Supplemental Cash Flow and Non-Cash Information (Table Of Supplmental Cash Flow Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Income taxes paid, net	$ 48,918	$ 6,453	$ 7,865
Interest paid	7,868	8,698	8,305
Cash Flow Non-cash Investing And Financing Activities Disclosure [Abstract]
Additions to property, plant and equipment in accounts payable	$ 6,148	$ 7,761	$ 2,111