Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities:
Net Income	$ 345,343	$ 350,715	$ 276,831
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	161,838	167,101	162,535
Amortization of debt deferred costs and intangibles, net	3,146	2,790	2,562
Impairment loss	10,120	15,257	98
Equity in earnings of real estate joint ventures and partnerships, net	(25,070)	(27,074)	(20,642)
Gain on sale and acquisition of real estate joint venture and partnership interests	0	0	(48,322)
Gain on sale of property	(207,865)	(218,611)	(100,714)
Distributions of income from real estate joint ventures and partnerships	19,605	1,321	1,149
Changes in accrued rent, accrued contract receivables and accounts receivable, net	(2,807)	(18,964)	(14,488)
Changes in unamortized lease costs and other assets, net	(8,632)	(13,299)	(16,900)
Changes in accounts payable, accrued expenses and other liabilities, net	(2,315)	4,970	8,963
Other, net	(7,403)	5,552	1,339
Net cash provided by operating activities	285,960	269,758	252,411
Cash Flows from Investing Activities:
Acquisition of real estate and land	(1,265)	(1,902)	(500,421)
Development and capital improvements	(155,528)	(133,336)	(101,179)
Proceeds from sale of property and real estate equity investments, net	607,486	433,661	234,952
Real estate joint ventures and partnerships - Investments	(38,096)	(37,173)	(52,834)
Real estate joint ventures and partnerships - Distributions of capital	6,936	28,791	51,714
Purchase of investments	0	(5,730)	(4,740)
Proceeds from investments	1,500	8,502	1,250
Other, net	11,921	6,179	5,086
Net cash provided by (used in) investing activities	432,954	298,992	(366,172)
Cash Flows from Financing Activities:
Proceeds from issuance of debt	638	0	249,999
Principal payments of debt	(257,028)	(28,723)	(144,788)
Changes in unsecured credit facilities	5,000	(245,000)	95,500
Repurchase of common shares of beneficial interest, net	(18,564)	0	0
Proceeds from issuance of common shares of beneficial interest, net	6,760	1,588	137,460
Common share dividends paid	(382,464)	(294,073)	(185,100)
Debt issuance and extinguishment costs paid	(1,271)	(488)	(5,396)
Distributions to noncontrolling interests	(19,155)	(19,342)	(9,563)
Contributions from noncontrolling interests	1,465	0	0
Other, net	508	(2,657)	(8,314)
Net cash (used in) provided by financing activities	(664,111)	(588,695)	129,798
Net increase (decrease) in cash, cash equivalents and restricted cash equivalents	54,803	(19,945)	16,037
Cash, cash equivalents and restricted cash equivalents at January 1	21,334	41,279	25,242
Cash, cash equivalents and restricted cash equivalents at December 31	76,137	21,334	41,279
Interest paid during the period (net of amount capitalized of $7,938, $4,868 and $2,656, respectively)	65,507	79,161	79,515
Income taxes paid during the period	$ 1,545	$ 1,009	$ 958