CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $) In Thousands, unless otherwise specified	Total	PREFERRED SHARES	COMMON SHARES, $0.01 PAR VALUE	PAID IN CAPITAL	RETAINED EARNINGS	ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME	OPERATING PARTNERSHIP	Partially Owned Properties [Member]
Beginning Balance, Noncontrolling Interest at Dec. 31, 2012	$ 237,294						$ 159,606	$ 77,688
Beginning Balance, Parent at Dec. 31, 2012	7,289,813	50,000	3,251	6,542,355	887,355	(193,148)
Common Share Issuance:
Conversion of OP Units held by Noncontrolling Interests into OP Units held by General Partner				684			(684)
Issuance of Common Shares			345	1,929,523
Exercise of share options			3	7,171
Employee Share Purchase Plan (ESPP)				1,763
Share-based employee compensation expense:
Restricted shares			2	3,050
Share options				3,367
ESPP discount				311
Offering costs				(406)
Supplemental Executive Retirement Plan (SERP)				(2,219)
Change in market value	(50,109)			50,109
Adjustment for Noncontrolling Interests ownership in Operating Partnership				(42,863)			42,863
Net income attributable to controlling interests	1,017,686				1,017,686
Common Share distributions					(144,015)
Preferred Share distributions					(1,036)
Accumulated other comprehensive (loss) income - derivative instruments:
Unrealized holding (losses) arising during the period	2,814					2,814
Losses reclassified into earnings from other comprehensive income	8,272					8,272
Accumulated other comprehensive income (loss) - other instruments:
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	427					427
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(873)					(873)
Issuance of LTIP Units to Noncontrolling Interests							3
Equity Compensation associated with Noncontrolling Interests							4,304
Net Income (Loss) Attributable to Noncontrolling Interest							43,323	25
Contributions by Noncontrolling Interests								3,299
Archstone Acquisition Noncontrolling Interests Partially Owned Properties								28,263
Distributions to Noncontrolling Interests							(5,691)	(3,345)
Change in carrying value	38,494						(38,494)
Ending Balance, Noncontrolling Interest at Mar. 31, 2013	311,160						205,230	105,930
Ending Balance, Parent at Mar. 31, 2013	$ 10,123,928	$ 50,000	$ 3,601	$ 8,492,845	$ 1,759,990	$ (182,508)