Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash Flows from Operating Activities:
Net income	$ 176,774	$ 340,646
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization (including amortization of deferred financing costs)	299,541	272,942
Real estate impairment losses	160,700	256
Net gain on disposition of wholly owned and partially owned assets	(160,225)	(1,860)
Straight-lining of rental income	(83,883)	(64,121)
Return of capital from real estate fund investments	71,888	83,443
Distributions of income from partially owned entities	46,500	37,821
Amortization of below-market leases, net	(29,811)	(26,132)
Other non-cash adjustments	23,049	26,569
Net realized and unrealized gains on real estate fund investments	(21,277)	(41,857)
Loss from partially owned entities	3,598	7,636
Net gains on sale of real estate and other	(2,210)	(32,243)
Reversal of allowance for deferred tax assets	0	(90,030)
Changes in operating assets and liabilities:
Real estate fund investments	0	(95,000)
Tenant and other receivables, net	2,358	(5,051)
Prepaid assets	(131,927)	(138,473)
Other assets	(29,303)	(46,858)
Accounts payable and accrued expenses	6,634	(26,440)
Other liabilities	(9,113)	(16,632)
Net cash provided by operating activities	323,293	184,616
Cash Flows from Investing Activities:
Development costs and construction in progress	(277,214)	(200,970)
Additions to real estate	(170,265)	(137,528)
Proceeds from sales of real estate and related investments	130,249	334,725
Investments in partially owned entities	(90,659)	(137,465)
Distributions of capital from partially owned entities	87,977	29,666
Acquisitions of real estate and other	(46,807)	(381,001)
Net deconsolidation of 7 West 34th Street	(42,000)	0
Investments in loans receivable and other	(11,700)	(23,919)
Restricted cash	(7,483)	25,118
Purchases of marketable securities	(4,379)	0
Proceeds from sales and repayments of mortgage and mezzanine loans receivable and other	22	16,772
Net cash used in investing activities	(432,259)	(474,602)
Cash Flows from Financing Activities:
Proceeds from borrowings	1,325,246	1,746,460
Repayments of borrowings	(1,032,115)	(1,607,574)
Dividends paid on common shares	(237,832)	(237,160)
Distributions to noncontrolling interests	(83,266)	(77,447)
Dividends paid on preferred shares	(40,727)	(39,849)
Debt issuance and other costs	(29,478)	(14,053)
Contributions from noncontrolling interests	11,874	51,725
Proceeds received from exercise of employee share options	3,810	13,683
Repurchase of shares related to stock compensation agreements and related tax withholdings and other	(186)	(2,939)
Cash included in the spin-off of Urban Edge Properties	0	(225,000)
Net cash used in financing activities	(82,674)	(392,154)
Net decrease in cash and cash equivalents	(191,640)	(682,140)
Cash and cash equivalents at beginning of period	1,835,707	1,198,477
Cash and cash equivalents at end of period	1,644,067	516,337
Supplemental Disclosure Of Cash Flow Information:
Cash payments for interest, excluding capitalized interest of $13,918 and $17,550	181,432	178,461
Cash payments for income taxes	5,003	6,584
Non-Cash Investing and Financing Activities:
Write-off of fully depreciated assets	(220,654)	(81,027)
Accrued capital expenditures included in accounts payable and accrued expenses	144,079	70,672
Change in unrealized net gain (loss) on securities available-for-sale	39,113	(46,332)
Adjustments to carry redeemable Class A units at redemption value	(20,369)	229,521
Decrease in assets and liabilities resulting from the deconsolidation of investments that were previously consolidated
Real estate, net	(122,047)	0
Mortgages payable, net	(290,418)	0
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
Acquisitions [Member]
Non-cash distribution of Urban Edge Properties:
Like-kind exchange of real estate	46,698	62,355
Dispositions [Member]
Non-cash distribution of Urban Edge Properties:
Like-kind exchange of real estate	$ (29,639)	$ (38,822)