Income taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Income Tax Disclosure [Line Items]
Dividends received from Kronos Worldwide, Inc.	$ 6,692	$ 6,692
Uncertain tax position	2,714		$ 2,714
Income tax expense (benefit)	(1,421)	(2,705)
Current payable to affiliate	$ 665		$ 665
Kronos
Income Tax Disclosure [Line Items]
Dividends received from Kronos Worldwide, Inc.		$ 6,700