Investment in Kronos Worldwide, Inc. - Changes in Carrying Value of Investment (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule Of Equity Method Investments [Line Items]
Balance at the beginning of the period			$ 284,523,000
Equity in earnings of Kronos	9,689,000	(9,101,000)	24,101,000	(31,891,000)
Dividends received from Kronos			(15,849,000)	(15,849,000)
Balance at the end of the period	274,132,000		274,132,000
Kronos
Schedule Of Equity Method Investments [Line Items]
Balance at the beginning of the period			284,523,000
Equity in earnings of Kronos			24,101,000
Dividends received from Kronos			(15,849,000)
Other, principally equity in Kronos' other comprehensive loss			(18,700,000)
Balance at the end of the period	$ 274,132,000		$ 274,132,000