CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2014	$ 106,964	$ 410	$ 457,242	$ 5,090	$ (355,778)
Beginning balance, Shares at Dec. 31, 2014		41,016
Net loss	(1,930)				(1,930)
Net unrealized change on investments (net of tax (benefit) provision of $(861), (1,172) & $204 for year 2015, 2016 & 2017 respectively)	(1,599)			(1,599)
Stock-based compensation, Value	144		144
Stock-based compensation, Shares		7
Issuance of shares under Employee Stock Purchase Plan, Value	91	$ 1	90
Issuance of shares under Employee Stock Purchase Plan, Shares		37
Ending balance at Dec. 31, 2015	103,670	$ 411	457,476	3,491	(357,708)
Ending balance, Shares at Dec. 31, 2015		41,060
Net loss	(29,282)				(29,282)
Net unrealized change on investments (net of tax (benefit) provision of $(861), (1,172) & $204 for year 2015, 2016 & 2017 respectively)	(2,175)			(2,175)
Stock-based compensation, Value	207		207
Stock-based compensation, Shares		7
Vested restricted stock units, net of repurchases, Value	(10)		(10)
Vested restricted stock units, net of repurchases, Shares		29
Issuance of shares under Employee Stock Purchase Plan, Value	78	$ 1	77
Issuance of shares under Employee Stock Purchase Plan, Shares		64
Ending balance at Dec. 31, 2016	$ 72,488	$ 412	457,750	1,316	(386,990)
Ending balance, Shares at Dec. 31, 2016	41,160	41,160
Net loss	$ (8,604)				(8,604)
Net unrealized change on investments (net of tax (benefit) provision of $(861), (1,172) & $204 for year 2015, 2016 & 2017 respectively)	498			498
Stock-based compensation, Value	299		299
Stock-based compensation, Shares		7
Issuance of shares under Employee Stock Purchase Plan, Value	76	$ 1	75
Issuance of shares under Employee Stock Purchase Plan, Shares		68
Reclassification of deferred tax resulting from change in corporate tax rate				86	(86)
Ending balance at Dec. 31, 2017	$ 64,757	$ 413	$ 458,124	$ 1,900	$ (395,680)
Ending balance, Shares at Dec. 31, 2017	41,160	41,235