Accumulated Other Comprehensive Income (Loss) (Schedule Of Reclassifications Of Balances Out Of Accumulated Other Comprehensive Income (Loss) Into Net Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	$ (198,581)		$ (176,486)	$ (396,069)		$ (352,343)
Total, before taxes	15,074		10,098	28,355		21,967
Income tax expense (benefit)	5,484		2,710	9,248		6,842
Total, net of tax	1,290		7,353	5,567		10,351
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Gain (Loss) On Derivative Financial Instruments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total, before taxes	(191)			(149)
Income tax expense (benefit)	(72)			(56)
Total, net of tax	(119)			(93)
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Gain (Loss) On Derivative Financial Instruments [Member] | Aluminum Futures Contracts [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	(191)			(149)
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Pension & Other Post-Retirement Benefit Adjust. [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Actuarial gain (loss) and prior service costs, before taxes	(3,649)	[1]		(7,298)	[1]
Income tax expense (benefit)	(1,337)			(2,673)
Total, net of tax	$ (2,312)			$ (4,625)

[1] This component of accumulated other comprehensive income is included in the computation of net periodic pension cost (see Note 10 for additional detail).