CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net income	$ 14,735	$ 8,762
Other comprehensive income (loss), net of tax:
Marketable securities		(1,722)
Currency translation	2,591	1,771
Interest rate swap		112
Total other comprehensive income, net	3,501	980
Comprehensive income	18,236	9,742
Comprehensive income attributable to noncontrolling interest	487	412
Comprehensive income attributable to NL stockholders	17,749	9,330
Defined Benefit Pension Plans
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	983	867
OPEB
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	$ (73)	$ (48)