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Losses Associated With Plant Shutdowns, Asset Impairments And Restructurings, Unusual Items, Gains From Sale Of Assets And Other Items (Details) (USD $) | 3 Months Ended | 12 Months Ended | 3 Months Ended | 17 Months Ended | 6 Months Ended |
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Mar. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Jun. 30, 2013 | Dec. 31, 2014 | Dec. 31, 2012 | Jun. 30, 2012 | Sep. 30, 2014 | Jun. 30, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Mar. 31, 2013 | Sep. 30, 2012 | Mar. 31, 2012 | Dec. 31, 2013 | Dec. 31, 2012 | Jun. 30, 2012 | Aug. 31, 2012 employee
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Asset impairments |  | $ 993,000 us-gaap_AssetImpairmentCharges |  | $ 1,639,000 us-gaap_AssetImpairmentCharges |  | $ 2,185,000 us-gaap_AssetImpairmentCharges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrealized gain (loss) on investments under fair value method |  | 2,000,000 us-gaap_UnrealizedGainLossOnInvestments |  | 3,400,000 us-gaap_UnrealizedGainLossOnInvestments |  | 16,100,000 us-gaap_UnrealizedGainLossOnInvestments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Losses Associated with Plant Shutdowns, Asset Impairments, Restructurings & Other | 13,800,000 tg_LossesAssociatedWithPlantShutdownsAssetImpairmentsRestructuringsUnusualItemsGainsLossesFromSaleOfAssetsOtherItems |  |  | 3,400,000 tg_LossesAssociatedWithPlantShutdownsAssetImpairmentsRestructuringsUnusualItemsGainsLossesFromSaleOfAssetsOtherItems |  | 5,500,000 tg_LossesAssociatedWithPlantShutdownsAssetImpairmentsRestructuringsUnusualItemsGainsLossesFromSaleOfAssetsOtherItems |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Losses Associated with Plant Shutdowns, Asset Impairments, Restructurings & Other After Taxes | 9,300,000 tg_LossesAssociatedWithPlantShutdownsAssetImpairmentsRestructuringsUnusualItemsGainsLossesFromSaleOfAssetsOtherItemsAfterTax |  |  | 2,200,000 tg_LossesAssociatedWithPlantShutdownsAssetImpairmentsRestructuringsUnusualItemsGainsLossesFromSaleOfAssetsOtherItemsAfterTax |  | 3,600,000 tg_LossesAssociatedWithPlantShutdownsAssetImpairmentsRestructuringsUnusualItemsGainsLossesFromSaleOfAssetsOtherItemsAfterTax |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Effect of LIFO inventory liquidation on income |  |  |  |  |  | 2,700,000 us-gaap_EffectOfLIFOInventoryLiquidationOnIncome |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
kaleo |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrealized gain (loss) on investments under fair value method |  | 2,000,000 us-gaap_UnrealizedGainLossOnInvestments / dei_LegalEntityAxis = tg_KaleoMember | [1] | 3,400,000 us-gaap_UnrealizedGainLossOnInvestments / dei_LegalEntityAxis = tg_KaleoMember | [1] | 16,100,000 us-gaap_UnrealizedGainLossOnInvestments / dei_LegalEntityAxis = tg_KaleoMember | [1] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrealized gain (loss) on investments, net of tax |  | 1,000,000 tg_UnrealizedGainLossOnInvestmentsNetOfTax / dei_LegalEntityAxis = tg_KaleoMember |  | 2,200,000 tg_UnrealizedGainLossOnInvestmentsNetOfTax / dei_LegalEntityAxis = tg_KaleoMember |  | 10,200,000 tg_UnrealizedGainLossOnInvestmentsNetOfTax / dei_LegalEntityAxis = tg_KaleoMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrealized gain (loss) on investments under fair value method after taxes |  |  |  |  |  | 10,200,000 tg_UnrealizedGainLossOnInvestmentUnderFairValueMethodAfterTaxes / dei_LegalEntityAxis = tg_KaleoMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Harbinger |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrealized loss on investments under fair value method, other than temporary impairment |  | 800,000 us-gaap_CostmethodInvestmentsOtherThanTemporaryImpairment / dei_LegalEntityAxis = tg_HarbingerCapitalPartnersSpecialSituationsFundLPMember |  | 400,000 us-gaap_CostmethodInvestmentsOtherThanTemporaryImpairment / dei_LegalEntityAxis = tg_HarbingerCapitalPartnersSpecialSituationsFundLPMember |  | 1,100,000 us-gaap_CostmethodInvestmentsOtherThanTemporaryImpairment / dei_LegalEntityAxis = tg_HarbingerCapitalPartnersSpecialSituationsFundLPMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrealized