Income taxes - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Line Items]
Dividends received from Kronos Worldwide, Inc.	$ 20,075	$ 20,074
Kronos
Income Tax Disclosure [Line Items]
Dividends received from Kronos Worldwide, Inc.	$ 20,100	$ 20,100

Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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