CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Noncontrolling interest in subsidiary
Beginning Balance at Dec. 31, 2019	$ 327,213	$ 6,094	$ 299,102	$ 251,000	$ (251,690)	$ 22,707
Net income	7,374			6,499		875
Other comprehensive income, net of tax	(3,831)				(3,831)
Issuance of NL common stock	100	4	96
Dividends paid	(3,902)			(3,902)
Dividends paid to noncontrolling interest	(338)					(338)
Other, net	(87)		(105)			18
Ending Balance at Jun. 30, 2020	326,529	6,098	299,093	253,597	(255,521)	23,262
Beginning Balance at Mar. 31, 2020	318,205	6,094	298,865	250,960	(260,845)	23,131
Net income	4,872			4,589		283
Other comprehensive income, net of tax	5,324				5,324
Issuance of NL common stock	100	4	96
Dividends paid	(1,952)			(1,952)
Dividends paid to noncontrolling interest	(170)					(170)
Other, net	150		132			18
Ending Balance at Jun. 30, 2020	326,529	6,098	299,093	253,597	(255,521)	23,262
Beginning Balance at Dec. 31, 2020	335,349	6,098	299,093	257,875	(251,189)	23,472
Net income	27,171			25,954		1,217
Other comprehensive income, net of tax	3,107				3,107
Issuance of NL common stock	101	2	99
Dividends paid	(5,855)			(5,855)
Dividends paid to noncontrolling interest	(669)					(669)
Other, net	(629)		1,117			(1,746)
Ending Balance at Jun. 30, 2021	358,575	6,100	300,309	277,974	(248,082)	22,274
Beginning Balance at Mar. 31, 2021	346,819	6,098	300,097	268,205	(249,564)	21,983
Net income	13,305			12,697		608
Other comprehensive income, net of tax	1,482				1,482
Issuance of NL common stock	101	2	99
Dividends paid	(2,928)			(2,928)
Dividends paid to noncontrolling interest	(330)					(330)
Equity transactions with noncontrollinginterest, net and other	126		113			13
Ending Balance at Jun. 30, 2021	$ 358,575	$ 6,100	$ 300,309	$ 277,974	$ (248,082)	$ 22,274