Inventories (Schedule Of Components Of Inventories) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Inventory, Net [Abstract]
Finished goods	$ 24,154	$ 20,281
Work-in-process	10,615	11,958
Raw materials	31,089	35,909
Stores, supplies and other	19,500	18,759
Total	$ 85,358	$ 86,907