Risk Management Activities and Derivative Transactions Cash Flow from Hedging (Details) $ in Millions	Jun. 30, 2025 USD ($)
Cash Flow from Hedging [Abstract]
Associated bond issues currency exposure	$ 400

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

No definition available.

Name:	tve_AssociatedBondIssuesCurrencyExposure
Namespace Prefix:	tve_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant