CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (Unaudited) - 6 months ended Jun. 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				331			(331)
Exercise of share options			1	2,616
Employee Share Purchase Plan (ESPP)			1	2,180
Share-based employee compensation expense:
Restricted shares			1	5,162
Share options				8,536
ESPP discount				400
Offering costs				(27)
Supplemental Executive Retirement Plan (SERP)				(538)
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	172			(172)
Adjustment for Noncontrolling Interests ownership in Operating Partnership				110			(110)
PAID IN CAPITAL
Conversion of OP Units into Common Shares				331			(331)
Exercise of share options			1	2,616
Employee Share Purchase Plan (ESPP)			1	2,180
RETAINED EARNINGS
Net income attributable to controlling interests	325,411				325,411
Common Share distributions					(397,796)
Preferred Share distributions					(1,545)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period	11,995					11,995
Losses reclassified into earnings from other comprehensive income	(9,307)					9,307
NONCONTROLLING INTERESTS
Issuance of restricted units to Noncontrolling Interests							1
Conversion of OP Units into Common Shares				331			(331)
Equity compensation associated with Noncontrolling Interests							8,116
Net income	338,958
Distributions to Noncontrolling Interests							(14,374)	(7,668)
Change in carrying value of Redeemable Noncontrolling Interests - Operating Partnership	(644)						644
Adjustment for Noncontrolling Interests ownership in Operating Partnership				110			(110)
Net income attributable to Noncontrolling Interests	12,358						12,358	1,189
PARTIALLY OWNED PROPERTIES
Net income	338,958
Distributions to Noncontrolling Interests							(14,374)	(7,668)
Net income attributable to Noncontrolling Interests	12,358						12,358	1,189
Contributions by Noncontrolling Interests								125
Balance, end of period at Jun. 30, 2018	10,208,437	$ 37,280	$ 3,683	$ 8,905,184	$ 1,329,600	$ (67,310)
Balance, end of period at Jun. 30, 2018	$ 231,349						$ 232,995	$ (1,646)