Consolidated Statements of Changes in Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Treasury Stock, at Cost [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2012	$ (253,887)	$ 6	$ 150,088	$ 0	$ (8,816)	$ (395,165)
Balance (shares) at Dec. 31, 2012		6,062,653
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of Class L common stock	854,101	$ 47	854,054
Conversion of Class L common stock (shares)		46,708,466
Initial public offering, net of offering costs of $20.6 million	234,944	$ 12	234,932
Initial public offering, net of offering costs of $20.6 million (shares)		11,615,000
Stock-based compensation	10,692		10,692
Exercise of stock options	11,040		11,040
Exercise of stock options (shares)		916,695
Tax benefit from stock option exercises	5,101		5,101
Acquisition of additional non-controlling interest	4,066		4,291		(225)
Translation adjustments, net of non-controlling interest	10,457				10,457
Net Income (Loss) Attributable to Parent	12,623					12,623
Balance at Dec. 31, 2013	889,137	$ 65	1,270,198	0	1,416	(382,542)
Balance (shares) at Dec. 31, 2013		65,302,814
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	7,922		7,922
Exercise of stock options	17,422	$ 2	17,420
Exercise of stock options (shares)		1,212,458
Tax benefit from stock option exercises	9,123		9,123
Purchase of treasury stock	(221,577)			(221,577)
Retirement of treasury stock	0	$ (5)	(221,572)	221,577
Retirement of treasury stock (in shares)		(4,980,470)
Translation adjustments, net of non-controlling interest	(23,103)				(23,103)
Net Income (Loss) Attributable to Parent	72,035					72,035
Balance at Dec. 31, 2014	750,959	$ 62	1,083,091	0	(21,687)	(310,507)
Balance (shares) at Dec. 31, 2014		61,534,802
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	9,200		9,200
Exercise of stock options	9,811	$ 0	9,811
Exercise of stock options (shares)		694,381
Tax benefit from stock option exercises	9,397		9,397
Purchase of treasury stock	(128,103)			(128,103)
Retirement of treasury stock	0	$ (2)	(128,101)	128,103
Retirement of treasury stock (in shares)		(2,221,047)
Translation adjustments, net of non-controlling interest	(17,583)				(17,583)
Net Income (Loss) Attributable to Parent	93,927					93,927
Balance at Dec. 31, 2015	$ 727,608	$ 60	$ 983,398	$ 0	$ (39,270)	$ (216,580)
Balance (shares) at Dec. 31, 2015		60,008,136