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Property, Plant and Equipment (Detail Textuals) (USD $)
3 Months Ended 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Property, Plant and Equipment [Line Items]      
Depreciation and amortization expense $ 163,000us-gaap_DepreciationAndAmortization $ 169,000us-gaap_DepreciationAndAmortization  
CPG      
Property, Plant and Equipment [Line Items]      
Construction in progress 2,528,000us-gaap_ConstructionInProgressGross
/ us-gaap_StatementBusinessSegmentsAxis
= svt_ConsumerProductsGroupMember
  2,817,000us-gaap_ConstructionInProgressGross
/ us-gaap_StatementBusinessSegmentsAxis
= svt_ConsumerProductsGroupMember
ATG      
Property, Plant and Equipment [Line Items]      
Construction in progress 300,000us-gaap_ConstructionInProgressGross
/ us-gaap_StatementBusinessSegmentsAxis
= svt_AdvancedTechnologyGroupMember
  2,817,000us-gaap_ConstructionInProgressGross
/ us-gaap_StatementBusinessSegmentsAxis
= svt_AdvancedTechnologyGroupMember
Land and building | Elma      
Property, Plant and Equipment [Line Items]      
Nominal amount of capital lease 5,000,000us-gaap_CapitalLeasedAssetsGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LandAndBuildingMember
/ us-gaap_StatementGeographicalAxis
= svt_ElmaMember
   
Buildings      
Property, Plant and Equipment [Line Items]      
Depreciation expense $ 2,844,000us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_BuildingMember
  $ 2,811,000us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_BuildingMember