Consolidated Statement of Income - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues	$ 1,401,981,000	$ 1,358,104,000	$ 1,196,809,000
Cost of Goods and Services Sold	765,369,000	746,241,000	657,918,000
Gross profit	636,612,000	611,863,000	538,891,000
Selling, general and administrative
Selling, general and administrative	330,502,000	324,784,000	300,062,000
Research and development	57,848,000	52,696,000	50,061,000
Restructuring charges (Note 2)	13,846,000	13,247,000	17,632,000
Currency exchange losses, net (Note 5)	19,814,000	2,330,000	5,127,000
Product liability (Note 19) and other operating expense	28,372,000	45,327,000	126,432,000
Operating income	186,230,000	173,479,000	39,577,000
Interest expense	13,589,000	18,881,000	15,360,000
Loss on extinguishment of debt (Note 11)	0	1,494,000	0
Other income, net (Note 15)	(11,094,000)	(9,231,000)	(5,558,000)
Total other expense, net	2,495,000	11,144,000	9,802,000
Income before income taxes	183,735,000	162,335,000	29,775,000
Provision for income taxes (Note 9)	46,086,000	37,220,000	2,819,000
Net income	137,649,000	125,115,000	26,956,000
Net income attributable to noncontrolling interests	(1,209,000)	(965,000)	(929,000)
Net income attributable to MSA Safety Incorporated	$ 136,440,000	$ 124,150,000	$ 26,027,000
Basic
Income from continuing operations	$ 3.52	$ 3.23	$ 0.68
Diluted
Income from continuing operations	$ 3.48	$ 3.18	$ 0.67
Dividends per common share (dollars per share)	$ 1.64	$ 1.49	$ 1.38