Condensed Consolidated Statements of Shareholders' Equity - Unaudited - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	Treasury Stock	Noncontrolling Interest
Beginning balance (shares) at Dec. 31, 2015		23,116
Beginning balance at Dec. 31, 2015	$ 434,004	$ 23	$ 494,207	$ (151,366)	$ 4,961	$ (1,413)	$ 87,592
Beginning balance, treasury stock (shares) at Dec. 31, 2015						78
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	506		455				51
Withholding taxes paid on vested restricted stock units	(45)		(25)				(20)
Net income	(6,842)			(6,801)			(41)
Unrealized gain on investments, net of deferred income tax and reclassification adjustments	40				40
Foreign currency translation	9				9
Ending balance (shares) at Mar. 31, 2016		23,116
Ending balance at Mar. 31, 2016	$ 427,672	$ 23	494,637	(158,167)	5,010	$ (1,413)	87,582
Ending balance, treasury stock (shares) at Mar. 31, 2016						78
Beginning balance (shares) at Dec. 31, 2016	23,125	23,125
Beginning balance at Dec. 31, 2016	$ 427,569	$ 23	495,468	(173,231)	6,661	$ (927)	99,575
Beginning balance, treasury stock (shares) at Dec. 31, 2016	55					55
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	$ 898		717				181
Exercise of restricted stock units (shares)		25
Exercise of restricted stock units	0
Withholding taxes paid on vested restricted stock units	(400)		(279)				(121)
Changes in ownership of noncontrolling interest	0		(411)				411
Distribution to noncontrolling interest	(26)						(26)
Purchases of treasury stock (shares)						13
Purchases of treasury stock	(184)					$ (184)
Retirement of treasury stock (shares)		(13)				(13)
Retirement of treasury stock	0		(184)			$ 184
Net income	6,034			4,643			1,391
Unrealized gain on investments, net of deferred income tax and reclassification adjustments	(590)				(590)
Foreign currency translation	$ 16				16
Ending balance (shares) at Mar. 31, 2017	23,137	23,137
Ending balance at Mar. 31, 2017	$ 433,317	$ 23	$ 495,311	$ (168,588)	$ 6,087	$ (927)	$ 101,411
Ending balance, treasury stock (shares) at Mar. 31, 2017	55					55