Shareholders' Equity (Schedule of Dividends) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Common stock	$ 0.528	$ 1.320	$ 1.320
Series B Preferred Stock [Member]
Class Of Stock [Line Items]
Cumulative Redeemable Preferred Stock	$ 1.812	$ 1.812	$ 1.812
Dividend rate percentage	7.25%	7.25%	7.25%
Series C Preferred Stock [Member]
Class Of Stock [Line Items]
Cumulative Redeemable Preferred Stock	$ 1.625	$ 1.625	$ 1.625
Dividend rate percentage	6.50%	6.50%	6.50%