Collaborative Agreements - Additional Information (Detail) - USD ($) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012	Oct. 31, 2012
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable	$ 200	$ 200
Termination of collaborative agreement prior to written notice in number of days	90 days
Licensing arrangement, convertible promissory note received	$ 3,326	52,288
Royalties on net product sales				7.00%
Royalties on net product sales				10.00%
Catalyst Pharmaceutical Partners, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable	$ 100	$ 100
Licensing arrangement, convertible promissory note received			$ 5,000
Licensing arrangement, shares received upon conversion promissory note			6.7