Income Taxes - Reconciliation Between Provision for Income Taxes and Income Taxes (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Income Tax Disclosure [Abstract] | |||
| Computed “expected” tax benefit | $ (3,051) | $ (3,152) | $ (5,607) |
| State income taxes, net of federal benefit | (534) | 0 | (444) |
| Tax effect of: | |||
| Change in valuation allowance | (8,148) | (4,069) | 5,102 |
| Rate change | 0 | 3,524 | 0 |
| Expiration of prior year credits and net operating losses | 692 | 786 | 675 |
| Stock compensation | 491 | 376 | 274 |
| Uncertain tax positions | 11,128 | 3,074 | 0 |
| Other | (578) | (539) | 0 |
| Provision for income taxes | $ 0 | $ 0 | $ 0 |