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		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (200,238)	$ (180,898)	$ (200,238)	$ (180,898)	$ (197,651)	$ (179,987)
Selling, general and administrative	20,420	19,154	61,654	56,399
Income before income taxes	22,918	(15,229)	31,616	(68,021)
Income taxes from continuing operations	5,942	(177)	8,308	(10,550)
Net income (loss)	(65,213)	17,133	(76,339)	51,395
Foreign Currency Translation
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(111,739)	(103,231)	(111,739)	(103,231)	(100,663)	(96,940)
Gain (Loss) on Derivative Financial Instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,611)	(2,457)	(1,611)	(2,457)	(1,307)	(1,601)
Pension & Other Post-retirement Benefit Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(86,888)	(75,210)	(86,888)	(75,210)	$ (95,681)	$ (81,446)
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	2,327	902	7,079	2,654
Income taxes from continuing operations	496	179	1,523	445
Net income (loss)	(1,831)	(723)	(5,556)	(2,209)
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	(575)	(816)	(2,766)	(2,039)
Reclassification Out Of Accumulated Other Comprehensive Income | Pension & Other Post-retirement Benefit Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial gain (loss) and prior service costs, before taxes	(3,767)	(2,672)	(11,300)	(8,014)
Income taxes from continuing operations	836	593	2,507	1,778
Net income (loss)	(2,931)	(2,079)	(8,793)	(6,236)
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]
Cost of goods sold		(101)		(661)
Selling, general and administrative	(1,767)		(4,359)
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	$ 46	$ 46