Commitments and Contingencies - Washington University License Agreement - Additional Information (Detail) - Washington University License Agreement [Member] - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
	Sep. 30, 2015	Nov. 30, 2013	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2013
Commitments And Contingencies [Line Items]
Upfront non-refundable payment		$ 50,000
Annual license maintenance fee					$ 15,000
Issuance of common stock, shares					47,619
Research and development expense related to issue of common stock obligation					$ 100,000
Research and development expense related to milestone expense			$ 0	$ 0
Milestone payments			$ 0	$ 0
Regulatory Milestones [Member]
Commitments And Contingencies [Line Items]
Research and development expense related to milestone expense	$ 50,000
Milestone payments	$ 50,000
Maximum [Member] | Clinical Development [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments		700,000
Maximum [Member] | Regulatory Milestones [Member]
Commitments And Contingencies [Line Items]
Expected milestone payments		$ 500,000