Notes Payable - Summary of Notes Payable (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Total	$ 61,172	$ 44,546
Less: Current portion	7,000
Non-current Notes payable, net of related discounts	54,172	44,546
Loan Agreement [Member]
Debt Instrument [Line Items]
Non-current Notes payable, net of related discounts	22,801	8,307
Reimbursement Notes [Member]
Debt Instrument [Line Items]
Non-current Notes payable, net of related discounts	755	636
Bridge Notes [Member]
Debt Instrument [Line Items]
Non-current Notes payable, net of related discounts	166	271
Convertible Notes [Member]
Debt Instrument [Line Items]
Non-current Notes payable, net of related discounts	$ 37,450	$ 35,332