Condensed consolidated statement of changes in equity (deficit) - 9 months ended Sep. 30, 2016 - USD ($) shares in Thousands, $ in Thousands	Total	Accumulated Other Comprehensive Loss [Member]	Additional Paid-in capital [Member]	Accumulated Deficit [Member]	Non-Controlling Interests [Member]	Class A Common Stock [Member]	Class A Common Stock [Member] Common Stock [Member]	Class B Common Stock [Member]	Class B Common Stock [Member] Common Stock [Member]
Beginning balance at Dec. 31, 2015	$ (1,080)	$ (1,710)	$ 352	$ (14,032)	$ 14,300		$ 4		$ 6
Beginning balance (shares) at Dec. 31, 2015						36,598		62,112
Net income	49,300			10,926	38,374
Equity-based compensation expense	1,373		1,373
Repurchase and retirement of Class B common stock	(1,583)		(441)	(1,142)
Repurchase and retirement of Class B common stock, shares								(141)
Exchanges of Class B common stock		730	5,269		(5,999)		1		(1)
Exchanges of Class B common stock, shares						13,306		(13,306)
Tax benefit arrangement liability and deferred taxes arising from secondary offerings	8,148		8,148
Exercise of stock options and vesting of restricted share units	124		124
Exercise of stock options and vesting of restricted share units, shares						10
Distributions paid to members of Pla-Fit Holdings	(27,071)				(27,071)
Other comprehensive loss	(553)	(143)			(410)
Ending balance at Sep. 30, 2016	$ 28,658	$ (1,123)	$ 14,825	$ (4,248)	$ 19,194		$ 5		$ 5
Ending balance (shares) at Sep. 30, 2016						49,914		48,665