Condensed Consolidated Statements of 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	1,280		1,102				178
Exercise of restricted stock units (shares)		9
Exercise of restricted stock units	0
Withholding taxes paid on vested restricted stock units	(45)		(25)				(20)
Changes in ownership of noncontrolling interest	0		(1,846)				1,846
Acquisition of interests held by noncontrolling owners	(159)						(159)
Net income	(9,567)			(10,201)			634
Unrealized gain/loss on investments, net of deferred income tax and reclassification adjustments	529				529
Foreign currency translation	27				27
Ending balance (shares) at Jun. 30, 2016		23,125
Ending balance at Jun. 30, 2016	426,069	$ 23	493,438	(161,567)	5,517	$ (1,413)	90,071
Ending balance, treasury stock (shares) at Jun. 30, 2016						78
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
Ending balance (shares) at Dec. 31, 2016	23,125	23,125
Ending balance at Dec. 31, 2016	$ 427,569	$ 23	495,468	(173,231)	6,661	$ (927)	99,575
Ending balance, treasury stock (shares) at Dec. 31, 2016	55					55
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	$ 1,565		1,334				231
Exercise of restricted stock units (shares)		62
Exercise of restricted stock units	0
Withholding taxes paid on vested restricted stock units	(832)		(711)				(121)
Changes in ownership of noncontrolling interest	0		(465)				465
Distribution to noncontrolling interest	(26)						(26)
Purchases of treasury stock (shares)						47
Purchases of treasury stock	(690)					$ (690)
Retirement of treasury stock (shares)		(47)				(47)
Retirement of treasury stock	0		(690)			$ 690
Distribution of treasury stock to deferred compensation plan participant (former CEO) (shares)						(54)
Distribution of treasury stock to deferred compensation plan participant (former CEO)	796		(106)			$ 902
Net income	9,015			6,219			2,796
Unrealized gain/loss on investments, net of deferred income tax and reclassification adjustments	(5,899)				(5,899)
Foreign currency translation	$ 25				25
Ending balance (shares) at Jun. 30, 2017	23,140	23,140
Ending balance at Jun. 30, 2017	$ 431,523	$ 23	$ 494,830	$ (167,012)	$ 787	$ (25)	$ 102,920
Ending balance, treasury stock (shares) at Jun. 30, 2017	1					1