XML 29 R67.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Benefit Plans Components of Benefit Plans (Details) | 3 Months Ended
--- | ---
Dec. 31, 2012 plans
Defined Benefit Plan Disclosure |
Number of defined benefit plans | 1
Number of definied contribution plans | 1
Number of unfunded post-retirement health care plans | 2

X
- Definition The number of qualified defined benefit pension plans. + References No definition available. + Details
Name: | tve_NumberOfQualifiedDefinedBenefitPlans
Namespace Prefix: | tve_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of qualified defined contribution pension plans. + References No definition available. + Details
Name: | tve_NumberOfQualifiedDefinedContributionPlans
Namespace Prefix: | tve_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of unfunded post-retirement health care plans that provide for non-vested contributions toward the cost of certain retirees' medical coverage. + References No definition available. + Details
Name: | tve_NumberOfUnfundedPostRetirementHealthCarePlans
Namespace Prefix: | tve_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration