Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash Flows from Operating Activities:
Net income	$ 340,646	$ 263,843
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization (including amortization of deferred financing costs)	272,942	288,187
Reversal of allowance for deferred tax assets	(90,030)	0
Return of capital from real estate fund investments	83,443	140,920
Straight-lining of rental income	(64,121)	(33,413)
Net realized and unrealized gains on real estate fund investments	(41,857)	(111,227)
Distributions of income from partially owned entities	37,821	25,784
Net gains on sale of real estate and other	(32,243)	0
Amortization of below-market leases, net	(26,132)	(22,624)
Other non-cash adjustments	26,569	20,546
Loss from partially owned entities	7,636	51,763
Net gain on disposition of wholly owned and partially owned assets	(1,860)	(10,540)
Impairment losses	256	20,842
Defeasance cost in connection with the refinancing of mortgage notes payable	0	5,589
Changes in operating assets and liabilities:
Real estate fund investments	(95,000)	(2,666)
Tenant and other receivables, net	(5,051)	(2,355)
Prepaid assets	(138,473)	(138,884)
Other assets	(46,858)	(43,842)
Accounts payable and accrued expenses	(26,440)	2,157
Other liabilities	(16,632)	(6,437)
Net cash provided by operating activities	184,616	447,643
Cash Flows from Investing Activities:
Acquisitions of real estate and other	(381,001)	(8,963)
Proceeds from sales of real estate and related investments	334,725	125,037
Development costs and construction in progress	(200,970)	(214,615)
Additions to real estate	(137,528)	(105,116)
Investments in partially owned entities	(137,465)	(62,894)
Distributions of capital from partially owned entities	29,666	1,791
Restricted cash	25,118	102,087
Investments in loans receivable	(23,919)	0
Proceeds from repayments of mortgage and mezzanine loans receivable and other	16,772	96,159
Net cash used in investing activities	(474,602)	(66,514)
Cash Flows from Financing Activities:
Proceeds from borrowings	1,746,460	1,398,285
Repayments of borrowings	(1,607,574)	(313,444)
Dividends paid on common shares	(237,160)	(273,694)
Cash included in the spin-off of Urban Edge Properties	(225,000)	0
Distributions to noncontrolling interests	(77,447)	(149,944)
Contributions from noncontrolling interests	51,725	5,297
Dividends paid on preferred shares	(39,849)	(40,737)
Debt issuance costs	(14,053)	(29,560)
Proceeds received from exercise of employee share options	13,683	10,125
Repurchase of shares related to stock compensation agreements and/or related tax withholdings	(2,939)	(637)
Purchase of marketable securities in connection with the defeasance of mortgage notes payable	0	(198,884)
Net Cash (used in) provided by financing activities	(392,154)	406,807
Net (decrease) increase in cash and cash equivalents	(682,140)	787,936
Cash and cash equivalents at beginning of period	1,198,477	583,290
Cash and cash equivalents at end of period	516,337	1,371,226
Supplemental Disclosure Of Cash Flow Information:
Cash payments for interest, excluding capitalized interest of $17,550 and $30,182	178,461	214,239
Cash payments for income taxes	6,584	6,726
Non-cash distribution of Urban Edge Properties:
Assets	1,722,263	0
Liabilities	(1,482,660)	0
Equity	(239,603)	0
Adjustments to carry redeemable Class A units at redemption value	229,521	(227,338)
Transfer of interest in real estate to Pennsylvania Real Estate Investment Trust	(145,313)	0
Write-off of fully depreciated assets	(81,027)	(85,037)
Accrued capital expenditures included in accounts payable and accrued expenses	70,672	111,742
Financing assumed in acquisitions	62,000	0
Marketable securities transferred in connection with the defeasance of mortgage notes payable	0	198,884
Defeasance of mortgage notes payable	0	(193,406)
Elimination of a mortgage and mezzanine loan asset and liability	0	59,375
Transfer of interest in real estate fund investments to an unconsolidated joint venture	0	(58,564)
Transfer of noncontrolling interest in real estate fund investments	0	(33,028)
Acquisitions [Member]
Non-cash distribution of Urban Edge Properties:
Like-kind exchange of real estate	62,355	0
Dispositions [Member]
Non-cash distribution of Urban Edge Properties:
Like-kind exchange of real estate	$ (38,822)	$ 0