Description of Business - Additional Information (Detail)		12 Months Ended
	Mar. 22, 2016 $ / shares shares	Dec. 31, 2016 USD ($) Segment shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Description Of Business [Line Items]
Entity incorporation, date of incorporation		Nov. 06, 2008
Number of operating segments | Segment		1
Reverse stock split, description		Fifteen-for-one reverse stock split of its common stock
Reverse stock split ratio		15
Agreement entered date		Nov. 18, 2015
Combined shares of common stock outstanding | shares		8,356,659	273,993
Cash and cash equivalents | $		$ 27,756,000	$ 4,778,000	$ 777,000	$ 145,000
Short-term marketable securities | $		32,180,000	0
Accumulated deficit | $		$ (76,358,000)	$ (29,271,000)
Reverse Stock Split [Member]
Description Of Business [Line Items]
Common stock exchange price per share | $ / shares	$ 0.09
Combined shares of common stock outstanding | shares	6,945,401
Reverse Merger [Member]
Description Of Business [Line Items]
Date of acquisition		Mar. 22, 2016
Reverse Stock Split [Member]
Description Of Business [Line Items]
Reverse stock split ratio	15
Issuance of common stock in connection with acquisition | shares	0