Schedule of Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings per share attributable to MSA Safety Incorporated common shareholders:
Net income attributable to continuing operations	$ 22,132	$ 23,315	$ 35,654	$ 41,942
Preferred stock dividends	(10)	(10)	(20)	(20)
Income from continuing operations available to common equity	22,122	23,305	35,634	41,922
Dividends and undistributed earnings allocated to participating securities	(137)	(171)	(227)	(336)
Income from continuing operations available to common shareholders	21,985	23,134	35,407	41,586
Net income attributable to discontinued operations	356	734	860	1,393
Preferred stock dividends	0	0	0	0
Income from discontinued operations available to common equity	356	734	860	1,393
Dividends and undistributed earnings allocated to participating securities	(2)	(5)	(6)	(11)
Income from discontinued operations available to common shareholders	$ 354	$ 729	$ 854	$ 1,382
Basic weighted-average shares outstanding	37,128	36,880	37,072	36,807
Stock options and other stock compensation	591	551	597	593
Diluted weighted-average shares outstanding	37,719	37,431	37,669	37,400
Antidilutive stock options	0	188	0	188
Earnings per share attributable to continuing operations:
Income from continuing operations, basic (dollars per share)	$ 0.59	$ 0.63	$ 0.96	$ 1.13
Income from continuing operations, diluted (dollars per share)	$ 0.58	$ 0.62	$ 0.94	$ 1.11
Earnings per share attributable to discontinued operations:
Income from discontinued operations, basic (dollars per share)	$ 0.01	$ 0.02	$ 0.02	$ 0.04
Income from discontinued operations, diluted (dollars per share)	$ 0.01	$ 0.02	$ 0.02	$ 0.04