Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Private Placement	Common stock	Common stock Private Placement	Treasury stock	Additional paid-in capital	Additional paid-in capital Private Placement	Accumulated deficit	Accumulated other comprehensive income (loss)	Noncontrolling Interest
Balance at Dec. 31, 2014	$ 540,255		$ 42		$ (329)	$ 761,026		$ (220,410)	$ (74)
Balance (in shares) at Dec. 31, 2014			41,884
Increase (Decrease) in Stockholders' Equity
Compensation expense for issuance of stock options to employees	25,026					25,026
Compensation expense for issuance of restricted stock to employees	8,441					8,441
Compensation expense for issuance of restricted stock to employees (in shares)			244
Exercise of stock options	18,096		$ 1			18,095
Exercise of stock options (in shares)			871
Excess tax benefit from (charges for) share-based compensation arrangements	194					194
Other comprehensive loss, net of tax	(45)								(45)
Net (loss) income	11,058							11,058
Balance at Dec. 31, 2015	603,025		$ 43		(329)	812,782		(209,352)	(119)
Balance (in shares) at Dec. 31, 2015			42,999
Increase (Decrease) in Stockholders' Equity
Compensation expense for issuance of stock options to employees	28,090					28,090
Compensation expense for issuance of restricted stock to employees	8,296					8,296
Compensation expense for issuance of restricted stock to employees (in shares)			236
Exercise of stock options	3,427					3,427
Exercise of stock options (in shares)			194
Excess tax benefit from (charges for) share-based compensation arrangements	(13)					(13)
Private placement, net of issuance costs		$ 72,091		$ 3			$ 72,088
Private placement, net of issuance costs (in shares)				2,251
Acquisition of subsidiary	25,736									$ 25,736
Purchase of noncontrolling interest	(27,946)					(3,305)				(24,641)
Other comprehensive loss, net of tax	(12,893)								(12,782)	(110)
Net (loss) income	(35,603)							(34,618)		(985)
Balance at Dec. 31, 2016	664,211		$ 46		(329)	921,365		(243,970)	(12,901)	$ 0
Balance (in shares) at Dec. 31, 2016			45,680
Increase (Decrease) in Stockholders' Equity
Adjustment to accumulated deficit (pursuant to adoption of ASU 2016-09) | ASU 2016-09	12,221							12,221
Compensation expense for issuance of stock options to employees	24,910					24,910
Compensation expense for issuance of restricted stock to employees	7,904					7,904
Compensation expense for issuance of restricted stock to employees (in shares)			263
Exercise of stock options	10,479					10,479
Exercise of stock options (in shares)			498
Restructuring Cost pursuant to equity modification	967					967
Purchase of Treasury Stock	(60)				(60)
Purchase of noncontrolling interest	2,955					2,955
Other comprehensive loss, net of tax	19,759								19,759
Net (loss) income	(223,359)							(223,359)
Balance at Dec. 31, 2017	$ 519,987		$ 46		$ (389)	$ 968,580		$ (455,108)	$ 6,858
Balance (in shares) at Dec. 31, 2017			46,441