Earnings Per Share (Schedule Of Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Income from continuing operations	$ 45,416	$ 33,379	$ 85,961	$ 68,818
Less: Preferred share dividends	(135)	(135)	(271)	(271)
Less: Income from continuing operations attributable to noncontrolling interests	(1,871)	(1,258)	(3,663)	(2,512)
Less: Earnings allocated to unvested shares	(237)	(214)	(475)	(428)
Income from continuing operations available for common shareholders	43,173	31,772	81,552	65,607
Results from discontinued operations attributable to the Trust	0	424	0	827
Gain on sale of real estate	0	4,994	0	4,994
Net income available for common shareholders, basic and diluted	43,173	37,190	81,552	71,428
Weighted average number of common shares, basic	67,110	65,149	66,858	64,922
Stock options	167	162	163	158
Weighted average common shares outstanding, diluted	67,277	65,311	67,021	65,080
Continuing operations	$ 0.64	$ 0.49	$ 1.22	$ 1.01
Discontinued operations	$ 0.00	$ 0.00	$ 0.00	$ 0.01
Gain on Sale of Real Estate	$ 0.00	$ 0.08	$ 0.00	$ 0.08
Earnings Per Share, Basic, Total	$ 0.64	$ 0.57	$ 1.22	$ 1.10
Continuing operations	$ 0.64	$ 0.49	$ 1.22	$ 1.01
Discontinued operations	$ 0.00	$ 0.00	$ 0.00	$ 0.01
Gain on Sale of Real Estate	$ 0.00	$ 0.08	$ 0.00	$ 0.08
Earnings Per Share, Diluted, Total	$ 0.64	$ 0.57	$ 1.22	$ 1.10
Income from continuing operations attributable to the Trust	$ 43,545	$ 32,121	$ 82,298	$ 66,306