Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2021

Investments Debt And Equity Securities [Abstract]

Classification of Marketable Securities

	Fair value
	measurement	Market		Cost		Unrealized
Marketable security	level	value		basis		gain (loss)
		(In millions)
December 31, 2020:
Valhi common stock	1	$	2.1	$	3.2	$	(1.1	)
NL and CompX common stocks	1		.1		.1		-
Total		$	2.2	$	3.3	$	(1.1	)
September 30, 2021:
Valhi common stock	1	$	3.3	$	3.2	$	.1
NL and CompX common stocks	1		.1		.1		-
Total		$	3.4	$	3.3	$	.1