Erp Operating LTD Partnership 10-Q 7 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 31, 2013
Entity Registrant Name	'EQUITY RESIDENTIAL	'
Entity Central Index Key	'0000906107	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Amendment Flag	'false	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Current Fiscal Year End Date	'--12-31	'
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	360,410,752
OPERATING PARTNERSHIP	'	'
Entity Registrant Name	'ERP OPERATING LIMITED PARTNERSHIP	'
Entity Central Index Key	'0000931182	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Amendment Flag	'false	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Current Fiscal Year End Date	'--12-31	'
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Non-accelerated Filer	'

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Investment in real estate	'	'
Land	$6,201,333	$4,554,912
Depreciable property	19,254,957	15,711,944
Projects under development	779,053	387,750
Land held for development	505,494	353,823
Real Estate Investment Property, at Cost	26,740,837	21,008,429
Real Estate Investment Property, Accumulated Depreciation	-4,654,594	-4,912,221
Investment in real estate, net	22,086,243	16,096,208
Cash and cash equivalents	972,761	612,590
Investments in unconsolidated entities	165,898	17,877
Deposits - restricted	98,874	250,442
Escrow deposits - mortgage	40,901	9,129
Deferred financing costs, net	66,775	44,382
Other assets	379,979	170,372
Total assets	23,811,431	17,201,000
Liabilities:	'	'
Mortgage notes payable	6,230,675	3,898,369
Notes, net	5,476,522	4,630,875
Lines of credit	0	0
Accounts payable and accrued expenses	166,939	38,372
Accrued interest payable	85,353	76,223
Other liabilities	331,797	304,518
Security deposits	71,462	66,988
Distributions payable	149,836	260,176
Total liabilities	12,512,584	9,275,521
Commitments and contingencies	'	'
Redeemable Noncontrolling Interests - Operating Partnership	376,057	398,372
Shareholders' equity:	'	'
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 1,000,000 shares issued and outstanding as of September 30, 2013 and December 31, 2012	50,000	50,000
Common Shares of beneficial interest, $0.01 par value; 1,000,000,000 shares authorized; 360,395,959 shares issued and outstanding as of September 30, 2013 and 325,054,654 shares issued and outstanding as of December 31, 2012	3,604	3,251
Paid in capital	8,542,822	6,542,355
Retained earnings	2,171,603	887,355
Accumulated other comprehensive (loss)	-169,392	-193,148
Total shareholders' equity	10,598,637	7,289,813
Noncontrolling Interests:	'	'
Operating Partnership	213,518	159,606
Noncontrolling Interests - Partially Owned Properties	110,635	77,688
Total Noncontrolling Interests	324,153	237,294
Total equity	10,922,790	7,527,107
Total liabilities and equity	$23,811,431	$17,201,000

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Shareholders' equity:	'	'
Preferred Shares of beneficial interest, par value	$0.01	$0.01
Preferred Shares of beneficial interest, shares authorized	100,000,000	100,000,000
Preferred Shares of beneficial interest, shares issued	1,000,000	1,000,000
Preferred Shares of beneficial interest, shares outstanding	1,000,000	1,000,000
Common Shares of beneficial interest, par value	$0.01	$0.01
Common Shares of beneficial interest, shares authorized	1,000,000,000	1,000,000,000
Common Shares of beneficial interest, shares issued	360,395,959	325,054,654
Common Shares of beneficial interest, shares outstanding	360,395,959	325,054,654

CONSOLIDATED_BALANCE_SHEETS_OF

CONSOLIDATED BALANCE SHEETS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Investment in real estate	'	'
Land	$6,201,333,000	$4,554,912,000
Depreciable property	19,254,957,000	15,711,944,000
Projects under development	779,053,000	387,750,000
Land held for development	505,494,000	353,823,000
Real Estate Investment Property, at Cost	26,740,837,000	21,008,429,000
Real Estate Investment Property, Accumulated Depreciation	-4,654,594,000	-4,912,221,000
Investment in real estate, net	22,086,243,000	16,096,208,000
Cash and cash equivalents	972,761,000	612,590,000
Investments in unconsolidated entities	165,898,000	17,877,000
Deposits - restricted	98,874,000	250,442,000
Escrow deposits - mortgage	40,901,000	9,129,000
Deferred financing costs, net	66,775,000	44,382,000
Other assets	379,979,000	170,372,000
Total assets	23,811,431,000	17,201,000,000
Liabilities:	'	'
Mortgage notes payable	6,230,675,000	3,898,369,000
Notes, net	5,476,522,000	4,630,875,000
Lines of credit	0	0
Accounts payable and accrued expenses	166,939,000	38,372,000
Accrued interest payable	85,353,000	76,223,000
Other liabilities	331,797,000	304,518,000
Security deposits	71,462,000	66,988,000
Distributions payable	149,836,000	260,176,000
Total liabilities	12,512,584,000	9,275,521,000
Commitments and contingencies	'	'
Partnersb Capital:	'	'
Accumulated other comprehensive (loss)	-169,392,000	-193,148,000
Noncontrolling Interests - Partially Owned Properties	110,635,000	77,688,000
Total liabilities and equity	23,811,431,000	17,201,000,000
OPERATING PARTNERSHIP	'	'
Investment in real estate	'	'
Land	6,201,333,000	4,554,912,000
Depreciable property	19,254,957,000	15,711,944,000
Projects under development	779,053,000	387,750,000
Land held for development	505,494,000	353,823,000
Real Estate Investment Property, at Cost	26,740,837,000	21,008,429,000
Real Estate Investment Property, Accumulated Depreciation	-4,654,594,000	-4,912,221,000
Investment in real estate, net	22,086,243,000	16,096,208,000
Cash and cash equivalents	972,761,000	612,590,000
Investments in unconsolidated entities	165,898,000	17,877,000
Deposits - restricted	98,874,000	250,442,000
Escrow deposits - mortgage	40,901,000	9,129,000
Deferred financing costs, net	66,775,000	44,382,000
Other assets	379,979,000	170,372,000
Total assets	23,811,431,000	17,201,000,000
Liabilities:	'	'
Mortgage notes payable	6,230,675,000	3,898,369,000
Notes, net	5,476,522,000	4,630,875,000
Lines of credit	0	0
Accounts payable and accrued expenses	166,939,000	38,372,000
Accrued interest payable	85,353,000	76,223,000
Other liabilities	331,797,000	304,518,000
Security deposits	71,462,000	66,988,000
Distributions payable	149,836,000	260,176,000
Total liabilities	12,512,584,000	9,275,521,000
Commitments and contingencies	'	'
Redeemable Limited Partners	376,057,000	398,372,000
Partnersb Capital:	'	'
Preference Units	50,000,000	50,000,000
General Partner	10,718,029,000	7,432,961,000
Limited Partners	213,518,000	159,606,000
Accumulated other comprehensive (loss)	-169,392,000	-193,148,000
Total partnersb capital	10,812,155,000	7,449,419,000
Noncontrolling Interests - Partially Owned Properties	110,635,000	77,688,000
Total capital	10,922,790,000	7,527,107,000
Total liabilities and equity	$23,811,431,000	$17,201,000,000

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
REVENUES	'	'	'	'
Rental income	$626,880	$448,647	$1,749,374	$1,295,431
Fee and asset management	2,566	3,052	7,399	7,328
Total revenues	629,446	451,699	1,756,773	1,302,759
EXPENSES	'	'	'	'
Property and maintenance	119,632	86,682	333,202	254,009
Real estate taxes and insurance	76,255	53,064	218,777	154,633
Property management	18,875	18,493	63,395	62,769
Fee and asset management	1,516	1,108	4,739	3,595
Depreciation	277,336	139,337	798,121	422,148
General and administrative	14,438	10,083	47,018	37,162
Total expenses	508,052	308,767	1,465,252	934,316
Operating Income	121,394	142,932	291,521	368,443
Interest and other income	816	70,087	1,320	70,514
Other expenses	-3,986	-3,984	-7,530	-18,587
Merger Expenses	-182	-87	-19,741	-1,921
Interest:	'	'	'	'
Expense incurred, net	-120,035	-113,222	-437,452	-345,476
Amortization of deferred financing costs	-4,335	-3,320	-15,636	-10,265
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	-6,328	92,406	-187,518	62,708
Income and other tax (expense) benefit	-493	-222	-1,326	-602
(Loss) from investments in unconsolidated entities due to operations	-1,454	-3	-2,984	-3
(Loss) from investments in unconsolidated entities due to merger expenses	-1,771	0	-54,781	0
Net Gain on Sales of Unconsolidated Entities	16	0	16	0
Net gain (loss) on sales of land parcels	-2,437	0	12,179	0
(Loss) income from continuing operations	-12,467	92,181	-234,414	62,103
Discontinued operations, net	404,184	144,142	2,023,897	434,702
Net income	391,717	236,323	1,789,483	496,805
Net (income) loss attributable to Noncontrolling Interests:	'	'	'	'
Net (Income) Attributable to Noncontrolling Interest	-14,836	-10,496	-70,947	-21,646
Net (income) loss attributable to Noncontrolling Interests - Partially Owned Properties	311	312	1,101	-457
Net income attributable to controlling interests	377,192	226,139	1,719,637	474,702
Preferred distributions	-1,037	-2,386	-3,109	-9,319
Redemption Premium	0	-5,150	0	-5,150
Net income available to Common Shares	$376,155	$218,603	$1,716,528	$460,233
Earnings per share - basic:	'	'	'	'
(Loss) income from continuing operations available to Common Shares	($0.04)	$0.27	($0.64)	$0.15
Net income available to Common Shares	$1.04	$0.73	$4.87	$1.53
Weighted average Common Shares outstanding	359,811	301,336	352,414	300,116
Earnings per share - diluted:	'	'	'	'
(Loss) income from continuing operations available to Common Shares	($0.04)	$0.27	($0.64)	$0.15
Net income available to Common Shares	$1.04	$0.72	$4.87	$1.52
Weighted average Common Shares outstanding	359,811	318,773	352,414	317,265
Distributions declared per Common Share outstanding	$0.40	$0.34	$1.20	$1.01

CONSOLIDATED_STATEMENTS_OF_OPE1

CONSOLIDATED STATEMENTS OF OPERATIONS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) (USD $)	3 Months Ended		9 Months Ended
Share data in Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
REVENUES	'	'	'	'
Rental income	$626,880,000	$448,647,000	$1,749,374,000	$1,295,431,000
Fee and asset management	2,566,000	3,052,000	7,399,000	7,328,000
Total revenues	629,446,000	451,699,000	1,756,773,000	1,302,759,000
EXPENSES	'	'	'	'
Property and maintenance	119,632,000	86,682,000	333,202,000	254,009,000
Real estate taxes and insurance	76,255,000	53,064,000	218,777,000	154,633,000
Property management	18,875,000	18,493,000	63,395,000	62,769,000
Fee and asset management	1,516,000	1,108,000	4,739,000	3,595,000
Depreciation	277,336,000	139,337,000	798,121,000	422,148,000
General and administrative	14,438,000	10,083,000	47,018,000	37,162,000
Total expenses	508,052,000	308,767,000	1,465,252,000	934,316,000
Operating Income	121,394,000	142,932,000	291,521,000	368,443,000
Interest and other income	816,000	70,087,000	1,320,000	70,514,000
Other expenses	-3,986,000	-3,984,000	-7,530,000	-18,587,000
Merger Expenses	-182,000	-87,000	-19,741,000	-1,921,000
Interest:	'	'	'	'
Expense incurred, net	-120,035,000	-113,222,000	-437,452,000	-345,476,000
Amortization of deferred financing costs	-4,335,000	-3,320,000	-15,636,000	-10,265,000
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	-6,328,000	92,406,000	-187,518,000	62,708,000
Income and other tax (expense) benefit	-493,000	-222,000	-1,326,000	-602,000
(Loss) from investments in unconsolidated entities due to operations	-1,454,000	-3,000	-2,984,000	-3,000
(Loss) from investments in unconsolidated entities due to merger expenses	-1,771,000	0	-54,781,000	0
Net Gain on Sales of Unconsolidated Entities	16,000	0	16,000	0
Net gain (loss) on sales of land parcels	-2,437,000	0	12,179,000	0
(Loss) income from continuing operations	-12,467,000	92,181,000	-234,414,000	62,103,000
Discontinued operations, net	404,184,000	144,142,000	2,023,897,000	434,702,000
Net income	391,717,000	236,323,000	1,789,483,000	496,805,000
Net (income) loss attributable to Noncontrolling Interests - Partially Owned Properties	311,000	312,000	1,101,000	-457,000
Net income attributable to controlling interests	377,192,000	226,139,000	1,719,637,000	474,702,000
ALLOCATION OF NET INCOME:	'	'	'	'
Redemption Premium	0	-5,150,000	0	-5,150,000
Earnings per Unit - basic:	'	'	'	'
(Loss) income from continuing operations available to Common Shares	($0.04)	$0.27	($0.64)	$0.15
Net income available to Units	$1.04	$0.73	$4.87	$1.53
Earnings per Unit - diluted:	'	'	'	'
Income (Loss) from Continuing Operations, Per Diluted Share	($0.04)	$0.27	($0.64)	$0.15
Net income available to Units	$1.04	$0.72	$4.87	$1.52
Weighted average Units outstanding	359,811	'	352,414	'
OPERATING PARTNERSHIP	'	'	'	'
REVENUES	'	'	'	'
Rental income	626,880,000	448,647,000	1,749,374,000	1,295,431,000
Fee and asset management	2,566,000	3,052,000	7,399,000	7,328,000
Total revenues	629,446,000	451,699,000	1,756,773,000	1,302,759,000
EXPENSES	'	'	'	'
Property and maintenance	119,632,000	86,682,000	333,202,000	254,009,000
Real estate taxes and insurance	76,255,000	53,064,000	218,777,000	154,633,000
Property management	18,875,000	18,493,000	63,395,000	62,769,000
Fee and asset management	1,516,000	1,108,000	4,739,000	3,595,000
Depreciation	277,336,000	139,337,000	798,121,000	422,148,000
General and administrative	14,438,000	10,083,000	47,018,000	37,162,000
Total expenses	508,052,000	308,767,000	1,465,252,000	934,316,000
Operating Income	121,394,000	142,932,000	291,521,000	368,443,000
Interest and other income	816,000	70,087,000	1,320,000	70,514,000
Other expenses	-3,986,000	-3,984,000	-7,530,000	-18,587,000
Merger Expenses	-182,000	-87,000	-19,741,000	-1,921,000
Interest:	'	'	'	'
Expense incurred, net	-120,035,000	-113,222,000	-437,452,000	-345,476,000
Amortization of deferred financing costs	-4,335,000	-3,320,000	-15,636,000	-10,265,000
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	-6,328,000	92,406,000	-187,518,000	62,708,000
Income and other tax (expense) benefit	-493,000	-222,000	-1,326,000	-602,000
(Loss) from investments in unconsolidated entities due to operations	-1,454,000	-3,000	-2,984,000	-3,000
(Loss) from investments in unconsolidated entities due to merger expenses	-1,771,000	0	-54,781,000	0
Net Gain on Sales of Unconsolidated Entities	16,000	0	16,000	0
Net gain (loss) on sales of land parcels	-2,437,000	0	12,179,000	0
(Loss) income from continuing operations	-12,467,000	92,181,000	-234,414,000	62,103,000
Discontinued operations, net	404,184,000	144,142,000	2,023,897,000	434,702,000
Net income	391,717,000	236,323,000	1,789,483,000	496,805,000
Net (income) loss attributable to Noncontrolling Interests - Partially Owned Properties	311,000	312,000	1,101,000	-457,000
Net income attributable to controlling interests	392,028,000	236,635,000	1,790,584,000	496,348,000
ALLOCATION OF NET INCOME:	'	'	'	'
Preference Units	1,037,000	2,386,000	3,109,000	9,319,000
Redemption Premium	0	-5,150,000	0	-5,150,000
General Partner	376,155,000	218,603,000	1,716,528,000	460,233,000
Limited Partners	14,836,000	10,496,000	70,947,000	21,646,000
Net income available to Units	$390,991,000	$229,099,000	$1,787,475,000	$481,879,000
Earnings per Unit - basic:	'	'	'	'
(Loss) income from continuing operations available to Common Shares	($0.04)	$0.27	($0.64)	$0.15
Net income available to Units	$1.04	$0.73	$4.87	$1.53
Weighted average Units outstanding	373,547	315,513	366,150	313,932
Earnings per Unit - diluted:	'	'	'	'
Income (Loss) from Continuing Operations, Per Diluted Share	($0.04)	$0.27	($0.64)	$0.15
Net income available to Units	$1.04	$0.72	$4.87	$1.52
Weighted average Units outstanding	373,547	318,773	366,150	317,265
Distributions declared per Unit outstanding	$0.40	$0.34	$1.20	$1.01

