Liquidity and management's plans - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended		0 Months Ended	6 Months Ended		12 Months Ended	6 Months Ended	12 Months Ended
	Jan. 31, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Feb. 07, 2014 Definitive Securities Purchase Agreement [Member]	Jun. 30, 2014 Definitive Securities Purchase Agreement [Member]	Jun. 30, 2014 Meda License Development and Supply Agreement [Member]	Dec. 31, 2013 Meda License Development and Supply Agreement [Member]	Jun. 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	$ 3,900,000			$ 3,900,000				$ 58,200,000	$ 58,200,000
Contract revenue under the Endo agreement				21,900,000
Research and development reimbursements under the Endo agreements		2,317,584		10,769,563								10,800,000	2,800,000
Net royalties under the Meda agreements		892,098	855,101	1,846,088	855,101					400,000	1,800,000
Exercise of Common Stock options and warrants				2,832,534	9,235	400,000
Exercise of warrants				3,994,356
Net proceeds from secured loan facility from Midcap						19,800,000
Contract revenue from licensing and supply agreement						300,000
Cash and cash equivalents		78,364,276	37,430,878	78,364,276	37,430,878	23,175,809	63,189,307
Cash from operations				(8,737,396)	(25,766,016)
Stockholders' equity		$ 61,796,498		$ 61,796,498		$ (812,351)