Commitments and Contingencies - University of California License Agreements - Additional Information (Detail) - University of California License Agreements [Member]	1 Months Ended		3 Months Ended	12 Months Ended
	Jun. 30, 2015 USD ($)	May 31, 2014 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) Milestone	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense			$ 0	$ 0		$ 0	$ 0
Milestone payments			$ 0	$ 0		$ 0	$ 0
Upfront payment	$ 50,000
Annual license maintenance fee					$ 15,000
After The Effective Date [Member]
Commitments And Contingencies [Line Items]
Licenses Expiration period, maximum		27 years
After The First Sale [Member]
Commitments And Contingencies [Line Items]
Licenses Expiration period, maximum		15 years
Clinical Development [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense					100,000
Milestone payments					$ 100,000
Milestones achieved | Milestone					3
Clinical Development [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Milestone payments		$ 100,000
Percentage of net sales paid as royalties		1.00%
Regulatory Milestones [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	700,000
Sales Milestones [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments	$ 2,000,000