Description Of Business And Segment Reporting (Summary Of Capital Expenditures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total capital expenditures	$ 16,759	$ 47,722	$ 56,827
Segment [Member]
Segment Reporting Information [Line Items]
Total capital expenditures	16,686	47,555	56,795
Corporate [Member]
Segment Reporting Information [Line Items]
Total capital expenditures	$ 73	$ 167	$ 32