Revenue Recognition - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2013	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Apr. 30, 2013
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront non-refundable, non-creditable license fee								$ 15,000
Issuance of convertible preferred stock	2,105,263
Stock purchase agreement, purchase price of preferred stock	8,000
Stock purchase agreement, purchase price fair value of preferred stock	7,663
Stock purchase agreement, purchase price premium of preferred stock	337
Revenue recognized from nonsubstantive milestones					8,000
Revenue recognized from substantive milestones					2,500
Non-refundable contingent payment		480
Deferred R&D service revenue		3,069	3,069		3,069		3,475
License fee revenue			302	9,637	302	9,637
Collaborative revenue			658	336	836	336
Amortization of deferred revenue			526	306	677	306
Revenue recognized from sale of clinical compound			132	30	159	30
Research and development expense			3,200	2,021	5,401	2,943
Maruishi License Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense			$ 714	$ 352	$ 1,112	$ 352