Investments In Real Estate (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Business Acquisition [Line Items]
Operating revenue	$ 380,931	$ 379,456	$ 363,502	$ 358,370	$ 349,736	$ 342,479	$ 303,704	$ 283,148	$ 1,482,259	$ 1,279,067	$ 1,062,710
Operating income									381,812	366,078	304,310
Sentrum Portfolio [Member]
Business Acquisition [Line Items]
Operating revenue									10,300
Operating income									$ 2,600