License Obligations - Arcion License Agreement - Additional Information (Detail) - USD ($)	1 Months Ended	6 Months Ended
	Feb. 28, 2015	Jun. 30, 2016
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential payments upon filing and acceptance	$ 10,000,000
Increase in milestone payments		$ 8,000,000
U.S. [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential Payments upon achieving certain pre-determined sales thresholds in the U.S		60,000,000
U.S. [Member] | Minimum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone Sales		200,000,000
Milestone payments receivable from sublicenses		70,000,000
Arcion Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential payments upon filing and acceptance		$ 2,500,000
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) the expiration of patent exclusivity or (iii) the tenth anniversary of the first commercial sale.
Arcion Agreement [Member] | Minimum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential milestone payments upon FDA approval		$ 17,500,000
Arcion Agreement [Member] | Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential milestone payments upon FDA approval		$ 35,000,000