Accounting Policies (Schedule of Inventories) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Raw materials	$ 42,215	$ 37,691
Work in process	65,448	58,715
Finished goods	28,856	37,500
Total inventories	$ 136,519	$ 133,906