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Nov. 08, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income	'	$391,717	$236,323	$1,789,483	$496,805
Other comprehensive income (loss) - derivative instruments:	'	'	'	'	'
Unrealized holding gains (losses) arising during the period	'	-3,600	-3,695	8,737	-12,337
Losses reclassified into earnings from other comprehensive income	'	3,986	3,704	16,084	10,907
Other comprehensive income (loss) - other instruments:	'	'	'	'	'
Unrealized holding gains (losses) arising during the period	'	-374	312	554	394
(Gain) Loss on Sale of Securities, Net	-1,300	-830	0	-830	0
Other comprehensive (loss) b foreign currency:	'	'	'	'	'
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	'	-1,730	0	-789	0
Other comprehensive income (loss)	'	-2,548	321	23,756	-1,036
Comprehensive income	'	389,169	236,644	1,813,239	495,769
Comprehensive loss (income) attributable to Noncontrolling Interests	'	-14,525	-10,184	-69,846	-22,103
Comprehensive income attributable to controlling interests	'	$374,644	$226,460	$1,743,393	$473,666

CONSOLIDATED_STATEMENTS_OF_COM1

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Comprehensive income:	'	'	'	'
Net income	$391,717	$236,323	$1,789,483	$496,805
Other comprehensive income (loss) - derivative instruments:	'	'	'	'
Unrealized holding gains (losses) arising during the period	-3,600	-3,695	8,737	-12,337
Losses reclassified into earnings from other comprehensive income	3,986	3,704	16,084	10,907
Other comprehensive income (loss) - other instruments:	'	'	'	'
Unrealized holding gains (losses) arising during the period	-374	312	554	394
(Gain) Loss on Sale of Securities, Net	-830	0	-830	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	-1,730	0	-789	0
Other comprehensive income (loss)	-2,548	321	23,756	-1,036
Comprehensive income	389,169	236,644	1,813,239	495,769
Comprehensive loss (income) attributable to Noncontrolling Interests	-14,525	-10,184	-69,846	-22,103
Comprehensive income attributable to controlling interests	374,644	226,460	1,743,393	473,666
OPERATING PARTNERSHIP	'	'	'	'
Comprehensive income:	'	'	'	'
Net income	391,717	236,323	1,789,483	496,805
Other comprehensive income (loss) - derivative instruments:	'	'	'	'
Unrealized holding gains (losses) arising during the period	-3,600	-3,695	8,737	-12,337
Losses reclassified into earnings from other comprehensive income	3,986	3,704	16,084	10,907
Other comprehensive income (loss) - other instruments:	'	'	'	'
Unrealized holding gains (losses) arising during the period	-374	312	554	394
(Gain) Loss on Sale of Securities, Net	-830	0	-830	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	-1,730	0	-789	0
Other comprehensive income (loss)	-2,548	321	23,756	-1,036
Comprehensive income	389,169	236,644	1,813,239	495,769
Comprehensive loss (income) attributable to Noncontrolling Interests	311	312	1,101	-457
Comprehensive income attributable to controlling interests	$389,480	$236,956	$1,814,340	$495,312

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'
Net income	$1,789,483	$496,805
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation	830,097	516,940
Amortization of deferred financing costs	15,864	10,384
Amortization of Intangible Assets	2,214	0
Amortization of discounts and premiums on debt	-37,612	-5,795
Amortization of deferred settlements on derivative instruments	15,683	10,506
Write-off of pursuit costs	3,969	6,141
Income Loss from Investments in Unconsolidated Entities Adjustment	57,765	3
Distributions from unconsolidated entities - return on capital	1,519	454
(Gain) Loss on Sale of Securities, Net	-830	0
Net Gain on Sales of Unconsolidated Entities	-16	0
Net (gain) on sales of land parcels	-12,179	0
Net (gain) on sales of discontinued operations	-1,990,577	-307,447
Unrealized (gain) loss on derivative instruments	32	-1
Compensation paid with Company Common Shares	29,019	20,836
Changes in assets and liabilities:	'	'
(Increase) decrease in deposits - restricted	4,152	-2,250
(Increase) decrease in mortgage deposits	271	-862
(Increase) decrease in other assets	7,315	-14,039
Increase in accounts payable and accrued expenses	65,001	67,479
(Decrease) in accrued interest payable	-2,175	-9,252
Increase (decrease) in other liabilities	-5,427	68,492
(Decrease) increase in security deposits	-6,475	3,472
Net cash provided by operating activities	767,093	861,866
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Payments to Acquire Businesses, Net of Cash Acquired	-4,000,875	0
Investment in real estate b acquisitions	-108,308	-764,859
Investment in real estate - development/other	-256,965	-116,715
Improvements to real estate	-96,866	-114,535
Additions to non-real estate property	-3,359	-6,716
Interest capitalized for real estate and unconsolidated entities under development	-32,946	-15,776
Proceeds from disposition of real estate, net	4,434,708	610,127
Investments in unconsolidated entities	-59,363	-5,423
Proceeds From Distributions Received From Unconsolidated Subsidiaries	25,471	0
Proceeds from Sale of Available-for-sale Securities	828	0
Decrease in deposits on real estate acquisitions and investments, net	147,890	31,677
Decrease in mortgage deposits	7,623	1,682
Acquisition of Noncontrolling Interests b Partially Owned Properties	0	-87
Net cash (used for) provided by investing activities	57,838	-380,625
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Loan and bond acquisition costs	-18,254	-4,599
Mortgage Deposits	-3,769	-590
Mortgage notes payable:	'	'
Proceeds from Issuance of Long-term Debt	5,951	0
Restricted cash	0	2,370
Lump sum payoffs	-701,762	-279,943
Scheduled principal repayments	-9,527	-11,022
Notes, net:	'	'
Proceeds from Notes Payable	1,245,550	0
Lump sum payoffs	-400,000	-253,858
Line of Credit Facility:	'	'
Proceeds	8,413,000	392,000
Repayments	-8,413,000	-385,000
Payments for (Proceeds from) Hedge, Financing Activities	-44,013	0
Proceeds from sale of Common Shares	0	220,753
Proceeds from Employee Stock Purchase Plan	2,973	4,944
Proceeds from exercise of options	16,044	46,781
Redemption of Preferred Shares	0	-150,000
Premium On Redemption Of Preferred Shares Cash	0	-21
Payment of offering costs	-954	-2,860
Proceeds from (Payments for) Other Financing Activities	-33	-33
Contributions - Noncontrolling Interests - Partially Owned Properties	11,520	5,992
Contributions - Noncontrolling Interests - Operating Partnership	5	5
Distributions:	'	'
Common Shares	-537,464	-371,319
Preferred Shares	-3,109	-11,344
Noncontrolling Interests b Operating Partnership	-22,216	-17,053
Noncontrolling Interests b Partially Owned Properties	-5,702	-4,742
Net cash (used for) financing activities	-464,760	-819,539
Net (decrease) increase in cash and cash equivalents	360,171	-338,298
Cash and cash equivalents, beginning of period	612,590	383,921
Cash and cash equivalents, end of period	972,761	45,623
SUPPLEMENTAL INFORMATION:	'	'
Cash paid for interest, net of amounts capitalized	451,495	353,329
Net cash paid for income and other taxes	1,064	573
Real estate acquisitions/dispositions/other:	'	'
Mortgage loans assumed	0	137,644
Valuation Of O P Units Issued	0	66,606
AmortizationOfDeferredFinancingCosts [Abstract]	'	'
Amortization Of Deferred Financing Costs Investment In Real Estate Net	-152	0
Amortization Of Deferred Financing Costs Deferred Financing Costs Net	16,016	10,384
Amortization of discounts and premiums on debt:	'	'
Mortgage notes payable	-39,232	-7,462
Notes, net	1,620	1,667
Amortization of deferred settlements on derivative instruments:	'	'
Other liabilities	-401	-401
Losses reclassified into earnings from other comprehensive income	16,084	10,907
Loss From Investments In Unconsolidated Entities [Abstract]	'	'
Income Loss From Equity Method Investments Merger	51,923	3
Other Liabilities Loss From Investments in unconsolidated entities	5,842	0
Unrealized (gain) loss on derivative instruments:	'	'
Other assets	-10,609	5,934
Mortgage notes payable	0	-2,589
Notes, net	-1,523	-3,345
Other liabilities	3,427	12,336
Unrealized holding gains (losses) arising during the period	8,737	-12,337
Acquisition of Archstone, net of cash acquired [Abstract]	'	'
Acquisition of Archstone Investment in Real Estate Net	-8,710,242	0
Acquisition of Archstone Investments in Unconsolidated Entities	-217,092	0
Acquisition of Archstone Deposits Restricted	-474	0
Acquisition of Archstone Escrow Deposits Mortgage	-35,897	0
Acquisition of Archstone Deferred Financing Costs	-25,780	0
Acquisition of Archstone Other Assets	-203,295	0
Acquisition of Archstone Mortgage Notes Payable	3,076,876	0
Acquisition of Archstone Accounts Payable And Accrued Liabilities	17,576	0
Acqusition of Archstone Interest Payable	11,305	0
Acquisition of Archstone Other Liabilities	117,068	0
Acquisition of Archstone Security Deposits	10,949	0
Acquisition of Archstone Common Shares Issued	1,929,868	0
Acquisition of Archstone Noncontrolling Interests Partially Owned Properties	28,263	0
Interest capitalized for real estate and unconsolidated entities under development:	'	'
Investment in real estate, net	-31,648	-15,163
Investment in unconsolidated entities	-1,298	-613
Equity Method Investments and Joint Ventures [Abstract]	'	'
Investments in unconsolidated entities	-9,317	-5,423
Investments in unconsolidated entities other liabilities	-50,046	0
Other:	'	'
Receivable For Common Shares OP Units Issued	0	28,457
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	$789	$0

