Consolidated Statement of Income - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenues	$ 1,348,223,000	$ 1,401,981,000	$ 1,358,104,000
Cost of Goods and Services Sold	757,775,000	765,369,000	746,241,000
Gross profit	590,448,000	636,612,000	611,863,000
Selling, general and administrative
Selling, general and administrative	290,334,000	330,502,000	324,784,000
Research and development	58,268,000	57,848,000	52,696,000
Restructuring charges (Note 2)	27,381,000	13,846,000	13,247,000
Currency exchange losses, net (Note 5)	8,578,000	19,814,000	2,330,000
Product liability (Note 19) and other operating expense	39,036,000	28,372,000	45,327,000
Operating income	166,851,000	186,230,000	173,479,000
Interest expense	9,432,000	13,589,000	18,881,000
Loss on extinguishment of debt (Note 11)	0	0	1,494,000
Other income, net (Note 15)	(5,684,000)	(11,094,000)	(9,231,000)
Total other expense, net	3,748,000	2,495,000	11,144,000
Income before income taxes	163,103,000	183,735,000	162,335,000
Provision for income taxes (Note 9)	41,941,000	46,086,000	37,220,000
Net income	121,162,000	137,649,000	125,115,000
Net income attributable to noncontrolling interests	(1,061,000)	(1,209,000)	(965,000)
Net income attributable to MSA Safety Incorporated	$ 120,101,000	$ 136,440,000	$ 124,150,000
Basic
Income from continuing operations	$ 3.09	$ 3.52	$ 3.23
Diluted
Income from continuing operations	$ 3.05	$ 3.48	$ 3.18
Dividends per common share (dollars per share)	$ 1.71	$ 1.64	$ 1.49