Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Schedule of Equity Method Investments [Line Items]
Total revenue	$ 515,320,000		$ 471,349,000		$ 998,334,000		$ 915,042,000
Expenses
Depreciation and amortization	134,604,000		111,168,000		255,199,000		219,630,000
Total expenses	344,505,000		298,030,000		697,084,000		598,156,000
Operating income	170,815,000		173,319,000		301,250,000		316,886,000
Other expense
Interest expense	(103,140,000)		(99,901,000)		(203,573,000)		(203,138,000)
Losses on Extinguishment of Debt	152,000		274,000		152,000		1,041,000
Income from continuing operations	505,888,000		97,079,000		546,817,000		152,344,000
Net income	506,761,000		134,174,000		564,692,000		190,009,000
Income from unconsolidated joint ventures	48,783,000		21,191,000		57,504,000		32,912,000
Gain on consolidation of joint ventures	387,801,000		0		387,801,000		0
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Total revenue	99,831,000	[1]	156,035,000	[1]	235,481,000	[1]	295,135,000	[1]
Expenses
Operating	32,497,000		39,261,000		74,863,000		78,153,000
Depreciation and amortization	27,141,000		42,679,000		66,418,000		84,578,000
Total expenses	59,638,000		81,940,000		141,281,000		162,731,000
Operating income	40,193,000		74,095,000		94,200,000		132,404,000
Other expense
Interest expense	(40,054,000)		(55,909,000)		(96,288,000)		(111,271,000)
Losses on Extinguishment of Debt	(1,677,000)		0		(1,677,000)		0
Income from continuing operations	(1,538,000)		18,186,000		(3,765,000)		21,133,000
Gain on sale of real estate	1,766,000		0		1,766,000		0
Net income	228,000		18,186,000		(1,999,000)		21,133,000
Company's share of net income (loss)	683,000		10,641,000		(1,175,000)		12,012,000
Gain on sale or real estate	43,327,000		0		43,327,000		0
Basis differential	(2,070,000)		431,000		(1,626,000)		897,000
Elimination of inter-entity interest on partner loan	6,843,000		10,119,000		16,978,000		20,003,000
Income from unconsolidated joint ventures	48,783,000		21,191,000		57,504,000		32,912,000
Straight-line rent adjustments	3,100,000		2,800,000		(7,100,000)		(7,100,000)
"Above" and "below" market rent adjustments, net	13,500,000		23,200,000		34,000,000		48,500,000
Termination income			19,600,000				19,600,000
Company Share Of Termination Income			11,800,000				11,800,000
Gain on consolidation of joint ventures	$ 387,801,000		$ 0		$ 387,801,000		$ 0

[1] Includes straight-line rent adjustments of $3.1 million and $2.8 million for the three months ended June 30, 2013 and 2012, respectively, and $7.1 million and $7.1 million for the six months ended June 30, 2013 and 2012, respectively. Includes net below-market rent adjustments of $13.5 million and $23.2 million for the three months ended June 30, 2013 and 2012, respectively, and $34.0 million and $48.5 million for the six months ended June 30, 2013 and 2012, respectively.