loss on investments under fair value method, other than temporary impairment, after taxes |  | 400,000 tg_CostMethodInvestmentsOtherThanTemporaryImpairmentNetOfTax / dei_LegalEntityAxis = tg_HarbingerCapitalPartnersSpecialSituationsFundLPMember |  | 300,000 tg_CostMethodInvestmentsOtherThanTemporaryImpairmentNetOfTax / dei_LegalEntityAxis = tg_HarbingerCapitalPartnersSpecialSituationsFundLPMember |  | 700,000 tg_CostMethodInvestmentsOtherThanTemporaryImpairmentNetOfTax / dei_LegalEntityAxis = tg_HarbingerCapitalPartnersSpecialSituationsFundLPMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Film Products Manufacturing Facility in Shanghai, China |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of equipment |  |  |  |  |  |  |  | (91,000)us-gaap_GainLossOnSaleOfPropertyPlantEquipment / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInShanghaiChinaMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Disposition of Property, Plant, and Equipment, Net of Tax |  |  |  |  |  |  |  | (91,000)tg_GainLossonDispositionofPropertyPlantandEquipmentNetofTax / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInShanghaiChinaMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alleghany and Bath County, Virginia |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Disposition of Assets |  | 1,208,000 us-gaap_GainLossOnDispositionOfAssets1 / dei_EntityByLocationAxis = tg_AlleghanyandBathCountyVirginiaMember |  | 0 us-gaap_GainLossOnDispositionOfAssets1 / dei_EntityByLocationAxis = tg_AlleghanyandBathCountyVirginiaMember |  | 0 us-gaap_GainLossOnDispositionOfAssets1 / dei_EntityByLocationAxis = tg_AlleghanyandBathCountyVirginiaMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Sale of Investment Property |  | 0 tg_UnrealizedGainLossonInvestmentProperty / dei_EntityByLocationAxis = tg_AlleghanyandBathCountyVirginiaMember |  | 1,018,000 tg_UnrealizedGainLossonInvestmentProperty / dei_EntityByLocationAxis = tg_AlleghanyandBathCountyVirginiaMember |  | 0 tg_UnrealizedGainLossonInvestmentProperty / dei_EntityByLocationAxis = tg_AlleghanyandBathCountyVirginiaMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrealized Gain Loss On Investment Property After Tax |  |  |  | (600,000)tg_UnrealizedGainLossOnInvestmentPropertyAfterTax / dei_EntityByLocationAxis = tg_AlleghanyandBathCountyVirginiaMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Sale of Investment Property, After Tax |  | (800,000)tg_GainLossonSaleofInvestmentPropertyAfterTax / dei_EntityByLocationAxis = tg_AlleghanyandBathCountyVirginiaMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Film Products Manufacturing Facility in LaGrange, Georgia |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Asset impairments |  |  |  |  |  |  |  |  |  |  | 800,000 us-gaap_AssetImpairmentCharges / dei_EntityByLocationAxis = tg_FilmsProductsManufacturingFacilityInLagrangeGeorgiaMember |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on sale of equipment |  |  |  |  |  |  |  |  | 100,000 us-gaap_GainLossOnSaleOfPropertyPlantEquipment / dei_EntityByLocationAxis = tg_FilmsProductsManufacturingFacilityInLagrangeGeorgiaMember |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Disposition of Property, Plant, and Equipment, Net of Tax |  |  |  |  |  |  |  |  | 73,000 tg_GainLossonDispositionofPropertyPlantandEquipmentNetofTax / dei_EntityByLocationAxis = tg_FilmsProductsManufacturingFacilityInLagrangeGeorgiaMember |  |  |  |  |  |  |  |  |  |  |  |  |
Gain on sale of property |  |  |  |  |  |  |  |  |  | 1,100,000 us-gaap_GainLossOnDispositionOfAssets / dei_EntityByLocationAxis = tg_FilmsProductsManufacturingFacilityInLagrangeGeorgiaMember |  |  |  |  |  |  |  |  |  |  |  |
Gain on sale of property after taxes |  |  |  |  |  |  |  |  |  | 600,000 tg_GainLossOnDispositionOfPropertyAfterTax / dei_EntityByLocationAxis = tg_FilmsProductsManufacturingFacilityInLagrangeGeorgiaMember |  |  |  |  |  |  |  |  |  |  |  |
Asset impairments after taxes |  |  |  |  |  |  |  |  |  |  | 500,000 tg_AssetImpairmentChargesAfterTaxes / dei_EntityByLocationAxis = tg_FilmsProductsManufacturingFacilityInLagrangeGeorgiaMember |  |  |  |  |  |  |  |  |  |  |