CONSOLIDATED_STATEMENTS_OF_CAS1

CONSOLIDATED STATEMENTS OF CASH FLOWS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'
Net income	$1,789,483,000	$496,805,000
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation	830,097,000	516,940,000
Amortization of deferred financing costs	15,864,000	10,384,000
Amortization of Intangible Assets	2,214,000	0
Amortization of discounts and premiums on debt	-37,612,000	-5,795,000
Amortization of deferred settlements on derivative instruments	15,683,000	10,506,000
Write-off of pursuit costs	3,969,000	6,141,000
Income Loss from Investments in Unconsolidated Entities Adjustment	57,765,000	3,000
Distributions from unconsolidated entities - return on capital	1,519,000	454,000
(Gain) Loss on Sale of Securities, Net	-830,000	0
Net Gain on Sales of Unconsolidated Entities	-16,000	0
Gain Loss On Sale Of Land Parcels	-12,179,000	0
Net (gain) on sales of discontinued operations	-1,990,577,000	-307,447,000
Unrealized (gain) loss on derivative instruments	32,000	-1,000
Compensation paid with Company Common Shares	29,019,000	20,836,000
Changes in assets and liabilities:	'	'
(Increase) decrease in deposits - restricted	4,152,000	-2,250,000
(Increase) decrease in mortgage deposits	271,000	-862,000
(Increase) decrease in other assets	7,315,000	-14,039,000
Increase in accounts payable and accrued expenses	65,001,000	67,479,000
(Decrease) in accrued interest payable	-2,175,000	-9,252,000
Increase (decrease) in other liabilities	-5,427,000	68,492,000
(Decrease) increase in security deposits	-6,475,000	3,472,000
Net cash provided by operating activities	767,093,000	861,866,000
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Payments to Acquire Businesses, Net of Cash Acquired	-4,000,875,000	0
Investment in real estate - acquisitions	-108,308,000	-764,859,000
Investment in real estate - development/other	-256,965,000	-116,715,000
Improvements to real estate	-96,866,000	-114,535,000
Additions to non-real estate property	-3,359,000	-6,716,000
Interest capitalized for real estate and unconsolidated entities under development	-32,946,000	-15,776,000
Proceeds from disposition of real estate, net	4,434,708,000	610,127,000
Investments in unconsolidated entities	-59,363,000	-5,423,000
Proceeds From Distributions Received From Unconsolidated Subsidiaries	25,471,000	0
Proceeds from Sale of Available-for-sale Securities	828,000	0
Decrease in deposits on real estate acquisitions and investments, net	147,890,000	31,677,000
Decrease in mortgage deposits	7,623,000	1,682,000
Acquisition of Noncontrolling Interests b Partially Owned Properties	0	-87,000
Net cash (used for) provided by investing activities	57,838,000	-380,625,000
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Loan and bond acquisition costs	-18,254,000	-4,599,000
Mortgage Deposits	-3,769,000	-590,000
Mortgage notes payable:	'	'
Proceeds from Issuance of Long-term Debt	5,951,000	0
Restricted cash	0	2,370,000
Scheduled principal repayments	-9,527,000	-11,022,000
Notes, net:	'	'
Proceeds from Notes Payable	1,245,550,000	0
Lump sum payoffs	-400,000,000	-253,858,000
Line of Credit Facility:	'	'
Proceeds	8,413,000,000	392,000,000
Repayments	-8,413,000,000	-385,000,000
Payments for (Proceeds from) Hedge, Financing Activities	-44,013,000	0
Proceeds from exercise of options	16,044,000	46,781,000
Redemption of Preferred Shares	0	-150,000,000
Premium On Redemption Of Preferred Shares Cash	0	-21,000
Payment of offering costs	-954,000	-2,860,000
Proceeds from (Payments for) Other Financing Activities	-33,000	-33,000
Contributions - Noncontrolling Interests - Partially Owned Properties	11,520,000	5,992,000
Contributions - Noncontrolling Interests - Operating Partnership	5,000	5,000
Distributions:	'	'
Noncontrolling Interests b Partially Owned Properties	-5,702,000	-4,742,000
Net cash (used for) financing activities	-464,760,000	-819,539,000
Net (decrease) increase in cash and cash equivalents	360,171,000	-338,298,000
Cash and cash equivalents, beginning of period	612,590,000	383,921,000
Cash and cash equivalents, end of period	972,761,000	45,623,000
SUPPLEMENTAL INFORMATION:	'	'
Cash paid for interest, net of amounts capitalized	451,495,000	353,329,000
Net cash paid for income and other taxes	1,064,000	573,000
Real estate acquisitions/dispositions/other:	'	'
Mortgage loans assumed	0	137,644,000
Valuation Of O P Units Issued	0	66,606,000
AmortizationOfDeferredFinancingCosts [Abstract]	'	'
Amortization Of Deferred Financing Costs Investment In Real Estate Net	-152,000	0
Amortization Of Deferred Financing Costs Deferred Financing Costs Net	16,016,000	10,384,000
Amortization of discounts and premiums on debt:	'	'
Mortgage notes payable	-39,232,000	-7,462,000
Notes, net	1,620,000	1,667,000
Amortization of deferred settlements on derivative instruments:	'	'
Other liabilities	-401,000	-401,000
Losses reclassified into earnings from other comprehensive income	16,084,000	10,907,000
Loss From Investments In Unconsolidated Entities [Abstract]	'	'
Income Loss From Equity Method Investments Merger	51,923,000	3,000
Other Liabilities Loss From Investments in unconsolidated entities	5,842,000	0
Unrealized (gain) loss on derivative instruments:	'	'
Other assets	-10,609,000	5,934,000
Mortgage notes payable	0	-2,589,000
Notes, net	-1,523,000	-3,345,000
Other liabilities	3,427,000	12,336,000
Unrealized holding gains (losses) arising during the period	8,737,000	-12,337,000
Acquisition of Archstone, net of cash acquired [Abstract]	'	'
Acquisition of Archstone Investment in Real Estate Net	-8,710,242,000	0
Acquisition of Archstone Investments in Unconsolidated Entities	-217,092,000	0
Acquisition of Archstone Deposits Restricted	-474,000	0
Acquisition of Archstone Escrow Deposits Mortgage	-35,897,000	0
Acquisition of Archstone Deferred Financing Costs	-25,780,000	0
Acquisition of Archstone Other Assets	-203,295,000	0
Acquisition of Archstone Mortgage Notes Payable	3,076,876,000	0
Acquisition of Archstone Accounts Payable And Accrued Liabilities	17,576,000	0
Acqusition of Archstone Interest Payable	11,305,000	0
Acquisition of Archstone Other Liabilities	117,068,000	0
Acquisition of Archstone Security Deposits	10,949,000	0
Acquisition of Archstone Common Shares Issued	1,929,868,000	0
Acquisition of Archstone Noncontrolling Interests Partially Owned Properties	28,263,000	0
Interest capitalized for real estate and unconsolidated entities under development:	'	'
Investment in real estate, net	-31,648,000	-15,163,000
Investment in unconsolidated entities	-1,298,000	-613,000
Investments in unconsolidated entities	-9,317,000	-5,423,000
Investments in unconsolidated entities other liabilities	-50,046,000	0
Other:	'	'
Receivable For Common Shares OP Units Issued	0	28,457,000
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	789,000	0
OPERATING PARTNERSHIP	'	'
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'
Net income	1,789,483,000	496,805,000
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation	830,097,000	516,940,000
Amortization of deferred financing costs	15,864,000	10,384,000
Amortization of Intangible Assets	2,214,000	0
Amortization of discounts and premiums on debt	-37,612,000	-5,795,000
Amortization of deferred settlements on derivative instruments	15,683,000	10,506,000
Write-off of pursuit costs	3,969,000	6,141,000
Income Loss from Investments in Unconsolidated Entities Adjustment	57,765,000	3,000
Distributions from unconsolidated entities - return on capital	1,519,000	454,000
(Gain) Loss on Sale of Securities, Net	-830,000	0
Net Gain on Sales of Unconsolidated Entities	-16,000	0
Gain Loss On Sale Of Land Parcels	-12,179,000	0
Net (gain) on sales of discontinued operations	-1,990,577,000	-307,447,000
Unrealized (gain) loss on derivative instruments	32,000	-1,000
Compensation paid with Company Common Shares	29,019,000	20,836,000
Changes in assets and liabilities:	'	'
(Increase) decrease in deposits - restricted	4,152,000	-2,250,000
(Increase) decrease in mortgage deposits	271,000	-862,000
(Increase) decrease in other assets	7,315,000	-14,039,000
Increase in accounts payable and accrued expenses	65,001,000	67,479,000
(Decrease) in accrued interest payable	-2,175,000	-9,252,000
Increase (decrease) in other liabilities	-5,427,000	68,492,000
(Decrease) increase in security deposits	-6,475,000	3,472,000
Net cash provided by operating activities	767,093,000	861,866,000
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Payments to Acquire Businesses, Net of Cash Acquired	-4,000,875,000	0
Investment in real estate - acquisitions	-108,308,000	-764,859,000
Investment in real estate - development/other	-256,965,000	-116,715,000
Improvements to real estate	-96,866,000	-114,535,000
Additions to non-real estate property	-3,359,000	-6,716,000
Interest capitalized for real estate and unconsolidated entities under development	-32,946,000	-15,776,000
Proceeds from disposition of real estate, net	4,434,708,000	610,127,000
Investments in unconsolidated entities	-59,363,000	-5,423,000
Proceeds From Distributions Received From Unconsolidated Subsidiaries	25,471,000	0
Proceeds from Sale of Available-for-sale Securities	828,000	0
Decrease in deposits on real estate acquisitions and investments, net	147,890,000	31,677,000
Decrease in mortgage deposits	7,623,000	1,682,000
Acquisition of Noncontrolling Interests b Partially Owned Properties	0	-87,000
Net cash (used for) provided by investing activities	57,838,000	-380,625,000
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Loan and bond acquisition costs	-18,254,000	-4,599,000
Mortgage Deposits	-3,769,000	-590,000
Mortgage notes payable:	'	'
Proceeds from Issuance of Long-term Debt	5,951,000	0
Restricted cash	0	2,370,000
Lump sum payoffs	-701,762,000	-279,943,000
Scheduled principal repayments	-9,527,000	-11,022,000
Notes, net:	'	'
Proceeds from Notes Payable	1,245,550,000	0
Lump sum payoffs	-400,000,000	-253,858,000
Line of Credit Facility:	'	'
Proceeds	8,413,000,000	392,000,000
Repayments	-8,413,000,000	-385,000,000
Payments for (Proceeds from) Hedge, Financing Activities	-44,013,000	0
Proceeds from sale of OP Units	0	220,753,000
Proceeds from EQR's Employee Share Purchase Plan (ESPP)	2,973,000	4,944,000
Proceeds from exercise of options	16,044,000	46,781,000
Redemption of Preferred Shares	0	-150,000,000
Premium On Redemption Of Preferred Shares Cash	0	-21,000
Payment of offering costs	-954,000	-2,860,000
Proceeds from (Payments for) Other Financing Activities	-33,000	-33,000
Contributions - Noncontrolling Interests - Partially Owned Properties	11,520,000	5,992,000
Contributions - Noncontrolling Interests - Operating Partnership	5,000	5,000
Distributions:	'	'
OP Units - General Partner	-537,464,000	-371,319,000
Preference Units	-3,109,000	-11,344,000
OP Units - Limited Partners	-22,216,000	-17,053,000
Noncontrolling Interests b Partially Owned Properties	-5,702,000	-4,742,000
Net cash (used for) financing activities	-464,760,000	-819,539,000
Net (decrease) increase in cash and cash equivalents	360,171,000	-338,298,000
Cash and cash equivalents, beginning of period	612,590,000	383,921,000
Cash and cash equivalents, end of period	972,761,000	45,623,000
SUPPLEMENTAL INFORMATION:	'	'
Cash paid for interest, net of amounts capitalized	451,495,000	353,329,000
Net cash paid for income and other taxes	1,064,000	573,000
Real estate acquisitions/dispositions/other:	'	'
Mortgage loans assumed	0	137,644,000
Valuation Of O P Units Issued	0	66,606,000
AmortizationOfDeferredFinancingCosts [Abstract]	'	'
Amortization Of Deferred Financing Costs Investment In Real Estate Net	-152,000	0
Amortization Of Deferred Financing Costs Deferred Financing Costs Net	16,016,000	10,384,000
Amortization of discounts and premiums on debt:	'	'
Mortgage notes payable	-39,232,000	-7,462,000
Notes, net	1,620,000	1,667,000
Amortization of deferred settlements on derivative instruments:	'	'
Other liabilities	-401,000	-401,000
Losses reclassified into earnings from other comprehensive income	16,084,000	10,907,000
Loss From Investments In Unconsolidated Entities [Abstract]	'	'
Income Loss From Equity Method Investments Merger	51,923,000	3,000
Other Liabilities Loss From Investments in unconsolidated entities	5,842,000	0
Unrealized (gain) loss on derivative instruments:	'	'
Other assets	-10,609,000	5,934,000
Mortgage notes payable	0	-2,589,000
Notes, net	-1,523,000	-3,345,000
Other liabilities	3,427,000	12,336,000
Unrealized holding gains (losses) arising during the period	8,737,000	-12,337,000
Acquisition of Archstone, net of cash acquired [Abstract]	'	'
Acquisition of Archstone Investment in Real Estate Net	-8,710,242,000	0
Acquisition of Archstone Investments in Unconsolidated Entities	-217,092,000	0
Acquisition of Archstone Deposits Restricted	-474,000	0
Acquisition of Archstone Escrow Deposits Mortgage	-35,897,000	0
Acquisition of Archstone Deferred Financing Costs	-25,780,000	0
Acquisition of Archstone Other Assets	-203,295,000	0
Acquisition of Archstone Mortgage Notes Payable	3,076,876,000	0
Acquisition of Archstone Accounts Payable And Accrued Liabilities	17,576,000	0
Acqusition of Archstone Interest Payable	11,305,000	0
Acquisition of Archstone Other Liabilities	117,068,000	0
Acquisition of Archstone Security Deposits	10,949,000	0
Acquisition of Archstone Common Shares Issued	1,929,868,000	0
Acquisition of Archstone Noncontrolling Interests Partially Owned Properties	28,263,000	0
Interest capitalized for real estate and unconsolidated entities under development:	'	'
Investment in real estate, net	-31,648,000	-15,163,000
Investment in unconsolidated entities	-1,298,000	-613,000
Investments in unconsolidated entities	-9,317,000	-5,423,000
Investments in unconsolidated entities other liabilities	-50,046,000	0
Other:	'	'
Receivable For Common Shares OP Units Issued	0	28,457,000
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	$789,000	$0

CONSOLIDATED_STATEMENT_OF_CHAN

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $)	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]
In Thousands, unless otherwise specified
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	'	'	'	1,203	'	'	-1,203	'
Issuance of Common Shares	'	'	345	1,929,523	'	'	'	'
Exercise of share options	'	'	5	16,039	'	'	'	'
Stock Issued During Period, Value, Employee Stock Purchase Plan	'	'	1	2,972	'	'	'	'
Adjustments to Additional Paid in Capital, Share-based Compensation, Restricted Stock Unit or Restricted Stock Award, Requisite Service Period Recognition	'	'	2	10,248	'	'	'	'
Share-based employee compensation expense:	'	'	'	'	'	'	'	'
Share options	'	'	'	8,684	'	'	'	'
ESPP discount	'	'	'	557	'	'	'	'
Offering costs	'	'	'	-954	'	'	'	'
Supplemental Executive Retirement Plan (SERP)	'	'	'	-439	'	'	'	'
Change in market value	-69,344	'	'	69,344	'	'	'	'
Adjustment for Noncontrolling Interests ownership in Operating Partnership	'	'	'	-36,710	'	'	36,710	'
Net income attributable to controlling interests	1,719,637	'	'	'	1,719,637	'	'	'
Common Share distributions	'	'	'	'	-432,280	'	'	'
Dividends, Preferred Stock, Cash	'	'	'	'	-3,109	'	'	'
Other comprehensive income (loss) - derivative instruments:	'	'	'	'	'	'	'	'
Unrealized holding gains (losses) arising during the period	8,737	'	'	'	'	8,737	'	'
Losses reclassified into earnings from other comprehensive income	-16,084	'	'	'	'	16,084	'	'
Other comprehensive income (loss) - other instruments:	'	'	'	'	'	'	'	'
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	554	'	'	'	'	554	'	'
(Gain) Loss on Sale of Securities, Net	-830	'	'	'	'	-830	'	'
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	-789	'	'	'	'	-789	'	'
Issuance of LTIP Units to Noncontrolling Interests	'	'	'	'	'	'	5	'
Equity Compensation associated with Noncontrolling Interests	'	'	'	'	'	'	11,542	'
Net (Income) Attributable to Noncontrolling Interest	70,947	'	'	'	'	'	70,947	-1,101
Contributions by Noncontrolling Interests	11,520	'	'	'	'	'	'	11,520
Archstone Acquisition Noncontrolling Interests Partially Owned Properties	'	'	'	'	'	'	'	28,263
Distributions to Noncontrolling Interests	'	'	'	'	'	'	-17,060	-5,735
Change in carrying value	47,029	'	'	'	'	'	-47,029	'
Ending Balance, Noncontrolling Interest at Sep. 30, 2013	324,153	'	'	'	'	'	213,518	110,635
Ending Balance, Parent at Sep. 30, 2013	$10,598,637	$50,000	$3,604	$8,542,822	$2,171,603	($169,392)	'	'

