Debt - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended		3 Months Ended	6 Months Ended		0 Months Ended	6 Months Ended			6 Months Ended		6 Months Ended
	Sep. 10, 2013	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Mar. 15, 2013	Jun. 30, 2013 Warrant Obligation [Member]	Jun. 30, 2014 Warrant Obligation [Member]	Jun. 30, 2013 Warrant Obligation [Member]	Mar. 15, 2013 Hercules Technology Growth Capital Inc. [Member]	Jun. 30, 2014 Hercules Technology Growth Capital Inc. [Member]	Sep. 10, 2013 Hercules Technology Growth Capital Inc. [Member]	Mar. 15, 2013 Hercules Technology Growth Capital Inc. [Member]	Jun. 30, 2014 Minimum [Member]	Jun. 30, 2014 Minimum [Member] Warrant Obligation [Member]	Jun. 30, 2014 Maximum [Member]	Jun. 30, 2014 Maximum [Member] Warrant Obligation [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												69,321
Warrants issued to purchase common stock, exercise price												11.20
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		(1,714,826)	(1,851,428)			105,292		89,859
Stock prices														$ 11.60		$ 11.80
Volatility			93.46%	93.43%			77.00%
Maturity period				5 years 3 months 29 days			5 years						4 years 7 months 6 days		4 years 9 months 29 days
Exercise prices		$ 3.20	$ 3.20	$ 6.40										$ 11.50		$ 11.60
Risk free interest rate of return			1.62%	1.75%			0.84%
Change in underlying unobservable inputs							10.00%
Initial loan discount amount		727,000	727,000
Loss on early extinguishment of debt	$ 1,000,000