Schedule of Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Earnings per share attributable to MSA Safety Incorporated common shareholders:
Net income attributable to continuing operations	$ 13,522	$ 18,627
Preferred stock dividends	(10)	(10)
Income from continuing operations available to common equity	13,512	18,617
Dividends and undistributed earnings allocated to participating securities	(90)	(165)
Income from continuing operations available to common shareholders	13,422	18,452
Net income attributable to discontinued operations	504	659
Preferred stock dividends	0	0
Income from discontinued operations available to common equity	504	659
Dividends and undistributed earnings allocated to participating securities	(4)	(6)
Income from discontinued operations available to common shareholders	$ 500	$ 653
Basic weighted-average shares outstanding	37,015	36,734
Stock options and other stock compensation	602	635
Diluted weighted-average shares outstanding	37,617	37,369
Antidilutive stock options	0	173
Earnings per share attributable to continuing operations:
Income from continuing operations, basic (dollars per share)	$ 0.37	$ 0.50
Income from continuing operations, diluted (dollars per share)	$ 0.36	$ 0.49
Earnings per share attributable to discontinued operations:
Income from discontinued operations, basic (dollars per share)	$ 0.01	$ 0.02
Income from discontinued operations, diluted (dollars per share)	$ 0.01	$ 0.02