Debt - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended	12 Months Ended		3 Months Ended				3 Months Ended		0 Months Ended	3 Months Ended
	Sep. 10, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 15, 2013	Mar. 31, 2014 Warrant Obligation [Member]	Mar. 31, 2013 Warrant Obligation [Member]	Mar. 31, 2014 Minimum [Member]	Mar. 31, 2014 Minimum [Member] Warrant Obligation [Member]	Mar. 31, 2014 Maximum [Member]	Mar. 31, 2014 Maximum [Member] Warrant Obligation [Member]	Mar. 15, 2013 Hercules Technology Growth Capital Inc. [Member]	Mar. 31, 2014 Hercules Technology Growth Capital Inc. [Member]	Sep. 10, 2013 Hercules Technology Growth Capital Inc. [Member]
Debt Instrument [Line Items]
Loan payable											$ 6,000,000
Accrued interest rate											10.45%
Maturity period of loan											42 months
Time period of interest payment												First 12 months
Prepayment of loan													6,400,000
Term fee													425,000
Prepayment penalty												180,000
Warrants issued to purchase common stock											693,202
Warrants issued to purchase common stock, exercise price											1.12
Expiry date for warrant outstanding												Apr. 26, 2018
Warrant issuance date												Apr. 25, 2013
Fair value of warrant obligation				563,000
Initial carrying value of the loan				5,300,000
Changes in fair value of warrants		137,000				15,000
Stock prices								$ 1.16		$ 1.18
Volatility		93.46%	93.43%		77.00%
Maturity period			5 years 3 months 29 days		5 years		4 years 10 months 6 days		5 years 29 days
Exercise prices		$ 0.62	$ 0.64					$ 1.15		$ 1.16
Risk free interest rate of return		1.73%	1.75%		0.84%
Change in underlying unobservable inputs					10.00%
Initial loan discount amount		727,000
Loss on early extinguishment of debt	$ 1,000,000