Refers to the margin rate on the debt instrument.

No definition available.

Name:	tvty_DebtInstrumentMarginRate
Namespace Prefix:	tvty_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments expressed as a percent of the original principal amount of debt instrument.

+ References

No definition available.

+ Details

Name:	tvty_DebtInstrumentPeriodicPaymentPercentageOfOriginalPrincipalAmount
Namespace Prefix:	tvty_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	tvty_DebtInstrumentVariableRateBasis
Namespace Prefix:	tvty_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of consolidated EBITDA.

+ References

No definition available.

+ Details

Name:	tvty_PercentageOfConsolidatedEBITDA
Namespace Prefix:	tvty_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the credit facility first became available, in CCYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityInitiationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=tvty_FederalFundsRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=tvty_OneMonthLondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
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_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=tvty_SwinglineSubFacilityMember
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_CreditFacilityAxis=tvty_TermLoanFacilityAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

Debt - Credit Facility - Additional Information (Details) - USD ($)		3 Months Ended
	Mar. 08, 2019	Mar. 31, 2019
Prior Credit Agreement
Line Of Credit Facility [Line Items]
Initiation date		Apr. 21, 2017
Credit Agreement
Line Of Credit Facility [Line Items]
Initiation date		Mar. 08, 2019
Credit Agreement \| Federal Funds Rate
Line Of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
Credit Agreement \| One-Month LIBOR
Line Of Credit Facility [Line Items]
Basis spread on variable rate	1.00%
Credit Agreement \| Minimum
Line Of Credit Facility [Line Items]
Unused commitment fee percentage	0.25%
Credit Agreement \| Minimum \| LIBOR
Line Of Credit Facility [Line Items]
Variable rate basis	0.00%
Credit Agreement \| Maximum
Line Of Credit Facility [Line Items]
Unused commitment fee percentage	0.50%
Credit Agreement \| Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	$ 125,000,000
Maturity date		Mar. 08, 2024
Credit Agreement \| Revolving Credit Facility \| Minimum \| LIBOR
Line Of Credit Facility [Line Items]
Margin rate	3.75%
Credit Agreement \| Revolving Credit Facility \| Minimum \| Base Rate
Line Of Credit Facility [Line Items]
Margin rate	2.75%
Credit Agreement \| Revolving Credit Facility \| Maximum \| LIBOR
Line Of Credit Facility [Line Items]
Margin rate	4.25%
Credit Agreement \| Revolving Credit Facility \| Maximum \| Base Rate
Line Of Credit Facility [Line Items]
Margin rate	3.25%
Credit Agreement \| Swingline Sub Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	$ 35,000,000
Maturity date		Mar. 08, 2024
Credit Agreement \| Letters of Credit Sub Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	50,000,000
Credit Agreement \| Term Loan Facility A
Line Of Credit Facility [Line Items]
Debt instrument, face amount	$ 350,000,000
Periodic principal payment as percentage of aggregate principal amount	2.50%
Maturity date		Mar. 08, 2024
Credit Agreement \| Term Loan Facility A \| LIBOR
Line Of Credit Facility [Line Items]
Margin rate	4.25%
Credit Agreement \| Term Loan Facility A \| Base Rate
Line Of Credit Facility [Line Items]
Margin rate	3.25%
Credit Agreement \| Term Loan Facility B
Line Of Credit Facility [Line Items]
Debt instrument, face amount	$ 830,000,000
Periodic principal payment as percentage of aggregate principal amount	0.75%
Maturity date		Mar. 08, 2026
Credit Agreement \| Term Loan Facility B \| LIBOR
Line Of Credit Facility [Line Items]
Margin rate	5.25%
Credit Agreement \| Term Loan Facility B \| Base Rate
Line Of Credit Facility [Line Items]
Margin rate	4.25%
Credit Agreement \| Uncommitted Incremental Accordion Facility \| Minimum
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	$ 125,000,000
Percentage of consolidated EBITDA requirement	50.00%