CONSOLIDATED_STATEMENT_OF_CHAN1

CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) (USD $)	Total	PREFERRED SHARES	General Partner [Member]	Limited Partner [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Partially Owned Properties [Member]
In Thousands, unless otherwise specified
Balance, beginning of year - Noncontrolling Interest at Dec. 31, 2012	'	'	'	'	'	$77,688
Balance, beginning of year at Dec. 31, 2012	'	50,000	7,432,961	159,606	-193,148	'
OP Unit Issuance:	'	'	'	'	'	'
Conversion of OP Units held by Limited Partners into OP Units held by General Partner	'	'	1,203	-1,203	'	'
Issuance of OP Units	'	'	1,929,868	'	'	'
Exercise of EQR share options	'	'	16,044	'	'	'
Stock Issued During Period, Value, Employee Stock Purchase Plan	'	'	2,973	'	'	'
Share-based employee compensation expense:	'	'	'	'	'	'
EQR restricted shares	'	'	10,250	'	'	'
EQR share options	'	'	8,684	'	'	'
EQR ESPP discount	'	'	557	'	'	'
Offering costs	'	'	-954	'	'	'
Net income available to Units - General Partner	'	'	1,716,528	'	'	'
OP Units - General Partner distributions	'	'	-432,280	'	'	'
Supplemental Executive Retirement Plan (SERP)	'	'	-439	'	'	'
Change in market value of Redeemable Limited Partners	'	'	69,344	'	'	'
Adjustment for Limited Partners ownership in Operating Partnership	'	'	-36,710	36,710	'	'
Issuance of LTIP Units to Noncontrolling Interests	'	'	'	5	'	'
Equity compensation associated with Units - Limited Partners	'	'	'	11,542	'	'
Net income available to Units - Limited Partners	'	'	'	70,947	'	'
Units - Limited Partners distributions	'	'	'	-17,060	'	'
Change in carrying value of Redeemable Limited Partners	'	'	'	-47,029	'	'
Other comprehensive income (loss) - derivative instruments:	'	'	'	'	'	'
Unrealized holding gains (losses) arising during the period	8,737	'	'	'	8,737	'
Losses reclassified into earnings from other comprehensive income	-16,084	'	'	'	16,084	'
Other comprehensive income (loss) - other instruments:	'	'	'	'	'	'
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	554	'	'	'	554	'
(Gain) Loss on Sale of Securities, Net	-830	'	'	'	-830	'
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	-789	'	'	'	-789	'
Net (Income) Attributable to Noncontrolling Interest	70,947	'	'	'	'	-1,101
Contributions by Noncontrolling Interests	11,520	'	'	'	'	11,520
Archstone Acquisition Noncontrolling Interests Partially Owned Properties	'	'	'	'	'	28,263
Distributions to Noncontrolling Interests	'	'	'	'	'	-5,735
Balance, end of period - Noncontrolling Interest at Sep. 30, 2013	'	'	'	'	'	110,635
Balance, end of period at Sep. 30, 2013	'	$50,000	$10,718,029	$213,518	($169,392)	'

Business

Business	9 Months Ended
	Sep. 30, 2013
Business [Abstract]	'
Business	'
	1	Business
	Equity Residential (“EQR”), a Maryland real estate investment trust (“REIT”) formed in March 1993, is an S&P 500 company focused on the acquisition, development and management of high quality apartment properties in top United States growth markets. ERP Operating Limited Partnership (“ERPOP”), an Illinois limited partnership, was formed in May 1993 to conduct the multifamily residential property business of Equity Residential. EQR has elected to be taxed as a REIT. References to the “Company,” “we,” “us” or “our” mean collectively EQR, ERPOP and those entities/subsidiaries owned or controlled by EQR and/or ERPOP. References to the “Operating Partnership” mean collectively ERPOP and those entities/subsidiaries owned or controlled by ERPOP. Unless otherwise indicated, the notes to consolidated financial statements apply to both the Company and the Operating Partnership.
	EQR is the general partner of, and as of September 30, 2013 owned an approximate 96.2% ownership interest in, ERPOP. All of the Company’s property ownership, development and related business operations are conducted through the Operating Partnership and EQR has no material assets or liabilities other than its investment in ERPOP. EQR issues equity from time to time but does not have any indebtedness as all debt is incurred by the Operating Partnership. The Operating Partnership holds substantially all of the assets of the Company, including the Company’s ownership interests in its joint ventures. The Operating Partnership conducts the operations of the business and is structured as a partnership with no publicly traded equity.
	As of September 30, 2013, the Company, directly or indirectly through investments in title holding entities, owned all or a portion of 389 properties located in 12 states and the District of Columbia consisting of 109,795 apartment units. The ownership breakdown includes (table does not include various uncompleted development properties):
			Properties	Apartment
				Units
	Wholly Owned Properties		363	99,192
	Master-Leased Properties – Consolidated		3	853
	Partially Owned Properties – Consolidated		19	3,752
	Partially Owned Properties – Unconsolidated		2	837
	Military Housing		2	5,161
			389	109,795

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2013
Summary of Significant Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	2	Summary of Significant Accounting Policies
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) and certain reclassifications considered necessary for a fair presentation have been included. Certain reclassifications have been made to the prior period financial statements in order to conform to the current year presentation. Operating results for the nine months ended September 30, 2013 are not necessarily indicative of the results that may be expected for the year ending December 31, 2013.
	In preparation of the Company’s financial statements in conformity with accounting principles generally accepted in the United States, management makes estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.
	The balance sheets at December 31, 2012 have been derived from the audited financial statements at that date but do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.
	For further information, including definitions of capitalized terms not defined herein, refer to the consolidated financial statements and footnotes thereto included in the Company’s and the Operating Partnership's annual report on Form 10-K for the year ended December 31, 2012.
	Real Estate Assets and Depreciation of Investment in Real Estate
	Effective for business combinations on or after January 1, 2009, an acquiring entity is required to recognize all assets acquired and liabilities assumed in a transaction at the acquisition-date fair value with limited exceptions. In addition, an acquiring entity is required to expense acquisition-related costs as incurred, value noncontrolling interests at fair value at the acquisition date and expense restructuring costs associated with an acquired business.
	The Company allocates the purchase price of properties to net tangible and identified intangible assets acquired based on their fair values. In making estimates of fair values for purposes of allocating purchase price, the Company utilizes a number of sources, including independent appraisals that may be obtained in connection with the acquisition or financing of the respective property, our own analysis of recently acquired and existing comparable properties in our portfolio and other market data. The Company also considers information obtained about each property as a result of its pre-acquisition due diligence, marketing and leasing activities in estimating the fair value of the tangible and intangible assets/liabilities acquired. The Company allocates the purchase price of acquired real estate to various components as follows:
	•	Land – Based on actual purchase price adjusted to fair value (as necessary) if acquired separately or market research/comparables if acquired with an operating property.
	•	Furniture, Fixtures and Equipment – Ranges between $3,000 and $13,000 per apartment unit acquired as an estimate of the fair value of the appliances and fixtures inside an apartment unit. The per-apartment unit amount applied depends on the type of apartment building acquired. Depreciation is calculated on the straight-line method over an estimated useful life of five to ten years.
	•	Lease Intangibles – The Company considers the value of acquired in-place leases and above/below market leases and the amortization period is the average remaining term of each respective acquired lease. In-place residential leases' average term at acquisition approximates six months. See Note 4 for more information on above and below market leases.
	•	Other Intangible Assets – The Company considers whether it has acquired other intangible assets, including any customer relationship intangibles and the amortization period is the estimated useful life of the acquired intangible asset.
	•	Building – Based on the fair value determined on an “as-if vacant” basis. Depreciation is calculated on the straight-line method over an estimated useful life of thirty years.
	•	Site Improvements – Based on replacement cost, which approximates fair value. Depreciation is calculated on the straight-line method over an estimated useful life of eight years.
	•	Long-Term Debt – The Company calculates the fair value by discounting the remaining contractual cash flows on each instrument at the current market rate for those borrowings.
	Income and Other Taxes
	Due to the structure of EQR as a REIT and the nature of the operations of its operating properties, no provision for federal income taxes has been made at the EQR level. In addition, ERPOP generally is not liable for federal income taxes as the partners recognize their proportionate share of income or loss in their tax returns; therefore no provision for federal income taxes has been made at the ERPOP level. Historically, the Company has generally only incurred certain state and local income, excise and franchise taxes. The Company has elected Taxable REIT Subsidiary (“TRS”) status for certain of its corporate subsidiaries and as a result, these entities will incur both federal and state income taxes on any taxable income of such entities after consideration of any net operating losses.
	Deferred tax assets and liabilities applicable to the TRS are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. These assets and liabilities are measured using enacted tax rates for which the temporary differences are expected to be recovered or settled. The effects of changes in tax rates on deferred tax assets and liabilities are recognized in earnings in the period enacted. The Company’s deferred tax assets are generally the result of tax affected amortization of goodwill, differing depreciable lives on capitalized assets and the timing of expense recognition for certain accrued liabilities. As of September 30, 2013, the Company has recorded a deferred tax asset, which is fully offset by a valuation allowance due to the uncertainty in forecasting future TRS taxable income.
	Other
	The Company is the controlling partner in various consolidated partnerships owning 19 properties and 3,752 apartment units and various completed and uncompleted development properties having a noncontrolling interest book value of $110.6 million at September 30, 2013. The Company is required to make certain disclosures regarding noncontrolling interests in consolidated limited-life subsidiaries. Of the consolidated entities described above, the Company is the controlling partner in limited-life partnerships owning six properties having a noncontrolling interest deficit balance of $8.5 million. These six partnership agreements contain provisions that require the partnerships to be liquidated through the sale of their assets upon reaching a date specified in each respective partnership agreement. The Company, as controlling partner, has an obligation to cause the property owning partnerships to distribute the proceeds of liquidation to the Noncontrolling Interests in these Partially Owned Properties only to the extent that the net proceeds received by the partnerships from the sale of their assets warrant a distribution based on the partnership agreements. As of September 30, 2013, the Company estimates the value of Noncontrolling Interest distributions for these six properties would have been approximately $46.8 million (“Settlement Value”) had the partnerships been liquidated. This Settlement Value is based on estimated third party consideration realized by the partnerships upon disposition of the six Partially Owned Properties and is net of all other assets and liabilities, including yield maintenance on the mortgages encumbering the properties, that would have been due on September 30, 2013 had those mortgages been prepaid. Due to, among other things, the inherent uncertainty in the sale of real estate assets, the amount of any potential distribution to the Noncontrolling Interests in the Company's Partially Owned Properties is subject to change. To the extent that the partnerships' underlying assets are worth less than the underlying liabilities, the Company has no obligation to remit any consideration to the Noncontrolling Interests in these Partially Owned Properties.
	Effective January 1, 2012, companies are required to separately disclose the amounts and reasons for any transfers of assets and liabilities into and out of Level 1 and Level 2 of the fair value hierarchy. For fair value measurements using significant unobservable inputs (Level 3), companies are required to disclose quantitative information about the significant unobservable inputs used for all Level 3 measurements and a description of the Company's valuation processes in determining fair value. In addition, companies are required to provide a qualitative discussion about the sensitivity of recurring Level 3 measurements to changes in the unobservable inputs disclosed, including the interrelationship between inputs. Companies are also required to disclose information about when the current use of a non-financial asset measured at fair value differs from its highest and best use and the hierarchy classification for items whose fair value is not recorded on the balance sheet but is disclosed in the notes. This does not have a material effect on the Company's consolidated results of operations or financial position. See Notes 4 and 9 for further discussion.
	Effective January 1, 2013, companies are required to report, in one place, information about reclassifications out of accumulated other comprehensive income ("AOCI"). Companies will also be required to report changes in AOCI balances. For significant items reclassified out of AOCI to net income in their entirety in the same reporting period, reporting is required about the effect of the reclassifications on the respective line items in the statement where net income is presented. For items that are not reclassified to net income in their entirety in the same reporting period, a cross reference to other disclosures currently required under US GAAP is required in the notes. This does not have a material effect on the Company's consolidated results of operations or financial position. See Note 9 for further discussion.

