Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2017

Investments Debt And Equity Securities [Abstract]

Schedule of Marketable Securities

	Fair value measurement level	Market value		Cost basis		Unrealized gain (loss)
		(In thousands)
December 31, 2016
Valhi common stock	1	$	49,731	$	24,347	$	25,384
September 30, 2017
Valhi common stock	1	$	34,926	$	24,347	$	10,579