EV-to-Adjusted EBITDA Multiple Method

No definition available.

Name:	tg_EVtoAdjustedEBITDAMultipleMethod
Namespace Prefix:	tg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple

+ References

No definition available.

+ Details

Name:	tg_FairValueSensitivityAnalysisWeightingtoDCFMethodatVariedEVtoAdjustedEBITDAMultiple
Namespace Prefix:	tg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Point Decrease Of Weighted Average Cost Of Capital Assumption

+ References

No definition available.

+ Details

Name:	tg_PointDecreaseOfWeightedAverageCostOfCapitalAssumption
Namespace Prefix:	tg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Point Increase Of Weighted Average Cost Of Capital Assumption

+ References

No definition available.

+ Details

Name:	tg_PointIncreaseOfWeightedAverageCostOfCapitalAssumption
Namespace Prefix:	tg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Unrealized gain loss on investment under fair value method after taxes.

+ References

No definition available.

+ Details

Name:	tg_UnrealizedGainLossOnInvestmentUnderFairValueMethodAfterTaxes
Namespace Prefix:	tg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Unrealized Gain Loss On Investments Net Of Tax.

+ References

No definition available.

+ Details

Name:	tg_UnrealizedGainLossOnInvestmentsNetOfTax
Namespace Prefix:	tg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Weighting of EBITDA Multiple Method versus DCF Method

+ References

No definition available.

+ Details

Name:	tg_WeightingofEBITDAMultipleMethodversusDCFMethod
Namespace Prefix:	tg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

+ Details

Name:	us-gaap_GainLossOnDispositionOfAssets1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=99383244&loc=d3e12121-115841

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-12C.Column C.7)
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14.Column E.2,3)
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-12.Column C.3,4)
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13.Column C.6)
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611282-123010

+ Details

Name:	us-gaap_InvestmentOwnedAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after discount, accretion and premium amortization, of interest income and dividend income classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.4)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

+ Details

Name:	us-gaap_OtherInterestAndDividendIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122596-111746

+ Details

Name:	us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate cost of investments for Federal income tax purposes.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-12(8)(d))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-12C(11)(d))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13(7)(d))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611282-123010

+ Details

Name:	us-gaap_TaxBasisOfInvestmentsCostForIncomeTaxPurposes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of investments, not including unrealized gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, held at each balance sheet date and included in earnings for the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

+ Details

Name:	us-gaap_UnrealizedGainLossOnInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 5A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=108788376&loc=SL6759159-111685

