Commitments and contingencies (Details)				9 Months Ended
	Jun. 02, 2015 USD ($)	Dec. 20, 2013 $ / shares	Dec. 10, 2013 $ / shares	Sep. 30, 2015 USD ($) ClinicalMilestone Lawsuit d	Dec. 31, 2014 USD ($)
Commitments and contingencies [Abstract]
Potential future payments				$ 7,500,000
Number of clinical milestones | ClinicalMilestone				2
Payments made on achievement of clinical milestones				$ 2,000,000
Potential future milestone payments on each additional final marketing approval				$ 1,000,000
Number of shareholders lawsuits | Lawsuit				3
Number of day's court afforded the plaintiffs to amend their complaint | d				30
Exercise price (in dollars per share) | $ / shares		$ 4.66	$ 2.39
Fees and expenses related to settlement	$ 1,100,000
Outstanding Receivable				$ 1,667,905	$ 2,019,293