Number of warrants exercised on pro rata basis.

No definition available.

Name:	tvty_NumberOfWarrantsExercisedOnProRataBasis
Namespace Prefix:	tvty_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of trading days where warrants are automatically exercised on prorata basis.

+ References

No definition available.

+ Details

Name:	tvty_PeriodOfTradingDaysWhereWarrantsAreAutomaticallyExercisedOnProrataBasis
Namespace Prefix:	tvty_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Stock issued during period exercise of warrants.

+ References

No definition available.

+ Details

Name:	tvty_StockIssuedDuringPeriodExerciseOfWarrants
Namespace Prefix:	tvty_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of warrants or rights outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
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

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=tvty_WarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=tvty_CashConvertibleNotesHedgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Cash Convertible Notes - Additional Information (Details) - $ / shares		3 Months Ended
	Oct. 01, 2018	Mar. 31, 2019	Jul. 31, 2013
Debt Instrument [Line Items]
Number of trading days, warrants automatically exercised on a pro rata basis	160 days
Number of warrants are automatically exercised on each trading day	48,000
Common Stock
Debt Instrument [Line Items]
Common stock shares issued related to automatic exercise of warrants		0
Common Stock \| Warrants \| Cash Convertible Notes Hedge
Debt Instrument [Line Items]
Shares issued upon conversion of debt			7,700,000
1.50% Cash Convertible Senior Notes Due 2018
Debt Instrument [Line Items]
Warrants strike price (in dollars per share)			$ 25.95