CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Series K Preferred Stock [Member]	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, 2012			$ 50,000	$ 3,251	$ 6,542,355	$ 887,355	$ (193,148)
Balance, beginning of year at Dec. 31, 2012								$ 159,606	$ 77,688
PREFERRED SHARES
Partial redemption of 8.29% Series K Cumulative Redeemable			0
Preferred Stock Preference Units Dividend Rate Percentage		8.29%
COMMON SHARES, $0.01 PAR VALUE
Conversion of OP Units into Common Shares				1	1,698			(1,699)
Issuance of Common Shares				345	1,929,523
Exercise of share options				5	17,247
Employee Share Purchase Plan (ESPP)				1	3,400
Restricted shares				2	13,262
PAID IN CAPITAL
Conversion of OP Units into Common Shares				1	1,698			(1,699)
Issuance of Common Shares				345	1,929,523
Exercise of share options				5	17,247
Employee Share Purchase Plan (ESPP)				1	3,400
Conversion of restricted shares to restricted units					0			0
Share-based employee compensation expense:
Restricted shares				2	13,262
Share options					10,514
ESPP discount					632
Common Shares repurchsed and retired					0
Offering costs					(1,047)
Supplemental Executive Retirement Plan (SERP)					(422)
Acquisition of Noncontrolling Interests – Partially Owned Properties					0				0
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	$ (79,667)				79,667
Adjustment for Noncontrolling Interests ownership in Operating Partnership					(35,329)			35,329
RETAINED EARNINGS
Net income attributable to controlling interests	1,830,613					1,830,613
Common Share distributions						(666,565)
Preferred Share distributions						(4,145)
Premium on redemption of Preferred Shares – cash charge						0
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the year	18,771						18,771
Losses reclassified into earnings from other comprehensive income	(20,141)						20,141
Accumulated other comprehensive income (loss) – other instruments:
Unrealized holding gains arising during the year	583						583
(Gains) realized during the year							(2,122)
Currency translation adjustments arising during the year	613						613
OPERATING PARTNERSHIP
Issuance of restricted units to Noncontrolling Interests								5
Conversion of OP Units into Common Shares				1	1,698			(1,699)
Conversion of restricted shares to restricted units					0			0
Equity compensation associated with Noncontrolling Interests								13,609
Net income (loss) attributable to Noncontrolling Interests	1,905,353							75,278	(538)
Distributions to Noncontrolling Interests								(26,277)	(6,490)
Change in carrying value of Redeemable Noncontrolling Interests – Operating Partnership	44,439							(44,439)
Adjustment for Noncontrolling Interests ownership in Operating Partnership					(35,329)			35,329
PARTIALLY OWNED PROPERTIES
Net income (loss) attributable to Noncontrolling Interests	1,905,353							75,278	(538)
Contributions – Noncontrolling Interests – Partially Owned Properties	27,660								27,660
Distributions to Noncontrolling Interests								(26,277)	(6,490)
Acquisition of Archstone									28,263
Acquisition of Noncontrolling Interests – Partially Owned Properties					0				0
Deconsolidation of previously consolidated Noncontrolling Interests									0
Other									0
Balance, end of year at Dec. 31, 2013			50,000	3,605	8,561,500	2,047,258	(155,162)
Balance, end of year at Dec. 31, 2013								211,412	126,583
PREFERRED SHARES
Partial redemption of 8.29% Series K Cumulative Redeemable			0
Preferred Stock Preference Units Dividend Rate Percentage		8.29%
COMMON SHARES, $0.01 PAR VALUE
Conversion of OP Units into Common Shares				1	2,364			(2,365)
Issuance of Common Shares				0	0
Exercise of share options				21	82,552
Employee Share Purchase Plan (ESPP)				0	3,392
Restricted shares				2	9,902
PAID IN CAPITAL
Conversion of OP Units into Common Shares				1	2,364			(2,365)
Issuance of Common Shares				0	0
Exercise of share options				21	82,552
Employee Share Purchase Plan (ESPP)				0	3,392
Conversion of restricted shares to restricted units					0			0
Share-based employee compensation expense:
Restricted shares				2	9,902
Share options					7,349
ESPP discount					859
Common Shares repurchsed and retired					(1,777)
Offering costs					(41)
Supplemental Executive Retirement Plan (SERP)					7,374
Acquisition of Noncontrolling Interests – Partially Owned Properties					(2,308)				(2,244)
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	139,818				(139,818)
Adjustment for Noncontrolling Interests ownership in Operating Partnership					4,992			(4,992)
RETAINED EARNINGS
Net income attributable to controlling interests	631,308					631,308
Common Share distributions						(723,782)
Preferred Share distributions						(4,145)
Premium on redemption of Preferred Shares – cash charge						0
