Segment Reporting (Schedule Of Identifiable Assets By Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Subtotal	$ 458,499	$ 430,026
General corporate	56,780	71,508
Cash, cash equivalents, and restricted cash at beginning of period	30,253	11,846	$ 35,022	$ 31,422
Disposal Group, Including Discontinued Operation, Assets	302	1,490
Total assets	545,834	514,870
PE Films [Member]
Total assets	111,690	119,013
Flexible Packaging Films [Member] [Domain]
Total assets	72,626	66,453
Aluminum Extrusions [Member]
Total assets	$ 274,183	$ 244,560