XML 100 R67.htm IDEA: XBRL DOCUMENT v3.19.2

Risk Management Activities and Derivative Transactions Cash Flow from Hedging (Details) $ in Millions	Jun. 30, 2019 USD ($)
Cash Flow from Hedging [Abstract]
Associated bond issues currency exposure	$ 600

X

- Definition

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

+ References

No definition available.

+ Details

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

X

- Definition

Cash Flow from Hedging [Abstract]

+ References

No definition available.

+ Details

Name:	tve_CashFlowfromHedgingAbstract
Namespace Prefix:	tve_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration