	454
Selling, general and administrative expenses	40	35	81	69
Acquisition, divestiture and integration expenses	0	0	0	0
Other operating (income) expense, net	(2)	(1)	(2)	(4)
Segment Earnings (Loss) from Operations	266	249	418	378
Operating Segments | West Group
Segment Reporting Information [Line Items]
Segment Revenues	853	860	1,520	1,505
Labor and benefits expense	105	102	200	201
Raw materials expense	112	129	188	208
Depreciation, depletion and amortization expense	73	64	140	127
Energy expense	37	37	69	71
External freight expense	60	58	111	103
Other costs of revenues	253	252	494	488
Selling, general and administrative expenses	49	46	101	95
Acquisition, divestiture and integration expenses	0	1	0	16
Other operating (income) expense, net	(1)	0	3	(1,274)
Segment Earnings (Loss) from Operations	165	171	214	1,470
Operating Segments | Magnesia Specialties
Segment Reporting Information [Line Items]
Segment Revenues	90	81	178	161
Labor and benefits expense	10	9	21	19
Raw materials expense	5	5	10	10
Depreciation, depletion and amortization expense	4	4	8	7
Energy expense	8	8	17	16
External freight expense	9	8	17	15
Other costs of revenues	18	20	31	38
Selling, general and administrative expenses	5	5	10	10
Acquisition, divestiture and integration expenses	0	0	0	0
Other operating (income) expense, net	0	(3)	0	(2)
Segment Earnings (Loss) from Operations	31	25	64	48
Operating Segments | Reportable Segments
Segment Reporting Information [Line Items]
Segment Revenues	1,811	1,764	3,164	3,015
Labor and benefits expense	223	214	421	412
Raw materials expense	138	157	220	241
Depreciation, depletion and amortization expense	157	133	300	248
Energy expense	83	85	155	158
External freight expense	101	98	179	170
Other costs of revenues	556	549	1,000	980
Selling, general and administrative expenses	94	86	192	174
Acquisition, divestiture and integration expenses	0	1	0	16
Other operating (income) expense, net	(3)	(4)	1	(1,280)
Segment Earnings (Loss) from Operations	462	445	696	1,896
Corporate
Segment Reporting Information [Line Items]
Segment Revenues	0	0	0	0
Labor and benefits expense	0	0	0	0
Raw materials expense	0	0	0	0
Depreciation, depletion and amortization expense	1	1	2	2
Energy expense	0	0	0	0
External freight expense	0	0	0	0
Other costs of revenues	8	10	8	14
Selling, general and administrative expenses	15	31	47	62
Acquisition, divestiture and integration expenses	2	20	4	25
Other operating (income) expense, net	(22)	(15)	(17)	(26)
Segment Earnings (Loss) from Operations	$ (4)	$ (47)	$ (44)	$ (77)