Segment Information (Reportable Segment Information) (Details) (USD $) In Thousands, 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
Segment Reporting Information [Line Items]
Sales to external customers	$ 303,754	$ 298,241	$ 294,733	$ 276,499	$ 285,005	$ 242,019	$ 237,173	$ 212,434	$ 1,173,227	$ 976,631	$ 909,991
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
Total assets	1,115,052				1,197,188				1,115,052	1,197,188	875,228
Interest income									1,861	1,979	1,489
Interest expense									14,117	8,707	7,080
Depreciation and amortization									32,866	29,192	27,362
Pension income (expense)									4,967	6,391	2,655
Income tax provision									34,773	18,290	22,003
Capital expenditures									30,390	25,024	25,737
Long-lived assets	192,882				210,669				192,882	210,669	158,118
North America [Member]
Segment Reporting Information [Line Items]
Sales to external customers									561,140	464,012	434,575
Intercompany sales									100,094	84,905	61,351
Net income attributable to Mine Safety Appliances Company									57,914	44,560	43,780
Total assets	742,707				810,345				742,707	810,345	523,708
Interest income									78	329	123
Interest expense									29	51	37
Depreciation and amortization									22,036	18,918	17,369
Pension income (expense)									10,800	13,451	8,329
Income tax provision									34,327	22,032	24,314
Capital expenditures									20,035	16,806	14,742
Long-lived assets	127,361				142,241				127,361	142,241	95,291
Europe [Member]
Segment Reporting Information [Line Items]
Sales to external customers									286,753	251,107	257,860
Intercompany sales									116,471	92,526	86,632
Net income attributable to Mine Safety Appliances Company									7,331	(5,371)	4,483
Total assets	340,305				336,095				340,305	336,095	284,429
Interest income									192	110	239
Interest expense									253	160	167
Depreciation and amortization									6,239	6,116	6,178
Pension income (expense)									(5,638)	(6,590)	(5,508)
Income tax provision									3,994	769	2,714
Capital expenditures									4,384	4,667	5,640
Long-lived assets	29,981				33,199				29,981	33,199	28,447
International [Member]
Segment Reporting Information [Line Items]
Sales to external customers									325,334	261,512	217,556
Intercompany sales									18,305	16,410	13,892
Net income attributable to Mine Safety Appliances Company									27,152	15,835	6,717
Total assets	194,127				205,837				194,127	205,837	183,742
Interest income									1,267	1,212	759
Interest expense									138	100	143
Depreciation and amortization									4,591	4,158	3,815
Pension income (expense)									(195)	(470)	(166)
Income tax provision									6,442	5,720	2,070
Capital expenditures									5,971	3,551	5,355
Long-lived assets	35,540				35,229				35,540	35,229	34,380
Reconciling Items [Member]
Segment Reporting Information [Line Items]
Intercompany sales									(234,870)	(193,841)	(161,875)
Net income attributable to Mine Safety Appliances Company									(22,545)	(16,920)	(11,685)
Total assets	(162,087)				(155,089)				(162,087)	(155,089)	(116,651)
Interest income									324	328	368
Interest expense									13,697	8,396	6,733
Income tax provision									$ (9,990)	$ (10,231)	$ (7,095)