Stockholders' Deficit (Details 2) (2010 Stock Incentive Plan)	1 Months Ended			12 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2010	Dec. 31, 2012 Stock options Employees, consultants and scientific advisors	Dec. 31, 2012 Stock options Non-employee director
Stock Compensation Plans
Maximum shares authorized for issuance	16,553,475	12,553,475
Vesting period (in years)				3 years	4 years
Expiration period (in years)				P7Y	P10Y
Number of shares that a new non-employee director joining the Board has the option to purchase					35,000
Granted annually, number of shares that a continuing Board member has the option to purchase					20,000
Number of shares originally authorized for issuance			5,400,000
Number of shares from previous plan which are now available for issuance under the current plan			653,475
Shares authorized for issuance before increase	12,553,475	6,053,475