XML 72 R47.htm IDEA: XBRL DOCUMENT
v3.20.2

Summary of Significant Accounting Policies Leases (Details) $ in Millions | Jun. 30, 2020 USD ($)
--- | ---
Lease obligation related to Purchased Power [Line Items] |
Lease Obligation Related to Purchased Power Agreements | $ 285

X
- Definition This is the portion of the total lease obligation related to purchased power agreements. + References No definition available. + Details
Name: | tve_LeaseObligationRelatedToPurchasedPowerAgreements
Namespace Prefix: | tve_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition [Line Items] for Lease obligation related to Purchased Power + References No definition available. + Details
Name: | tve_LeaseobligationrelatedtoPurchasedPowerLineItems
Namespace Prefix: | tve_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration