Nature of Operations and Liquidity - Additional Information (Detail) (USD $)	0 Months Ended		3 Months Ended
	Dec. 09, 2014	Aug. 20, 2014 Borrowing	Mar. 31, 2015	Mar. 31, 2014	Jan. 06, 2015	Dec. 31, 2014	Nov. 04, 2014	Dec. 31, 2013	Apr. 06, 2015	Sep. 30, 2015
Debt Instrument [Line Items]
Accumulated deficit			$ (547,107,000)			$ (514,139,000)
Stockholders' deficit			(144,873,000)			(111,950,000)
Net loss from operation			(4,668,000)	(2,345,000)
Net loss			(32,968,000)	(3,358,000)
Cash			4,849,000	2,916,000		3,683,000		4,053,000
Maximum borrowing capacity		20,000,000	20,000,000
Maturity date of loans			Dec. 31, 2019
Loan interest rate			13.00%
Principal amount		5,000,000			5,000,000		3,000,000
Number of expected additional borrowings		1
Sale of unused net operating losses	300,000
Maximum [Member]
Debt Instrument [Line Items]
Additional borrowings capacity					5,000,000
Number of expected additional borrowings			1
Loan Agreement [Member]
Debt Instrument [Line Items]
Company's financial obligations under Loan Agreement			13,300,000
Principal amount			13,310,000
Second Amended and Restated [Member]
Debt Instrument [Line Items]
Company's financial obligations under Convertible Notes			40,900,000
Company's financial obligations under Reimbursement Notes			700,000
Company's financial obligations under Bridge Notes			1,900,000
Scenario Forecast [Member]
Debt Instrument [Line Items]
Principal amount									5,000,000
Scenario Forecast [Member] | Maximum [Member]
Debt Instrument [Line Items]
Additional borrowings capacity									$ 5,000,000	$ 2,000,000