Aluminum Extrusions Manufacturing Facility In Newnan Georgia |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expected future environmental costs |  |  |  |  |  |  |  | 85,000 us-gaap_EnvironmentalExitCostsAnticipatedCost / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 700,000 us-gaap_EnvironmentalExitCostsAnticipatedCost / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 100,000 us-gaap_EnvironmentalExitCostsAnticipatedCost / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember |  | 75,000 us-gaap_EnvironmentalExitCostsAnticipatedCost / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 200,000 us-gaap_EnvironmentalExitCostsAnticipatedCost / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 1,500,000 us-gaap_EnvironmentalExitCostsAnticipatedCost / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 100,000 us-gaap_EnvironmentalExitCostsAnticipatedCost / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember |  |  |  |  |  |  |
Expected future environmental costs after taxes |  |  |  |  |  |  |  | 53,000 tg_EnvironmentalExitCostsAnticipatedCostAfterTaxes / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 400,000 tg_EnvironmentalExitCostsAnticipatedCostAfterTaxes / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 49,000 tg_EnvironmentalExitCostsAnticipatedCostAfterTaxes / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember |  | 46,000 tg_EnvironmentalExitCostsAnticipatedCostAfterTaxes / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 100,000 tg_EnvironmentalExitCostsAnticipatedCostAfterTaxes / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 900,000 tg_EnvironmentalExitCostsAnticipatedCostAfterTaxes / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember | 62,000 tg_EnvironmentalExitCostsAnticipatedCostAfterTaxes / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInNewnanGeorgiaMember |  |  |  |  |  |  |
Facility Closing | Film Products Manufacturing Facility in Red Springs, NC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Plant shutdown related expenditures | (500,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (700,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  | (500,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  | 100,000 tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  | (37,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (300,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (300,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (200,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  |  |  |
Plant shutdown related expenditures after taxes | (300,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  |  |  |  | 63,000 tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  | (23,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (200,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (200,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (83,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  |  |  |
Severance and other employee-related costs |  | 400,000 us-gaap_SeveranceCosts1 / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  |  |  |  |  |  |  |  | 300,000 us-gaap_SeveranceCosts1 / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  |  |  |  |
Asset Impairment and Other Plant Shutdown Related Costs |  | 300,000 tg_AssetImpairmentandOtherPlantShutdownRelatedCosts / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Asset impairments |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 200,000 us-gaap_AssetImpairmentCharges / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  |  |  |
Number of employees employed |  | 66 dei_EntityNumberOfEmployees / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  |  |  | 66 dei_EntityNumberOfEmployees / dei_EntityByLocationAxis = tg_FilmProductsManufacturingFacilityInRedSpringsNorthCarolinaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |  |  |  |  |  |  |  |  |  |
Facility Closing | Aluminum Extrusions Manufacturing Facility In Kentland, Indiana |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Plant shutdown related expenditures |  |  |  |  |  |  |  | (400,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (11,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (900,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (1,000,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (20,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (24,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  | (45,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (200,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (800,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (900,000)tg_PlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |
