Inventories (Schedule of Inventory) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Inventories [Abstract]
Finished goods	$ 46,673	$ 62,547
Work-in-process	21,716	20,178
Raw materials	18,032	19,492
Total inventories at current costs	86,421	102,217
Less: LIFO reserve	(3,178)	(5,821)
Inventory	83,243	96,396
Excess of Book LIFO Over Tax LIFO	8,925	5,046
Effect Of Inventory Liquidation On Cost Of Good Sold, Increase/(Decrease)	$ 1,304	$ 115	$ 6