Stockholders' Equity - Additional Information (Detail) - USD ($)						1 Months Ended	3 Months Ended		9 Months Ended		55 Months Ended
	Aug. 14, 2017	Feb. 08, 2017	May 12, 2016	Aug. 13, 2014	Aug. 14, 2013	May 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2016	Aug. 15, 2013	Jun. 06, 2011
Stockholders Equity [Line Items]
Preferred stock, shares authorized							10,000,000		10,000,000			10,000,000
Preferred stock, par value							$ 0.001		$ 0.001			$ 0.001
Preferred stock, outstanding							0		0			0
Common stock reserved for future issuance							3,892,838		3,892,838
Unrecognized compensation expense							$ 700,000		$ 700,000
Unrecognized stock-based compensation expense, weighted average period of recognition									1 year 8 months 12 days
Shares excluded from calculation of diluted net loss per share							3,203,620	3,129,479	3,203,620	3,129,479
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax							$ 2,600,000		$ 2,600,000			$ 2,100,000
Restricted Stock Units (RSUs)
Stockholders Equity [Line Items]
Unrecognized compensation expense							$ 4,700,000		$ 4,700,000
Unrecognized stock-based compensation expense, weighted average period of recognition									2 years 9 months 19 days
2011 Plan
Stockholders Equity [Line Items]
Common stock reserved for future issuance														400,000
Number of shares available for grant														859,956
Increase in shares of common stock authorized for issuance			2,000,000								1,000,000
2011 Plan | Restricted Stock Units (RSUs)
Stockholders Equity [Line Items]
Aggregate restricted stock units outstanding							1,403,514		1,403,514
2007 Plan and 2010 Plan
Stockholders Equity [Line Items]
Number of shares available for grant														459,956
Loan and Security Agreements | Opus Bank
Stockholders Equity [Line Items]
Warrants to purchase common stock cancelled		400,000
2014 Consultant Warrant
Stockholders Equity [Line Items]
Warrant exercise price				$ 10.70			$ 10.70		$ 10.70
Warrants expiration date				Aug. 13, 2019					Aug. 13, 2019
Warrants exercised							0		0
VLL7 Warrant
Stockholders Equity [Line Items]
Warrants issued to purchase common stock		290,000
Warrant exercise price		$ 2.00
Warrants expiration date		Feb. 08, 2022
Private placement warrant estimated volatility		78.80%
Private placement warrant risk free interest rate		1.94%
Private placement warrant dividend yield		0.00%
Private placement warrant expected life (in years)		5 years
Common stock warrants fair value		$ 1,037,500
Warrants expiration period		5 years
EWB Warrant
Stockholders Equity [Line Items]
Warrants issued to purchase common stock		40,000
Warrant exercise price		$ 3.64					$ 3.64		$ 3.64
Warrants expiration date		Feb. 08, 2022							Feb. 08, 2022
Warrants exercised		0
Private placement warrant estimated volatility		78.80%
Private placement warrant risk free interest rate		1.94%
Private placement warrant dividend yield		0.00%
Private placement warrant expected life (in years)		5 years
Common stock warrants fair value		$ 125,000
Warrants expiration period		5 years
VLL8 Warrant
Stockholders Equity [Line Items]
Warrants issued to purchase common stock		290,000
Warrant exercise price		$ 2.00
Warrants expiration date		Feb. 08, 2022
Private placement warrant estimated volatility		78.80%
Private placement warrant risk free interest rate		1.94%
Private placement warrant dividend yield		0.00%
Private placement warrant expected life (in years)		5 years
Common stock warrants fair value		$ 1,037,500
Warrants expiration period		5 years
2017 Consultant Warrant
Stockholders Equity [Line Items]
Warrants issued to purchase common stock		60,000
Warrant exercise price		$ 4.60					$ 4.60		$ 4.60
Warrants expiration date		Feb. 08, 2019							Feb. 08, 2019
Warrants exercised		0
Private placement warrant estimated volatility		78.80%
Private placement warrant risk free interest rate		1.22%
Private placement warrant dividend yield		0.00%
Private placement warrant expected life (in years)		2 years
Common stock warrants fair value		$ 119,000
Warrants expiration period		2 years
2013 Private Placement Warrants
Stockholders Equity [Line Items]
Number of warrants expired unexercised	186,878
Private Placement
Stockholders Equity [Line Items]
Warrants issued to purchase common stock													747,969
Warrant exercise price					$ 10.00
Issuance of common stock in connection with common stock offerings (in shares)					834,847
Shares issued, price per share					$ 8.50
Warrant term					4 years
Private Placement Agent
Stockholders Equity [Line Items]
Warrant exercise price					$ 10.00
Common Stock
Stockholders Equity [Line Items]
Issuance of common stock in connection with common stock offerings (in shares)									2,845,000
Common Stock | Maximum | 2014 Consultant Warrant
Stockholders Equity [Line Items]
Warrants issued to purchase common stock				85,000
Common Stock | Underwritten Public Offering
Stockholders Equity [Line Items]
Sale of stock						2,845,360
Public offering price, per share						$ 4.85
Proceeds from sale of stock in initial public offering						$ 12,600,000
Underwriting discount and other offering related expenses						$ 1,200,000
Common Stock | Private Placement
Stockholders Equity [Line Items]
Warrants issued to purchase common stock					834,847
Common Stock | Private Placement Agent
Stockholders Equity [Line Items]
Number of additional common stock to be purchased by the warrant					100,000
Series A Participating Preferred Stock
Stockholders Equity [Line Items]
Preferred stock, shares authorized							40,000		40,000
Preferred stock, par value							$ 0.001		$ 0.001
Preferred stock, outstanding							0		0			0