CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Net sales	$ 103,846	$ 92,045	$ 83,196
Cost of sales	71,598	64,471	58,869
Gross margin	32,248	27,574	24,327
Selling, general and administrative expense	18,641	18,246	17,747
Other operating income (expense):
Insurance recoveries	10,368	9,427	3,311
Litigation settlement gain	1,150,000		14,964
Assets held for sale write-down			(1,162)
Other income, net	186	29	3,612
Goodwill impairment			(6,406)
Corporate expense	(21,323)	(87,042)	(28,958)
Income (loss) from operations	2,838	(68,258)	(8,059)
Equity in earnings (loss) of Kronos Worldwide, Inc.	30,161	(31,007)	66,437
Other income (expense):
Securities transactions, net	16	11	16,567
Interest and dividends	1,618	2,927	3,200
Interest expense		(127)	(1,023)
Income (loss) from continuing operations before taxes	34,633	(96,454)	77,122
Income tax expense (benefit)	5,003	(41,911)	19,933
Income (loss) from continuing operations	29,630	(54,543)	57,189
Income from discontinued operations, net of tax			21,893
Net income (loss)	29,630	(54,543)	79,082
Noncontrolling interest in net income of subsidiary	1,131	790	4,546
Net income (loss) attributable to NL stockholders	28,499	(55,333)	74,536
Amounts attributable to NL stockholders:
Income (loss) from continuing operations	28,499	(55,333)	56,730
Income from discontinued operations			17,806
Net income (loss) attributable to NL stockholders	$ 28,499	$ (55,333)	$ 74,536
Basic and diluted net income (loss) per share:
Continuing operations	$ 0.59	$ (1.14)	$ 1.16
Discontinued operations			$ 0.37
Net income (loss) per share	$ 0.59	$ (1.14)	$ 1.53
Cash dividends per share		$ 0.50	$ 0.50
Weighted average shares used in the calculation of net income (loss) per share	48,679	48,672	48,667