Plants Shutdowns, Asset Impairments, Restructurings And Other (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Restructuring Cost and Reserve [Line Items]
Pretax charges for asset impairments		$ 1,131,000
Unrealized gain (loss) on investment under fair value method	1,100,000	3,600,000
Intelliject [Member]
Restructuring Cost and Reserve [Line Items]
Unrealized gain (loss) on investment under fair value method	1,100,000	3,600,000
Unrealized gain (loss) on investment under fair value method, after taxes	700,000	2,300,000
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Plant shutdown related expenditures	200,000	900,000
Accelerated depreciation		700,000
Pretax charges for severance and other employee-related costs		600,000
Other shutdown-related charges		100,000
Effect of LIFO Inventory Liquidation on Income		500,000
Aluminum Extrusions [Member]
Restructuring Cost and Reserve [Line Items]
Pretax charges for severance and other employee-related costs		200,000
Film Products [Member]
Restructuring Cost and Reserve [Line Items]
Pretax charges for severance and other employee-related costs	100,000
Harbinger Fund [Member]
Restructuring Cost and Reserve [Line Items]
Cost-method investment, OTTI		1,100,000
Cost-method investment, OTTI net of tax		700,000
Terphane [Member]
Restructuring Cost and Reserve [Line Items]
Integration-related expenses and other non-recurring transactions		300,000
AACOA [Member]
Restructuring Cost and Reserve [Line Items]
Integration-related expenses and other non-recurring transactions	$ 100,000