Description Of Business And Segment Reporting (Summary Of Capital Expenditures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total capital expenditures	$ 76,708	$ 49,166	$ 53,119
Segment [Member]
Segment Reporting Information [Line Items]
Total capital expenditures	76,300	49,023	52,989
Corporate [Member]
Segment Reporting Information [Line Items]
Total capital expenditures	$ 408	$ 143	$ 130