Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 36,600	$ 43,802
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments (Note 5)	(10,223)	(22,947)
Pension and post-retirement plan actuarial gains, net of tax (Note 5)	3,712	3,102
Unrealized loss on available-for-sale securities (Note 5)	(5)	(62)
Reclassification of currency translation from accumulated other comprehensive (loss) into net income (Note 5)	0	720
Total other comprehensive (loss) income, net of tax	(6,516)	(19,187)
Comprehensive income	30,084	24,615
Comprehensive income attributable to noncontrolling interests	(221)	(13)
Comprehensive income attributable to MSA Safety Incorporated	$ 29,863	$ 24,602