CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net income (loss)	$ 1,237	$ 14,180	$ (17,306)	$ 24,020
Other comprehensive income (loss), net of tax:
Marketable securities	(34,513)	1,022	(41,657)	(105,842)
Currency translation	(3,538)	(9,215)	(15,309)	(10,589)
Interest rate swap	(733)		(733)
Total other comprehensive loss, net	(38,019)	(7,819)	(55,386)	(115,315)
Comprehensive income (loss)	(36,782)	6,361	(72,692)	(91,295)
Comprehensive income attributable to noncontrolling interest	294	291	976	904
Comprehensive income (loss) attributable to NL stockholders	(37,076)	6,070	(73,668)	(92,199)
Defined Benefit Pension Plans
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	902	530	2,723	1,585
OPEB
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	$ (137)	$ (156)	$ (410)	$ (469)