Condensed Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Net sales	$ 340,197	$ 304,392	$ 989,915	$ 959,975
Cost of products sold	194,199	172,160	556,263	528,799
Gross profit	145,998	132,232	433,652	431,176
Selling, general and administrative	87,450	64,793	246,339	214,066
Research and development	14,946	13,851	42,149	41,723
Restructuring charges (Note 4)	3,853	7,603	12,239	18,475
Currency exchange losses (gains), net (Note 6)	100	2,759	(359)	3,821
Product liability expense (Note 18)	10,688	2,077	25,235	4,878
Operating income	28,961	41,149	108,049	148,213
Interest expense	3,764	2,305	7,847	7,907
Other income, net	(2,266)	(1,117)	(8,773)	(4,376)
Total other expense (income), net	1,498	1,188	(926)	3,531
Income before income taxes	27,463	39,961	108,975	144,682
Provision for income taxes (Note 10)	8,640	11,727	28,165	36,251
Net income	18,823	28,234	80,810	108,431
Net income attributable to noncontrolling interests	0	(200)	(448)	(668)
Net income attributable to MSA Safety Incorporated	$ 18,823	$ 28,034	$ 80,362	$ 107,763
Earnings per share attributable to MSA Safety Incorporated common shareholders (Note 9):
Basic (in dollars per share)	$ 0.48	$ 0.72	$ 2.05	$ 2.77
Diluted (in dollars per share)	0.48	0.71	2.04	2.74
Dividends per common share (in dollars per share)	$ 0.44	$ 0.43	$ 1.31	$ 1.28