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Debt and Other Obligations Debt and Other Obligations - Put and Call Options (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Sep. 30, 2020 USD ($) | Sep. 30, 2019 USD ($) Units
Debt Instrument |  |
Amount of redeemable bond issues outstanding |  | $ 357
Call price |  | 10000.00%
Bond issues with survivor's option | Units |  | 217,000,000
PARRS 1998 Series D Bond |  |
Debt Instrument |  |
Amount of redeemable bond issues outstanding | $ 256 |
PARRS interest rate prior to rate reset | 6.75% |
PARRS interest rate after rate reset | 2.134% |
Amount of bonds redeemed | $ 318 |
PARRS 1999 Series A Bond |  |
Debt Instrument |  |
Amount of redeemable bond issues outstanding | $ 208 |
PARRS interest rate prior to rate reset | 6.50% |
PARRS interest rate after rate reset | 2.216% |
Amount of bonds redeemed | $ 316 |

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- Definition The amount of bonds redeemed. + References No definition available. + Details
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Balance Type: | debit
Period Type: | duration

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- Definition Amount of redeemable bond issues outstanding + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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- Definition The number of bond issues which include a "survivor's option" allowing for the right of redemption upon the death of a beneficial owner in certain specified circumstances. + References No definition available. + Details
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Namespace Prefix: | tve_
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- Definition Call price - low end of range. Shown as a percent of principal amount. + References No definition available. + Details
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- Definition The PARRS interest rate after rate reset. + References No definition available. + Details
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- Definition The PARRS interest rate prior to rate reset. + References No definition available. + Details
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- 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
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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
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Balance Type: |
Period Type: |