Business Segments (Schedule Of Segment Reporting Information By Segment) (Details) - USD ($) $ in Thousands		3 Months Ended											12 Months Ended
		Dec. 31, 2015		Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Mar. 31, 2009	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenue from External Customer [Line Items]
Total net sales	[1],[2]												$ 866,339		$ 923,033		$ 930,721
Add back freight													29,838		28,793		28,625
Sales as shown in consolidated statements of income		$ 216,989		$ 223,772	$ 221,245	$ 234,171	$ 239,219		$ 240,429	$ 236,965	$ 235,213		896,177		951,826		959,346
Goodwill, Impairment Loss													(44,465)		0		0
Total													34,622		69,915		85,838
Interest income													294		588		594
Interest expense													3,502		2,713		2,870
Gain (loss) on investment accounted for under the fair value method													(20,500)		2,000		3,400
Stock option-based compensation expense													483		1,272		1,155
Corporate expenses, net	[3]												33,638		24,310		31,857
Income (loss) from continuing operations before income taxes													(23,207)		45,416		52,932
Income taxes	[3]												8,928		9,387		16,995
Income (loss) from continuing operations		(5,876)		(36,723)	594	9,870	13,054		10,745	3,752	8,479		(32,135)		36,029		35,937
Income (loss) from discontinued operations		0		0	0	0	0		850	0	0		0	[3]	850	[3]	(13,990)	[3]
Net income (loss)		(5,876)		(36,723)	$ 594	$ 9,870	13,054		$ 11,595	$ 3,752	$ 8,479		(32,135)		36,879		21,947
Freight													29,838		28,793		28,625
Cash and cash equivalents		44,156	[1]				50,056	[1]					44,156	[1]	50,056	[1]	52,617		$ 48,822
Foreign Country
Revenue from External Customer [Line Items]
Cash and cash equivalents		27,700					40,500						27,700		40,500
Pension Benefits
Revenue from External Customer [Line Items]
Defined benefit pension plan net liability		(93,210)					(96,409)						(93,210)		(96,409)
kaleo
Revenue from External Customer [Line Items]
Gain (loss) on investment accounted for under the fair value method	[3]												(20,500)		2,000		3,400
Income taxes													481		(8,100)		(1,586)
Net income (loss)													(41,939)		(22,992)		(1,740)
Cash and cash equivalents		$ 91,844					$ 117,589						91,844		117,589
Alleghany and Bath County, Virginia
Revenue from External Customer [Line Items]
Gain (Loss) on Disposition of Assets													0		1,208		0
Unrealized Gain (Loss) on Investment Property													0		0		(1,018)
PE Films [Member]
Revenue from External Customer [Line Items]
Total net sales													385,550		464,339		495,386
Ongoing operations													48,275		60,971		61,866
Plant shutdowns, asset impairments, restructurings and other	[3]												(4,180)		(12,236)		(671)
Goodwill, Impairment Loss													0
Aluminum Extrusions
Revenue from External Customer [Line Items]
Total net sales													375,457		344,346		309,482
Ongoing operations													30,432		25,664		18,291
Plant shutdowns, asset impairments, restructurings and other	[3]												(708)		(976)		(2,748)
Goodwill, Impairment Loss												$ (30,600)	0
Flexible Packaging Films [Member] [Domain]
Revenue from External Customer [Line Items]
Total net sales													105,332		114,348		125,853
Ongoing operations													5,453		(2,917)		9,100
Plant shutdowns, asset impairments, restructurings and other	[3]												(185)		(591)		0
Goodwill, Impairment Loss				$ (44,465)									$ (44,465)		$ 0		$ 0

[1] Information on exports and foreign operations are provided on the previous page. Cash and cash equivalents includes funds held in locations outside the U.S. of $27.7 million and $40.5 million at December 31, 2015 and 2014, respectively. Export sales relate almost entirely to PE Films. Operations outside the U.S. in The Netherlands, Hungary, China and India also relate to PE Films. Operations in Brazil are primarily related to Flexible Packaging Films, but also include PE Films operations. Sales from locations in The Netherlands and Hungary are primarily to customers located in Europe. Sales from locations in China (Guangzhou and Shanghai) are primarily to customers located in China, but also include other customers in Asia.

[2] The difference between total consolidated sales as reported in the consolidated statements of income and segment, geographic and product group net sales reported in this note is freight of $29.8 million in 2015, $28.8 million in 2014 and $28.6 million in 2013.

[3] See Notes 1, 3, 4 and 18 for more information on losses associated with plant shutdowns, asset impairments and restructurings, unusual items, gains or losses from sale of assets, gains or losses on an investment accounted for under the fair value method and other items.