Liquidity and management's plans - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended		0 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Jan. 31, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Feb. 07, 2014 Definitive Securities Purchase Agreement [Member]	Sep. 30, 2014 Definitive Securities Purchase Agreement [Member]	Dec. 31, 2013 Meda License Development and Supply Agreement [Member]	Sep. 30, 2014 Endo License and Development Agreement [Member]	Dec. 31, 2013 Endo License and Development Agreement [Member]
Liquidity and Management's Plans [Line Items]
Proceeds from issuance of common stock	$ 8,600,000	$ 3,900,000			$ 12,500,000				$ 58,200,000	$ 58,200,000
Contract revenue under the Endo agreement					22,300,000
Research and development reimbursements under the Endo agreements			1,297,761		12,067,324							12,100,000	2,800,000
Exercise of Common Stock options and warrants					4,572,919	347,434	400,000
Exercise of warrants					4,930,796
Net proceeds from secured loan facility from Midcap							19,800,000
Net royalties under the Meda agreements			11,832	924,272	1,857,920	1,779,373					1,800,000
Contract revenue from licensing and supply agreement							300,000
Cash and cash equivalents	85,793,950		85,793,950	38,296,062	85,793,950	38,296,062	23,175,809	63,189,307
Cash from operations					$ (10,798,781)	$ (44,940,535)