Segment Reporting (Schedule Of Segment Reporting Information By Segment) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total net sales	$ 177,917		$ 198,880	$ 543,544	$ 606,573
Gross Sales	184,370		205,968	562,766	628,011
Goodwill, Impairment Loss	0	$ (13,700)	0	(13,696)	0
Amortization of identifiable intangibles	753		3,400	2,264	5,182
Goodwill, Impairment Loss, Net of Tax		$ 10,500
Total Segment Income (Loss)	24,869		21,766	62,640	70,466
Interest income	11		11	43	25
Interest expense	494		859	1,598	3,354
Gain (loss) on investment in kaléo accounted for under fair value method				(61,000)	10,900
Gain (Loss) on Disposition of Assets				0	(6,328)
Stock option-based compensation costs	518		791	1,786	2,060
Corporate expenses, net	10,586		9,198	29,915	25,538
Income from continuing operations before income taxes	(22,918)		15,229	(31,616)	68,021
Income taxes from continuing operations	(5,942)		177	(8,308)	10,550
Income from continuing operations	(16,976)		15,052	(23,308)	57,471
Net loss	(65,213)		17,133	(76,339)	51,395
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	(48,237)		2,081	(53,031)	(6,076)
kaleo
Segment Reporting Information [Line Items]
Gain (loss) on investment in kaléo accounted for under fair value method	36,200		(4,300)	(61,000)	28,482
PE Films
Segment Reporting Information [Line Items]
Total net sales	26,440		34,487	103,444	99,313
EBITDA	(56)		(60)	(225)	(555)
Earnings before interest, taxes, depreciation and amortization (EBITDA)	6,041		10,257	33,928	30,452
Depreciation, Depletion and Amortization	(1,785)		(1,458)	(4,868)	(4,380)
Earnings before interest and taxes (EBIT)	4,256		8,799	29,060	26,072
Flexible Packaging Films [Member] [Domain]
Segment Reporting Information [Line Items]
Total net sales	35,856		34,888	100,534	101,950
EBITDA	(3)		0	(14)	0
Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	115,621		129,505	339,566	405,310
EBITDA	(720)		(610)	(2,637)	(667)
Goodwill, Impairment Loss	0		0	13,696	0
Amortization of identifiable intangibles	0		(2,510)	0	(2,510)
Earnings before interest, taxes, depreciation and amortization (EBITDA)	16,540		16,464	41,496	51,231
Depreciation, Depletion and Amortization	(4,251)		(4,317)	(12,632)	(12,481)
Earnings before interest and taxes (EBIT)	12,289		12,147	28,864	38,750
Flexible Packaging Films [Member]
Segment Reporting Information [Line Items]
Earnings before interest, taxes, depreciation and amortization (EBITDA)	9,546		4,394	22,594	10,477
Depreciation, Depletion and Amortization	(443)		(394)	(1,306)	(1,101)
Earnings before interest and taxes (EBIT)	9,103		4,000	21,288	9,376
Shipping and Handling [Member]
Segment Reporting Information [Line Items]
Cost of goods sold	6,453		7,088	19,222	21,438
Personal Care Materials [Member] \| PE Films
Segment Reporting Information [Line Items]
Total net sales	5,042		5,607	17,262	17,305
Surface Protection Films [Member] \| PE Films
Segment Reporting Information [Line Items]
Total net sales	19,868		27,053	79,919	76,194
Films For Other Markets [Member] \| PE Films
Segment Reporting Information [Line Items]
Total net sales	1,530		1,827	6,263	5,814
Film Products Subtotal [Member] \| PE Films
Segment Reporting Information [Line Items]
Total net sales	26,440		34,487	103,444	99,313
Nonresidential Building And Construction [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	62,611		64,340	190,476	202,998
Consumer Durables [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	11,160		12,939	31,491	44,865
Distribution [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	7,796		9,366	22,055	26,678
Automotive [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	10,332		11,091	25,375	36,214
Residential Building And Construction [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	10,149		11,110	29,016	33,060
Machinery and Equipment BNL [Domain] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	7,581		10,191	23,147	29,585
Electrical [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	5,992		10,468	18,006	31,910
Aluminum Extrusions Subtotal [Member] \| Aluminum Extrusions [Member]
Segment Reporting Information [Line Items]
Total net sales	115,621		129,505	339,566	405,310
Product [Member]
Segment Reporting Information [Line Items]
Cost of goods sold	$ 136,008		$ 159,989	$ 415,212	$ 488,320

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