Basis Of Presentation (Schedule Of Preferred Stock) (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Class of Stock [Line Items]
Shares Outstanding	14,700,000		14,700,000
Series C Preferred Shares [Member]
Class of Stock [Line Items]
Shares Outstanding	3,000,000		3,000,000
Aggregate Liquidation Preference	$ 75,000
Distribution Rate	6.875%
Dividend Per Share	$ 1.2891	$ 1.2891
Series D Preferred Shares [Member]
Class of Stock [Line Items]
Shares Outstanding	7,700,000		7,700,000
Aggregate Liquidation Preference	$ 192,500
Distribution Rate	6.50%
Dividend Per Share	$ 1.2189	$ 0.6094
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Shares Outstanding	4,000,000		4,000,000
Aggregate Liquidation Preference	$ 100,000
Distribution Rate	6.50%
Dividend Per Share	$ 1.2189