Interest coverage ratio required in two years and each quarter thereafter.

No definition available.

Name:	ten_InterestCoverageRatioRequiredInTwoYearsAndEachQuarterThereafter
Namespace Prefix:	ten_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Interest coverage ratio required minimum.

+ References

No definition available.

+ Details

Name:	ten_InterestCoverageRatioRequiredMinimum
Namespace Prefix:	ten_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Leverage ratio required each quarter thereafter.

+ References

No definition available.

+ Details

Name:	ten_LeverageRatioRequiredEachQuarterThereafter
Namespace Prefix:	ten_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Leverage ratio required maximum.

+ References

No definition available.

+ Details

Name:	ten_LeverageRatioRequiredMaximum
Namespace Prefix:	ten_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum percentage of stock of certain first-tier foreign subsidiaries pledged to secure senior credit facility.

+ References

No definition available.

+ Details

Name:	ten_MaximumPercentageOfStockOfCertainFirstTierForeignSubsidiariesPledgedToSecureSeniorCreditFacility
Namespace Prefix:	ten_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_InterestExpenseDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the required periodic payment applied to principal.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityPeriodicPaymentPrincipal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(a))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

+ Details

Name:	us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

+ Details

Name:	us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_UnsecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=ten_FivePointThreeSevenFivePercentSeniorNotesDueDecember152024MemberDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ten_FivePercentSeniorNotesDueJuly152026MemberDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ten_OtherDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ten_TrancheTermFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ten_AmendedAndRestatedFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ten_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	ten_RegulatoryCapitalRequirementsByTypeOfRegulatedEntityAxis=ten_ActualMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-Term Debt and Financing Arrangements - Additional Information (Details)	1 Months Ended	3 Months Ended					9 Months Ended		18 Months Ended
	May 31, 2017 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2020 USD ($)	Sep. 30, 2017 USD ($)	Mar. 31, 2022 USD ($)	May 12, 2017 USD ($)	May 11, 2017 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Maximum percentage of stock of certain first-tier foreign subsidiaries pledged to secure senior credit facility				66.00%				66.00%
Debt outstanding				$ 1,573,000,000				$ 1,573,000,000				$ 1,294,000,000
Leverage Ratio Required (Maximum) for future quarters								3.50
Interest coverage ratio (minimum)								2.75
5.375% Senior Notes Due 2024
Debt Instrument [Line Items]
Outstanding debt				225,000,000				$ 225,000,000
Debt issuance costs				3,000,000				3,000,000
Debt outstanding				222,000,000				222,000,000
5% Senior Notes Due July 15 2026
Debt Instrument [Line Items]
Outstanding debt				500,000,000				500,000,000
Debt issuance costs				8,000,000				8,000,000
Debt outstanding				492,000,000				492,000,000
Other Debt
Debt Instrument [Line Items]
Unsecured debt				121,000,000				121,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity				1,600,000,000				1,600,000,000		$ 1,600,000,000	$ 1,200,000,000
Outstanding debt				453,000,000				453,000,000
Unused borrowing capacity				1,147,000,000				1,147,000,000
Revolving Credit Facility \| Tranche Term Facility
Debt Instrument [Line Items]
Outstanding debt											$ 264,000,000
Debt issuance costs				2,000,000				2,000,000
Debt outstanding				393,000,000				393,000,000		$ 400,000,000
Principal payments excluded from current liabilities				20,000,000				20,000,000
Revolving Credit Facility \| Amended and Restated Facility
Debt Instrument [Line Items]
Pre-tax interest charges	$ 1,000,000
Revolving Credit Facility \| Term loan
Debt Instrument [Line Items]
Outstanding debt				395,000,000				395,000,000
Letter of Credit
Debt Instrument [Line Items]
Outstanding debt				$ 0				$ 0
Future payment \| Revolving Credit Facility \| Tranche Term Facility
Debt Instrument [Line Items]
Repayment of term loan		$ 260,000,000	$ 5,000,000				$ 7,500,000		$ 10,000,000
Actual
Debt Instrument [Line Items]
Leverage Ratio (maximum)				2.15	1.97	1.62
Interest Coverage Ratio (minimum)				11.48	12.44	15.38