Stockholders' Equity - Additional Information (Detail) $ / shares in Units, $ in Millions		12 Months Ended
	Mar. 25, 2015 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) Stock_Plan $ / shares shares	Dec. 31, 2015 $ / shares shares
Stockholders Equity [Line Items]
Options to purchase common stock outstanding, number of stockholder-approved plans | Stock_Plan		2
Number of shares authorized for grant			4,000,000
Weighted average period for recognizing unrecognized compensation cost as expense		2 years 7 months 6 days
Unrecognized compensation cost related to stock option awards | $		$ 1.3
Weighted average fair value | $ / shares		$ 0.51	$ 1.05
Dividend yield		0.00%	0.00%
March 2015 Financing [Member]
Stockholders Equity [Line Items]
Gross proceeds from issuance of common stock and warrants | $	$ 10.0
Net proceeds from issuance of common stock and warrants | $	$ 9.2
Share price of common stock and warrants issued | $ / shares	$ 1.7125
Number of warrants issued for each unit issued	0.5
Common stock issued during period	5,839,420
Warrants exercised	2,919,710
Term of warrants	5 years
Common Stock [Member]
Stockholders Equity [Line Items]
Warrants exercised		0	0
2015 Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Number of shares authorized for grant		4,000,000
Number of additional shares authorized for grant		726,000
Private Placement [Member] | March 2015 Financing [Member]
Stockholders Equity [Line Items]
Warrants exercised	233,577
Exercise Price | $ / shares	$ 2.13
Warrant expiration date	Mar. 20, 2020