Name:	tve_Commingledfundsmeasuredatnetassetvalue
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The fair value as of the balance sheet date of firm obligations in physical commodity contracts (for example, agricultural products, metals and energy).

No definition available.

Name:	tve_Commoditycontractderivativeliabilitiesfairvaluedisclosure
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Data Type:	xbrli:monetaryItemType
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The fair value as of the balance sheet date of firm holdings in mortgages, residential mortgage backed securities (investment instruments that represent ownership of an undivided interest in a group of mortgages, where principal and interest from the individual mortgages are used to pay investors' principal and interest on the mortgage backed security) and asset-backed securities that are primarily paid from the cash flows of a discrete pool of receivables or other financial assets (such as credit-card receivables), either fixed or revolving, that by their terms convert into cash within a finite time period. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

No definition available.

Name:	tve_FinancialInstrumentsOwnedMortgagesResidentialMortgagebackedandAssetbackedSecuritiesatFairValue
Namespace Prefix:	tve_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Fair value as of the balance sheet date of forward contract derivative assets.

No definition available.

Name:	tve_ForwardContractDerivativeAssetatFairValue
Namespace Prefix:	tve_
Data Type:	xbrli:monetaryItemType
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The fair value measurements of institutional mutual funds that are classified based on their existing investment portfolio as of the measurement date.

No definition available.

Name:	tve_Institutionalmutualfunds
Namespace Prefix:	tve_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Private credit measured at net asset value

No definition available.

Name:	tve_Privatecreditmeasuredatnetassetvalue
Namespace Prefix:	tve_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The fair value measurements of private partnerships measured at net asset value. Private partnership investments may include holdings of investments in private real estate, venture capital, buyout, mezzanine or subordinated debt, restructuring or distressed debt, and special situations through funds management by third-party managers.

No definition available.

Name:	tve_Privatepartnershipsmeasuredatnetassetvalue
Namespace Prefix:	tve_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Fair value measurements of private real estate funds measured at net asset value

No definition available.

Name:	tve_Privaterealestatemeasuredatnetassetvalue
Namespace Prefix:	tve_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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Data Type:	xbrli:monetaryItemType
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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as noncurrent.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=123594786&loc=SL75136599-209740

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Data Type:	xbrli:monetaryItemType
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Fair value of firm holdings in corporate fixed income securities. Includes pledged and unpledged holdings.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=35711157&loc=d3e42546-110969

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The fair value as of the balance sheet date of firm holdings in physical commodity contracts (for example, agricultural products, metals and energy). Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

No definition available.

Name:	us-gaap_FinancialInstrumentsOwnedPhysicalCommoditiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The fair value as of the balance sheet date of firm holdings in debt obligations issued by the US government including short-term Treasury bills, medium-term Treasury notes, and long-term Treasury bonds, as well as debt issued by agencies. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

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

Fair value portion of liability contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into.

No definition available.

Name:	us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

No definition available.

Name:	us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

Name:	us-gaap_InvestmentsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Fair value of financial and nonfinancial obligations.

Name:	us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.