STATEMENTS OF STOCKHOLDERS EQUITY (DEFICIT) - USD ($) shares in Thousands, $ in Thousands	Total	Employees and Directors	Non-employee	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Employees and Directors	Additional Paid-in Capital Non-employee	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balance at Dec. 31, 2014	$ (3,388)			$ 101	$ 320,511				$ (324,000)
Beginning Balance (in shares) at Dec. 31, 2014				101,395
Issuance of common stock upon exercise of options	$ 5,193			$ 3	5,190
Issuance of common stock upon exercise of options (in shares)	2,041			2,041
Issuance of common stock upon exercise of warrants, net	$ 17,088			$ 6	17,082
Issuance of common stock upon exercise of warrants, net (in shares)				6,206
Stock-based compensation		$ 5,926	$ 87			$ 5,926	$ 87
Net income (loss)	(6,408)								(6,408)
Ending Balance at Dec. 31, 2015	18,498			$ 110	348,796				(330,408)
Ending Balance (in shares) at Dec. 31, 2015				109,642
Issuance of common stock upon exercise of options	$ 7,683			$ 3	7,680
Issuance of common stock upon exercise of options (in shares)	3,068			3,068
Stock-based compensation		7,002	56			7,002	56
Net income (loss)	$ 8,140								8,140
Ending Balance at Dec. 31, 2016	41,379			$ 113	363,534				(322,268)
Ending Balance (in shares) at Dec. 31, 2016				112,710
Issuance of common stock upon exercise of options	$ 7,181			$ 2	7,179
Issuance of common stock upon exercise of options (in shares)	2,007			2,007
Stock-based compensation		$ 13,330	$ 31			$ 13,330	$ 31
Net unrealized loss on marketable securities	$ (75)							$ (75)
Net income (loss)	129,122								129,122
Ending Balance at Dec. 31, 2017	$ 190,968			$ 115	$ 384,074			$ (75)	$ (193,146)
Ending Balance (in shares) at Dec. 31, 2017				114,717