Segment Reporting (Schedule Of Segment Reporting Information By Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Total net sales	$ 178,599	$ 185,261
Gross Sales	184,822	192,136
Goodwill, Impairment Loss	0	(13,696)
Amortization of identifiable intangibles	723	758
Goodwill, Impairment Loss, Net of Tax		10,500
Total Segment Income (Loss)	24,143	10,196
Interest income	7	27
Interest expense	822	555
Gain (loss) on investment in kaléo accounted for under fair value method	400	(26,100)
Stock option-based compensation costs	468	566
Corporate expenses, net	10,863	9,891
Income from continuing operations before income taxes	12,715	(26,889)
Income taxes from continuing operations	3,097	(6,226)
Income from continuing operations	9,618	(20,663)
Net Income (Loss) Attributable to Parent	9,031	(22,321)
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	(587)	(1,658)
kaleo
Segment Reporting Information [Line Items]
Gain (loss) on investment in kaléo accounted for under fair value method	718	(26,100)
PE Films
Segment Reporting Information [Line Items]
Total net sales	27,953	36,800
EBITDA	(124)	(28)
Earnings before interest, taxes, depreciation and amortization (EBITDA)	7,213	12,413
Depreciation, Depletion and Amortization	(1,420)	(1,494)
Earnings before interest and taxes (EBIT)	5,793	10,919
Flexible Packaging Films [Member] [Domain]
Segment Reporting Information [Line Items]
Total net sales	32,521	30,574
EBITDA	(38)	0
Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	118,125	117,887
EBITDA	183	(688)
Goodwill, Impairment Loss	0	13,696
Amortization of identifiable intangibles		(13,696)
Earnings before interest, taxes, depreciation and amortization (EBITDA)	13,302	11,677
Depreciation, Depletion and Amortization	(4,130)	(4,113)
Earnings before interest and taxes (EBIT)	9,172	7,564
Flexible Packaging Films [Member]
Segment Reporting Information [Line Items]
Earnings before interest, taxes, depreciation and amortization (EBITDA)	9,623	6,553
Depreciation, Depletion and Amortization	(466)	(428)
Earnings before interest and taxes (EBIT)	9,157	6,125
Shipping and Handling [Member]
Segment Reporting Information [Line Items]
Cost of goods sold	6,223	6,875
Personal Care Materials [Member] \| PE Films
Segment Reporting Information [Line Items]
Total net sales	7,352	6,769
Surface Protection Films [Member] \| PE Films
Segment Reporting Information [Line Items]
Total net sales	20,601	28,353
Films For Other Markets [Member] \| PE Films
Segment Reporting Information [Line Items]
Total net sales	0	1,678
Film Products Subtotal [Member] \| PE Films
Segment Reporting Information [Line Items]
Total net sales	27,953	36,800
Nonresidential Building And Construction [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	57,229	63,139
Consumer Durables [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	13,152	12,549
Distribution [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	7,516	7,738
Automotive [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	11,415	9,471
Residential Building And Construction [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	12,708	9,815
Machinery and Equipment BNL [Domain] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	8,925	7,936
Electrical [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	7,180	7,239
Aluminum Extrusions Subtotal [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	118,125	117,887
Product [Member]
Segment Reporting Information [Line Items]
Cost of goods sold	$ 141,285	$ 145,169

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