Equity_Capital_and_Other_Inter

Equity, Capital and Other Interests	9 Months Ended
	Sep. 30, 2013
Equity, Capital and other Interests [Abstract]	'
Equity Capital And Other Interests [Text Block]	'
	3	Equity, Capital and Other Interests
	Equity and Redeemable Noncontrolling Interests of Equity Residential
	The following tables present the changes in the Company’s issued and outstanding Common Shares and “Units” (which includes OP Units and Long-Term Incentive Plan (“LTIP”) Units) for the nine months ended September 30, 2013:
			2013
	Common Shares
	Common Shares outstanding at January 1,		325,054,654
	Common Shares Issued:
	Conversion of OP Units		47,939
	Issuance of Common Shares		34,468,085
	Exercise of share options		530,847
	Employee Share Purchase Plan (ESPP)		63,788
	Restricted share grants, net		230,646
	Common Shares outstanding at September 30,		360,395,959
	Units
	Units outstanding at January 1,		13,968,758
	LTIP Units, net		279,557
	Conversion of OP Units to Common Shares		(47,939	)
	Units outstanding at September 30,		14,200,376
	Total Common Shares and Units outstanding at September 30,		374,596,335
	Units Ownership Interest in Operating Partnership		3.8	%
	The equity positions of various individuals and entities that contributed their properties to the Operating Partnership in exchange for OP Units, as well as the equity positions of the holders of LTIP Units, are collectively referred to as the “Noncontrolling Interests – Operating Partnership”. Subject to certain exceptions (including the “book-up” requirements of LTIP Units), the Noncontrolling Interests – Operating Partnership may exchange their Units with EQR for Common Shares on a one-for-one basis. The carrying value of the Noncontrolling Interests – Operating Partnership (including redeemable interests) is allocated based on the number of Noncontrolling Interests – Operating Partnership Units in total in proportion to the number of Noncontrolling Interests – Operating Partnership Units in total plus the number of Common Shares. Net income is allocated to the Noncontrolling Interests – Operating Partnership based on the weighted average ownership percentage during the period.
	The Operating Partnership has the right but not the obligation to make a cash payment instead of issuing Common Shares to any and all holders of Noncontrolling Interests – Operating Partnership Units requesting an exchange of their OP Units with EQR. Once the Operating Partnership elects not to redeem the Noncontrolling Interests – Operating Partnership Units for cash, EQR is obligated to deliver Common Shares to the exchanging holder of the Noncontrolling Interests – Operating Partnership Units.
	The Noncontrolling Interests – Operating Partnership Units are classified as either mezzanine equity or permanent equity. If EQR is required, either by contract or securities law, to deliver registered Common Shares, such Noncontrolling Interests – Operating Partnership are differentiated and referred to as “Redeemable Noncontrolling Interests – Operating Partnership”. Instruments that require settlement in registered shares can not be classified in permanent equity as it is not always completely within an issuer’s control to deliver registered shares. Therefore, settlement in cash is assumed and that responsibility for settlement in cash is deemed to fall to the Operating Partnership as the primary source of cash for EQR, resulting in presentation in the mezzanine section of the balance sheet. The Redeemable Noncontrolling Interests – Operating Partnership are adjusted to the greater of carrying value or fair market value based on the Common Share price of EQR at the end of each respective reporting period. EQR has the ability to deliver unregistered Common Shares for the remaining portion of the Noncontrolling Interests – Operating Partnership Units that are classified in permanent equity at September 30, 2013 and December 31, 2012.
	The carrying value of the Redeemable Noncontrolling Interests – Operating Partnership is allocated based on the number of Redeemable Noncontrolling Interests – Operating Partnership Units in proportion to the number of Noncontrolling Interests – Operating Partnership Units in total. Such percentage of the total carrying value of Units which is ascribed to the Redeemable Noncontrolling Interests – Operating Partnership is then adjusted to the greater of carrying value or fair market value as described above. As of September 30, 2013, the Redeemable Noncontrolling Interests – Operating Partnership have a redemption value of approximately $376.1 million, which represents the value of Common Shares that would be issued in exchange with the Redeemable Noncontrolling Interests – Operating Partnership Units.
	The following table presents the change in the redemption value of the Redeemable Noncontrolling Interests – Operating Partnership for the nine months ended September 30, 2013 (amounts in thousands):
			2013
	Balance at January 1,		$	398,372
	Change in market value		(69,344		)
	Change in carrying value		47,029
	Balance at September 30,		$	376,057
	Net proceeds from EQR Common Share and Preferred Share (see definition below) offerings are contributed by EQR to ERPOP. In return for those contributions, EQR receives a number of OP Units in ERPOP equal to the number of Common Shares it has issued in the equity offering (or in the case of a preferred equity offering, a number of preference units in ERPOP equal in number and having the same terms as the Preferred Shares issued in the equity offering). As a result, the net offering proceeds from Common Shares and Preferred Shares are allocated between shareholders’ equity and Noncontrolling Interests – Operating Partnership to account for the change in their respective percentage ownership of the underlying equity of ERPOP.
	The Company’s declaration of trust authorizes it to issue up to 100,000,000 preferred shares of beneficial interest, $0.01 par value per share (the “Preferred Shares”), with specific rights, preferences and other attributes as the Board of Trustees may determine, which may include preferences, powers and rights that are senior to the rights of holders of the Company’s Common Shares.
	The following table presents the Company’s issued and outstanding Preferred Shares as of September 30, 2013 and December 31, 2012:
							Amounts in thousands
			Redemption		Annual		September 30,		December 31,
			Date (1)		Dividend per		2013		2012
					Share (2)
	Preferred Shares of beneficial interest, $0.01 par value;
	100,000,000 shares authorized:
	8.29% Series K Cumulative Redeemable Preferred; liquidation		12/10/26			$4.14	$	50,000	$	50,000
	value $50 per share; 1,000,000 shares issued and outstanding
	at September 30, 2013 and December 31, 2012
							$	50,000	$	50,000
	-1	On or after the redemption date, redeemable preferred shares may be redeemed for cash at the option of the Company, in whole or in part, at a redemption price equal to the liquidation price per share, plus accrued and unpaid distributions, if any.
	-2	Dividends on Preferred Shares are payable quarterly.
	Capital and Redeemable Limited Partners of ERP Operating Limited Partnership
	The following tables present the changes in the Operating Partnership’s issued and outstanding Units and in the limited partners’ Units for the nine months ended September 30, 2013:
			2013
	General and Limited Partner Units
	General and Limited Partner Units outstanding at January 1,		339,023,412
	Issued to General Partner:
	Issuance of OP Units		34,468,085
	Exercise of EQR share options		530,847
	EQR’s Employee Share Purchase Plan (ESPP)		63,788
	EQR's restricted share grants, net		230,646
	Issued to Limited Partners:
	LTIP Units, net		279,557
	General and Limited Partner Units outstanding at September 30,		374,596,335
	Limited Partner Units
	Limited Partner Units outstanding at January 1,		13,968,758
	Limited Partner LTIP Units, net		279,557
	Conversion of Limited Partner OP Units to EQR Common Shares		(47,939	)
	Limited Partner Units outstanding at September 30,		14,200,376
Limited Partner Units Ownership Interest in Operating Partnership		3.8	%
The Limited Partners of the Operating Partnership as of September 30, 2013 include various individuals and entities that contributed their properties to the Operating Partnership in exchange for OP Units, as well as the equity positions of the holders of LTIP Units. Subject to certain exceptions (including the “book-up” requirements of LTIP Units), Limited Partners may exchange their Units with EQR for Common Shares on a one-for-one basis. The carrying value of the Limited Partner Units (including redeemable interests) is allocated based on the number of Limited Partner Units in total in proportion to the number of Limited Partner Units in total plus the number of General Partner Units. Net income is allocated to the Limited Partner Units based on the weighted average ownership percentage during the period.
The Operating Partnership has the right but not the obligation to make a cash payment instead of issuing Common Shares to any and all holders of Limited Partner Units requesting an exchange of their OP Units with EQR. Once the Operating Partnership elects not to redeem the Limited Partner Units for cash, EQR is obligated to deliver Common Shares to the exchanging limited partner.
The Limited Partner Units are classified as either mezzanine equity or permanent equity. If EQR is required, either by contract or securities law, to deliver registered Common Shares, such Limited Partner Units are differentiated and referred to as “Redeemable Limited Partner Units”. Instruments that require settlement in registered shares can not be classified in permanent equity as it is not always completely within an issuer's control to deliver registered shares. Therefore, settlement in cash is assumed and that responsibility for settlement in cash is deemed to fall to the Operating Partnership as the primary source of cash for EQR, resulting in presentation in the mezzanine section of the balance sheet. The Redeemable Limited Partner Units are adjusted to the greater of carrying value or fair market value based on the Common Share price of EQR at the end of each respective reporting period. EQR has the ability to deliver unregistered Common Shares for the remaining portion of the Limited Partner Units that are classified in permanent equity at September 30, 2013 and December 31, 2012.
The carrying value of the Redeemable Limited Partner Units is allocated based on the number of Redeemable Limited Partner Units in proportion to the number of Limited Partner Units in total. Such percentage of the total carrying value of Limited Partner Units which is ascribed to the Redeemable Limited Partner Units is then adjusted to the greater of carrying value or fair market value as described above. As of September 30, 2013, the Redeemable Limited Partner Units have a redemption value of approximately $376.1 million, which represents the value of Common Shares that would be issued in exchange with the Redeemable Limited Partner Units.
The following table presents the change in the redemption value of the Redeemable Limited Partners for the nine months ended September 30, 2013 (amounts in thousands):
		2013
Balance at January 1,		$	398,372
Change in market value		(69,344		)
Change in carrying value		47,029
Balance at September 30,		$	376,057
EQR contributes all net proceeds from its various equity offerings (including proceeds from exercise of options for Common Shares) to ERPOP. In return for those contributions, EQR receives a number of OP Units in ERPOP equal to the number of Common Shares it has issued in the equity offering (or in the case of a preferred equity offering, a number of preference units in ERPOP equal in number and having the same terms as the preferred shares issued in the equity offering).
The following table presents the Operating Partnership’s issued and outstanding “Preference Units” as of September 30, 2013 and December 31, 2012:
						Amounts in thousands
		Redemption		Annual		September 30,		December 31,
		Date (1)		Dividend per		2013		2012
				Unit (2)
Preference Units:
8.29% Series K Cumulative Redeemable Preference Units;		12/10/26			$4.14	$	50,000	$	50,000
liquidation value $50 per unit; 1,000,000 units issued and
outstanding at September 30, 2013 and December 31, 2012
						$	50,000	$	50,000
-1	On or after the redemption date, redeemable preference units may be redeemed for cash at the option of the Operating Partnership, in whole or in part, at a redemption price equal to the liquidation price per unit, plus accrued and unpaid distributions, if any, in conjunction with the concurrent redemption of the corresponding Company Preferred Shares.
-2	Dividends on Preference Units are payable quarterly.
Other
On February 27, 2013, the Company issued 34,468,085 Common Shares to an affiliate of Lehman Brothers Holdings Inc. as partial consideration for the portion of the Archstone Portfolio acquired by the Company (as discussed in Note 4 below). The shares had a total value of $1.9 billion based on the February 27, 2013 closing price of EQR Common Shares of $55.99 per share. Concurrent with this transaction, ERPOP issued 34,468,085 OP Units to EQR. On March 7, 2013, EQR filed a shelf registration statement relating to the resale of these shares by the selling shareholders.
On November 28, 2012, as a partial source of funding for the Archstone Acquisition (see definition below), EQR priced the issuance of 21,850,000 Common Shares at a price of $54.75 per share for total consideration of approximately $1.2 billion, after deducting underwriting commissions of $35.9 million. Concurrent with this transaction, ERPOP issued 21,850,000 OP Units to EQR.
In September 2009, the Company announced the establishment of an At-The-Market (“ATM”) share offering program which would allow EQR to sell up to 17.0 million Common Shares from time to time over the next three years (later increased by 5.7 million Common Shares and extended to February 2014) into the existing trading market at current market prices as well as through negotiated transactions. Per the terms of ERPOP's partnership agreement, EQR contributes the net proceeds from all equity offerings to the capital of ERPOP in exchange for additional OP Units (on a one-for-one Common Share per OP Unit basis). EQR has not issued any shares under this program since September 14, 2012. On July 30, 2013, the Company filed a new universal shelf registration statement to replace its existing universal shelf registration statement, which expired October 15, 2013. The Board of Trustees also approved an increase to the amount of shares which may be offered under the ATM program to 13.0 million Common Shares and extended the program maturity to July 2016.
EQR has a share repurchase program authorized by the Board of Trustees under which it previously had authorization to repurchase up to $464.6 million of its shares. Effective July 30, 2013, the Board of Trustees approved an increase and modification to the Company's share repurchase program to allow for the potential repurchase of up to 13.0 million Common Shares. No shares were repurchased during the nine months ended September 30, 2013.
See Note 6 for a discussion of the Noncontrolling Interests assumed in conjunction with the acquisition of Archstone.

