Business Segments (Schedule Of Segment Reporting Information By Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Revenue from External Customer [Line Items]
Total net sales											$ 923,033	[1],[2]	$ 930,721	[1],[2]	$ 857,342	[1],[2]
Add back freight											28,793		28,625		24,846
Sales as shown in consolidated statements of income	239,219		240,429	236,965	235,213	231,096		243,194	243,530	241,526	951,826		959,346		882,188
Total											69,915		85,838		73,451
Interest income											588		594		418
Interest expense											2,713		2,870		3,590
Gain (loss) on investment accounted for under the fair value method											2,000		3,400		16,100
Stock option-based compensation expense											1,272		1,155		1,432
Corporate expenses, net											24,310	[3]	31,857	[3]	23,443	[3]
Income from continuing operations before income taxes											45,416		52,932		61,504
Income taxes											9,387	[3]	16,995	[3]	18,319	[3]
Income from continuing operations	13,054		10,745	3,752	8,479	9,402		7,428	9,590	9,517	36,029		35,937		43,185
Income (loss) from discontinued operations	0		850	0	0	0		(450)	(8,300)	(5,240)	850	[3]	(13,990)	[3]	(14,934)	[3]
Net income	13,054		11,595	3,752	8,479	9,402		6,978	1,290	4,277	36,879		21,947		28,251
Freight											28,793		28,625		24,846
Cash and cash equivalents	50,056	[2]				52,617	[2]				50,056	[2]	52,617	[2]	48,822		68,939
Foreign Country
Revenue from External Customer [Line Items]
Cash and cash equivalents	40,500					38,600					40,500		38,600
Pension Benefits
Revenue from External Customer [Line Items]
Defined benefit pension plan net liability	(96,409)					(42,461)					(96,409)		(42,461)
kaleo
Revenue from External Customer [Line Items]
Gain (loss) on investment accounted for under the fair value method											2,000	[3]	3,400	[3]	16,100	[3]
Income taxes											(8,100)		(1,586)		9,642
Net income											(22,992)		(1,740)		15,464
Cash and cash equivalents	117,589					33,560					117,589		33,560
Alleghany and Bath County, Virginia
Revenue from External Customer [Line Items]
Gain (Loss) on Disposition of Assets											1,208		0		0
Unrealized Gain (Loss) on Investment Property											0		1,018		0
Aluminum Extrusions
Revenue from External Customer [Line Items]
Total net sales											344,346		309,482		245,465
Ongoing operations											25,664		18,291		9,037
Plant shutdowns, asset impairments, restructurings and other											(976)	[3]	(2,748)	[3]	(5,427)	[3]
Film Products
Revenue from External Customer [Line Items]
Total net sales											578,687		621,239		611,877
Ongoing operations											58,054		70,966		69,950
Plant shutdowns, asset impairments, restructurings and other											$ (12,827)	[3]	$ (671)	[3]	$ (109)	[3]

[1] 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 $28.8 million in 2014, $28.6 million in 2013 and $24.8 million in 2012.

[2] 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 $40.5 million and $38.6 million at December 31, 2014 and 2013, respectively. Export sales relate almost entirely to Film Products. Operations outside the U.S. in The Netherlands, Hungary, China, Brazil and India also relate to Film Products. 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.

[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.