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Summary of Significant Accounting Policies - Goodwill (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill impairment		$ 0	$ 4,100,000	$ 2,403,000
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount			23.00%
Horizon Plastics reporting unit
Goodwill [Line Items]
Goodwill impairment	$ 4,100,000
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	19.00%

X

- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Percentage of fair value of reporting unit in excess of carrying amount.

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