Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 28,234	$ 42,611	$ 108,431	$ 106,100
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments (Note 6)	15,520	(16,091)	(2,758)	(16,115)
Pension and post-retirement plan actuarial gains, net of tax (Note 6)	3,058	2,257	9,250	5,658
Unrealized (loss) gain on available-for-sale securities (Note 6)	(74)	(9)	(12)	554
Reclassification of currency translation from accumulated other comprehensive (loss) into net income (Note 6)	0	(212)	720	15,147
Total other comprehensive income (loss), net of tax	18,504	(14,055)	7,200	5,244
Comprehensive income	46,738	28,556	115,631	111,344
Comprehensive income attributable to noncontrolling interests	(494)	(145)	(865)	(601)
Comprehensive income attributable to MSA Safety Incorporated	$ 46,244	$ 28,411	$ 114,766	$ 110,743