Investment in Kronos Worldwide, Inc. - Selected Financial Information of Kronos Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 159,903	$ 237,958
Property and equipment, net	23,709	24,026
Other noncurrent assets	616	1,034
Total assets	464,220	578,258
Current liabilities	20,580	91,062
Other noncurrent liabilities	1,277	6,259
Stockholders' equity	358,769	396,904
Total liabilities and equity	464,220	578,258
Kronos | Reportable Legal Entities
Schedule Of Equity Method Investments [Line Items]
Current assets	994,500	1,105,300
Property and equipment, net	724,300	694,100
Other noncurrent assets	98,000	114,100
Total assets	1,816,800	1,913,500
Current liabilities	368,800	476,600
Long-term debt	557,400	429,100
Accrued pension costs	80,900	117,500
Other noncurrent liabilities	58,600	73,300
Stockholders' equity	751,100	817,000
Total liabilities and equity	$ 1,816,800	$ 1,913,500