Income Tax Considerations (Schedule Of Cash Dividends Distributed To Common Shareholders) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Ordinary income	79.90%	65.40%	42.20%
Capital gain distributions	20.10%	34.60%	57.80%
Total	100.00%	100.00%	100.00%