Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator [Abstract]
Net income from continuing operations attributable to Tivity Health, Inc. - numerator for earnings per share		$ 17,240	$ 19,962	$ 32,720	$ 39,168
Net loss from discontinued operations attributable to Tivity Health, Inc. - numerator for loss per share		(3,673)	(195,558)	(3,893)	(228,973)
Net income (loss) attributable to Tivity Health, Inc.		$ 13,567	$ (175,596)	$ 28,827	$ (189,805)
Denominator [Abstract]
Shares used for basic income (loss) per share (in shares)		39,246	36,172	39,158	36,140
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Shares used for diluted income (loss) per share (in shares)		42,369	37,227	41,456	37,043
Earnings (loss) per share attributable to Tivity Health, Inc. - basic [Abstract]
Continuing operations (in dollars per share)		$ 0.44	$ 0.55	$ 0.84	$ 1.08
Discontinued operations (in dollars per share)		(0.09)	(5.41)	(0.10)	(6.34)
Net income (loss) (in dollars per share)	[1]	0.35	(4.85)	0.74	(5.25)
Earnings (loss) per share attributable to Tivity Health, Inc. - diluted [Abstract]
Continuing operations (in dollars per share)		0.41	0.54	0.79	1.06
Discontinued operations (in dollars per share)		(0.09)	(5.25)	(0.09)	(6.18)
Net income (loss) (in dollars per share)	[1]	$ 0.32	$ (4.72)	$ 0.70	$ (5.12)
Non-Qualified Stock Options [Member]
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)		481	235	462	177
Restricted Stock Units [Member]
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)		602	586	606	524
Market Stock Units [Member]
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)		312	231	303	202
Warrants Related to Cash Convertible Notes [Member]
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)		1,728	0	927	0
CareFirst Warrants [Member]
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)		0	3	0	0
Non-Qualified Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities outstanding not included in the computation of earnings (loss) per share because their effect is anti-dilutive (in shares)		0	1,198	8	1,486
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities outstanding not included in the computation of earnings (loss) per share because their effect is anti-dilutive (in shares)		3	579	10	679
Warrants Related to Cash Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities outstanding not included in the computation of earnings (loss) per share because their effect is anti-dilutive (in shares)		0	7,707	0	7,707
CareFirst Convertible Note [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities outstanding not included in the computation of earnings (loss) per share because their effect is anti-dilutive (in shares)		0	892	0	892
CareFirst Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities outstanding not included in the computation of earnings (loss) per share because their effect is anti-dilutive (in shares)		0	472	0	591

[1] Figures may not add due to rounding.