Summary Of Significant Accounting Policies (Calculation Of Earnings Per Share) (Details) - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Summary Of Significant Accounting Policies [Abstract]
Net income	$ 44,483,000	$ 49,373,000	$ 109,511,000	$ 95,948,000
Net income allocated to Preferred shareholders based upon distributions	(12,047,000)	(12,959,000)	(24,093,000)	(25,918,000)
Net income allocated to Noncontrolling interests - joint venture	(13,000)	(10,000)	(30,000)	(13,000)
Net income allocated to Restricted stock unit holders	(119,000)	(212,000)	(394,000)	(480,000)
Net income allocable to common shareholders and noncontrolling interests - common units	32,304,000	36,192,000	84,994,000	69,537,000
Net income allocation to noncontrolling interests - common units	(6,782,000)	(7,613,000)	(17,857,000)	(14,637,000)
Net income allocable to common shareholders	$ 25,522,000	$ 28,579,000	$ 67,137,000	$ 54,900,000
Weighted average common shares outstanding	27,479	27,426	27,464	27,400
Weighted average common partnership units outstanding	7,305	7,305	7,305	7,305
Total common share equivalents	34,784	34,731	34,769	34,705
Common partnership units as a percentage of common share equivalents	21.00%	21.00%	21.00%	21.00%
Net effect of dilutive stock compensation - based on treasury stock method using average market price	81	106	93	105
Diluted weighted average common shares outstanding	27,560	27,532	27,557	27,505