Plant shutdown related expenditures after taxes |  |  |  |  |  |  |  | (200,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (7,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (500,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (700,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (12,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (15,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  | (28,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (94,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (500,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | (500,000)tg_PlantShutdownRelatedExpendituresNetAfterTax / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |
Severance and other employee-related costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,200,000 us-gaap_SeveranceCosts1 / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | 1,200,000 us-gaap_SeveranceCosts1 / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |
Gain (loss) on sale of equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 800,000 us-gaap_GainLossOnSaleOfPropertyPlantEquipment / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |
Accelerated depreciation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,400,000 tg_AcceleratedDepreciation / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | 2,400,000 tg_AcceleratedDepreciation / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |
Other shutdown-related charges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,300,000 tg_OtherShutdownRelatedCharges / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember | 1,000,000 tg_OtherShutdownRelatedCharges / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |
Effect of LIFO inventory liquidation on income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,500,000 us-gaap_EffectOfLIFOInventoryLiquidationOnIncome / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |  |
Number of employees employed |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 146 dei_EntityNumberOfEmployees / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember
Estimated charges related to plant shutdown |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,500,000 tg_EstimatedTotalPlantShutdownRelatedExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |
Cash expenditures related to restructuring charges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,500,000 tg_PlantShutdownRelatedCashExpendituresNet / dei_EntityByLocationAxis = tg_AluminumExtrusionsManufacturingFacilityInKentlandIndianaMember / us-gaap_RestructuringCostAndReserveAxis = us-gaap_FacilityClosingMember |  |  |
Cash expenditures related to restructuring charges, period of recognition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 18 months |  |  |
Film Products |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Severance and other employee-related costs |  |  |  |  |  |  |  |  |  | 200,000 us-gaap_SeveranceCosts1 / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember | 100,000 us-gaap_SeveranceCosts1 / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember |  |  |  |  | 100,000 us-gaap_SeveranceCosts1 / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember |  |  |  |  |  |
Asset impairments |  |  |  |  |  |  |  |  |  | 200,000 us-gaap_AssetImpairmentCharges / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember |  |  |  |  |  |  |  |  |  |  |  |
Severance and other employee-related costs after taxes |  |  |  |  |  |  |  |  |  | 100,000 tg_SeveranceCostsAfterTaxes / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember | 46,000 tg_SeveranceCostsAfterTaxes / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember |  |  |  |  | 67,000 tg_SeveranceCostsAfterTaxes / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember |  |  |  |  |  |
