Supplemental Cash Flow Information (Summary Of Non-Cash Investing And Financing Activities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Accrued property construction costs	$ 8,014	$ 11,135	$ 7,728
Reduction of debt service guaranty liability	(3,520)	(3,245)	(2,980)
Right-of-use assets exchanged for operating lease liabilities	43,729	0	0
Increase (decrease) in equity associated with deferred compensation plan (see Note 1)	$ 0	$ 0	$ 44,758