Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total Stockholders' Equity	Noncontrolling interest
Beginning balance (in shares) at Dec. 31, 2014		69,032,818
Beginning balance at Dec. 31, 2014	$ 310,605	$ 360	$ 442,969	$ (127,068)	$ (5,656)	$ 0	$ 310,605	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	10,750		10,750				10,750
Investments by noncontrolling interests	7,873							7,873
Vesting of restricted stock units (in shares)		88,124
Vesting of restricted stock units	41	$ 1	40				41
Exercise of stock options (in shares)		747,224
Exercise of stock options	214	$ 4	210				214
Employee stock purchase plan (in shares)		202,732
Employee stock purchase plan	3,244	$ 1	3,243				3,244
Repurchases of common stock (in shares)		(10,690)
Repurchases of common stock	(187)				(187)		(187)
Other comprehensive Income	(678)					(372)	(372)	(306)
Other	(209)		(209)				(209)
Net income (loss)	(2,231)			(1,273)			(1,273)	(958)
Ending balance (in shares) at Dec. 31, 2015		70,060,208
Ending balance at Dec. 31, 2015	329,422	$ 366	457,003	(128,341)	(5,843)	(372)	322,813	6,609
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	17,385		17,385				17,385
Issuance of common stock through vesting of restricted stock units and option exercises (in shares)		1,237,969
Issuance of common stock through vesting of restricted stock units and option exercises	203	$ 6	197				203
Employee stock purchase plan (in shares)		456,008
Employee stock purchase plan	2,943	$ 2	2,941				2,943
Repurchases of common stock (in shares)		(148,477)
Repurchases of common stock	(854)				(854)		(854)
Other comprehensive Income	(20)					(7)	(7)	(13)
Net income (loss)	$ (85,482)			(82,958)			(82,958)	(2,524)
Ending balance (in shares) at Dec. 31, 2016	71,605,708	71,605,708
Ending balance at Dec. 31, 2016	$ 263,597	$ 374	477,526	(211,299)	(6,697)	(379)	259,525	4,072
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	12,690		12,690				12,690
Investments by noncontrolling interests	$ 3,440							3,440
Exercise of stock options (in shares)	1,407,646
Issuance of common stock through vesting of restricted stock units and option exercises (in shares)		2,014,497
Issuance of common stock through vesting of restricted stock units and option exercises	$ 464	$ 10	454				464
Employee stock purchase plan (in shares)		467,944
Employee stock purchase plan	1,841	$ 2	1,839				1,841
Repurchases of common stock (in shares)		(266,148)
Repurchases of common stock	(1,268)				(1,268)		(1,268)
Return of equity to noncontrolling interests	(957)							(957)
Other comprehensive Income	594					327	327	267
Net income (loss)	$ (14,345)			(11,534)			(11,534)	(2,811)
Ending balance (in shares) at Dec. 31, 2017	73,822,001	73,822,001
Ending balance at Dec. 31, 2017	$ 266,056	$ 386	$ 492,509	$ (222,833)	$ (7,965)	$ (52)	$ 262,045	$ 4,011