Basis of Presentation (Policies)	9 Months Ended
Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	Our financial statements and accompanying notes are prepared in accordance with generally accepted accounting principles in the United States (“U.S. GAAP”). In our opinion, the accompanying consolidated financial statements of Tivity Health, Inc. and its wholly owned subsidiaries (collectively, “Tivity Health,” the “Company,” or such terms as “we,” “us,” or “our”) reflect all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement. We have reclassified certain items in prior periods to conform to current classifications. Our results from continuing operations do not include the results of Nutrisystem, Inc. (“Nutrisystem”), which we sold effective December 9, 2020. Results of operations for Nutrisystem have been classified as discontinued operations for all periods presented in the accompanying consolidated financial statements. We have omitted certain financial information that is normally included in financial statements prepared in accordance with U.S. GAAP but that is not required for interim reporting purposes. You should read the accompanying consolidated financial statements in conjunction with the financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2020.
Recent Relevant Accounting Standards	In October 2018, the FASB issued ASU 2018-16, "Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (“SOFR”) Overnight Index Swap (“OIS”) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes" (“ASU 2018-16”), which adds the OIS rate based on SOFR as a U.S. benchmark interest rate to facilitate the LIBOR to SOFR transition and provide lead time for entities to prepare for changes to interest rate risk hedging strategies. ASU 2018-16 is effective for fiscal years beginning after December 15, 2018, and interim periods within those years, with early adoption permitted. As of September 30, 2021, the benchmark interest rate in our existing interest rate swap agreements is LIBOR. The adoption of this standard did not have an impact on our financial position, results of operations, or cash flows. In March 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-04, “Reference Rate Reform (“ASC 848”): Facilitation of the Effects of Reference Rate Reform on Financial Reporting”. In January 2021, the FASB issued ASU 2021-01, “Reference Rate Reform: Scope”, which refines the scope of ASC 848 and clarifies the application of its guidance. ASC 848 contains temporary optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform, such as a transition away from the use of LIBOR. ASC 848 was effective for the Company as of January 1, 2020. The provisions of ASC 848 are available through December 31, 2022, at which time the reference rate replacement activity is expected to have been completed. The provisions of ASC 848 must be applied at a Topic, Subtopic or Industry Subtopic level for all transactions other than derivatives, which may be applied at a hedging relationship level. The accounting relief provided by ASC 848 is applicable only to legacy contracts if the amendments made to the agreements are solely for reference rate reform activities. Modifications that are unrelated to reference rate reform will scope out a given contract. ASC 848 allows for different elections to be made at different points in time, and the timing of those elections will be documented as applicable. For the avoidance of doubt, we intend to reassess the elections of optional expedients and exceptions included within ASC 848 related to our hedging activities and will document the election of these items on a quarterly basis. In March 2020, we elected the expedient that allows us to assume that our hedged interest payments are probable of occurring regardless of any expected modification in their terms related to reference rate reform. In addition, we have the option to change the method of assessing effectiveness upon a change in the critical terms of the derivative or the hedged transactions and upon the end of relief under ASC 848. In June 2020, we elected to (i) continue the method of assessing effectiveness as documented in the original hedge documentation and (ii) apply the expedient wherein the reference rate on the hypothetical derivative matches the reference rate on the hedging instrument. We will also apply the aforementioned elections to any future designated cash flow hedging relationship.

Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Our financial statements and accompanying notes are prepared in accordance with generally accepted accounting principles in the United States (“U.S. GAAP”). In our opinion, the accompanying consolidated financial statements of Tivity Health, Inc. and its wholly owned subsidiaries (collectively, “Tivity Health,” the “Company,” or such terms as “we,” “us,” or “our”) reflect all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement. We have reclassified certain items in prior periods to conform to current classifications.

Our results from continuing operations do not include the results of Nutrisystem, Inc. (“Nutrisystem”), which we sold effective December 9, 2020. Results of operations for Nutrisystem have been classified as discontinued operations for all periods presented in the accompanying consolidated financial statements.

We have omitted certain financial information that is normally included in financial statements prepared in accordance with U.S. GAAP but that is not required for interim reporting purposes. You should read the accompanying consolidated financial statements in conjunction with the financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2020.

Recent Relevant Accounting Standards

In October 2018, the FASB issued ASU 2018-16, "Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (“SOFR”) Overnight Index Swap (“OIS”) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes" (“ASU 2018-16”), which adds the OIS rate based on SOFR as a U.S. benchmark interest rate to facilitate the LIBOR to SOFR transition and provide lead time for entities to prepare for changes to interest rate risk hedging strategies. ASU 2018-16 is effective for fiscal years beginning after December 15, 2018, and interim periods within those years, with early adoption permitted. As of September 30, 2021, the benchmark interest rate in our existing interest rate swap agreements is LIBOR. The adoption of this standard did not have an impact on our financial position, results of operations, or cash flows.

In March 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-04, “Reference Rate Reform (“ASC 848”): Facilitation of the Effects of Reference Rate Reform on Financial Reporting”. In January 2021, the FASB issued ASU 2021-01, “Reference Rate Reform: Scope”, which refines the scope of ASC 848 and clarifies the application of its guidance. ASC 848 contains temporary optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform, such as a transition away from the use of LIBOR. ASC 848 was effective for the Company as of January 1, 2020. The provisions of ASC 848 are available through December 31, 2022, at which time the reference rate replacement activity is expected to have been completed. The provisions of ASC 848 must be applied at a Topic, Subtopic or Industry Subtopic level for all transactions other than derivatives, which may be applied at a hedging relationship level. The accounting relief provided by ASC 848 is applicable only to legacy contracts if the amendments made to the agreements are solely for reference rate reform activities. Modifications that are unrelated to reference rate reform will scope out a given contract. ASC 848 allows for different elections to be made at different points in time, and the timing of those elections will be documented as applicable. For the avoidance of doubt, we intend to reassess the elections of optional expedients and exceptions included within ASC 848 related to our hedging activities and will document the election of these items on a quarterly basis. In March 2020, we elected the expedient that allows us to assume that our hedged interest payments are probable of occurring regardless of any expected modification in their terms related to reference rate reform. In addition, we have the option to change the method of assessing effectiveness upon a change in the critical terms of the derivative or the hedged transactions and upon the end of relief under ASC 848. In June 2020, we elected to (i) continue the method of assessing effectiveness as documented in the original hedge documentation and (ii) apply the expedient wherein the reference rate on the hypothetical derivative matches the reference rate on the hedging instrument. We will also apply the aforementioned elections to any future designated cash flow hedging relationship.