CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Net sales	$ 28,918	$ 26,848	$ 56,808	$ 52,629
Cost of sales	19,758	18,235	39,082	36,267
Gross margin	9,160	8,613	17,726	16,362
Selling, general and administrative expense	4,854	4,701	9,719	9,162
Other operating income (expense):
Insurance recoveries	233	411	3,367	1,198
Other income	17		17	131
Corporate expense	(5,656)	(9,008)	(9,487)	(13,278)
Income (loss) from operations	(1,100)	(4,685)	1,904	(4,749)
Equity in earnings (losses) of Kronos Worldwide, Inc.	(48,589)	10,069	(42,984)	14,412
Other income - interest and dividend income	282	297	584	1,022
Income (loss) before income taxes	(49,407)	5,681	(40,496)	10,685
Income tax expense (benefit)	(20,507)	(125)	(21,953)	845
Net income (loss)	(28,900)	5,806	(18,543)	9,840
Noncontrolling interest in net income of subsidiary	367	334	682	613
Net income (loss) attributable to NL stockholders	$ (29,267)	$ 5,472	$ (19,225)	$ 9,227
Amounts attributable to NL stockholders:
Basic and diluted net income per share	$ (0.60)	$ 0.11	$ (0.39)	$ 0.19
Weighted average shares used in the calculation of net income per share	48,687	48,678	48,685	48,676