Marketable securities - Schedule of Marketable Securities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Market value, Current assets	$ 53,149	$ 70,164
Market value, Noncurrent assets	18,194	26,350
Level 1 | Valhi Inc | Common stock
Marketable Securities [Line Items]
Market value, Noncurrent assets	18,194	26,350
Cost or amortized cost, Noncurrent assets	24,347	24,347
Unrealized gain (loss), Noncurrent assets	(6,153)	2,003
Level 2 | Fixed income securities
Marketable Securities [Line Items]
Market value, Current assets	53,149	70,164
Cost or amortized cost, Current Assets	53,181	70,226
Unrealized gain (loss), Current assets	$ (32)	$ (62)