Real_Estate

Real Estate	9 Months Ended
	Sep. 30, 2013
Real Estate [Abstract]	'
Real Estate Disclosure [Text Block]	'
	4	Real Estate and Lease Intangibles
	The following table summarizes the carrying amounts for the Company’s investment in real estate (at cost) as of September 30, 2013 and December 31, 2012 (amounts in thousands):
			September 30,				December 31,
			2013				2012
	Land		$	6,201,333			$	4,554,912
	Depreciable property:
	Buildings and improvements		17,555,388				14,135,740
	Furniture, fixtures and equipment		1,196,410				1,343,765
	In-Place lease intangibles		503,159				232,439
	Projects under development:
	Land		280,718				210,632
	Construction-in-progress		498,335				177,118
	Land held for development:
	Land		435,227				294,868
	Construction-in-progress		70,267				58,955
	Investment in real estate		26,740,837				21,008,429
	Accumulated depreciation		(4,654,594		)		(4,912,221		)
	Investment in real estate, net		$	22,086,243			$	16,096,208
	The following table summarizes the carrying amounts for the Company's above and below market ground and retail lease intangibles as of September 30, 2013 (amounts in thousands):
	Description		Balance Sheet Location		Value
	Assets
	Ground lease intangibles – below market		Other Assets		$	178,251
	Retail lease intangibles – above market		Other Assets		2,310
	Lease intangible assets				180,561
	Accumulated amortization				(3,221		)
	Lease intangible assets, net				$	177,340
	Liabilities
	Ground lease intangibles – above market		Other Liabilities		$	2,400
	Retail lease intangibles – below market		Other Liabilities		7,790
	Lease intangible liabilities				10,190
	Accumulated amortization				(993		)
	Lease intangible liabilities, net				$	9,197
	During the nine months and quarter ended September 30, 2013, the Company amortized approximately $2.5 million and $1.1 million, respectively, of above and below market ground lease intangibles which is included (net increase) in property and maintenance expense in the accompanying consolidated statements of operations and comprehensive income and approximately $0.3 million and $0.1 million, respectively, of above and below market retail lease intangibles which is included (net increase) in rental income in the accompanying consolidated statements of operations and comprehensive income.
	The weighted average amortization period for above and below market ground lease intangibles and retail lease intangibles is 49.8 years and 5.3 years, respectively.
	The following table provides a summary of the aggregate amortization expense for above and below market ground lease intangibles and retail lease intangibles for each of the next five years (amounts in thousands):
			Remaining
			2013				2014				2015			2016			2017			2018
	Ground lease intangibles		$	1,080			$	4,321			$	4,321		$	4,321		$	4,321		$	4,321
	Retail lease intangibles		(218		)		(1,144		)		(1,150		)	(1,042		)	(674		)	(205		)
	Total		$	862			$	3,177			$	3,171		$	3,279		$	3,647		$	4,116
	Archstone Acquisition
	On February 27, 2013, the Company, AvalonBay Communities, Inc. (“AVB”) and certain of their respective subsidiaries completed their previously announced acquisition (the “Archstone Acquisition”) from Archstone Enterprise LP, an affiliate of Lehman Brothers Holdings, Inc. (“Enterprise”) (which subsequently changed its name to Jupiter Enterprise LP) and its affiliates, of all of the assets of Enterprise (including interests in various entities affiliated with Enterprise), constituting a portfolio of apartment properties and other assets (the “Archstone Portfolio”).
	The Company acquired assets representing approximately 60% of the Archstone Portfolio which consisted principally of high-quality apartment properties in major markets in the United States. The acquisition allowed the Company to accelerate the completion of its strategic shift into coastal apartment markets. Pursuant to the Archstone transaction, the Company acquired directly or indirectly, 71 wholly owned, stabilized properties consisting of 20,160 apartment units, one partially owned and consolidated stabilized property consisting of 432 apartment units, one partially owned and unconsolidated stabilized property consisting of 336 apartment units, three consolidated master-leased properties consisting of 853 apartment units, four projects in various stages of construction (two consolidated and two unconsolidated) for 964 apartment units and fourteen land sites for approximately $9.0 billion. During the nine months ended September 30, 2013, the Company recorded revenues and net operating income ("NOI") of $358.0 million and $244.2 million, respectively, from the acquired assets. During the quarter ended September 30, 2013, the Company recorded revenues and NOI of $153.5 million and $104.2 million, respectively, from the acquired assets.
	The consideration paid by the Company in connection with the Archstone Acquisition consisted of cash of approximately $4.0 billion (inclusive of $2.0 billion of Archstone secured mortgage principal paid off in conjunction with the closing), 34,468,085 Common Shares (which shares had a total value of $1.9 billion based on the February 27, 2013 closing price of EQR common shares of $55.99 per share) issued to the seller and the assumption of approximately $3.1 billion of mortgage debt (inclusive of a net mark-to-market premium of $127.9 million) and approximately 60% of all of the other assets and liabilities related to the Archstone Portfolio. The cash consideration was funded with proceeds from the November 2012 public equity offering, the asset sales discussed below, the Company's new $750.0 million senior unsecured delayed draw term loan facility and the Company's revolving credit facility.
	The Company owns the building and improvements and leases the land underlying the improvements under long-term ground leases that expire beginning in 2042 and running through 2103 for nine of the operating properties acquired and discussed above. These properties are consolidated and reflected as real estate assets while the ground leases are accounted for as operating leases. The Company also leases the three master-leased properties discussed above to third party operators and earns monthly net rental income.
	The Company is accounting for the acquisition under the acquisition method in accordance with Accounting Standards Codification ("ASC") 805, Business Combinations (“ASC 805”), and the initial accounting for this business combination is substantially complete but subject to further adjustment as certain information becomes available (see further discussion below). The following table summarizes the acquisition date fair values of the assets acquired and liabilities assumed, which the Company determined using Level 1, Level 2 and Level 3 inputs (amounts in thousands):
	Land		$	2,239,000
	Depreciable property:
	Buildings and improvements		5,832,554
	Furniture, fixtures and equipment		61,470
	In-Place lease intangibles		304,830
	Projects under development		36,583
	Land held for development		239,898
	Investments in unconsolidated entities		188,139
	Other assets		196,310
	Other liabilities		(112,369		)
	Net assets acquired		$	8,986,415
	The allocation of fair values of the assets acquired and liabilities assumed has changed from the allocation reported in “Note 4 – Real Estate” in the Notes to Consolidated Financial Statements included in Part I of our Quarterly Report on Form 10-Q for the quarter ended June 30, 2013 filed with the SEC on August 8, 2013. The changes to our valuation assumptions were based on more accurate information concerning the subject assets and liabilities. None of these changes had a material impact on our Consolidated Financial Statements. This allocation is subject to further adjustment due primarily to information not readily available at the acquisition date, final purchase price settlement with our partner in accordance with the terms of the purchase agreement, reclassification adjustments for presentation and adjustments to our valuation assumptions. The Company's assessment of the fair values and the allocation of the purchase price to the identified tangible and intangible assets/liabilities is its current best estimate of fair value.
	The fair values of investment in real estate were determined using internally developed models that were based on market assumptions and comparable sales data as well as external valuations performed by unrelated third parties. The market assumptions used as inputs to the Company’s fair value model include construction costs, leasing assumptions, growth rates, discount rates, terminal capitalization rates and development yields. The Company uses data on its existing portfolio of properties and its recent acquisition and development properties, as well as similar market data from third party sources, when available, in determining these inputs (Level 2 and 3). The fair value of Noncontrolling Interests was calculated similar to the investment in real estate described above. The fair value of mortgage debt was calculated using indicative rates, leverage and coverage provided by lenders of similar loans (Level 2). The Common Shares issued to an affiliate of Lehman Brothers Holdings, Inc. were valued using the quoted market price of Common Shares (Level 1).
	The following table summarizes the acquisition date fair values of the above and below market ground and retail lease intangibles, which we determined using Level 2 and Level 3 inputs (amounts in thousands):
	Description		Balance Sheet Location		Fair Value
	Ground lease intangibles – below market		Other Assets		$	178,251
	Retail lease intangibles – above market		Other Assets		2,310
Ground lease intangibles – above market		Other Liabilities		2,400
Retail lease intangibles – below market		Other Liabilities		8,040
As of September 30, 2013, the Company has incurred Archstone-related expenses of approximately $95.4 million, of which approximately $13.5 million of this total was financing-related and approximately $81.9 million was merger costs. During the nine months ended September 30, 2013, the Company expensed $19.7 million of direct merger costs primarily related to investment banking and legal/accounting fees, which were included in merger expenses in the accompanying consolidated statements of operations and comprehensive income, and $54.8 million of indirect merger costs related to severance obligations and retention bonuses through our 60% interest in an unconsolidated joint venture with AVB, which were included in (loss) from investments in unconsolidated entities due to merger expenses in the accompanying consolidated statements of operations and comprehensive income. During the nine months ended September 30, 2013, the Company also expensed $2.5 million of financing-related costs, which were included in interest expense in the accompanying consolidated statements of operations and comprehensive income.
Unaudited Pro Forma Financial Information
Equity Residential
The following table illustrates the effect on net income, earnings per share – basic and earnings per share – diluted as if the Company had consummated the Archstone Acquisition as of January 1, 2012:
		Nine Months Ended September 30,								Quarter Ended September 30,
		2013				2012				2013			2012
		(Amounts in thousands, except per share amounts)
Total revenues		$	1,854,509			$	1,726,304			$	629,446		$	596,734
Income (loss) from continuing operations (1)		132,592				(179,574		)		84,978			107,024
Discontinued operations, net		2,024,346				434,253				403,181			145,145
Net income		2,156,938				254,679				488,159			252,169
Net income available to Common Shares		2,070,153				232,053				468,959			234,471
Earnings per share - basic:
Net income available to Common Shares		$	5.76			$	0.65			$	1.3		$	0.66
Weighted average Common Shares outstanding (2)		359,611				356,434				359,811			357,654
Earnings per share - diluted (1):
Net income available to Common Shares		$	5.74			$	0.65			$	1.3		$	0.66
Weighted average Common Shares outstanding (2)		375,808				356,434				375,883			375,091
-1	Potential common shares issuable from the assumed conversion of OP Units and the exercise/vesting of long-term compensation shares/units are automatically anti-dilutive and therefore excluded from the diluted earnings per share calculation as the Company had a pro forma loss from continuing operations for the nine months ended September 30, 2012.
-2	Includes an adjustment for Common Shares issued to the public in December 2012 and to an affiliate of Lehman Brothers Holdings Inc. in February 2013 as partial consideration for the Archstone Acquisition.
ERP Operating Limited Partnership
The following table illustrates the effect on net income, earnings per Unit – basic and earnings per Unit – diluted as if the Operating Partnership had consummated the Archstone Acquisition as of January 1, 2012:
		Nine Months Ended September 30,								Quarter Ended September 30,
		2013				2012				2013			2012
		(Amounts in thousands, except per Unit amounts)
Total revenues		$	1,854,509			$	1,726,304			$	629,446		$	596,734
Income (loss) from continuing operations (1)		132,592				(179,574		)		84,978			107,024
Discontinued operations, net		2,024,346				434,253				403,181			145,145
Net income		2,156,938				254,679				488,159			252,169
Net income available to Units		2,155,736				242,962				487,433			245,725
Earnings per Unit - basic:
Net income available to Units		$	5.76			$	0.65			$	1.3		$	0.66
Weighted average Units outstanding (2)		373,347				370,250				373,547			371,831
Earnings per Unit - diluted (1):
Net income available to Units		$	5.74			$	0.65			$	1.3		$	0.66
Weighted average Units outstanding (2)		375,808				370,250				375,883			375,091
-1	Potential Units issuable from the assumed exercise/vesting of the Company's long-term compensation shares/units are automatically anti-dilutive and therefore excluded from the diluted earnings per Unit calculation as the Operating Partnership had a pro forma loss from continuing operations for the nine months ended September 30, 2012.
-2	Includes an adjustment for Common Shares issued to the public in December 2012 and to an affiliate of Lehman Brothers Holdings Inc. in February 2013 as partial consideration for the Archstone Acquisition. Concurrent with these transactions, ERPOP issued the same number of OP Units to EQR.
For the nine months ended September 30, 2013 and 2012, acquisition costs of $19.7 million and $1.9 million, respectively, and severance/retention and other costs of $53.6 million and none, respectively, related to the Archstone Acquisition are not expected to have a continuing impact on the Company's financial results and therefore have been excluded from these pro forma results. The pro forma results also do not include the impact of any synergies or lower borrowing costs that the Company has or may achieve as a result of the acquisition or any strategies that management has or may consider in order to more efficiently manage the Company's operations, nor do they give pro forma effect to any other acquisitions, dispositions or capital markets transactions (excluding the equity offering in December 2012 which proceeds were used for the Archstone Acquisition) that the Company completed during the periods presented. These pro forma results are not necessarily indicative of the operating results that would have been obtained had the Archstone Acquisition occurred at the beginning of the periods presented, nor are they necessarily indicative of future operating results.
Other
In addition to the Archstone acquisition described above, during the nine months ended September 30, 2013, the Company acquired the entire equity interest in the following from unaffiliated parties (purchase price in thousands):
		Properties			Apartment Units			Purchase Price
Rental Properties – Consolidated		1			322			$	91,500
Land Parcel (one)		—			—			16,500
Total		1			322			$	108,000
During the nine months ended September 30, 2013, the Company disposed of the following to unaffiliated parties (sales price in thousands):
		Properties			Apartment Units			Sales Price
Consolidated:
Rental Properties		92			28,328			$	4,362,689
Land Parcels (six)		—			—			77,650
Other (1)		—			—			30,734
Unconsolidated:
Land Parcel (one) (2)		—			—			26,350
Total		92			28,328			$	4,497,423
(1) Represents a 97,000 square foot commercial building adjacent to our Harbor Steps apartment property in downtown Seattle that was acquired in 2011.
(2) Sales price listed is the gross sales price. EQR's share of the net sales proceeds approximated 25%.
The Company recognized a net gain on sales of discontinued operations of approximately $2.0 billion and a net gain on sales of land parcels of approximately $12.2 million on the above sales.

Commitments_to_AcquireDispose_

Commitments to Acquire/Dispose of Real Estate	9 Months Ended
	Sep. 30, 2013
Commitments to Acquire Dispose of Real Estate [Abstract]	'
Commitments To Acquire Dispose Of Real Estate Text Block	'
	5	Commitments to Acquire/Dispose of Real Estate
	The Company has entered into a separate agreement to acquire the following (purchase price in thousands):
			Properties	Apartment Units	Purchase Price
	Land Parcel (one)		—	—	$	12,500
	Total		—	—	$	12,500
	The Company has entered into a separate agreement to dispose of the following (sales price in thousands):
			Properties	Apartment Units	Sales Price
	Land Parcel (one)		—	—	$	27,000
	Total		—	—	$	27,000
	The closings of these pending transactions are subject to certain conditions and restrictions, therefore, there can be no assurance that these transactions will be consummated or that the final terms will not differ in material respects from those summarized in the preceding paragraphs.

