Earnings Per Share (Schedule Of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
INCOME FROM CONTINUING OPERATIONS	$ 56,253	$ 54,550	$ 166,701	$ 136,917
Less: Preferred share dividends	(136)	(136)	(406)	(406)
Less: Net income attributable to noncontrolling interests	1,982	2,103	5,961	6,161
Less: Earnings allocated to unvested shares	(170)	(221)	(534)	(638)
Income from continuing operations available for common shareholders	53,965	52,090	159,800	129,712
Gain on change in control of interests and sale of real estate, net	4,706	0	31,133	11,509
Net income available for common shareholders, basic and diluted	$ 58,671	$ 52,090	$ 190,933	$ 141,221
Weighted average common shares outstanding—basic	71,319	69,006	70,626	68,637
Stock options	170	175	178	184
Weighted average common shares outstanding—diluted	71,489	69,181	70,804	68,821
Continuing operations	$ 0.75	$ 0.75	$ 2.26	$ 1.89
Gain on sale of real estate and change in control of interests, net	0.07	0.00	0.44	0.17
Earnings per common share, basic	0.82	0.75	2.70	2.06
Continuing operations	0.75	0.75	2.26	1.88
Gain on sale of real estate and change in control of interests, net	0.07	0.00	0.44	0.17
Earnings per common share, diluted	$ 0.82	$ 0.75	$ 2.70	$ 2.05
Income from continuing operations attributable to the Trust	$ 54,271	$ 52,447	$ 160,740	$ 130,756