Leases - Schedule of Right-of-Use Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Right-of-use assets:
Operating	$ 17,145	$ 23,895
Finance	994	1,680
Total leased assets	18,139	25,575
Current
Operating	$ 7,408	$ 7,274
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	tvty:CurrentLeaseLiabilities	tvty:CurrentLeaseLiabilities
Finance	$ 644	$ 624
Non-current
Operating	$ 11,097	$ 18,505
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	tvty:NoncurrentLeaseLiabilities	tvty:NoncurrentLeaseLiabilities
Finance	$ 397	$ 1,080
Total lease liabilities	$ 19,546	$ 27,483