CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss	Noncontrolling interest in subsidiary
Beginning Balance at Dec. 31, 2014	$ 251,450	$ 6,085	$ 300,388	$ 112,588	$ (182,039)	$ 14,428
Net income (loss)	(22,716)			(23,909)		1,193
Other comprehensive income (loss), net of tax	(63,319)				(63,319)
Issuance of NL common stock	66	1	65
Cash dividends	(330)					(330)
Other, net	100		90			10
Ending Balance at Dec. 31, 2015	165,251	6,086	300,543	88,679	(245,358)	15,301
Net income (loss)	16,693			15,325		1,368
Other comprehensive income (loss), net of tax	12,512				12,512
Issuance of NL common stock	37	2	35
Cash dividends	(332)					(332)
Other, net	109		96			13
Ending Balance at Dec. 31, 2016	194,270	6,088	300,674	104,004	(232,846)	16,350
Net income (loss)	117,826			116,100		1,726
Other comprehensive income (loss), net of tax	41,109				41,109
Issuance of NL common stock	83	1	82
Cash dividends	(333)					(333)
Other, net	123		110			13
Ending Balance at Dec. 31, 2017	$ 353,078	$ 6,089	$ 300,866	$ 220,104	$ (191,737)	$ 17,756