Revenue Recognition and Significant Collaborative Research and Development Agreements - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended			9 Months Ended	12 Months Ended
	Jun. 30, 2010	Sep. 30, 2017	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2017	Dec. 31, 2015
Mitsubishi Tanabe
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Up-front license fees						$ 30,000,000
Collaborative agreement maximum additional payment to receive						85,000,000
Patent rights period					The longer of ten years or the life of the related patent rights.
Clinical trial cost						$ 12,000,000
Collaborative arrangement right description					Under the terms of the Company’s agreement with Mitsubishi Tanabe, the collaboration effort between the parties to advance valbenazine towards commercialization in Japan and other select Asian markets is governed by a joint steering committee and joint development committee with representatives from both the Company and Mitsubishi Tanabe. There are no performance, cancellation, termination or refund provisions in the agreement that would have a material financial consequence to the Company. The Company does not directly control when event-based payments will be achieved or when royalty payments will begin. Mitsubishi Tanabe may terminate the agreement at its discretion upon 180 days’ written notice to the Company. In such event, all valbenazine product rights for Japan and other select Asian markets would revert to the Company.
Collaboration termination notice period					180 days
Revenues recognized under collaboration agreement		$ 15,000,000		$ 19,800,000
Deferred revenues under collaboration				$ 10,200,000
AbbVie
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Patent rights period					Ten years or the life of the related patent rights.
Collaborative arrangement right description					The Company will be entitled to a percentage of worldwide sales of GnRH Compounds for the longer of ten years or the life of the related patent rights.
Collaboration termination notice period					180 days
Revenues recognized under collaboration agreement			$ 15,000,000
AbbVie
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Up-front license fees	$ 75,000,000
Amount remains outstanding under collaboration agreement		485,000,000			$ 485,000,000
AbbVie | Development and Regulatory Milestone Payments
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement maximum additional payment to receive		480,000,000			480,000,000
Collaborative agreement payment received					45,000,000
AbbVie | Commercial Milestone Payments
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement maximum additional payment to receive		$ 50,000,000			$ 50,000,000