Statements of Changes in Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	4 Months Ended	12 Months Ended
	Dec. 31, 2003	Dec. 31, 2005	Dec. 31, 2009 Private Placement	Dec. 31, 2007 Private Placement	Dec. 31, 2006 Private Placement	Dec. 31, 2012 Registered direct offering	Dec. 31, 2010 Registered direct offering	Dec. 31, 2009 Registered direct offering	Dec. 31, 2011 Securities Offering	Dec. 31, 2011 Collaboration Agreement
Stockholders' contribution, date	Sep. 09, 2003
Issuance of Series A convertible preferred stock, expenses		$ 1,340
Issuance of Series A convertible preferred stock, warrant cost		1,683
Series A convertible preferred stock, par value		$ 0.001
Common stock, par value		$ 0.001
Conversion of Series A convertible preferred stock into common stock, conversion date		Sep. 13, 2005
Conversion of Series A convertible preferred stock into common stock, exchange ratio		0.500974
Issuance of common stock, issuance expenses			465	1,909	2,719	3,426	2,203	2,802	245	86
Issuance of common stock and warrants in a registered direct offering, warrants								$ 22,860