Loans Payable - Additional Information (Detail)					9 Months Ended
	Sep. 24, 2014 USD ($) $ / shares shares	Mar. 31, 2012 USD ($)	Jun. 02, 2010 USD ($) $ / shares shares	May. 28, 2010 USD ($)	Sep. 30, 2015 USD ($) Installment	Jun. 30, 2014 USD ($)	May. 31, 2012 USD ($)
Debt Instrument [Line Items]
Loan outstanding	$ 11,600,000				$ 13,000,000
Loan payable, end-of-term payment due					540,000
Deferred financing charge						$ 1,200,000	$ 1,300,000
Warrants issued to lenders as part of new loan agreement, shares of common stock to purchase | shares	608,696		156,641
Warrants issued to lenders as part of new loan agreement, exercise price | $ / shares	$ 1.15		$ 7.98
Warrants issued to lenders as part of new loan agreement, fair value	$ 400,000		$ 800,000
Maximum amount of debt conversion					$ 2,000,000
Loans Payable | Security Agreement Hercules
Debt Instrument [Line Items]
Loan payable, aggregate principal amount		$ 26,500,000		$ 25,000,000
Loan payable, start date of first principal payment		Apr. 01, 2013
Loan payable, Commencement date				Jan. 01, 2012
Loan payable, number of installments of principal and interest | Installment					30
Loan payable, frequency of installments of principal and interest					30 equal monthly installments
Loan payable, due date					Jan. 01, 2016
Loan payable, description of interest rate terms					Per annum interest is payable on the principal balance of both loans at the greater of 11.9% and an amount equal to 11.9% plus the prime rate of interest minus 4.75% as determined daily, provided however, that the per annum interest shall not exceed 15.0% (11.9% as of September 30, 2015).
Loan payable, interest rate, base rate					11.90%
Loan payable, interest rate, additional rate deducted from base rate					4.75%
Loan payable, maximum per annum interest rate					15.00%
Loan payable, interest rate					11.90%
Loan issuance costs paid				$ 200,000
Debt instrument convertible beneficial conversion feature					$ 0
Loans Payable | Security Agreement Hercules | Minimum
Debt Instrument [Line Items]
Loan payable, interest rate					11.90%
Option to purchase equity, net cash proceeds of equity securities					$ 10,000,000
Loans Payable | Hercules Amended Loan Agreement
Debt Instrument [Line Items]
Loan payable, aggregate principal amount	$ 10,000,000
Loan payable, Commencement date	Jan. 01, 2015
Loan payable, number of installments of principal and interest | Installment					12
Loan payable, frequency of installments of principal and interest					12 principal and interest payments
Loan payable, due date					Jan. 01, 2018
Loan payable, end-of-term payment due					$ 500,000
Liquidity ratio					125.00%
Option to purchase equity, description					The Company has agreed to maintain, with respect to the new loan of $10.0 million, a liquidity ratio equal to or greater than 1.25 to 1.00 or the equivalent of $12.5 million in unrestricted and unencumbered cash and cash equivalents.
Loans Payable | Hercules Amended Loan Agreement | Financial covenant
Debt Instrument [Line Items]
Unrestricted and unencumbered cash and cash equivalents					$ 12,500,000