Goodwill and Other Intangible Assets - Intangible Assets Deemed to Indefinite Life that are Therefore Not Amortized (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	$ 34.1	$ 35.8
Operating Permits
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	6.6	6.6
Use Rights
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	25.0	26.7
Trade names
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	2.5	2.5
Building Materials Business
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	31.6	33.3
Building Materials Business | Operating Permits
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	6.6	6.6
Building Materials Business | Use Rights
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	25.0	26.7
Building Materials Business | Trade names
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	0.0	0.0
Magnesia Specialties
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	2.5	2.5
Magnesia Specialties | Operating Permits
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	0.0	0.0
Magnesia Specialties | Use Rights
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	0.0	0.0
Magnesia Specialties | Trade names
Indefinite Lived Intangible Assets By Major Class [Line Items]
Indefinite life intangible assets	$ 2.5	$ 2.5