CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 53,360	$ 16,103	$ 28,035
Other comprehensive income (loss), net of tax:
Currency translation	(1,660)	3,268	(409)
Defined benefit pension plans	12,236	(2,447)	(2,971)
Other postretirement benefit plans	(143)	(320)	(40)
Total other comprehensive income (loss), net	10,433	501	(3,420)
Comprehensive income	63,793	16,604	24,615
Comprehensive income attributable to noncontrolling interest	2,172	1,423	2,191
Comprehensive income attributable to NL stockholders	$ 61,621	$ 15,181	$ 22,424