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Stock Plans - Additional Information (Detail)
3 Months Ended
Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expiration period 10 years
Stock options exercisable period after grant date 3 years
Share-based compensation arrangement by share-based payment award, fair value assumptions, average closing price used to calculated expected dividend rate, period 1 year
Minimum  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Percentage of target award based on achieving targeted performance conditions 0.00%msa_PercentageOfTargetAwardBasedOnAchievingTargetedTotalShareholderReturnBasedOnWhichFinalNumberOfSharesToBeIssuedForPerformanceStockUnits
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= us-gaap_MinimumMember
Maximum  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Percentage of target award based on achieving targeted performance conditions 200.00%msa_PercentageOfTargetAwardBasedOnAchievingTargetedTotalShareholderReturnBasedOnWhichFinalNumberOfSharesToBeIssuedForPerformanceStockUnits
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Percentage of target award based on achieving specified performance targets 133.60%msa_PercentageOfTargetAwardBasedOnAchievingTargetedReturnOnNetAssetsBasedOnWhichFinalNumberOfSharesToBeIssuedForPerformanceStockUnits
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= us-gaap_MaximumMember
Performance Stock Unit  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Award vesting period (in years) 3 years
Performance Stock Unit  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based compensation arrangement by share-based payment award, fair value assumptions, average closing price used to calculated expected dividend rate, period 1 year
Stock beta, daily price data period 3 years