Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2022

Investments Debt And Equity Securities [Abstract]

Schedule of Marketable Securities

	Fair value
	measurement	Market		Cost		Unrealized
	level	value		basis		gain
		(In thousands)
December 31, 2021
Noncurrent assets
Valhi common stock	1	$	34,435	$	24,347	$	10,088
March 31, 2022
Noncurrent assets
Valhi common stock	1	$	35,106	$	24,347	$	10,759