Debt - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended		9 Months Ended				9 Months Ended
	May 23, 2014 Silicon Valley Bank [Member] Loan and security agreement [Member]	Jun. 30, 2012 Silicon Valley Bank [Member] Loan and security agreement [Member]	Jan. 31, 2013 Silicon Valley Bank [Member] Loan and security agreement [Member]	Sep. 30, 2014 Square 1 Bank [Member] Maximum [Member]	Sep. 30, 2014 Square 1 Bank [Member] Minimum [Member]	Sep. 30, 2014 Square 1 Bank [Member] Loan and security agreement [Member]	May 28, 2014 Square 1 Bank [Member] Loan and security agreement [Member]	Sep. 30, 2014 Square 1 Bank [Member] Loan and security agreement [Member] Warrant [Member]	Sep. 30, 2014 Square 1 Bank [Member] Loan and security agreement [Member] Prime Rate [Member]
Debt Instrument [Line Items]
Loan and security agreement, maximum credit capacity		$ 3,000,000
Loan and security agreement, interest rate		4.50%
Loan and security agreement, payback period		24 months
Loan and security agreement, amount drawn			3,000,000
Repayment of principal and accrued interest	2,400,000
Loan and security agreement, available credit							4,500,000
Variable interest rate, prime rate plus									1.75%
Other interest rate,						5.00%
Fixed interest rate						5.50%
Cash burn under credit facility				3.00	1.00
Loan and security agreement, amount of other indebtedness						400,000
Issuance of Warrant to purchase common stock						3.00%
Warrant expiration period								10 years
Line of credit facility, loan origination cost						$ 83,000
Loan and security agreement, Amortization period						42 months