Income Taxes - Summary of Statutory Federal Tax Rate to Income or Loss before Taxes (Detail) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Income Tax Disclosure [Abstract] | |||
| Federal tax benefit at statutory rate | 34.00% | 34.00% | 34.00% |
| Change in valuation allowance | (3.00%) | (8.00%) | (23.00%) |
| Research and development credits | 4.00% | 2.00% | 2.00% |
| Non-deductible warrant | (7.00%) | ||
| Foreign loss not benefitted | (30.00%) | (27.00%) | (5.00%) |
| Other Non-deductible expenses | (5.00%) | (2.00%) | (1.00%) |
| Total | 0.00% | 0.00% | 0.00% |