The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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Goodwill And Other Intangible Assets Goodwill and Other Intangible Assets (Rollforward Schedule of Identifiable Intangibles) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	$ 22,636
PE Films [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	610	$ 730	$ 845
Amortization	(120)	(115)
Flexible Packaging Films [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	2,327	2,811	3,528
Amortization	(426)	(436)
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss)	(58)	(281)
Aluminum Extrusions [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	19,699	32,754	36,179
Amortization	(13,055)	(3,425)
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	20,198	22,785
Customer Relationships [Member] \| PE Films [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	0	0	0
Amortization	0	0
Customer Relationships [Member] \| Flexible Packaging Films [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	554	661	831
Amortization	(91)	(82)
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss)	(16)	(88)
Impairment of Intangible Assets, Finite-lived			(9,444)
Customer Relationships [Member] \| Aluminum Extrusions [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	19,644	22,124	24,613
Amortization	(2,480)	(2,489)
Proprietary Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	895	1,093
Proprietary Technology [Member] \| PE Films [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	610	730	845
Amortization	(120)	(115)
Proprietary Technology [Member] \| Flexible Packaging Films [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	230	288	360
Amortization	(55)	(55)
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss)	(3)	(17)
Impairment of Intangible Assets, Finite-lived			(4,051)
Proprietary Technology [Member] \| Aluminum Extrusions [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	55	75	495
Amortization	(20)	(420)
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	1,543	12,417		$ 10,200
Trade Names [Member] \| PE Films [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	0	0	0
Amortization	0	0
Impairment of Intangible Assets, Finite-lived			(4,005)
Trade Names [Member] \| Flexible Packaging Films [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	1,543	1,862	2,337
Amortization	(280)	(299)
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss)	(39)	(176)
Trade Names [Member] \| Aluminum Extrusions [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	0	10,555	$ 11,071
Amortization	$ (10,555)	$ (516)