Subsequent Events - Additional Information (Detail) - Subsequent Event [Member] - USD ($) $ in Millions	Apr. 28, 2017	Apr. 27, 2017
Novartis Pharma AG [Member]
Subsequent Event [Line Items]
License agreement upfront payment		$ 7.5
License agreement, potential future milestone payments		7.5
Payments for subsequently licensed products and low single digit royalty payments on net sales of covered products		$ 1.1
GlaxoSmithKline Intellectual Property Development Limited [Member]
Subsequent Event [Line Items]
License agreement upfront payment	$ 3.0
License agreement, potential future milestone payments	$ 1.3