XML 150 R109.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Benefit Plans Asset Holdings (Details) | 12 Months Ended |
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017
Defined Benefit Plan Disclosure |  |
Target Allocation | 100.00% |
Plan Asset Allocations | 100.00% | 100.00%
Global public equity |  |
Defined Benefit Plan Disclosure |  |
New Policy Target Allocation | 43.00% |
Target Allocation | 35.00% |
Plan Asset Allocations | 44.00% | 44.00%
Fixed income |  |
Defined Benefit Plan Disclosure |  |
New Policy Target Allocation | 32.00% |
Public real assets |  |
Defined Benefit Plan Disclosure |  |
Target Allocation | 15.00% |
Plan Asset Allocations | 15.00% | 13.00%
Private equity |  |
Defined Benefit Plan Disclosure |  |
Target Allocation | 8.00% |
Plan Asset Allocations | 7.00% | 5.00%
Safety oriented fixed income |  |
Defined Benefit Plan Disclosure |  |
Target Allocation | 17.00% |
Plan Asset Allocations | 16.00% | 21.00%
Opportunistic fixed income |  |
Defined Benefit Plan Disclosure |  |
Target Allocation | 15.00% |
Plan Asset Allocations | 10.00% | 10.00%
Private real assets |  |
Defined Benefit Plan Disclosure |  |
New Policy Target Allocation | 25.00% |
Target Allocation | 10.00% |
Plan Asset Allocations | 8.00% | 7.00%

X
- Definition New policy target allocation of investments of this type to total plan assets presented on a weighted average basis. + References No definition available. + Details
Name: | tve_DefinedBenefitPlanNewPolicyTargetPlanAssetAllocations
Namespace Prefix: | tve_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=112275985&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=tve_PublicRealAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_PrivateEquityFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=tve_SafetyorientedfixedincomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=tve_OpportunisticfixedincomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=tve_PrivateRealAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |