CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Net sales	$ 26,473	$ 24,209	$ 79,102	$ 69,701
Cost of sales	18,331	16,695	54,598	48,557
Gross margin	8,142	7,514	24,504	21,144
Selling, general and administrative expense	4,710	4,537	13,872	13,790
Other operating income (expense):
Insurance recoveries	8,843	2,198	10,041	3,774
Other income	9	9	140	23
Corporate expense and other, net	(4,304)	(5,627)	(17,582)	(26,869)
Income (loss) from operations	7,980	(443)	3,231	(15,718)
Equity in earnings (loss) of Kronos Worldwide, Inc.	9,689	(9,101)	24,101	(31,891)
Other income (expense):
Interest and dividend income	311	725	1,333	2,209
Interest expense		(10)		(127)
Income (loss) before income taxes	17,980	(8,829)	28,665	(45,527)
Income tax expense (benefit)	3,800	(3,145)	4,645	(23,827)
Net income (loss)	14,180	(5,684)	24,020	(21,700)
Noncontrolling interest in net income of subsidiary	291	256	904	613
Net income (loss) attributable to NL stockholders	$ 13,889	$ (5,940)	$ 23,116	$ (22,313)
Amounts attributable to NL stockholders:
Basic and diluted net income (loss) per share	$ 0.29	$ (0.12)	$ 0.47	$ (0.46)
Cash dividend per share		$ 0.125		$ 0.375
Weighted average shares used in the calculation of net income (loss) per share	48,683	48,674	48,678	48,671