XML 96 R84.htm IDEA: XBRL DOCUMENT v2.4.1.9
Employee Stock and Savings Plans Weighting of elements included in volatility assumption (Details)
 12 Months Ended
Jan. 31, 2013
Common Stock  
Weighting of elements used in determining volatility assumption 20.00%ment_WeightingOfElementsUsedInDeterminingVolatilityAssumption
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
Exchange Traded Options  
Weighting of elements used in determining volatility assumption 15.00%ment_WeightingOfElementsUsedInDeterminingVolatilityAssumption
/ us-gaap_StatementClassOfStockAxis
= us-gaap_ExchangeTradedOptionsMember
Mentor Graphics | Common Stock  
Weighting of elements used in determining volatility assumption 35.00%ment_WeightingOfElementsUsedInDeterminingVolatilityAssumption
/ ment_PeerGroupCompaniesAxis
= ment_MentorGraphicsDomain
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
Mentor Graphics | Exchange Traded Options  
Weighting of elements used in determining volatility assumption 30.00%ment_WeightingOfElementsUsedInDeterminingVolatilityAssumption
/ ment_PeerGroupCompaniesAxis
= ment_MentorGraphicsDomain
/ us-gaap_StatementClassOfStockAxis
= us-gaap_ExchangeTradedOptionsMember