XML 94 R70.htm IDEA: XBRL DOCUMENT
v3.23.1

Risk Management Activities and Derivative Transactions Derivatives Under FTP (Details) - USD ($) $ in Millions | Mar. 31, 2023 | Sep. 30, 2022
--- | --- | ---
Derivative |  |
Forward Contract Derivative Asset, at Fair Value | $ 10 | $ 4
Natural Gas Contract Derivatives |  |
Derivative |  |
Fair value | 21 | 145
Commodity Contract under FHP |  |
Derivative |  |
Fair value | (273) | 115
Fair Value, Inputs, Level 2 |  |
Derivative |  |
Forward Contract Derivative Asset, at Fair Value | $ 10 | $ 4

X
- Definition Fair value as of the balance sheet date of forward contract derivative assets. + References No definition available. + Details
Name: | tve_ForwardContractDerivativeAssetatFairValue
Namespace Prefix: | tve_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=srt_NaturalGasReservesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=tve_CommodityContractUnderFHPMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |