Arcion License Agreement - Additional Information (Detail) (USD $)	3 Months Ended					12 Months Ended	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 U.S. [Member]	Mar. 31, 2014 U.S. [Member] Minimum [Member]	Mar. 31, 2014 Arcion License Agreement [Member]	Dec. 31, 2013 Arcion License Agreement [Member]	Mar. 31, 2014 Arcion License Agreement [Member] Minimum [Member]	Mar. 31, 2014 Arcion License Agreement [Member] Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Share issued to Arcion					500,516
Fair market value of unregistered shares issued					$ 2,100,000
Common stock locking period	9 months
Potential payments upon filing and acceptance					2,500,000
Potential Payments upon achieving certain pre-determined sales thresholds in the U.S			60,000,000
Milestone Sales				200,000,000
Milestone payment receivable from sublicenses				70,000,000
Potential milestone payment upon FDA approval							17,500,000	35,000,000
Milestone payments increased	8,000,000
Royalty term description					The royalty term for any given country is the later of (i) the first date there are no valid claims against any Arcion patent, (ii) expiration of patent exclusivity or (iii) tenth anniversary of the first commercial sale.
Research and development expense	$ 14,623,221	$ 12,032,168				$ 2,100,000