Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash Flows from Operating Activities:
Net income	$ 740,000,000	$ 708,031,000	$ 128,450,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization (including amortization of deferred financing costs)	580,990,000	556,312,000	559,053,000
Equity in income of partially owned entities including ToysRUs	(120,310,000)	(94,062,000)	(72,390,000)
Distributions of income from partially owned entities	93,635,000	61,037,000	30,473,000
Net (gain) loss on extinguishment of debt	(83,907,000)	(97,728,000)	25,915,000
Mezzanine loans loss (reversal) accrual	(82,744,000)	(53,100,000)	190,738,000
Amortization Of Below Market Leases Net Adjusted For Discontinued Operations	(63,044,000)	(66,202,000)	(72,481,000)
Impairment losses, write-off of tenant buy-outs and litigation loss accrual	58,173,000	137,367,000	91,184,000
Net gain on sale of real estate	(51,623,000)	(2,506,000)	(45,284,000)
Straight-lining of rental income	(45,788,000)	(76,926,000)	(98,355,000)
Other non-cash adjustments	27,325,000	36,352,000	15,196,000
Recognition of disputed account receivable from Stop & Shop	(23,521,000)	0	0
Net realized and unrealized gains on Real Estate Fund assets	(17,386,000)	0	0
Net gain on disposition of wholly owned and partially owned assets	(15,134,000)	(81,432,000)	(5,641,000)
(Income) loss from the mark-to-market of J.C. Penney derivative position	(12,984,000)	(130,153,000)	0
Interest received on repayment on mezzanine loan	0	40,467,000	0
Write Off Of Unamortized Costs From Voluntary Surrender Of Equity Awards	0	0	32,588,000
Changes in operating assets and liabilities:
Real Estate Fund Investments	(184,841,000)	(144,423,000)	0
Accounts receivable, net	8,869,000	2,019,000	15,383,000
Prepaid assets	(7,779,000)	6,321,000	(90,519,000)
Other assets	(87,488,000)	(66,736,000)	(61,878,000)
Accounts payable and accrued expenses	(28,699,000)	2,645,000	(3,606,000)
Other liabilities	18,755,000	33,803,000	(5,247,000)
Net cash provided by operating activities	702,499,000	771,086,000	633,579,000
Increase Decrease Allowance Relating To Litigation	23,521,000	0	0
Cash Flows from Investing Activities:
Investments in partially owned entities	(571,922,000)	(165,170,000)	(38,266,000)
Distributions of capital from partially owned entities	318,966,000	51,677,000	16,790,000
Proceeds from sales and repayments of mezzanine loans receivable and other	187,294,000	70,762,000	47,397,000
Additions to real estate	(165,680,000)	(144,794,000)	(216,669,000)
Proceeds from sales of real estate and related investments	140,186,000	127,736,000	367,698,000
Restricted cash	126,380,000	138,586,000	111,788,000
Investments in mezzanine loans receivable and other	(98,979,000)	(85,336,000)	0
Development costs and construction in progress	(93,066,000)	(156,775,000)	(465,205,000)
Acquisitions of real estate and other	(90,858,000)	(173,413,000)	0
Proceeds from sales of, and return of investment in, marketable securities	70,418,000	280,462,000	64,355,000
Return of J.C. Penney derivative collateral	56,350,000	0	0
Funding of J.C. Penney derivative collateral	(43,850,000)	(12,500,000)	0
Proceeds from the repayment of loan to officer	13,123,000	0	0
Loan to officer	(13,123,000)	0	0
Purchases of marketable securities including J.C. Penney common shares and other	0	(491,596,000)	(90,089,000)
Proceeds from maturing short-term investments	0	40,000,000	15,000,000
Purchases of short-term investments	0	0	(55,000,000)
Net cash provided by (used in) investing activities	(164,761,000)	(520,361,000)	(242,201,000)
Cash Flows from Financing Activities:
Repayments of borrowings	(3,740,327,000)	(1,564,143,000)	(2,075,236,000)
Proceeds from borrowings	3,412,897,000	2,481,883,000	2,648,175,000
Dividends paid on common shares	(508,745,000)	(474,299,000)	(262,397,000)
Proceeds from the issuance of Series J preferred shares	238,842,000	0	0
Contributions from noncontrolling interests	204,185,000	103,831,000	2,180,000
Distributions to noncontrolling interests	(116,510,000)	(53,842,000)	(42,451,000)
Dividends paid on preferred shares	(61,464,000)	(55,669,000)	(57,076,000)
Debt issuance and other costs	(47,395,000)	(14,980,000)	(30,186,000)
Purchase of outstanding preferred units and shares	(28,000,000)	(78,954,000)	(24,330,000)
Proceeds received from exercise of employee share options	25,507,000	26,993,000	1,750,000
Repurchase of shares related to stock compensation agreements and related tax withholdings	(964,000)	(25,660,000)	(32,203,000)
Acquisition of convertible senior debentures and senior unsecured notes	0	(440,575,000)	(2,221,204,000)
Proceeds from issuance of common shares	0	0	710,226,000
Net cash used in by financing activities	(621,974,000)	(95,415,000)	(1,382,752,000)
Net (decrease) increase in cash and cash equivalents	(84,236,000)	155,310,000	(991,374,000)
Cash and cash equivalents at beginning of period	690,789,000	535,479,000	1,526,853,000
Cash and cash equivalents at end of period	606,553,000	690,789,000	535,479,000
Supplemental Disclosure Of Cash Flow Information [Abstract]
Cash payments for interest (net of amounts capitalized of $1,197, $864 and $17,256)	531,174,000	549,327,000	631,573,000
Cash payments for income taxes	26,187,000	23,960,000	21,775,000
Non-Cash Investing and Financing Activities:
Adjustment to carry redeemable Class A units at redemption value	98,092,000	(191,826,000)	(167,049,000)
Contribution of mezzanine loan receivable to joint venture	73,750,000	0	0
Write-off of fully depreciated assets	(72,279,000)	(63,007,000)	(86,291,000)
Common shares issued upon redemption of Class A units at redemption value	64,830,000	126,764,000	90,955,000
Change in unrealized net gain on securities available-for-sale	46,177,000	46,447,000	6,147,000
Like-kind exchange of real estate	(23,626,000)	0	0
Financing assumed in acquisitions	0	102,616,000	0
Dividends paid in common shares	0	0	285,596,000
Unit distributions paid in Class A units	0	0	23,876,000
Increase in assets and liabilities resulting from the consolidation of investments previously accounted for on the equity method:
Real Estate, net	0	(102,804,000)	0
Notes and mortgages payable	0	57,563,000	0
Decrease in assets and liabilities resulting from deconsolidation of investments that were previously consolidated:
Real Estate, Net	145,333,000	401,857,000	0
Notes and Mortgages Payable	(232,502,000)	(316,490,000)	0
Toys R Us [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income of partially owned entities including ToysRUs	(48,540,000)	(71,624,000)	(92,300,000)
All Equity Method Investees Excluding Toys [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income of partially owned entities including ToysRUs	$ (71,770,000)	$ (22,438,000)	$ 19,910,000