CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 17,800	$ 7,760	$ 68,160	$ 6,744
Other comprehensive income (loss), net of tax:
Marketable securities	(5,260)	6,983	(9,851)	9,182
Currency translation	5,908	1,777	10,604	3,628
Interest rate swap	362	145	390	(583)
Total other comprehensive income, net	1,699	9,590	2,996	14,278
Comprehensive income	19,499	17,350	71,156	21,022
Comprehensive income attributable to noncontrolling interest	328	388	1,171	996
Comprehensive income attributable to NL stockholders	19,171	16,962	69,985	20,026
Defined Benefit Pension Plans
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	738	817	1,998	2,447
OPEB
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	$ (49)	$ (132)	$ (145)	$ (396)