Notes Payable - Additional Information (Detail) - Comerica [Member]			3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 17, 2015 USD ($)	Sep. 09, 2013 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Aug. 31, 2014 USD ($)	Sep. 30, 2015 USD ($) Installment	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Additional interest expense			$ 73,000	$ 16,000		$ 96,000	$ 49,000
Unamortized debt discount			$ 0			0		$ 96,000
Loan and Security Agreement [Member]
Debt Instrument [Line Items]
Borrowings amount		$ 3,000,000
Amount received from borrowings		$ 1,000,000			$ 2,000,000			3,000,000
Principal repayments amount						$ 900,000		$ 400,000
Number of installments | Installment						30
Interest rate description						Term loans under the loan and security agreement bear interest at an annual rate equal to 3.0% plus the greater of (1) the bank’s prime rate and (2) the LIBOR rate plus 2.5%. As of September 30, 2015, the greater rate was 6.25%.
Interest rate percentage			3.00%			3.00%
Interest rate percentage						6.25%
Debt maturity date start						Sep. 01, 2014
Debt maturity date end						Feb. 01, 2017
Final payment of term loan						$ 60,000
Payments of Debt	$ 1,765,000
Extinguishment amount of outstanding principal	1,700,000
Final fees and accrued interest	$ 65,000
Loss on extinguishment debt			$ 140,000			$ 140,000
Loan and Security Agreement [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Interest rate percentage						2.50%