Investments_in_Partially_Owned

Investments in Partially Owned Entities	9 Months Ended
	Sep. 30, 2013
Investments in Partially Owned Entities [Abstract]	'
Investments in Partially Owned Entities	'
	6	Investments in Partially Owned Entities
	The Company has co-invested in various properties with unrelated third parties which are either consolidated or accounted for under the equity method of accounting (unconsolidated). The following tables and information summarize the Company’s investments in partially owned entities as of September 30, 2013 (amounts in thousands except for project and apartment unit amounts):
		Consolidated									Unconsolidated
		Development Projects									Development Projects
		Held for			Operating			Total			Held for			Completed, Not Stabilized (3)			Operating			Total
		and/or Under									and/or Under
		Development									Development
	Total projects (1)	—			19			19			—			1			1			2
	Total apartment units (1)	—			3,752			3,752			—			501			336			837
	Balance sheet information at 9/30/13 (at 100%):
	ASSETS
	Investment in real estate	$	308,893		$	672,958		$	981,851		$	238,872		$	77,292		$	55,369		$	371,533
	Accumulated depreciation	—			(167,457		)	(167,457		)	(84		)	—			(4,165		)	(4,249		)
	Investment in real estate, net	308,893			505,501			814,394			238,788			77,292			51,204			367,284
	Cash and cash equivalents	4,253			17,659			21,912			1,153			317			1,357			2,827
	Investments in unconsolidated entities	—			55,040			55,040			—			—			—			—
	Deposits – restricted	43,631			206			43,837			—			—			—			—
	Deferred financing costs, net	—			2,521			2,521			—			5			5			10
	Other assets	5,781			27,170			32,951			333			5			1,038			1,376
	Total assets	$	362,558		$	608,097		$	970,655		$	240,274		$	77,619		$	53,604		$	371,497
	LIABILITIES AND EQUITY/CAPITAL
	Mortgage notes payable (2)	$	—		$	358,730		$	358,730		$	118,723		$	45,217		$	30,550		$	194,490
	Accounts payable & accrued expenses	27,052			2,495			29,547			13,781			2,864			(143		)	16,502
	Accrued interest payable	—			1,259			1,259			432			208			—			640
	Other liabilities	1,045			1,254			2,299			365			156			1,345			1,866
	Security deposits	1			1,821			1,822			94			75			18			187
	Total liabilities	28,098			365,559			393,657			133,395			48,520			31,770			213,685
	Noncontrolling Interests - Partially Owned	98,126			12,509			110,635			78,556			23,205			20,450			122,211
	Properties/Partners' equity
	Company equity/General and Limited	236,334			230,029			466,363			28,323			5,894			1,384			35,601
	Partners' Capital
	Total equity/capital	334,460			242,538			576,998			106,879			29,099			21,834			157,812
	Total liabilities and equity/capital	$	362,558		$	608,097		$	970,655		$	240,274		$	77,619		$	53,604		$	371,497
		Consolidated									Unconsolidated
		Development Projects									Development Projects
		Held for									Held for						Operating
		and/or Under									and/or Under			Completed, Not Stabilized (3)
		Development			Operating			Total			Development									Total
	Operating information for the nine months ended 9/30/13 (at 100%):
	Operating revenue	$	12		$	59,666		$	59,678		$	1,305		$	1,861		$	3,173		$	6,339
	Operating expenses	407			18,458			18,865			1,141			1,023			1,402			3,566
	Net operating (loss) income	(395		)	41,208			40,813			164			838			1,771			2,773
	Depreciation	—			26,478			26,478			84			—			4,165			4,249
	General and administrative/other	520			79			599			23			—			141			164
	Operating (loss) income	(915		)	14,651			13,736			57			838			(2,535		)	(1,640		)
	Interest and other income	2			3			5			—			—			10			10
	Other expenses	(334		)	(4		)	(338		)	—			—			—			—
	Interest:
	Expense incurred, net	(2		)	(10,615		)	(10,617		)	(152		)	(501		)	(658		)	(1,311		)
	Amortization of deferred financing costs	—			(216		)	(216		)	—			—			(1		)	(1		)
	(Loss) income before income and other taxes, (loss)	(1,249		)	3,819			2,570			(95		)	337			(3,184		)	(2,942		)
	from investments in unconsolidated entities, net
	(loss) gain on sales of land parcels and
	discontinued operations
	Income and other tax (expense) benefit	(11		)	(56		)	(67		)	—			—			—			—
	(Loss) from investments in unconsolidated entities	—			(1,010		)	(1,010		)	—			—			—			—
	Net (loss) on sales of land parcels	(17		)	—			(17		)	—			—			—			—
	Net gain on sales of discontinued operations	—			26,673			26,673			—			—			—			—
	Net (loss) income	$	(1,277	)	$	29,426		$	28,149		$	(95	)	$	337		$	(3,184	)	$	(2,942	)
	-1	Project and apartment unit counts exclude all uncompleted development projects until those projects are substantially completed.
	-2	All debt is non-recourse to the Company with the exception of 50% of the current $5.7 million outstanding debt balance on one unconsolidated development project.
	-3	Projects included here are substantially complete. However, they may still require additional exterior and interior work for all units to be available for leasing.
	Note:	The above tables exclude the Company's interests in unconsolidated joint ventures entered into with AVB in connection with the Archstone transaction. These ventures own certain non-core Archstone assets that are held for sale and succeeded to certain residual Archstone liabilities, such as liability for various employment-related matters as well as responsibility for tax protection arrangements and third-party preferred interests in former Archstone subsidiaries. The preferred interests have an aggregate liquidation value of $88.3 million at September 30, 2013. The ventures are owned 60% by the Company and 40% by AVB.
The Company is the controlling partner in various consolidated partnership properties and development properties having a noncontrolling interest book value of $110.6 million at September 30, 2013. The Company has identified one development partnership, consisting of a land parcel with a book value of $5.0 million, as a VIE. The Company does not have any unconsolidated VIEs.
On February 27, 2013, in conjunction with the Archstone Acquisition, the Company acquired interests in several joint ventures. Details of these interests follow by project:
Park Aire (formerly known as Enclave at Wellington) – This venture is currently developing certain land parcels into a 268 unit apartment building located in Wellington, Florida. The Company has a 95% equity interest with an initial basis of $26.2 million. Total project costs are expected to be approximately $50.0 million. The Company is the managing member, is responsible for constructing the project and its partner does not have substantive kick-out or participating rights. As a result, the entity is required to be consolidated on the Company's balance sheet.
East Palmetto Park – This venture was formed to ultimately develop certain land parcels into a 377 unit apartment building located in Boca Raton, Florida. The Company has a 90% equity interest with an initial basis of $20.2 million. The Company is the managing member, is responsible for constructing the project and its partner does not have substantive kick-out or participating rights. As a result, the entity is required to be consolidated on the Company's balance sheet.
Wisconsin Place – This venture was formed to develop and operate a mixed-use site located in Chevy Chase, Maryland consisting of residential, retail, office and accessory uses, including underground parking facilities. The Company has a 75% equity interest with an initial basis of $198.5 million in the 432 unit residential component. The Company is the managing member, was responsible for constructing the residential project and its partner does not have substantive kick-out or participating rights. As a result, the entity that owns the residential component of this mixed-use site is required to be consolidated on the Company's balance sheet. Such entity also retains an unconsolidated interest in an entity that owns the land underlying the project and owns and operates the parking facility. The initial fair value of this investment is $56.5 million. The Company does not have any ownership interest in the retail and office components.
San Norterra – This venture is currently developing certain land parcels into a 388 unit apartment building located in Phoenix, Arizona. The Company has an 85% equity interest with an initial basis of $16.9 million. Total project costs are approximately $56.3 million and construction is being partially funded with a construction loan that is guaranteed by the partner and non-recourse to the Company. The loan has a maximum debt commitment of $34.8 million and a current unconsolidated outstanding balance of $30.8 million; the loan bears interest at LIBOR plus 2.00% and matures January 6, 2015. The partner is the managing member and is developing the project. The Company does not have substantive kick-out or participating rights. As a result, the entity is unconsolidated and recorded using the equity method of accounting.
Waterton Tenside – This venture was formed to develop and operate a 336 unit apartment property located in Atlanta, Georgia. The Company has a 20% equity interest with an initial basis of $5.1 million. The partner is the managing member and developed the project. The project is encumbered by a non-recourse mortgage loan that has a current outstanding balance of $30.6 million, bears interest at 3.66% and matures December 1, 2018. The Company does not have substantive kick-out or participating rights. As a result, the entity is unconsolidated and recorded using the equity method of accounting.
Parkside at Emeryville – This venture is currently developing certain land parcels into a 180 unit apartment building located in Emeryville, California. The Company has a 5% equity interest with an initial obligation of approximately $2.1 million. Total project costs are expected to be approximately $75.0 million and construction is being partially funded with a construction loan. The loan has a maximum debt commitment of $39.5 million and a current unconsolidated outstanding balance of $5.7 million; the loan bears interest at LIBOR plus 2.25% and matures August 14, 2015. The Company has given a repayment guaranty on the construction loan of 50% of the outstanding balance, up to a maximum of $19.7 million, and has given certain construction cost overrun guarantees. The partner is the managing member and is developing the project. The Company does not have substantive kick-out or participating rights. As a result, the entity is unconsolidated and recorded using the equity method of accounting.
On February 27, 2013, in connection with the Archstone Acquisition, subsidiaries of the Company and AVB entered into three limited liability company agreements (collectively, the “Residual JV”). The Residual JV owns certain non-core Archstone assets that are held for sale, such as interests in a German portfolio of apartment buildings, and succeeded to certain residual Archstone liabilities, such as liability for various employment-related matters. The Residual JV is owned 60% by the Company and 40% by AVB and the Company's initial investment was $105.1 million. The venture is managed by a Management Committee consisting of two members from each of the Company and AVB. Both partners have equal participation in the Management Committee and all significant participating rights are shared by both partners. As a result, the venture is unconsolidated and recorded using the equity method of accounting.
On February 27, 2013, in connection with the Archstone Acquisition, a subsidiary of the Company and AVB entered into a limited liability company agreement (the “Legacy JV”), through which they assumed obligations of Archstone in the form of preferred interests, some of which are governed by tax protection arrangements. During the nine months ended September 30, 2013, the Company purchased with AVB $65.0 million (of which the Company's 60% share was $39.0 million) of the preferred interests assumed by Legacy JV. At September 30, 2013, the remaining preferred interests have an aggregate liquidation value of $88.3 million, our share of which is included in other liabilities in the accompanying consolidated balance sheets. Obligations of the venture are borne 60% by the Company and 40% by AVB. The venture is managed by a Management Committee consisting of two members from each of the Company and AVB. Both partners have equal participation in the Management Committee and all significant participating rights are shared by both partners. As a result, the venture is unconsolidated and recorded using the equity method of accounting.
In December 2011, the Company and Toll Brothers (NYSE: TOL) jointly acquired a vacant land parcel at 400 Park Avenue South in New York City. The Company's and Toll Brothers' allocated portions of the purchase price were approximately $76.1 million and $57.9 million, respectively. The Company is the managing member and Toll Brothers does not have substantive kick-out or participating rights. Until the core and shell of the building is complete, the building and land will be owned jointly and are required to be consolidated on the Company's balance sheet. Thereafter, the Company will solely own and control the rental portion of the building (floors 2-22) and Toll Brothers will solely own and control the for sale portion of the building (floors 23-40). Once the core and shell are complete, the Toll Brothers' portion of the property will be deconsolidated from the Company's balance sheet. The acquisition was financed through contributions by the Company and Toll Brothers of approximately $102.5 million and $75.7 million, respectively, which included the land purchase noted above, restricted deposits and taxes and fees. As of September 30, 2013, the Company's and Toll Brothers' consolidated contributions to the joint venture were approximately $259.1 million, of which Toll Brothers' noncontrolling interest balance totaled $95.5 million.
The Company admitted an 80% institutional partner to two separate entities/transactions (Nexus Sawgrass in December 2010 and Domain in August 2011), each owning a developable land parcel, in exchange for $40.1 million in cash and retained a 20% equity interest in both of these entities. These projects are now unconsolidated. Details of these projects follow:
•	Nexus Sawgrass – This development project was substantially completed as of September 30, 2013. Total project costs are expected to be approximately $78.2 million and construction is being predominantly funded with a long-term, non-recourse secured loan from the partner. The mortgage loan has a maximum debt commitment of $48.7 million and a current unconsolidated outstanding balance of $45.2 million; the loan bears interest at 5.60% and matures January 1, 2021.
•	Domain – This project is currently under development. Total project costs are expected to be approximately $154.6 million and construction is being predominantly funded with a long-term, non-recourse secured loan from the partner. The mortgage loan has a maximum debt commitment of $98.6 million and a current unconsolidated outstanding balance of $82.2 million; the loan bears interest at 5.75% and matures January 1, 2022.
While the Company is the managing member of both of the joint ventures, was/is responsible for constructing both of the projects and has given certain construction cost overrun guarantees, the joint venture partner has significant participating rights and has active involvement in and oversight of the ongoing projects. The Company currently has no further funding obligations related to these projects.

Deposits_Restricted

Deposits - Restricted	9 Months Ended
	Sep. 30, 2013
Deposits - Restricted [Abstract]	'
Restricted Cash And Cash Equivalents Disclosure [Text Block]	'
	7	Deposits – Restricted
	The following table presents the Company’s restricted deposits as of September 30, 2013 and December 31, 2012 (amounts in thousands):
			September 30,		December 31,
			2013		2012
	Tax–deferred (1031) exchange proceeds		$	—	$	152,182
	Earnest money on pending acquisitions		350		5,613
	Restricted deposits on real estate investments		53,764		44,209
	Resident security and utility deposits		44,255		44,199
	Other		505		4,239
	Totals		$	98,874	$	250,442

Debt

Debt	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Debt Disclosure [Text Block]	'
	8.    Debt
	EQR does not have any indebtedness as all debt is incurred by the Operating Partnership. EQR guarantees the Operating Partnership’s $750.0 million senior unsecured delayed draw term loan facility and also guarantees the Operating Partnership’s revolving credit facility up to the maximum amount and for the full term of the facility.
	Mortgage Notes Payable
	As of September 30, 2013, the Company had outstanding mortgage debt of approximately $6.2 billion.
	During the nine months ended September 30, 2013, the Company:
	▪	Repaid $711.3 million of mortgage loans;
	▪	Assumed $2.2 billion of mortgage debt held in two Fannie Mae loan pools, consisting of $1.2 billion collateralized by 16 properties with an interest rate of 6.256% and a maturity date of November 1, 2017 and $1.0 billion collateralized by 15 properties with an interest rate of 5.883% and a maturity date of November 1, 2014;
	▪	Assumed $346.6 million of tax-exempt bonds on four properties with interest rates ranging from SIFMA plus 0.860% to SIFMA plus 1.402% and maturity dates through November 15, 2036;
	▪	Assumed $339.0 million of other mortgage debt on three properties with fixed interest rates ranging from 0.100% to 5.240% and maturity dates through May 1, 2061;
	▪	Assumed $34.1 million of other mortgage debt on one property with a variable rate of LIBOR plus 1.75% and a maturity date of September 1, 2014; and
	▪	Recorded $127.9 million of net mark-to-market premiums on the mortgage debt described in the bullets above.
	The Company recorded approximately $71.4 million, $1.6 million and $3.3 million of prepayment penalties, write-offs of unamortized deferred financing costs and write-offs of unamortized discounts, respectively, during the nine months ended September 30, 2013 as additional interest expense related to debt extinguishment of mortgages.
	As of September 30, 2013, the Company had $700.5 million of secured debt subject to third party credit enhancement.
	As of September 30, 2013, scheduled maturities for the Company’s outstanding mortgage indebtedness were at various dates through May 1, 2061. At September 30, 2013, the interest rate range on the Company’s mortgage debt was 0.05% to 7.25%. During the nine months ended September 30, 2013, the weighted average interest rate on the Company’s mortgage debt was 4.25%.
	Notes
	As of September 30, 2013, the Company had outstanding unsecured notes of approximately $5.5 billion.
	During the nine months ended September 30, 2013, the Company:
	▪	Repaid $400.0 million of 5.200% unsecured notes at maturity;
	▪	Issued $500.0 million of ten-year 3.00% fixed rate public notes, receiving net proceeds of $495.6 million before underwriting fees, hedge termination costs and other expenses, at an all-in effective interest rate of 3.998%; and
	▪	Entered into a senior unsecured $750.0 million delayed draw term loan facility which was fully drawn on February 27, 2013 in connection with the Archstone acquisition. The maturity date of January 11, 2015 is subject to a one-year extension option exercisable by the Company. The interest rate on advances under the term loan facility will generally be LIBOR plus a spread (currently 1.20%), which is dependent on the credit rating of the Company's long-term debt.
	In November 2012, the Company obtained a commitment for a senior unsecured bridge loan facility in an aggregate principal amount not to exceed $2.5 billion to finance the acquisition of Archstone and to pay fees and expenses relating to this transaction. On January 11, 2013, the Company terminated this $2.5 billion bridge loan facility in connection with the execution of the term loan facility discussed above and the new revolving credit facility discussed below. The Company wrote off approximately $2.5 million of unamortized deferred financing costs during the nine months ended September 30, 2013 as additional interest expense.
	As of September 30, 2013, scheduled maturities for the Company’s outstanding notes were at various dates through 2026. At September 30, 2013, the interest rate range on the Company’s notes was 1.34% to 7.57%. During the nine months ended September 30, 2013, the weighted average interest rate on the Company’s notes was 5.06%.
	Lines of Credit
	On January 11, 2013, the Company replaced its existing $1.75 billion facility with a $2.5 billion unsecured revolving credit facility maturing April 1, 2018. The Company has the ability to increase available borrowings by an additional $500.0 million by adding additional banks to the facility or obtaining the agreement of existing banks to increase their commitments. The interest rate on advances under the new credit facility will generally be LIBOR plus a spread (currently 1.05%) and the Company pays an annual facility fee (currently 15 basis points). Both the spread and the facility fee are dependent on the credit rating of the Company's long-term debt. The existing $1.75 billion facility was scheduled to mature in July 2014.
	As of September 30, 2013, the amount available on the credit facility was $2.47 billion (net of $34.9 million which was restricted/dedicated to support letters of credit). During the nine months ended September 30, 2013, the weighted average interest rate was 1.28%.

