Income Taxes - Additional Information (Detail) - USD ($) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Operating Loss Carryforwards [Line Items] | ||
| Accrual on interest and penalties related to income taxes | $ 0 | $ 0 |
| Net operating loss carryforwards | $ 17,400,000 | |
| Cumulative change in ownership for limitation of use of net operating loss and research and development credit carryforwards | 50.00% | |
| Period of cumulative change of ownership | 3 years | |
| Research and development credit | $ 2,100,000 | |
| Federal [Member] | ||
| Operating Loss Carryforwards [Line Items] | ||
| Net operating loss carry forwards | $ 43,900,000 | |
| Expiry date of carry forwards | Dec. 31, 2027 | |
| Tax credit carry forwards | $ 1,500,000 | |
| California [Member] | ||
| Operating Loss Carryforwards [Line Items] | ||
| Net operating loss carry forwards | $ 42,900,000 | |
| Expiry date of carry forwards | Dec. 31, 2017 | |
| Tax credit carry forwards | $ 1,000,000 | |
| Earliest Tax Year [Member] | ||
| Operating Loss Carryforwards [Line Items] | ||
| Tax years subject to examination by taxing authorities | 2007 |