Liquidity and Management's Plans - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 05, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Nov. 30, 2012 Series A Non-Voting Convertible Preferred Stock [Member]
Liquidity and Management's Plans [Line Items]
Proceeds from secured loan facility from Midcap				$ 20,000,000
Net royalties under the meda agreements		924,272		1,779,373
Exercise of Common Stock options				347,434	1,873,397	2,100,000
Upfront and milestone payments from Endo license agreement						45,000,000
Preferred Stock, par value		$ 0.001		$ 0.001		$ 0.001		$ 0.001
Net proceeds from registered direct offering of Common Stock and newly designated Series						38,400,000
Exercise of Common Stock warrants					135,000	900,000
Secured loan facility	20,000,000
Net proceeds in the aggregate amount	19,900,000
Cash and cash equivalents		38,296,062	31,319,153	38,296,062	31,319,153	63,189,307	10,750,205
Cash from operations				(44,940,535)	19,650,639
Stockholders' equity		$ 11,046,777		$ 11,046,777		$ 49,777,213