Supplementary Balance Sheet Detail (Schedule Of Amounts Recognized In Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Balance Sheet Related Disclosures [Abstract]
Raw materials and supplies	$ 54,469	$ 66,201
Work in process	52,379	89,453
Finished goods	49,263	62,476
Inventories	156,111	218,130
Prepaid expenses	6,096	9,041
Value added tax and other indirect taxes receivable	12,984	10,069
Other current assets	2,585	2,040
Prepaid Expense and Other Assets, Current	21,665	21,150
Land and improvements	43,737	44,052
Buildings	55,440	55,843
Machinery and equipment and other	460,892	431,226
Construction in progress	25,635	40,208
Property, plant and equipment	585,704	571,329
Payrolls (including incentive programs)	4,802	4,028
Employee compensation and benefits	11,439	6,199
Other	14,278	10,760
Accrued liabilities, net	30,519	20,987
Postretirement benefits	19,002	20,102
Pension and related benefits	45,876	55,364
Other	17,270	18,852
Other long - term obligations	$ 82,148	$ 94,318