Investment in Kronos Worldwide, Inc. - Selected Financial Information of Kronos Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 175,104	$ 171,164
Property and equipment, net	28,461	28,950
Other noncurrent assets	5,321	5,262
Total assets	559,080	548,150
Current liabilities	24,878	27,507
Accrued pension costs	5,962	6,392
Other	3,673	3,780
Stockholders' equity	324,836	311,877
Total liabilities and equity	559,080	548,150
Kronos
Schedule Of Equity Method Investments [Line Items]
Current assets	1,200,200	1,218,300
Property and equipment, net	507,100	524,600
Investment in TiO2 joint venture	106,700	103,300
Other noncurrent assets	182,600	190,500
Total assets	1,996,600	2,036,700
Current liabilities	255,200	260,200
Long-term debt	465,900	486,700
Accrued pension costs	355,800	372,600
Other	118,800	120,700
Stockholders' equity	800,900	796,500
Total liabilities and equity	$ 1,996,600	$ 2,036,700