XML 163 R56.htm IDEA: XBRL DOCUMENT
v3.21.2

Summary of Significant Accounting Policies - General (Details) $ in Millions | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2021 USD ($) People | Sep. 30, 2020 USD ($) | Sep. 30, 2019 USD ($) | Sep. 30, 2018 USD ($) | Sep. 30, 2014 USD ($)
Accounting Policies [Abstract] |  |  |  |  |
Cash and Cash Equivalents, at Carrying Value | $ 499 | $ 500 |  |  |
Allowance for uncollectible accounts - loans | 4 | 1 |  |  |
Recorded cost for emission allowances granted by the Environmental Protection Agency | 0 |  |  |  |
Reimbursements from DOE | 137 |  |  |  |
Restricted Cash and Investments, Noncurrent | 19 | 21 |  |  |
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents | 518 | 521 | $ 322 | $ 322 |
Accounts receivable from DOE | 11 |  |  |  |
Appropriation-investment power program | $ 258 | 258 |  |  | $ 1,000
Population of Service Area [Line Items] |  |  |  |  |
Population of service area | People | 10,000,000 |  |  |  |
Cash and Cash Equivalents, at Carrying Value | $ 499 | 500 |  |  |
Restricted Cash and Investments, Noncurrent | $ 19 | $ 21 |  |  |

X
- Definition Accounts receivable + References No definition available. + Details
Name: | tve_AccountsreceivablefromDOE
Namespace Prefix: | tve_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Balance of appropriated funds advanced and property transferred to/from the reporting entity by the U.S. government as an investment in its power program. + References No definition available. + Details
Name: | tve_AppropriationInvestmentPowerProgram
Namespace Prefix: | tve_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The population of the company's service area. + References No definition available. + Details
Name: | tve_PopulationOfServiceArea
Namespace Prefix: | tve_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Population of Service Area [Line Items] + References No definition available. + Details
Name: | tve_PopulationOfServiceAreaLineItems
Namespace Prefix: | tve_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Recorded cost for emission allowances granted by the Environmental Protection Agency + References No definition available. + Details
Name: | tve_RecordedCostForEmissionAllowancesGrantedByEnvironmentalProtectionAgency
Namespace Prefix: | tve_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Reimbursements from DOE + References No definition available. + Details
Name: | tve_ReimbursementsfromDOE
Namespace Prefix: | tve_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of allowance for credit loss on financing receivable, classified as noncurrent. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5074-111524 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(4)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_AllowanceForNotesAndLoansReceivableNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3044-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CashAndCashEquivalentsAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3521-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3044-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=123431023&loc=SL98516268-108586 + Details
Name: | us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The noncurrent cash, cash equivalents and investments that is restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits classified as long-term; that is not expected to be released from such existing restrictions within one year of the balance sheet date or operating cycle, whichever is longer. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. Includes noncurrent cash equivalents and investments that are similarly restricted as to withdrawal, usage or disposal. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 954 -SubTopic 210 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=120413173&loc=SL6242262-115580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 954 -SubTopic 210 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=120413209&loc=SL6242269-115581 + Details
Name: | us-gaap_RestrictedCashAndInvestmentsNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant