Consolidated Statements of Changes in Stockholders' Equity (Deficit) (USD $) In Thousands, except Share data	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
Beginning Balance at Dec. 31, 2011	$ 1	$ 16,657	$ (47,817)	$ (31,159)
Beginning Balance, (in shares) at Dec. 31, 2011	53,760,471
Share-based compensation expense		1,233		1,233
Issuance of common stock in public offering		18,155		18,155
Issuance of stock (in shares)	9,523,810
Issuance of stock for services		25		25
Issuance of stock for services (in shares)	15,000
Issuance of common stock upon exercise of warrants		1,129		1,129
Issuance of stock upon exercise of warrants (in shares)	1,779,716
Issuance of common stock upon exercise of stock options		111		111
Issuance of stock upon exercise of stock options (in shares)	755,020
Issuance of stock to 401(k) plan (in dollars)		91		91
Issuance of stock to 401(k) plan (in shares)	47,105
Fair value of warrants issued for services		32		32
Fair value of derivative warrant liability reclassified to additional paid-in capital		3,409		3,409
Net income (loss)			4,664	4,664
Ending Balance at Dec. 31, 2012	1	40,842	(43,153)	(2,310)
Ending Balance, (in shares) at Dec. 31, 2012	65,881,122
Share-based compensation expense		3,136		3,136
Issuance of common stock upon exercise of warrants		15,952		15,952
Issuance of stock upon exercise of warrants (in shares)	12,224,846
Issuance of common stock upon exercise of stock options		455		455
Issuance of stock upon exercise of stock options (in shares)	588,884
Issuance of stock to 401(k) plan (in dollars)		192		192
Issuance of stock to 401(k) plan (in shares)	78,884
Fair value of derivative warrant liability reclassified to additional paid-in capital		33,456		33,456
Incremental fair value from warrant modification		765		765
Net income (loss)			(38,756)	(38,756)
Ending Balance at Dec. 31, 2013	1	94,798	(81,909)	12,890
Ending Balance, (in shares) at Dec. 31, 2013	78,773,736
Share-based compensation expense		2,730		2,730
Issuance of common stock in public offering		7,770		7,770
Issuance of stock (in shares)	14,001,250
Issuance of stock for services		477		477
Issuance of stock for services (in shares)	298,505
Issuance of common stock upon exercise of warrants		12		12
Issuance of stock upon exercise of warrants (in shares)	39,900
Issuance of common stock upon exercise of stock options		212		212
Issuance of stock upon exercise of stock options (in shares)	531,598
Issuance of stock to 401(k) plan (in dollars)		173		173
Issuance of stock to 401(k) plan (in shares)	167,011
Net income (loss)			(18,346)	(18,346)
Ending Balance at Dec. 31, 2014	$ 1	$ 106,172	$ (100,255)	$ 5,918
Ending Balance, (in shares) at Dec. 31, 2014	93,812,000