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Income Taxes - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2017 | Dec. 31, 2016
Income Taxes [Line Items] |  |
Net Operating Loss Carryforwards |  | $ 23.9
Alternative minimum tax credit carryforwards |  | $ 3.4
Internal Revenue Service (IRS) |  |
Income Taxes [Line Items] |  |
NOL carryforward assets expiration date |  | 2029
Federal, Maine, Massachusetts, and New Hampshire Tax Authorities |  |
Income Taxes [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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