Debt and Warrants - Schedule of Long-Term Debt and Unamortized Discount Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	May. 04, 2015	Dec. 31, 2014	Jun. 30, 2014
Debt Instrument [Line Items]
Convertible debt, principal amount		$ 43,000
Oxford Finance Term Loan [Member]
Debt Instrument [Line Items]
Convertible debt, principal amount	$ 15,000		$ 15,000	$ 15,000
Exit fee	755		600
Unamortized debt discount associated with issuance of preferred stock warrants, exit fee, and loan origination fees	(681)		(811)
Term loan, net	$ 15,074		$ 14,789