Stockholders' Equity - Additional Information (Detail) - USD ($)					1 Months Ended	3 Months Ended		6 Months Ended		55 Months Ended
	Feb. 08, 2017	May 12, 2016	Aug. 13, 2014	Aug. 14, 2013	May 31, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2015	Dec. 31, 2016	Aug. 15, 2013	Jun. 06, 2011	Jun. 30, 2010
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
Number of warrants not exercised						951,878		951,878
Common stock reserved for future issuance						4,482,168		4,482,168
Unrecognized compensation expense						$ 800,000		$ 800,000
Unrecognized stock-based compensation expense, weighted average period of recognition								1 year 10 months 24 days
Shares excluded from calculation of diluted net loss per share						3,406,382	2,130,423	3,406,382	2,130,423
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax						$ 2,200,000		$ 2,200,000			$ 2,100,000
Restricted Stock Units (RSUs)
Stockholders Equity [Line Items]
Unrecognized compensation expense						$ 4,200,000		$ 4,200,000
Unrecognized stock-based compensation expense, weighted average period of recognition								2 years 10 months 24 days
2010 Plan
Stockholders Equity [Line Items]
Common stock reserved for future issuance														300,000
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						1,475,286		1,475,286
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
Number of warrants not exercised						85,000		85,000
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
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
Number of warrants not exercised						40,000		40,000
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
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
Number of warrants not exercised						60,000		60,000
2013 Private Placement Warrants
Stockholders Equity [Line Items]
Warrant exercise price						$ 10.00		$ 10.00
Warrants expiration date								Aug. 14, 2017
Number of warrants not exercised						186,878		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