Income Taxes - Additional Information (Detail) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Income Tax [Line Items] | |||
| Current income tax expense | $ 0 | $ 100,000 | |
| Deferred income tax expense | 0 | 0 | |
| Valuation allowance Increase (Decrease) | $ (1,400,000) | 18,700,000 | |
| Tax Credit Carryforward expiration Description | Expire starting in 2028. | ||
| Unrecognized tax benefit | $ 1,430,000 | 1,216,000 | $ 865,000 |
| Unrecognized tax benefits that would affect income tax expense if recognized | 1,400,000 | ||
| Loss before provision for income tax including foreign Losses | 23,000,000 | ||
| Federal [Member] | |||
| Income Tax [Line Items] | |||
| Deferred income tax expense | 0 | $ 0 | |
| Net operating loss carryforwards | 92,500,000 | ||
| Tax credits | 2,100,000 | ||
| State [Member] | |||
| Income Tax [Line Items] | |||
| Net operating loss carryforwards | 77,600,000 | ||
| MASSACHUSETTS | |||
| Income Tax [Line Items] | |||
| Tax credits | $ 1,400,000 | ||