Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Cash Flows from Operating Activities:
Net Income	$ 276,831		$ 181,222		$ 307,579
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	162,535		145,940		150,616
Amortization of debt deferred costs and intangibles, net	2,562		2,650		3,641
Impairment loss	98		153		1,024
Equity in earnings of real estate joint ventures and partnerships, net	(20,642)		(19,300)		(22,317)
Gain on sale and acquisition of real estate joint venture and partnership interests	(48,322)		(879)		(1,718)
Gain on sale of property	(100,714)		(59,621)		(190,872)
Distributions of income from real estate joint ventures and partnerships	1,149		1,216		4,058
Changes in accrued rent and accounts receivable, net	(13,989)		(8,116)		(3,494)
Changes in unamortized lease costs and other assets, net	(16,900)		(14,617)		(16,299)
Changes in accounts payable, accrued expenses and other liabilities, net	3,010		4,184		2,890
Other, net	1,339		11,584		5,661
Net cash provided by operating activities	246,957		244,416		240,769
Cash Flows from Investing Activities:
Acquisition of real estate and land	(500,591)		(221,779)		(43,587)
Development and capital improvements	(101,179)		(83,702)		(100,926)
Proceeds from sale of property and real estate equity investments	234,858		101,866		351,224
Change in restricted deposits and mortgage escrows	(20,049)		76,574		(75,299)
Notes receivable from real estate joint ventures and partnerships and other receivables - Collections	0		0		10,336
Real estate joint ventures and partnerships - Investments	(52,834)		(30,053)		(5,223)
Real estate joint ventures and partnerships - Distributions of capital	51,714		35,341		31,260
Purchase of investments	(4,740)		0		(3,000)
Proceeds from investments	1,250		1,250		51,788
Other, net	2,952		(473)		1,504
Net cash (used in) provided by investing activities	(388,619)		(120,976)		218,077
Cash Flows from Financing Activities:
Proceeds from issuance of debt	249,999		448,083		4,500
Principal payments of debt	(144,788)		(240,505)		(508,997)
Changes in unsecured credit facilities	95,500		(39,500)		189,000
Proceeds from issuance of common shares of beneficial interest, net	137,460		42,572		7,987
Redemption of preferred shares of beneficial interest	0		(150,000)		0
Common and preferred dividends paid	(185,100)		(174,628)		(199,343)
Debt issuance and extinguishment costs paid	(5,396)		(9,878)		(463)
Distributions to noncontrolling interests	(9,563)		(5,478)		(21,055)
Contributions from noncontrolling interests	0		1,318		980
Other, net	(2,361)		3,555		158
Net cash provided by (used in) financing activities	135,751		(124,461)		(527,233)
Net decrease in cash and cash equivalents	(5,911)		(1,021)		(68,387)
Cash and cash equivalents at January 1	22,168	[1]	23,189		91,576
Cash and cash equivalents at September 30	16,257	[1]	22,168	[1]	23,189
Interest paid during the period (net of amount capitalized of $2,656, $3,252 and $3,302, respectively)	79,515		79,580		91,277
Income taxes paid during the period	$ 958		$ 1,474		$ 1,705

[1] Consolidated variable interest entities' assets held as collateral and debt included in the above balances at December 31, 2016 and December 31, 2015 are Property, net of $476,117 and $240,689; Investment in Real Estate Joint Ventures and Partnerships, net of $0, and $18,278; Accrued Rent and Accounts Receivable, net of $11,066 and $9,245; Cash and Cash Equivalents of $9,560 and $13,250; Debt, net of $47,112 and $47,919.