Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Operating activities
Net income (loss)	$ 512,300,000		$ 138,280,000		$ 294,840,000
Adjustments to reconcile net income to net cash provided from (used in) operating activities:
Depreciation and amortization expenses	844,130,000		873,960,000		533,585,000
Other amortization expenses	6,971,000		8,097,000		15,185,000
Provision for loan losses	0		2,110,000		27,008,000
Impairment of assets	0		0		29,287,000
Stock-based compensation expense	32,075,000		20,177,000		18,521,000
Loss on derivatives	(1,495,000)		4,470,000		(1,825,000)
Loss (gain) on extinguishment of debt, net	9,558,000		(909,000)		(775,000)
Income from unconsolidated entities	27,426,000		8,187,000		(2,482,000)
Rental income less than (in excess of) cash received	(74,552,000)		(46,068,000)		(32,362,000)
Amortization related to above (below) market leases, net	739,000		460,000		165,000
Loss (gain) on sales of properties, net	(153,522,000)		(49,138,000)		(100,549,000)
Distributions by unconsolidated entities operating	9,060,000		8,885,000		17,607,000
Increase (decrease) in accrued expenses and other liabilities	(48,381,000)		67,557,000		38,213,000
Decrease (increase) in receivables and other assets	(25,639,000)		(47,571,000)		(18,285,000)
Net cash provided from (used in) operating activities	1,138,670,000		988,497,000		818,133,000
Investing activities
Cash disbursed for acquisitions	(2,210,600,000)		(3,597,955,000)		(2,923,251,000)
Cash disbursed for capital improvements to existing properties	(132,780,000)		(135,832,000)		(135,450,000)
Cash disbursed for construction in progress	(197,881,000)		(247,560,000)		(286,410,000)
Capitalized interest	(7,150,000)		(6,700,000)		(9,777,000)
Investment in real estate loans receivable	(202,207,000)		(117,059,000)		(665,094,000)
Other investments, net of payments	(100,033,000)		(15,634,000)		25,425,000
Principal collected on real estate loans receivable	105,496,000		102,886,000		35,020,000
Contributions to unconsolidated entities	(353,496,000)		(99,769,000)		(227,735,000)
Distributions by unconsolidated entities investing	57,183,000		30,853,000		13,136,000
Proceeds from (payments on) derivatives investing	10,269,000		(6,803,000)		6,652,000
Decrease (increase) in restricted cash	(6,072,000)		79,957,000		(35,766,000)
Proceeds from sales of real property	911,065,000		482,023,000		610,271,000
Net cash provided from (used in) investing activities	(2,126,206,000)		(3,531,593,000)		(3,592,979,000)
Financing activities
Net increase (decrease) under unsecured lines of credit arrangements	(130,000,000)		130,000,000		(610,000,000)
Proceeds from issuance of senior unsecured notes	773,992,000		1,756,192,000		2,025,708,000
Payments to extinguish senior unsecured notes	(365,188,000)		(517,625,000)		(370,524,000)
Secured debt issued	109,503,000		89,208,000		157,418,000
Payments on secured debt	(341,839,000)		(674,103,000)		(406,210,000)
Net proceeds from the issuance of common stock	2,343,868,000		1,854,637,000		3,581,292,000
Net proceeds from issuance of preferred stock	0		0		277,687,000
Redemption of preferred stock	0		0		(275,000,000)
Decrease (increase) in deferred loan expenses	(16,782,000)		(13,503,000)		(7,152,000)
Contributions by noncontrolling interests	9,962,000	[1]	5,072,000	[1]	24,115,000	[1]
Distributions to noncontrolling interests	(43,691,000)	[1]	(35,592,000)	[1]	(29,353,000)	[1]
Acquisitions of non controlling interests	(1,175,000)		(23,247,000)		0
Cash distributions to stockholders	(1,035,069,000)		(906,275,000)		(722,450,000)
Other financing activities	(409,000)		2,906,000		(403,000)
Net cash provided from (used in) financing activities	1,303,172,000		1,667,670,000		3,645,128,000
Effect of foreign currency translation on cash and cash equivalents	(690,000)		442,000		0
Increase (decrease) in cash and cash equivalents	314,946,000		(874,984,000)		870,282,000
Cash and cash equivalents at beginning of period	158,780,000		1,033,764,000		163,482,000
Cash and cash equivalents at end of period	473,726,000		158,780,000		1,033,764,000
Supplemental cash flow information:
Interest paid	504,165,000		447,108,000		369,511,000
Income taxes paid	$ 18,548,000		$ 12,110,000		$ 3,071,000

[1] Includes amounts attributable to redeemable noncontrolling interests. See accompanying notes.