Organization and basis of presentation (Details) (USD $)	1 Months Ended
	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Organization and basis of presentation
Deficit accumulated during the development stage		$ (16,134,000)	$ (2,624,000)
Reverse stock split conversion ratio	2.023
Cash resources sufficient to fund current operating plan		$ 31,400,000