Schedule III Properties And Accumulated Depreciation (Summary Of Historical Cost) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule III Properties And Accumulated Depreciation [Abstract]
Balance, beginning of year	$ 8,742,519	$ 6,118,583	$ 5,227,542
Additions during period (acquisitions and improvements)	1,345,046	2,623,936	891,041
Deductions during period (dispositions and write-off of tenant improvements)	(207,987)
Balance, end of year	$ 9,879,578	$ 8,742,519	$ 6,118,583