XML 105 R108.htm IDEA: XBRL DOCUMENT v3.3.0.814

Benefit Plans Actuarial Assumptions (Details)	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2021	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure
Rate of compensation increase			5.70%
Expected return on plan assets			7.25%
Period during which actual company compensation experience study performed		5 years
Rate of compensation increase		5.70%	5.72%	4.44%
Minimum percentage increase in twelve-month average CPI-U necessary to receive COLA		1.00%
Cost of living adjustment assumption					2.50%
Pension Benefits
Defined Benefit Plan Disclosure
Discount rate		4.50%	4.45%	5.00%
Rate of compensation increase		5.70%	5.70%
Discount rate		4.45%	5.00%
Expected return on plan assets		7.00%	7.25%
Rate of compensation increase		5.70%	5.72%
Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Discount rate		4.65%	4.50%	5.05%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year		7.00%	7.50%	8.00%	8.50%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate		5.00%	5.00%	5.00%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate		2019	2019
Discount rate		4.50%	5.05%
Minimum
Defined Benefit Plan Disclosure
Rate of compensation increase		3.50%
Cost of living adjustment assumption		1.00%
Target Fed Funds Rate		0.00%
Maximum
Defined Benefit Plan Disclosure
Rate of compensation increase		13.00%
Cost of living adjustment assumption		5.00%
Target Fed Funds Rate		0.25%
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure
Cost of living adjustment assumption						2.40%	2.20%	0.00%
Scenario, Forecast [Member] | Other Post-retirement Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%

X

- Definition

The cost of living adjustment percentage used for defined benefit plans.

+ References

No definition available.

+ Details

Name:	tve_DefinedBenefitPlanCostOfLivingAdjustmentAssumption
Namespace Prefix:	tve_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Minimum percentage increase in twelve-month average CPI-U necessary to receive COLA.

+ References

No definition available.

+ Details

Name:	tve_MinimumpercentageincreaseintwelvemonthaverageCPIUnecessarytoreceiveCOLA
Namespace Prefix:	tve_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The period in which an actual compensation experience study is performed at TVA to determine assumptions related to compensation increases for defined benefit plans.

+ References

No definition available.

+ Details

Name:	tve_PeriodDuringWhichActualCompanyCompensationExperienceStudyPerformed
Namespace Prefix:	tve_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The Federal Reserve target range for the federal funds rate.

+ References

No definition available.

+ Details

Name:	tve_TargetFedFundsRate
Namespace Prefix:	tve_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The interest rate used to adjust for the time value of money for the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (k)(1)



-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (k)(2)



-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The interest rate used to adjust for the time value of money.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (k)(1)



-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Glossary Expected Long-Term Rate of Return on Plan Assets



-URI http://asc.fasb.org/extlink&oid=6512046



Reference 2: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (k)(3)



-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (k)(2)



-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease
Namespace Prefix:	us-gaap_
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

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Glossary Health Care Cost Trend Rate



-URI http://asc.fasb.org/extlink&oid=6514820



Reference 2: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (l)



-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The ultimate trend rate for health care costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (l)



-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Year the ultimate health care cost trend rate is expected to be reached, in CCYY format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (l)



-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanYearThatRateReachesUltimateTrendRate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	instant

X

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: