CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales	$ 28,413	$ 29,948
Cost of sales	18,910	20,262
Gross margin	9,503	9,686
Selling, general and administrative expense	5,130	5,162
Other operating income (expense):
Insurance recoveries	163	50
Other income, net	619
Corporate expense	(7,953)	(5,320)
Loss from operations	(2,798)	(746)
Equity in earnings of Kronos Worldwide, Inc.	21,479	11,175
Other income (expense):
Securities transactions, net	(1,581)
Other components of net periodic pension and OPEB cost	(99)	(177)
Interest and dividend income	1,072	696
Interest expense	(8)	(7)
Income before income taxes	18,065	10,941
Income tax expense	3,330	2,179
Net income	14,735	8,762
Noncontrolling interest in net income of subsidiary	487	412
Net income attributable to NL stockholders	$ 14,248	$ 8,350
Amounts attributable to NL stockholders:
Basic and diluted net income per share	$ 0.29	$ 0.17
Weighted average shares used in the calculation of net income per share	48,715	48,706