Marketing and Supply Agreement with Ildong (Detail) - USD ($)	1 Months Ended		3 Months Ended
	Mar. 31, 2015	Nov. 30, 2012	Mar. 31, 2016	Mar. 31, 2015
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Net product sales			$ 3,518,000	$ 6,618,000
Ildong
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement upfront payments		$ 5,000,000.0
Collaborative agreement, revenue recognition period		14 years
Milestone payment	$ 3,000,000.0
Purchase price range minimum		35.00%
Purchase price range maximum		45.00%
Annual net product sales threshold for maximum purchase price		$ 15,000,000.0
Net product sales			$ 1,100,000	$ 2,200,000