+ Details

Name:	us-gaap_VariableInterestEntityOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=tg_KaleoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=tg_DCFMethodforFairValueEstimateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	tg_EBITDAMultipleCalculationAmountAxis=tg_A8.6xDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	tg_EBITDAMultipleCalculationAmountAxis=tg_A9.6xDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	tg_EBITDAMultipleCalculationAmountAxis=tg_A10.6xDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	tg_EBITDAMultipleCalculationAmountAxis=tg_A11.6xDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=tg_EBITDAMultipleMethodforFairValueEstimateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RiskWeightedAssetsCalculationMethodologyAxis=tg_A40Domain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RiskWeightedAssetsCalculationMethodologyAxis=tg_A30Domain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RiskWeightedAssetsCalculationMethodologyAxis=tg_A20Domain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RiskWeightedAssetsCalculationMethodologyAxis=tg_A10Domain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RiskWeightedAssetsCalculationMethodologyAxis=tg_A0Domain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Investments (Narrative) (Details) 1 - USD ($)	3 Months Ended		6 Months Ended
Investments (Narrative) (Details) 1 - USD ($)	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2008
Unrealized gain (loss) on investment under fair value method			$ 6,600,000	$ 14,000,000
Gain (Loss) on Disposition of Assets			$ (11,000)	(109,000)
kaleo
Total cash invested in private company						$ 7,500,000
Ownership interest percentage			20.00%
Carrying value	$ 91,200,000		$ 91,200,000		$ 84,600,000
Other Interest and Dividend Income			17,582,000
Unrealized gain (loss) on investment under fair value method	7,100,000	$ 5,800,000	24,182,000	14,000,000
Unrealized Gain Loss On Investments Net Of Tax	$ 5,600,000		$ 19,900,000
Unrealized Gain Loss On Investment Under Fair Value Method After Taxes		$ 4,523,000		$ (10,900,000)
Basis point decrease of weighted average cost of capital assumption
Basis point increase of weighted average cost of capital assumption
DCF Method for Fair Value Estimate [Member] \| kaleo
EV-to-Adjusted EBITDA Multiple Method			5.1 x
Weighting of EBITDA Multiple Method versus DCF Method	50.00%		50.00%
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 75,400		$ 75,400
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate			15.00%
DCF Method for Fair Value Estimate [Member] \| 8.6x [Domain] \| kaleo
EV-to-Adjusted EBITDA Multiple Method			6.1 x
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	83,300		$ 83,300
DCF Method for Fair Value Estimate [Member] \| 9.6x [Domain] \| kaleo
EV-to-Adjusted EBITDA Multiple Method			7.1 x
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	91,200		$ 91,200
DCF Method for Fair Value Estimate [Member] \| 10.6x [Domain] \| kaleo
EV-to-Adjusted EBITDA Multiple Method			8.1 x
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	99,100		$ 99,100
DCF Method for Fair Value Estimate [Member] \| 11.6x [Domain] \| kaleo
EV-to-Adjusted EBITDA Multiple Method			9.1 x
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 107,000		$ 107,000
EBITDA Multiple Method for Fair Value Estimate [Member] \| kaleo
Weighting of EBITDA Multiple Method versus DCF Method	80.00%		80.00%
40% [Domain] \| DCF Method for Fair Value Estimate [Member] \| kaleo
Weighting of EBITDA Multiple Method versus DCF Method	40.00%		40.00%
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 72,300		$ 72,300
40% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 8.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	81,700		81,700
40% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 9.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	91,200		91,200
40% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 10.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	100,700		100,700
40% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 11.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 110,200		$ 110,200
30% [Domain] \| DCF Method for Fair Value Estimate [Member] \| kaleo
Weighting of EBITDA Multiple Method versus DCF Method	30.00%		30.00%
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 69,100		$ 69,100
30% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 8.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	80,100		80,100
30% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 9.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	91,200		91,200
30% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 10.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	102,300		102,300
30% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 11.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 113,300		$ 113,300
20% [Domain] \| DCF Method for Fair Value Estimate [Member] \| kaleo
Weighting of EBITDA Multiple Method versus DCF Method	20.00%		20.00%
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 65,900		$ 65,900
20% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 8.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	78,600		78,600
20% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 9.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	91,200		91,200
20% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 10.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	103,800		103,800
20% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 11.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 116,500		$ 116,500
10% [Domain] \| DCF Method for Fair Value Estimate [Member] \| kaleo
Weighting of EBITDA Multiple Method versus DCF Method	10.00%		10.00%
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 62,700		$ 62,700
10% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 8.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	77,000		77,000
10% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 9.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	91,200		91,200
10% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 10.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	105,400		105,400
10% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 11.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 119,600		$ 119,600
0% [Domain] \| DCF Method for Fair Value Estimate [Member] \| kaleo
Weighting of EBITDA Multiple Method versus DCF Method	0.00%		0.00%
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 59,600		$ 59,600
0% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 8.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	75,400		75,400
0% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 9.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	91,200		91,200
0% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 10.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	107,000		107,000
0% [Domain] \| DCF Method for Fair Value Estimate [Member] \| 11.6x [Domain] \| kaleo
Fair Value Sensitivity Analysis: Weighting to DCF Method at Varied EV-to-Adjusted EBITDA Multiple	$ 122,800		$ 122,800