CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Net sales	$ 29,948	$ 27,075
Cost of sales	20,263	18,870
Gross margin	9,685	8,205
Selling, general and administrative expense	5,159	4,852
Other operating income (expense):
Insurance recoveries	50	90
Corporate expense	(5,499)	(5,649)
Loss from operations	(923)	(2,206)
Equity in earnings (losses) of Kronos Worldwide, Inc.	11,175	(1,150)
Other income (expense):
Interest and dividend income	696	353
Interest expense	7
Income (loss) before income taxes	10,941	(3,003)
Income tax expense (benefit)	2,179	(822)
Net income (loss)	8,762	(2,181)
Noncontrolling interest in net income of subsidiary	412	288
Net income (loss) attributable to NL stockholders	$ 8,350	$ (2,469)
Amounts attributable to NL stockholders:
Basic and diluted net income (loss) per share	$ 0.17	$ (0.05)
Weighted average shares used in the calculation of net income (loss) per share	48,706	48,692