Investment in Kronos Worldwide, Inc. - Selected Financial Information of Kronos Income Statement (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule Of Equity Method Investments [Line Items]
Net sales	$ 34,556	$ 28,426	$ 106,733	$ 84,537
Cost of sales	23,634	21,098	73,470	59,412
Income from operations	2,284	(308)	9,143	2,240
Income tax expense (benefit)	1,054	1,163	5,460	(3,616)
Net income	10,313	3,872	36,267	10,371
Kronos
Schedule Of Equity Method Investments [Line Items]
Net sales	499,800	416,900	1,443,400	1,223,900
Cost of sales	376,800	336,300	1,115,700	959,400
Income from operations	57,300	19,300	135,100	95,800
Income tax expense (benefit)	12,100	1,800	27,300	15,300
Net income	$ 36,000	$ 8,100	$ 81,300	$ 53,700