Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 25,387	$ 36,406	$ 61,987	$ 80,209
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments (Note 5)	6,018	4,669	(4,205)	(18,278)
Pension and post-retirement plan actuarial gains, net of tax (Note 5)	3,657	3,090	7,369	6,192
Unrealized gain (loss) on available-for-sale securities (Note 5)	1	124	(4)	62
Reclassification of currency translation from accumulated other comprehensive loss into net income (Note 5)	0	0	0	720
Total other comprehensive income (loss), net of tax	9,676	7,883	3,160	(11,304)
Comprehensive income	35,063	44,289	65,147	68,905
Less: Comprehensive income attributable to noncontrolling interests	(135)	(358)	(356)	(371)
Comprehensive income attributable to MSA Safety Incorporated	$ 34,928	$ 43,931	$ 64,791	$ 68,534