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Income Taxes - Additional Information (Detail) $ in Millions	9 Months Ended
	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.

X

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 25
-Paragraph 20
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=96869850&loc=d3e28680-109314

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319

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+ References

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