Property (Schedule Of Property) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Real Estate [Abstract]
Land	$ 1,094,096	$ 1,107,072
Land held for development	70,715	82,953
Land under development	48,805	51,761
Buildings and improvements	3,374,867	3,489,685
Construction in-progress	78,798	57,674
Total	$ 4,667,281	$ 4,789,145