Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Schedule of Equity Method Investments [Line Items]
Total revenue	$ 574,082,000		$ 466,680,000		$ 1,566,834,000		$ 1,376,448,000
Expenses
Depreciation and amortization	154,193,000		110,653,000		408,923,000		329,819,000
Total expenses	386,730,000		305,989,000		1,081,817,000		902,129,000
Operating income	187,352,000		160,691,000		485,017,000		474,319,000
Other expense
Interest expense	(122,173,000)		(105,030,000)		(325,746,000)		(308,168,000)
Losses on Extinguishment of Debt	(30,000)		(5,494,000)		122,000		(4,453,000)
Income from continuing operations	82,910,000		63,972,000		626,142,000		213,058,000
Net income	170,436,000		65,522,000		735,128,000		255,531,000
Income from unconsolidated joint ventures	14,736,000		9,217,000		72,240,000		42,129,000
Gains on consolidation of joint ventures	(1,810,000)		0		385,991,000		0
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Total revenue	37,983,000	[1]	135,998,000	[1]	273,464,000	[1]	431,133,000	[1]
Expenses
Operating	14,963,000		42,298,000		89,826,000		120,451,000
Depreciation and amortization	9,784,000		39,291,000		76,202,000		123,869,000
Total expenses	24,747,000		81,589,000		166,028,000		244,320,000
Operating income	13,236,000		54,409,000		107,436,000		186,813,000
Other expense
Interest expense	(8,148,000)		(56,521,000)		(104,436,000)		(167,792,000)
Losses on Extinguishment of Debt	0		0		(1,677,000)		0
Income from continuing operations	5,088,000		(2,112,000)		1,323,000		19,021,000
Gain on sale of real estate	12,441,000		990,000		14,207,000		990,000
Net income	17,529,000		(1,122,000)		15,530,000		20,011,000
Company's share of net income (loss)	3,149,000		(1,420,000)		1,974,000		10,591,000
Gain on sale or real estate	11,174,000		0		54,501,000		0
Basis differential	413,000		384,000		(1,213,000)		1,282,000
Elimination of inter-entity interest on partner loan	0		10,253,000		16,978,000		30,256,000
Income from unconsolidated joint ventures	14,736,000		9,217,000		72,240,000		42,129,000
Straight-line rent adjustments	600,000		2,200,000		(7,600,000)		(9,300,000)
"Above" and "below" market rent adjustments, net	(100,000)		22,100,000		33,900,000		70,600,000
Termination income							19,600,000
Company Share Of Termination Income							11,800,000
Gains on consolidation of joint ventures	$ (1,810,000)		$ 0		$ 385,991,000		$ 0

[1] Includes straight-line rent adjustments of $0.6 million and $2.2 million for the three months ended September 30, 2013 and 2012, respectively, and $7.6 million and $9.3 million for the nine months ended September 30, 2013 and 2012, respectively. Includes net below-market rent adjustments of $(0.1) million and $22.1 million for the three months ended September 30, 2013 and 2012, respectively, and $33.9 million and $70.6 million for the nine months ended September 30, 2013 and 2012, respectively.