Gain associated with insurance recovery on idle equipment that was destroyed in a fire at outside warehouse |  |  |  |  |  |  |  |  |  | 1,300,000 tg_GainAssociatedWithInsuranceRecoveryOnIdleEquipment / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember |  |  |  |  |  |  |  |  |  |  |  |
Gain associated with insurance recovery on idle equipment that was destroyed in a fire at outside warehouse after taxes |  |  |  |  |  |  |  |  |  | 700,000 tg_GainAssociatedWithInsuranceRecoveryOnIdleEquipmentAfterTaxes / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember |  |  |  |  |  |  |  |  |  |  |  |
Asset impairments after taxes |  |  |  |  |  |  |  |  |  | 200,000 tg_AssetImpairmentChargesAfterTaxes / us-gaap_RestructuringCostAndReserveAxis = tg_FilmProductsMember |  |  |  |  |  |  |  |  |  |  |  |
Aluminum Extrusions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Severance and other employee-related costs |  |  |  |  |  |  |  |  |  |  |  |  |  | 300,000 us-gaap_SeveranceCosts1 / us-gaap_RestructuringCostAndReserveAxis = tg_AluminumExtrusionsMember |  |  |  | 200,000 us-gaap_SeveranceCosts1 / us-gaap_RestructuringCostAndReserveAxis = tg_AluminumExtrusionsMember |  |  |  |
Severance and other employee-related costs after taxes |  |  |  |  |  |  |  |  |  |  |  |  |  | 200,000 tg_SeveranceCostsAfterTaxes / us-gaap_RestructuringCostAndReserveAxis = tg_AluminumExtrusionsMember |  |  |  | 100,000 tg_SeveranceCostsAfterTaxes / us-gaap_RestructuringCostAndReserveAxis = tg_AluminumExtrusionsMember |  |  |  |
AACOA |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Integration-related expenses and other non-recurring transactions |  |  |  |  |  |  |  | 90,000 tg_IntegrationExpensesAndOtherNonRecurringCharges / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  | 200,000 tg_IntegrationExpensesAndOtherNonRecurringCharges / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  |  |  |  |  | 100,000 tg_IntegrationExpensesAndOtherNonRecurringCharges / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  |  |  |  |  |
Integration-related expenses and other non-recurring transactions after taxes |  |  |  |  |  |  |  | 54,000 tg_IntegrationExpensesAndOtherNonRecurringChargesAfterTaxes / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  | 100,000 tg_IntegrationExpensesAndOtherNonRecurringChargesAfterTaxes / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  |  |  |  |  | 63,000 tg_IntegrationExpensesAndOtherNonRecurringChargesAfterTaxes / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  |  |  |  |  |
Acquisition-related expenses |  |  |  |  |  | 2,000,000 us-gaap_BusinessCombinationAcquisitionRelatedCosts / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  |  |  | 900,000 us-gaap_BusinessCombinationAcquisitionRelatedCosts / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  |  |  |  |  |  | 300,000 us-gaap_BusinessCombinationAcquisitionRelatedCosts / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  |  | 1,200,000 us-gaap_BusinessCombinationAcquisitionRelatedCosts / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember | 800,000 us-gaap_BusinessCombinationAcquisitionRelatedCosts / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |
Acquisition-related expenses after taxes |  |  |  |  |  |  |  |  |  | 600,000 tg_AcquisitionRelatedExpensesAfterTaxes / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  |  |  |  |  |  | 200,000 tg_AcquisitionRelatedExpensesAfterTaxes / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember |  |  |  |  |
AACOA | Aluminum Extrusions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Charge associated with purchase accounting adjustements |  |  |  |  |  |  |  |  |  | 100,000 tg_InventoryFvPurchaseAccountingAdjustmentIncludedInCogs / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember / us-gaap_RestructuringCostAndReserveAxis = tg_AluminumExtrusionsMember |  |  |  |  |  |  |  |  |  |  |  |
Charge associated with purchase accounting adjustments after taxes |  |  |  |  |  |  |  |  |  | 100,000 tg_InventoryFvPurchaseAccountingAdjustmentIncludedInCogsAfterTax / us-gaap_BusinessAcquisitionAxis = tg_AacoaIncMember / us-gaap_RestructuringCostAndReserveAxis = tg_AluminumExtrusionsMember |  |  |  |  |  |  |  |  |  |  |  |
