Consolidated Statements of Cash Flows (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash Flows from Operating Activities:
Net income	$ 280,264,000	$ 445,821,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization (including amortization of deferred financing costs)	145,304,000	136,860,000
Equity in net income of partially owned entities, including Toys R Us	(136,504,000)	(129,228,000)
Net gains on sale of real estate	(55,817,000)	(51,165,000)
Straight-lining of rental income	(21,808,000)	(13,942,000)
Distributions of income from partially owned entities	14,194,000	25,921,000
Amortization of below-market leases, net	(13,813,000)	(16,892,000)
Other non-cash adjustments	7,795,000	8,211,000
Unrealized gain on Real Estate Fund assets	(6,844,000)	0
Income from the mark-to-market of J.C. Penney derivative position	(1,045,000)	(17,163,000)
Net gain on extinguishment of debt	0	(83,907,000)
Mezzanine loans loss reversal and net gain on disposition	0	(82,744,000)
Net gain on disposition of wholly owned and partially owned assets	0	(6,677,000)
Changes in operating assets and liabilities:
Real Estate Fund investments	28,980,000	(85,536,000)
Accounts receivable, net	(19,386,000)	(10,475,000)
Prepaid assets	51,202,000	34,761,000
Other assets	(8,872,000)	2,947,000
Accounts payable and accrued expenses	40,609,000	30,906,000
Other liabilities	2,844,000	8,404,000
Net cash provided by operating activities	307,103,000	196,102,000
Cash Flows from Investing Activities:
Proceeds from sales of real estate and related investments	306,022,000	127,199,000
Investments in partially owned entities	(46,732,000)	(316,129,000)
Additions to real estate	(44,052,000)	(30,281,000)
Acquisitions of real estate and other	(21,054,000)	0
Development costs and construction in progress	(20,614,000)	(10,994,000)
Restricted cash	(19,355,000)	12,174,000
Proceeds from the repayment of loan to officer	13,123,000	0
Distributions of capital from partially owned entities	4,203,000	192,523,000
Proceeds from sales and repayments of mezzanine loans	554,000	73,608,000
Proceeds from sales of marketable securities	0	15,162,000
Investments in mezzanine loans receivable and other	0	(2,841,000)
Net cash provided by investing activities	172,095,000	60,421,000
Cash Flows from Financing Activities:
Repayments of borrowings	(884,679,000)	(1,197,312,000)
Proceeds from borrowings	625,000,000	937,518,000
Dividends paid on common shares	(127,973,000)	(126,936,000)
Distributions to noncontrolling interests	(34,092,000)	(23,639,000)
Repurchase of shares related to stock compensation agreements and related tax withholdings	(30,034,000)	(570,000)
Dividends paid on preferred shares	(17,789,000)	(13,559,000)
Debt issuance and other costs	(9,822,000)	(12,161,000)
Proceeds received from exercise of employee share options	7,997,000	15,470,000
Contributions from noncontrolling interests	0	92,238,000
Net cash used in financing activities	(471,392,000)	(328,951,000)
Net increase (decrease) in cash and cash equivalents	7,806,000	(72,428,000)
Cash and cash equivalents at beginning of period	606,553,000	690,789,000
Cash and cash equivalents at end of period	614,359,000	618,361,000
Supplemental Disclosure of Cash Flow Information:
Cash payments for interest, net of capitalized interest of $16 and $0	117,282,000	108,458,000
Cash payments for income taxes	2,563,000	2,509,000
Non-Cash Investing and Financing Activities:
Adjustment to carry redeemable Class A units at redemption value	(96,061,000)	(42,227,000)
Common shares issued upon redemption of Class A units, at redemption value	13,028,000	27,539,000
Change in unrealized net gain on securities available-for-sale	12,693,000	68,039,000
Contribution of mezzanine loan receivable to a joint venture	0	73,750,000
Like-kind exchange of real estate	0	(45,625,000)
Decrease in assets and liabilities resulting from deconsolidation of discontinued operations:
Assets related to discontinued operations	0	(145,333,000)
Liabilities related to discontinued operations	0	(232,502,000)
Write-off of fully depreciated assets	(37,890,000)	(25,893,000)
Toys R Us [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in net income of partially owned entities, including Toys R Us	(116,471,000)	(112,944,000)
All Equity Method Investees Excluding Toys [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in net income of partially owned entities, including Toys R Us	$ (20,033,000)	$ (16,284,000)