Goodwill And Other Intangible Assets (Schedule Of Goodwill And Other Intangibles) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill And Other Intangible Assets [Line Items]
Goodwill, Impairment Loss	$ 13,696	$ 0	$ 0
Goodwill	67,708	81,404	81,404
Finite-Lived Intangible Assets, Net	18,820
Identifiable intangible assets:
Total carrying value of identifiable intangibles	18,820	22,636
Intangible Assets, Net (Including Goodwill)	86,528	104,040
Goodwill, Impairment Loss, Net of Tax	10,500
Customer relationships
Goodwill And Other Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	17,551	20,198
Identifiable intangible assets:
Finite-Lived Intangible Assets, Gross	29,450	29,550
Proprietary technology
Goodwill And Other Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	194	895
Identifiable intangible assets:
Finite-Lived Intangible Assets, Gross	3,726	6,181
Trade Names [Member]
Goodwill And Other Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	1,075	1,543
Identifiable intangible assets:
Finite-Lived Intangible Assets, Gross	13,397	13,645
Noncompete agreements
Identifiable intangible assets:
Finite-Lived Intangible Assets, Gross	$ 1,600	1,854
Minimum | Customer relationships
Identifiable intangible assets:
Identifiable Intangible Asset, Useful Life (Yrs)	10 years
Minimum | Trade Names [Member]
Identifiable intangible assets:
Identifiable Intangible Asset, Useful Life (Yrs)	5 years
Maximum | Customer relationships
Identifiable intangible assets:
Identifiable Intangible Asset, Useful Life (Yrs)	12 years
Maximum | Proprietary technology
Identifiable intangible assets:
Identifiable Intangible Asset, Useful Life (Yrs)	15 years
Maximum | Trade Names [Member]
Identifiable intangible assets:
Identifiable Intangible Asset, Useful Life (Yrs)	13 years
Aluminum Extrusions
Goodwill And Other Intangible Assets [Line Items]
Goodwill, Impairment Loss	$ 13,696	0	0
Goodwill	10,370	24,066	24,066
Finite-Lived Intangible Assets, Net	17,199	19,699	32,754
Aluminum Extrusions | Customer relationships
Goodwill And Other Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	17,164	19,644	22,124
Aluminum Extrusions | Proprietary technology
Goodwill And Other Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	35	55	75
Aluminum Extrusions | Trade Names [Member]
Goodwill And Other Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	0	0	10,555
PE Films [Member]
Goodwill And Other Intangible Assets [Line Items]
Goodwill, Impairment Loss	0	0
Goodwill	57,338	57,338	57,338
Finite-Lived Intangible Assets, Net	0	610	730
PE Films [Member] | Customer relationships
Goodwill And Other Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	0	0	0
PE Films [Member] | Proprietary technology
Goodwill And Other Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	0	610	730
PE Films [Member] | Trade Names [Member]
Goodwill And Other Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	$ 0	$ 0	$ 0