Significant Accounting Policies - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 36,079	$ 54,059
Restricted cash	94	94
Total assets	36,173	54,153
Warrant liability	115	3,219
Total liabilities	115	3,219
Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	36,079	54,059
Restricted cash	94	94
Total assets	36,173	54,153
Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	115	3,219
Total liabilities	$ 115	$ 3,219