Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2010	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net revenue	$ 105,328	$ 98,641	$ 99,993	$ 99,080	$ 96,107	$ 98,534	$ 100,935	$ 101,345		$ 403,042	$ 396,921	$ 424,323
Operating (loss) income	9,806	(6,269)	3,518	(118)	1,425	(2,624)	(1,462)	(3,722)		6,937	(6,383)	7,114
Net income	$ 20,990	$ (13,276)	$ (410)	$ (2,935)	$ (259)	$ (5,506)	$ 20,733	$ (6,925)		$ 4,369	$ 8,043	$ 21,158
Earnings per share:
Basic (in dollars per share)	$ 0.78	$ (0.50)	$ (0.02)	$ (0.11)	$ (0.01)	$ (0.21)	$ 0.81	$ (0.28)		$ 0.16	$ 0.31	$ 0.86
Diluted (in dollars per share)	$ 0.76	$ (0.50)	$ (0.02)	$ (0.11)	$ (0.01)	$ (0.21)	$ 0.79	$ (0.28)		$ 0.16	$ 0.31	$ 0.84
Fixed asset impairment charge		$ 6,497				$ 742				$ 6,497	$ 742	$ 14,571
Personal training revenue recognized for unused and expired sessions	$ 3,557								$ 2,697
Gain (loss) on extinguishment of debt							$ 38,497			$ 0	$ 37,893	$ 17,911
Repurchase amount							$ 71,152