Summary of Significant Accounting Policies - Summary of changes to goodwill by business segment (Details 2) $ in Thousands	9 Months Ended
Sep. 30, 2016 USD ($)
Goodwill [Roll Forward]
Gross Balance December 31, 2015	$ 39,732
Accumulated Impairments
Balance (net of impairments) December 31, 2015	39,732
Adjustments to Goodwill in 2016	(2,160)
Balance (net of impairments) September 30, 2016	37,572
Manufacturing
Goodwill [Roll Forward]
Gross Balance December 31, 2015	20,430
Accumulated Impairments
Balance (net of impairments) December 31, 2015	20,430
Adjustments to Goodwill in 2016	(2,160)
Balance (net of impairments) September 30, 2016	18,270
Plastics
Goodwill [Roll Forward]
Gross Balance December 31, 2015	19,302
Accumulated Impairments
Balance (net of impairments) December 31, 2015	19,302
Adjustments to Goodwill in 2016
Balance (net of impairments) September 30, 2016	$ 19,302

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=64834752&loc=SL49117168-202975

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease) of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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