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the year	(33,306)						(33,306)
Losses reclassified into earnings from other comprehensive income	(16,868)						16,868
Accumulated other comprehensive income (loss) – other instruments:
Unrealized holding gains arising during the year	0						0
(Gains) realized during the year							0
Currency translation adjustments arising during the year	(552)						(552)
OPERATING PARTNERSHIP
Issuance of restricted units to Noncontrolling Interests								3
Conversion of OP Units into Common Shares				1	2,364			(2,365)
Conversion of restricted shares to restricted units					0			0
Equity compensation associated with Noncontrolling Interests								11,969
Net income (loss) attributable to Noncontrolling Interests	658,683							24,831	2,544
Distributions to Noncontrolling Interests								(28,676)	(7,827)
Change in carrying value of Redeemable Noncontrolling Interests – Operating Partnership	(2,229)							2,229
Adjustment for Noncontrolling Interests ownership in Operating Partnership					4,992			(4,992)
PARTIALLY OWNED PROPERTIES
Net income (loss) attributable to Noncontrolling Interests	658,683							24,831	2,544
Contributions – Noncontrolling Interests – Partially Owned Properties	5,684								5,684
Distributions to Noncontrolling Interests								(28,676)	(7,827)
Acquisition of Archstone									0
Acquisition of Noncontrolling Interests – Partially Owned Properties					(2,308)				(2,244)
Deconsolidation of previously consolidated Noncontrolling Interests									0
Other									169
Balance, end of year at Dec. 31, 2014	10,368,456		50,000	3,629	8,536,340	1,950,639	(172,152)
Balance, end of year at Dec. 31, 2014	10,707,776							214,411	124,909
PREFERRED SHARES
Partial redemption of 8.29% Series K Cumulative Redeemable			(12,720)
Preferred Stock Preference Units Dividend Rate Percentage		8.29%
COMMON SHARES, $0.01 PAR VALUE
Conversion of OP Units into Common Shares				2	4,964			(4,966)
Issuance of Common Shares				0	0
Exercise of share options				14	59,494
Employee Share Purchase Plan (ESPP)				1	4,403
Restricted shares				2	15,064
PAID IN CAPITAL
Conversion of OP Units into Common Shares				2	4,964			(4,966)
Issuance of Common Shares				0	0
Exercise of share options				14	59,494
Employee Share Purchase Plan (ESPP)				1	4,403
Conversion of restricted shares to restricted units					(70)			70
Share-based employee compensation expense:
Restricted shares				2	15,064
Share options					3,756
ESPP discount					884
Common Shares repurchsed and retired					0
Offering costs					(79)
Supplemental Executive Retirement Plan (SERP)					1,380
Acquisition of Noncontrolling Interests – Partially Owned Properties					0				0
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	64,378				(64,378)
Adjustment for Noncontrolling Interests ownership in Operating Partnership					10,607			(10,607)
RETAINED EARNINGS
Net income attributable to controlling interests	870,120					870,120
Common Share distributions						(804,825)
Preferred Share distributions						(3,357)
Premium on redemption of Preferred Shares – cash charge						(3,486)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the year	2,219						2,219
Losses reclassified into earnings from other comprehensive income	(18,244)						18,244
Accumulated other comprehensive income (loss) – other instruments:
Unrealized holding gains arising during the year	0						0
(Gains) realized during the year							0
Currency translation adjustments arising during the year	(327)						(327)
OPERATING PARTNERSHIP
Issuance of restricted units to Noncontrolling Interests								3
Conversion of OP Units into Common Shares				2	4,964			(4,966)
Conversion of restricted shares to restricted units					(70)			70
Equity compensation associated with Noncontrolling Interests								21,503
Net income (loss) attributable to Noncontrolling Interests	908,018							34,241	3,657
Distributions to Noncontrolling Interests								(31,604)	(6,608)
Change in carrying value of Redeemable Noncontrolling Interests – Operating Partnership	1,672							(1,672)
Adjustment for Noncontrolling Interests ownership in Operating Partnership					10,607			(10,607)
PARTIALLY OWNED PROPERTIES
Net income (loss) attributable to Noncontrolling Interests	908,018							34,241	3,657
Contributions – Noncontrolling Interests – Partially Owned Properties	0								0
Distributions to Noncontrolling Interests								(31,604)	(6,608)
Acquisition of Archstone									0
Acquisition of Noncontrolling Interests – Partially Owned Properties					0				0
Deconsolidation of previously consolidated Noncontrolling Interests									(117,350)
Other									0
Balance, end of year at Dec. 31, 2015	10,470,368		$ 37,280	$ 3,648	$ 8,572,365	$ 2,009,091	$ (152,016)
Balance, end of year at Dec. 31, 2015	$ 10,696,355							$ 221,379	$ 4,608