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Assumptions Used to Calculate Net Periodic Benefit Cost for Domestic Defined Benefit Pension and Postretirement Benefit Plans (Detail)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Defined benefit pension plans      
Net Period Benefit Cost Assumptions [Line Items]      
Discount rate 4.70%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
4.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
4.50%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Weighted average rate of future compensation increases 3.80%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
3.80%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
3.80%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Long-term rate of return on plan assets 8.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
8.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
8.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Postretirement benefit plans      
Net Period Benefit Cost Assumptions [Line Items]      
Discount rate 4.70%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
4.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
4.50%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Annual increase in Medicare Part B premium 6.00%mat_AnnualIncreaseInMedicarePartBPremiumUsedToDetermineNetPeriodicBenefitCostForDomesticPostretirementBenefitPlans
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
6.00%mat_AnnualIncreaseInMedicarePartBPremiumUsedToDetermineNetPeriodicBenefitCostForDomesticPostretirementBenefitPlans
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
6.00%mat_AnnualIncreaseInMedicarePartBPremiumUsedToDetermineNetPeriodicBenefitCostForDomesticPostretirementBenefitPlans
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Net Periodic Benefit Cost | Pre-65      
Net Period Benefit Cost Assumptions [Line Items]      
Health care cost trend rate 8.50%mat_HealthCareCostTrendRateUsedToDetermineNetPeriodBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_PriorToAgeSixtyFiveMember
8.50%mat_HealthCareCostTrendRateUsedToDetermineNetPeriodBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_PriorToAgeSixtyFiveMember
7.50%mat_HealthCareCostTrendRateUsedToDetermineNetPeriodBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_PriorToAgeSixtyFiveMember
Ultimate cost trend rate 6.10%us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_PriorToAgeSixtyFiveMember
6.10%us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_PriorToAgeSixtyFiveMember
5.00%us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_PriorToAgeSixtyFiveMember
Year that the rate reaches the ultimate cost trend rate 2030 2030 2017
Net Periodic Benefit Cost | Post-65      
Net Period Benefit Cost Assumptions [Line Items]      
Health care cost trend rate 7.50%mat_HealthCareCostTrendRateUsedToDetermineNetPeriodBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_AfterAgeSixtyFiveMember
7.50%mat_HealthCareCostTrendRateUsedToDetermineNetPeriodBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_AfterAgeSixtyFiveMember
7.50%mat_HealthCareCostTrendRateUsedToDetermineNetPeriodBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_AfterAgeSixtyFiveMember
Ultimate cost trend rate 5.40%us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_AfterAgeSixtyFiveMember
5.40%us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_AfterAgeSixtyFiveMember
5.00%us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= mat_NetPeriodicBenefitCostMember
/ mat_EventTimingAxis
= mat_AfterAgeSixtyFiveMember
Year that the rate reaches the ultimate cost trend rate 2030 2030 2017