Real Estate and Accumulated Depreciation (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Real Estate
Balance at beginning of year	$ 8,333,419,000		$ 8,917,137,000		$ 9,468,165,000
Additions during the year:
Acquisitions	66,058,000		131,374,000		44,681,000
Capital additions	376,038,000		272,103,000		207,263,000
Deductions during the year:
Casualty and other write-offs	(98,489,000)	[1]	(62,589,000)	[1]	(192,542,000)	[1]
Reclassification of real estate included in sale of asset management business	0		(160,420,000)		0
Sales	(462,945,000)		(764,186,000)		(610,430,000)
Balance at end of year	8,214,081,000		8,333,419,000		8,917,137,000
Accumulated Depreciation
Balance at beginning of year	2,820,765,000		2,872,190,000		2,934,912,000
Additions during the year
Depreciation	288,666,000		353,414,000		382,213,000
Deductions during the year:
Casualty and other write-offs	(92,775,000)	[1]	(46,869,000)	[1]	(173,941,000)	[1]
Reclassification of real estate included in sale of asset management business	0		(33,394,000)		0
Sales	(193,784,000)		(324,576,000)		(270,994,000)
Balance at end of year	2,822,872,000		2,820,765,000		2,872,190,000
Write-off of fully depreciated assets	$ 91,900,000		$ 38,700,000		$ 165,900,000

[1] Includes the write-off of fully depreciated assets totaling $91.9 million, $38.7 million and $165.9 million, during the years ended December 31, 2013, 201