Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash Flows from Operating Activities:
Net (loss) income	$ (91,608)	$ 125,246
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Real estate impairment losses	160,700	256
Depreciation and amortization (including amortization of deferred financing costs)	150,648	131,112
Straight-lining of rental income	(41,626)	(29,474)
Distributions of income from partially owned entities	29,860	15,874
Amortization of below-market leases, net	(17,507)	(12,754)
Other non-cash adjustments	15,248	15,865
Return of capital from real estate fund investments	14,676	72,208
Net realized and unrealized gains on real estate fund investments	(6,611)	(17,639)
Loss from partially owned entities	4,240	2,405
Net gain on disposition of wholly owned and partially owned assets	(714)	(1,860)
Net gains on sale of real estate and other	0	(32,243)
Changes in operating assets and liabilities:
Real estate fund investments	0	(95,022)
Tenant and other receivables, net	800	975
Prepaid assets	64,851	62,658
Other assets	(20,113)	(13,093)
Accounts payable and accrued expenses	12,774	(12,691)
Other liabilities	1,027	(17,307)
Net cash provided by operating activities	276,645	194,516
Cash Flows from Investing Activities:
Development costs and construction in progress	(127,283)	(88,052)
Additions to real estate	(77,243)	(54,466)
Investments in partially owned entities	(63,188)	(23,912)
Distributions of capital from partially owned entities	25,524	13,409
Proceeds from sales of real estate and related investments	2,867	334,725
Restricted cash	(1,348)	1,282
Acquisitions of real estate and other	(938)	(49,878)
Proceeds from sales and repayments of mortgage and mezzanine loans receivable and other	11	16,763
Net cash (used in) provided by investing activities	(241,598)	149,871
Cash Flows from Financing Activities:
Repayments of borrowings	(909,617)	(907,431)
Proceeds from borrowings	887,500	800,000
Dividends paid on common shares	(118,867)	(118,447)
Distributions to noncontrolling interests	(21,474)	(60,287)
Dividends paid on preferred shares	(20,364)	(19,484)
Debt issuance and other costs	(16,704)	(5,076)
Proceeds received from exercise of employee share options	2,523	12,018
Repurchase of shares related to stock compensation agreements and related tax withholdings and other	(185)	(2,939)
Cash included in the spin-off of Urban Edge Properties	0	(225,000)
Contributions from noncontrolling interests	0	51,350
Net cash used in financing activities	(197,188)	(475,296)
Net decrease in cash and cash equivalents	(162,141)	(130,909)
Cash and cash equivalents at beginning of period	1,835,707	1,198,477
Cash and cash equivalents at end of period	1,673,566	1,067,568
Supplemental Disclosure Of Cash Flow Information:
Cash payments for interest, excluding capitalized interest of $7,497 and $8,479	91,719	91,702
Cash payments for income taxes	2,193	2,175
Non-Cash Investing and Financing Activities:
Accrued capital expenditures included in accounts payable and accrued expenses	113,755	87,232
Adjustments to carry redeemable Class A units at redemption value	36,524	25,349
Write-off of fully depreciated assets	(187,419)	(18,790)
Non-cash distribution of Urban Edge Properties:
Assets	0	1,722,263
Liabilities	0	(1,482,660)
Equity	0	(239,603)
Transfer of interest in real estate to Pennsylvania Real Estate Investment Trust	0	(145,313)
Financing assumed in acquisitions	0	62,000
Receipt of security deposits included in restricted cash and other liabilities	0	42,346
Acquisitions [Member]
Non-cash distribution of Urban Edge Properties:
Like-kind exchange of real estate	0	57,722
Dispositions [Member]
Non-cash distribution of Urban Edge Properties:
Like-kind exchange of real estate	$ 0	$ (38,822)