Accumulated Other Comprehensive Income (Loss) (Schedule Of Reclassifications Of Balances Out Of Accumulated Other Comprehensive Income (Loss) Into Net Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (172,436)	$ (176,278)	$ (176,669)	$ (183,234)
Cost of goods sold	(203,189)	(179,761)
Selling, general and administrative	21,829	19,949
Income before income taxes	(23,451)	(6,121)
Income taxes from continuing operations	(5,287)	(2,418)
Net income	18,164	3,703
Foreign Currency Translation
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(84,272)	(89,338)	(86,178)	(93,970)
Gain (Loss) on Derivative Financial Instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	174	1,237	459	863
Pension & Other Post-retirement Benefit Adjust.
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(88,338)	(88,177)	$ (90,950)	$ (90,127)
Reclassification Out Of Accumulated Other Comprehensive Income | Gain (Loss) on Derivative Financial Instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(206)	(248)
Income taxes from continuing operations	(53)	(94)
Net income	153	154
Reclassification Out Of Accumulated Other Comprehensive Income | Gain (Loss) on Derivative Financial Instruments | Aluminum Futures Contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of goods sold	232	233
Reclassification Out Of Accumulated Other Comprehensive Income | Pension & Other Post-retirement Benefit Adjust.
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial gain (loss) and prior service costs, before taxes	(3,374)	(3,061)
Income taxes from continuing operations	762	1,111
Net income	(2,612)	(1,950)
Selling, General and Administrative Expenses [Member] | Reclassification Out Of Accumulated Other Comprehensive Income | Gain (Loss) on Derivative Financial Instruments | Foreign Currency Forward Contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Selling, general and administrative	(41)
Cost of Sales [Member] | Reclassification Out Of Accumulated Other Comprehensive Income | Gain (Loss) on Derivative Financial Instruments | Foreign Currency Forward Contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of goods sold	$ (15)	$ (15)