Quarterly Financial Information (Schedule Of Quarterly Financial Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly Financial Information [Abstract]
Net sales	$ 303,754	$ 298,241	$ 294,733	$ 276,499	$ 285,005	$ 242,019	$ 237,173	$ 212,434	$ 1,173,227	$ 976,631	$ 909,991
Gross profit	119,942	120,888	119,009	110,397	106,741	90,679	90,226	82,453	470,236	370,099
Net income attributable to Mine Safety Appliances Company	$ 16,979	$ 19,972	$ 19,592	$ 13,309	$ 11,768	$ 9,603	$ 11,827	$ 4,906	$ 69,852	$ 38,104	$ 43,295
Basic	$ 0.46	$ 0.54	$ 0.53	$ 0.36	$ 0.33	$ 0.27	$ 0.33	$ 0.14	$ 1.91	$ 1.06	$ 1.21
Diluted	$ 0.46	$ 0.54	$ 0.53	$ 0.36	$ 0.32	$ 0.26	$ 0.32	$ 0.14	$ 1.87	$ 1.05	$ 1.21