Supplemental Cash Flow and Non-Cash Information (Table Of Supplmental Cash Flow Information) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Supplemental Cash Flow Information [Abstract]
Income taxes paid, net	$ 1,416	$ 816
Interest paid	2,256	2,214
Cash Flow Non-cash Investing And Financing Activities Disclosure [Abstract]
Additions to property, plant and equipment in accounts payable	$ 11,035	$ 3,301