CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (Unaudited) - 9 months ended Sep. 30, 2018 - USD ($) $ in Thousands	Total	PREFERRED SHARES	COMMON SHARES, $0.01 PAR VALUE	PAID IN CAPITAL	RETAINED EARNINGS	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	OPERATING PARTNERSHIP	PARTIALLY OWNED PROPERTIES
Balance, beginning of year at Dec. 31, 2017	$ 10,242,464	$ 37,280	$ 3,680	$ 8,886,586	$ 1,403,530	$ (88,612)
Balance, beginning of year at Dec. 31, 2017	231,399						$ 226,691	$ 4,708
COMMON SHARES, $0.01 PAR VALUE
Conversion of OP Units into Common Shares				356			(356)
Exercise of share options			2	5,998
Employee Share Purchase Plan (ESPP)			1	3,073
Share-based employee compensation expense:
Restricted shares			1	6,803
Share options				9,206
ESPP discount				604
Offering costs				(27)
Supplemental Executive Retirement Plan (SERP)				(533)
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	14,361			(14,361)
Adjustment for Noncontrolling Interests ownership in Operating Partnership				2,619			(2,619)
PAID IN CAPITAL
Conversion of OP Units into Common Shares				356			(356)
Exercise of share options			2	5,998
Employee Share Purchase Plan (ESPP)			1	3,073
RETAINED EARNINGS
Net income attributable to controlling interests	540,348				540,348
Common Share distributions					(596,735)
Preferred Share distributions					(2,318)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period	24,021					24,021
Losses reclassified into earnings from other comprehensive income	(13,902)					13,902
NONCONTROLLING INTERESTS
Issuance of restricted units to Noncontrolling Interests							1
Conversion of OP Units into Common Shares				356			(356)
Equity compensation associated with Noncontrolling Interests							11,074
Net income	562,804
Distributions to Noncontrolling Interests							(21,560)	(8,930)
Change in carrying value of Redeemable Noncontrolling Interests - Operating Partnership	(77)						77
Adjustment for Noncontrolling Interests ownership in Operating Partnership				2,619			(2,619)
Net income attributable to Noncontrolling Interests	20,517						20,517	1,939
PARTIALLY OWNED PROPERTIES
Net income	562,804
Distributions to Noncontrolling Interests							(21,560)	(8,930)
Net income attributable to Noncontrolling Interests	20,517						20,517	1,939
Contributions by Noncontrolling Interests								125
Balance, end of period at Sep. 30, 2018	10,235,424	$ 37,280	$ 3,684	$ 8,900,324	$ 1,344,825	$ (50,689)
Balance, end of period at Sep. 30, 2018	$ 231,667						$ 233,825	$ (2,158)