Research and License Agreements - Additional Information (Detail)	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2016 USD ($)	Sep. 30, 2016 USD ($) LicenseAgreement	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) LicenseAgreement	Sep. 30, 2015 USD ($)	Dec. 31, 2013 USD ($)
University Research Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research agreement date				2013-12
Maximum allowable research and development expenses per year		$ 1,800,000		$ 1,800,000		$ 386,000
Increasing the maximum research expenditure limit	$ 750,000
Research agreement expiration date				Aug. 31, 2017
Payments pursuant to research agreements		$ 188,000	$ 375,000	$ 645,000	$ 563,000
License Agreements
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research agreement date				2013-12
Number of license agreements | LicenseAgreement		2		2
Up front license fee paid						$ 10,000
Annual license fees payable in 2016				$ 5,000
Annual license fees payable in 2018 and thereafter				25,000
Maximum future contingent license payment				6,400,000
Aggregate potential milestone payments for receipt of regulatory approval				5,000,000
Aggregate potential milestone payments for final regulatory approval of second indication				$ 500,000