Terphane |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Integration-related expenses and other non-recurring transactions |  |  |  |  |  |  |  |  |  | 100,000 tg_IntegrationExpensesAndOtherNonRecurringCharges / us-gaap_BusinessAcquisitionAxis = tg_TerphaneHoldingsLlcMember | 600,000 tg_IntegrationExpensesAndOtherNonRecurringCharges / us-gaap_BusinessAcquisitionAxis = tg_TerphaneHoldingsLlcMember |  |  |  |  |  | 100,000 tg_IntegrationExpensesAndOtherNonRecurringCharges / us-gaap_BusinessAcquisitionAxis = tg_TerphaneHoldingsLlcMember | 300,000 tg_IntegrationExpensesAndOtherNonRecurringCharges / us-gaap_BusinessAcquisitionAxis = tg_TerphaneHoldingsLlcMember |  |  |  |
Integration-related expenses and other non-recurring transactions after taxes |  |  |  |  |  |  |  |  |  | 100,000 tg_IntegrationExpensesAndOtherNonRecurringChargesAfterTaxes / us-gaap_BusinessAcquisitionAxis = tg_TerphaneHoldingsLlcMember | 400,000 tg_IntegrationExpensesAndOtherNonRecurringChargesAfterTaxes / us-gaap_BusinessAcquisitionAxis = tg_TerphaneHoldingsLlcMember |  |  |  |  |  | 100,000 tg_IntegrationExpensesAndOtherNonRecurringChargesAfterTaxes / us-gaap_BusinessAcquisitionAxis = tg_TerphaneHoldingsLlcMember | 200,000 tg_IntegrationExpensesAndOtherNonRecurringChargesAfterTaxes / us-gaap_BusinessAcquisitionAxis = tg_TerphaneHoldingsLlcMember |  |  |  |
Tredegar vs. 3M [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Litigation Settlement, Amount | 10,000,000 us-gaap_LitigationSettlementAmount / us-gaap_LitigationCaseAxis = tg_Tredegarvs.3MMember |  |  |  |  |  |  |  |  |  |  | 10,000,000 us-gaap_LitigationSettlementAmount / us-gaap_LitigationCaseAxis = tg_Tredegarvs.3MMember |  |  |  |  |  |  |  |  |  |
Litigation Settlement Amount, Net of Tax | 6,800,000 tg_LitigationSettlementAmountNetofTax / us-gaap_LitigationCaseAxis = tg_Tredegarvs.3MMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Film Products |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Severance and other employee-related costs | 800,000 us-gaap_SeveranceCosts1 / us-gaap_StatementBusinessSegmentsAxis = tg_FilmProductsMember |  |  |  |  |  |  |  | 500,000 us-gaap_SeveranceCosts1 / us-gaap_StatementBusinessSegmentsAxis = tg_FilmProductsMember |  |  | 400,000 us-gaap_SeveranceCosts1 / us-gaap_StatementBusinessSegmentsAxis = tg_FilmProductsMember | 600,000 us-gaap_SeveranceCosts1 / us-gaap_StatementBusinessSegmentsAxis = tg_FilmProductsMember |  |  |  |  |  |  |  |  |
Severance and other employee-related costs after taxes | 500,000 tg_SeveranceCostsAfterTaxes / us-gaap_StatementBusinessSegmentsAxis = tg_FilmProductsMember |  |  |  |  |  |  |  | 300,000 tg_SeveranceCostsAfterTaxes / us-gaap_StatementBusinessSegmentsAxis = tg_FilmProductsMember |  |  | 200,000 tg_SeveranceCostsAfterTaxes / us-gaap_StatementBusinessSegmentsAxis = tg_FilmProductsMember | 400,000 tg_SeveranceCostsAfterTaxes / us-gaap_StatementBusinessSegmentsAxis = tg_FilmProductsMember |  |  |  |  |  |  |  |  |
Aluminum Extrusions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Severance and other employee-related costs |  |  |  |  |  |  |  |  |  |  |  | 31,000 us-gaap_SeveranceCosts1 / us-gaap_StatementBusinessSegmentsAxis = tg_AluminumExtrusionsMember |  |  |  |  |  |  |  |  |  |
Severance and other employee-related costs after taxes |  |  |  |  |  |  |  |  |  |  |  | $ 18,000 tg_SeveranceCostsAfterTaxes / us-gaap_StatementBusinessSegmentsAxis = tg_AluminumExtrusionsMember |  |  |  |  |  |  |  |  |  |
[1] | See Notes 1, 3, 4 and 18 for more information on losses associated with plant shutdowns, asset impairments and restructurings, unusual items, gains or losses from sale of assets, gains or losses on an investment accounted for under the fair value method and other items.

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- Definition Total anticipated costs associated with remediation, site restoration, postclosure, monitoring commitments, or other exit costs that may occur on the sale, disposal, or abandonment of a particular property resulting from unanticipated contamination of the assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 5.Y.Q4) -URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section Y -Paragraph Question 4 + Details
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