CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (Unaudited) - 3 months ended Mar. 31, 2017 - USD ($) $ in Thousands	Total	PREFERRED SHARES	COMMON SHARES, $0.01 PAR VALUE	PAID IN CAPITAL	RETAINED EARNINGS	ACCUMULATED OTHER COMPREHENSIVE (LOSS)	OPERATING PARTNERSHIP	PARTIALLY OWNED PROPERTIES
Balance, beginning of year at Dec. 31, 2016	$ 10,229,078	$ 37,280	$ 3,659	$ 8,758,422	$ 1,543,626	$ (113,909)
Balance, beginning of year at Dec. 31, 2016	231,906						$ 221,297	$ 10,609
COMMON SHARES, $0.01 PAR VALUE
Conversion of OP Units into Common Shares			10	14,233			(14,243)
Exercise of share options			1	3,141
Restricted shares			1	2,695
Share options				4,184
ESPP discount				307
PAID IN CAPITAL
Conversion of OP Units into Common Shares			10	14,233			(14,243)
Exercise of share options			1	3,141
Employee Share Purchase Plan (ESPP)				1,574
Share-based employee compensation expense
Offering costs				(21)
Supplemental Executive Retirement Plan (SERP)				132
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	(50,766)			50,766
Adjustment for Noncontrolling Interests ownership in Operating Partnership				11,564			(11,564)
RETAINED EARNINGS
Net income attributable to controlling interests	143,742				143,742
Common Share distributions					(184,941)
Preferred Share distributions					(773)
Accumulated other comprehensive income (loss) – derivative instruments:
Losses reclassified into earnings from other comprehensive income	(4,583)					4,583
OPERATING PARTNERSHIP
Conversion of OP Units into Common Shares			10	14,233			(14,243)
Equity compensation associated with Noncontrolling Interests							2,964
Net income	149,941
Distributions to Noncontrolling Interests							(6,696)	(5,134)
Change in carrying value of Redeemable Noncontrolling Interests – Operating Partnership	(31,593)						31,593
Adjustment for Noncontrolling Interests ownership in Operating Partnership				11,564			(11,564)
Net income attributable to Noncontrolling Interests	5,411						5,411	788
PARTIALLY OWNED PROPERTIES
Net income	149,941
Distributions to Noncontrolling Interests							(6,696)	(5,134)
Net income attributable to Noncontrolling Interests	5,411						5,411	788
Contributions – Noncontrolling Interests – Partially Owned Properties	125							125
Balance, end of period at Mar. 31, 2017	10,280,276	$ 37,280	$ 3,671	$ 8,846,997	$ 1,501,654	$ (109,326)
Balance, end of period at Mar. 31, 2017	$ 235,150						$ 228,762	$ 6,388