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Income Taxes - Additional Information (Detail) $ in Millions | 9 Months Ended
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Sep. 30, 2017 USD ($)
Income Taxes [Line Items] |
Net Operating Loss Carryforwards | $ 23.9
NOL carryforward assets expiration date | 2029
Alternative minimum tax credit carryforwards | $ 3.4
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, 2014; December 31, 2015; and December 31, 2016. The Company received notice that its Maine income tax return filings for the years ended December 31, 2014; December 31, 2015; and December 31, 2016 are under examination by the Maine Revenue Service. Auditor fieldwork is scheduled to occur in the fourth quarter of 2017 and the Company does not expect that the results of this examination will have a material impact on its financial position, operating results or cash flows.

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