Commitments and Contingencies - Narrative (Details) - Rochester, New Hampshire - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2017	Dec. 31, 2018
Loss Contingencies [Line Items]
Expense associated with expected costs of site investigation	$ 200,000	$ 100,000
Capital expenditures		200,000
Environmental Contamination
Loss Contingencies [Line Items]
Accrual for environmental liability, including revision (fully offset)		$ 0

Accrual For Environmental Loss Contingencies Including Revision In Estimates

No definition available.

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- Definition

Amount of environmental remediation costs capitalized. These expenditures may relate to long-lived improvements in operating facilities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 25
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=39739230&loc=d3e11660-110855

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- Definition

The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109237650&loc=d3e13064-110858

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13296-110859

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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