Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 137,649	$ 125,115	$ 26,956
Foreign currency translation adjustments (Note 5)	(1,657)	(30,103)	41,129
Pension and post-retirement plan actuarial gains (losses), net of tax (Note 5)	(5,559)	(17,569)	20,120
Unrealized gains (losses) on available-for-sale securities (Note 5)	578	(572)	0
Reclassification from accumulated other comprehensive (loss) into net income (Note 5)	15,261	774	0
Total other comprehensive income (loss), net of tax	8,623	(47,470)	61,249
Comprehensive income	146,272	77,645	88,205
Comprehensive income attributable to noncontrolling interests	(1,136)	(660)	(3,694)
Comprehensive income attributable to MSA Safety Incorporated	$ 145,136	$ 76,985	$ 84,511