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Income Taxes - Additional Information (Detail) - USD ($) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015 | Dec. 31, 2015
Operating Loss Carryforwards [Line Items] |  |  |  |  |
Alternative Minimum tax credit carryforwards | $ 1,500,000 |  | $ 1,500,000 |  |
Income tax benefit | 2,000,000 | $ 100,000 | 10,200,000 | $ 10,100,000 |
Federal Research and Development Tax Credit | Tax Year 2014 |  |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |  |
Income tax benefit |  |  |  |  | $ (63,000)
Federal Research and Development Tax Credit | Tax Year 2015 |  |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |  |
Income tax benefit |  |  |  |  | $ (288,000)
Federal Research and Development Tax Credit | 2016 expenditures |  |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |  |
Income tax benefit |  |  | (362,852) |  |
Internal Revenue Service (IRS) |  |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |  |
NOL carryforward assets and Research and Development (R&D) credit carryforwards | $ 12,200,000 |  | $ 12,200,000 |  |
NOL carryforward assets expiration date |  |  | 2029 |  |
R&D credits expiration year |  |  | 2035 |  |
Federal |  |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |  |
Tax examination description |  |  | The Company remains subject to examination by Federal, Maine, Massachusetts, and New Hampshire tax authorities for the tax periods ended December 31, 2013; December 31, 2014; and December 31, 2015. |  |

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