Derivative_and_Other_Fair_Valu

Derivative and Other Fair Value Instruments	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Derivatives and Fair Value [Text Block]	'
	9	Derivative and Other Fair Value Instruments
	The valuation of financial instruments requires the Company to make estimates and judgments that affect the fair value of the instruments. The Company, where possible, bases the fair values of its financial instruments, including its derivative instruments, on listed market prices and third party quotes. Where these are not available, the Company bases its estimates on current instruments with similar terms and maturities or on other factors relevant to the financial instruments.
	The carrying values of the Company’s mortgage notes payable and unsecured notes were approximately $6.2 billion and $5.5 billion, respectively, at September 30, 2013. The fair values of the Company’s mortgage notes payable and unsecured notes were approximately $6.4 billion (Level 2) and $5.8 billion (Level 2), respectively, at September 30, 2013. The carrying values of the Company's mortgage notes payable and unsecured notes were approximately $3.9 billion and $4.6 billion, respectively, at December 31, 2012. The fair values of the Company’s mortgage notes payable and unsecured notes were approximately $4.3 billion (Level 2) and $5.2 billion (Level 2), respectively, at December 31, 2012. The fair values of the Company’s financial instruments (other than mortgage notes payable, unsecured notes, derivative instruments and investment securities), including cash and cash equivalents and other financial instruments, approximate their carrying or contract values.
	In the normal course of business, the Company is exposed to the effect of interest rate changes. The Company seeks to manage these risks by following established risk management policies and procedures including the use of derivatives to hedge interest rate risk on debt instruments. The Company may also use derivatives to manage its exposure to foreign exchange rates or manage commodity prices in the daily operations of the business.
	The following table summarizes the Company’s consolidated derivative instruments at September 30, 2013 (dollar amounts are in thousands):
			Forward
			Starting
			Swaps (1)
	Current Notional Balance		$	400,000
	Lowest Possible Notional		$	400,000
	Highest Possible Notional		$	400,000
	Lowest Interest Rate		2.125		%
	Highest Interest Rate		3.23		%
	Earliest Maturity Date		2024
	Latest Maturity Date		2024
	-1	Forward Starting Swaps – Designed to partially fix the interest rate in advance of a planned future debt issuance. These swaps have mandatory counterparty terminations in 2015, and are targeted to 2014 issuances.
	In April 2013, the Company's remaining fair value hedges matured.
	A three-level valuation hierarchy exists for disclosure of fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The three levels are defined as follows:
	•	Level 1 – Inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities in active markets.
	•	Level 2 – Inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument.
	•	Level 3 – Inputs to the valuation methodology are unobservable and significant to the fair value measurement.
	The Company’s derivative positions are valued using models developed by the respective counterparty as well as models developed internally by the Company that use as their basis readily observable market parameters (such as forward yield curves and credit default swap data). Employee holdings other than Common Shares within the supplemental executive retirement plan (the “SERP”) are valued using quoted market prices for identical assets and are included in other assets and other liabilities on the consolidated balance sheet. The Company’s investment securities are valued using quoted market prices or readily available market interest rate data. Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners are valued using the quoted market price of Common Shares. The fair values disclosed for mortgage notes payable and unsecured notes were calculated using indicative rates provided by lenders of similar loans in the case of mortgage notes payable and the private unsecured notes and quoted market prices for each underlying issuance in the case of the public unsecured notes.
	The following tables provide a summary of the fair value measurements for each major category of assets and liabilities measured at fair value on a recurring basis and the location within the accompanying Consolidated Balance Sheets at September 30, 2013 and December 31, 2012, respectively (amounts in thousands):
								Fair Value Measurements at Reporting Date Using
	Description		Balance Sheet		9/30/13			Quoted Prices in			Significant  Other				Significant
			Location					Active Markets for			Observable Inputs				Unobservable Inputs
								Identical Assets/Liabilities			(Level 2)				(Level  3)
								(Level 1)
	Assets
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Forward Starting Swaps		Other Assets		$	12,132		$	—		$	12,132			$	—
	Supplemental Executive Retirement Plan		Other Assets		78,629			78,629			—				—
	Available-for-Sale Investment Securities		Other Assets		1,675			1,675			—				—
	Total				$	92,436		$	80,304		$	12,132			$	—
	Liabilities
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Forward Starting Swaps		Other Liabilities		$	3,456		$	—		$	3,456			$	—
	Supplemental Executive Retirement Plan		Other Liabilities		78,629			78,629			—				—
	Total				$	82,085		$	78,629		$	3,456			$	—
	Redeemable Noncontrolling Interests –
	Operating Partnership/Redeemable
	Limited Partners		Mezzanine		$	376,057		$	—		$	376,057			$	—
								Fair Value Measurements at Reporting Date Using
	Description		Balance Sheet		12/31/12			Quoted Prices in			Significant  Other				Significant
			Location					Active Markets for			Observable Inputs				Unobservable Inputs
								Identical Assets/Liabilities			(Level 2)				(Level  3)
								(Level 1)
	Assets
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Fair Value Hedges		Other Assets		$	1,524		$	—		$	1,524			$	—
	Supplemental Executive Retirement Plan		Other Assets		70,655			70,655			—				—
	Available-for-Sale Investment Securities		Other Assets		2,214			2,214			—				—
	Total				$	74,393		$	72,869		$	1,524			$	—
	Liabilities
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Forward Starting Swaps		Other Liabilities		$	44,050		$	—		$	44,050			$	—
	Supplemental Executive Retirement Plan		Other Liabilities		70,655			70,655			—				—
	Total				$	114,705		$	70,655		$	44,050			$	—
	Redeemable Noncontrolling Interests –
Operating Partnership/Redeemable
Limited Partners		Mezzanine		$	398,372		$	—		$	398,372			$	—
The following tables provide a summary of the effect of fair value hedges on the Company’s accompanying Consolidated Statements of Operations and Comprehensive Income for the nine months ended September 30, 2013 and 2012, respectively (amounts in thousands):
30-Sep-13		Location of		Amount of			Hedged Item		Income Statement	Amount of
Type of Fair Value Hedge		Gain/(Loss)		Gain/(Loss)					Location of	Gain/(Loss)
		Recognized in		Recognized in					Hedged	Recognized in
		Income		Income					Item Gain/(Loss)	Income
		on Derivative		on Derivative						on Hedged Item
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Interest Rate Swaps		Interest expense		$	(1,524	)	Fixed rate debt		Interest expense	$	1,524
Total				$	(1,524	)				$	1,524
30-Sep-12		Location of		Amount of			Hedged Item		Income Statement	Amount of
Type of Fair Value Hedge		Gain/(Loss)		Gain/(Loss)					Location of	Gain/(Loss)
		Recognized in		Recognized in					Hedged	Recognized in
		Income		Income					Item Gain/(Loss)	Income
		on Derivative		on Derivative						on Hedged Item
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Interest Rate Swaps		Interest expense		$	(5,934	)	Fixed rate debt		Interest expense	$	5,934
Total				$	(5,934	)				$	5,934
The following tables provide a summary of the effect of cash flow hedges on the Company’s accompanying Consolidated Statements of Operations and Comprehensive Income for the nine months ended September 30, 2013 and 2012, respectively (amounts in thousands):
		Effective Portion								Ineffective Portion
30-Sep-13		Amount of				Location of Gain/	Amount of Gain/			Location of		Amount of Gain/
Type of Cash Flow Hedge		Gain/(Loss)				(Loss)	(Loss)			Gain/(Loss)		(Loss)
		Recognized in OCI				Reclassified from	Reclassified from			Recognized in		Reclassified from
		on Derivative				Accumulated	Accumulated			Income		Accumulated
						OCI	OCI			on Derivative		OCI
						into Income	into Income					into Income
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Forward Starting Swaps/Treasury Locks		$	8,737			Interest expense	$	(16,084	)	N/A		$	—
Total		$	8,737				$	(16,084	)			$	—
		Effective Portion								Ineffective Portion
30-Sep-12		Amount of				Location of Gain/	Amount of Gain/			Location of		Amount of Gain/
Type of Cash Flow Hedge		Gain/(Loss)				(Loss)	(Loss)			Gain/(Loss)		(Loss)
		Recognized in OCI				Reclassified from	Reclassified from			Recognized in		Reclassified from
		on Derivative				Accumulated	Accumulated			Income		Accumulated
						OCI	OCI			on Derivative		OCI
						into Income	into Income					into Income
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Forward Starting Swaps/Treasury Locks		$	(12,337	)		Interest expense	$	(10,907	)	N/A		$	—
Total		$	(12,337	)			$	(10,907	)			$	—
As of September 30, 2013 and December 31, 2012, there were approximately $169.9 million and $194.7 million in deferred losses, net, included in accumulated other comprehensive (loss), respectively, related to derivative instruments. Based on the estimated fair values of the net derivative instruments at September 30, 2013, the Company may recognize an estimated $21.7 million of accumulated other comprehensive (loss) as additional interest expense during the twelve months ending September 30, 2014.
In April 2013, the Company paid approximately $44.7 million to settle three forward starting swaps in conjunction with the issuance of $500.0 million of ten-year fixed rate public notes. The accrued interest of $0.7 million was recorded as interest expense. The remaining amount of $44.0 million will be deferred as a component of accumulated other comprehensive (loss) and recognized as an increase to interest expense over the approximate term of the notes.
The following tables set forth the maturity, amortized cost, gross unrealized gains and losses, book/fair value and interest and other income of the various investment securities held as of September 30, 2013 and December 31, 2012, respectively (amounts in thousands):
				Other Assets
30-Sep-13		Maturity		Amortized			Unrealized			Unrealized				Book/		Interest and
Security				Cost			Gains			Losses				Fair Value		Other Income
Available-for-Sale Investment Securities		N/A		$	412		$	1,263		$	—			$	1,675	$	830
Total				$	412		$	1,263		$	—			$	1,675	$	830
				Other Assets
31-Dec-12		Maturity		Amortized			Unrealized			Unrealized				Book/		Interest and
Security				Cost			Gains			Losses				Fair Value		Other Income
Available-for-Sale Investment Securities		N/A		$	675		$	1,539		$	—			$	2,214	$	—
Total				$	675		$	1,539		$	—			$	2,214	$	—
During the nine months ended September 30, 2013, the Company sold certain investment securities, receiving proceeds of approximately $0.8 million (with an additional $0.3 million recorded as a receivable and received after quarter-end), and recorded a $0.8 million realized gain on sale (specific identification) which is included in interest and other income.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Earnings Per Share And Earnings Per Unit [Text Block]	'
	10	Earning Per Share and Earnings Per Unit
	Equity Residential
	The following tables set forth the computation of net income per share – basic and net income per share – diluted for the Company (amounts in thousands except per share amounts):
			Nine Months Ended September 30,						Quarter Ended September 30,
			2013			2012			2013			2012
	Numerator for net income per share – basic:
	(Loss) income from continuing operations		$	(234,414	)	$	62,103		$	(12,467	)	$	92,181
	Allocation to Noncontrolling Interests – Operating Partnership, net		9,402			(2,128		)	483			(3,895		)
	Net loss (income) attributable to Noncontrolling Interests – Partially		1,101			(457		)	311			312
	Owned Properties
	Preferred distributions		(3,109		)	(9,319		)	(1,037		)	(2,386		)
	Premium on redemption of Preferred Shares		—			(5,150		)	—			(5,150		)
	(Loss) income from continuing operations available to Common Shares,		(227,020		)	45,049			(12,710		)	81,062
	net of Noncontrolling Interests
	Discontinued operations, net of Noncontrolling Interests		1,943,548			415,184			388,865			137,541
	Numerator for net income per share – basic		$	1,716,528		$	460,233		$	376,155		$	218,603
	Numerator for net income per share – diluted (1):
	(Loss) income from continuing operations					$	62,103					$	92,181
	Net loss (income) attributable to Noncontrolling Interests – Partially					(457		)				312
	Owned Properties
	Preferred distributions					(9,319		)				(2,386		)
	Premium on redemption of Preferred Shares					(5,150		)				(5,150		)
	(Loss) income from continuing operations available to Common Shares					47,177						84,957
	Discontinued operations, net					434,702						144,142
	Numerator for net income per share – diluted (1)		$	1,716,528		$	481,879		$	376,155		$	229,099
	Denominator for net income per share – basic and diluted (1):
	Denominator for net income per share – basic		352,414			300,116			359,811			301,336
	Effect of dilutive securities:
	OP Units					13,816						14,177
	Long-term compensation shares/units					3,333						3,260
	Denominator for net income per share – diluted (1)		352,414			317,265			359,811			318,773
	Net income per share – basic		$	4.87		$	1.53		$	1.05		$	0.73
	Net income per share – diluted		$	4.87		$	1.52		$	1.05		$	0.72
	Net income per share – basic:
	(Loss) income from continuing operations available to Common Shares,		$	(0.644	)	$	0.15		$	(0.035	)	$	0.269
	net of Noncontrolling Interests
	Discontinued operations, net of Noncontrolling Interests		5.515			1.384			1.08			0.456
	Net income per share – basic		$	4.871		$	1.534		$	1.045		$	0.725
	Net income per share – diluted (1):
	(Loss) income from continuing operations available to Common Shares		$	(0.644	)	$	0.149		$	(0.035	)	$	0.267
	Discontinued operations, net		5.515			1.37			1.08			0.452
	Net income per share – diluted		$	4.871		$	1.519		$	1.045		$	0.719
	-1	Potential common shares issuable from the assumed conversion of OP Units and the exercise/vesting of long-term compensation shares/units are automatically anti-dilutive and therefore excluded from the diluted earnings per share calculation as the Company had a loss from continuing operations for the nine months and quarters ended September 30, 2013.
	ERP Operating Limited Partnership
	The following tables set forth the computation of net income per Unit – basic and net income per Unit – diluted for the Operating Partnership (amounts in thousands except per Unit amounts):
			Nine Months Ended September 30,						Quarter Ended September 30,
			2013			2012			2013			2012
	Numerator for net income per Unit – basic and diluted (1):
	(Loss) income from continuing operations		$	(234,414	)	$	62,103		$	(12,467	)	$	92,181
	Net loss (income) attributable to Noncontrolling Interests – Partially		1,101			(457		)	311			312
	Owned Properties
	Allocation to Preference Units		(3,109		)	(9,319		)	(1,037		)	(2,386		)
	Allocation to premium on redemption of Preference Units		—			(5,150		)	—			(5,150		)
	(Loss) income from continuing operations available to Units		(236,422		)	47,177			(13,193		)	84,957
	Discontinued operations, net		2,023,897			434,702			404,184			144,142
	Numerator for net income per Unit – basic and diluted (1)		$	1,787,475		$	481,879		$	390,991		$	229,099
	Denominator for net income per Unit – basic and diluted (1):
	Denominator for net income per Unit – basic		366,150			313,932			373,547			315,513
	Effect of dilutive securities:
	Dilution for Units issuable upon assumed exercise/vesting of the					3,333						3,260
	Company's long-term compensation shares/units
	Denominator for net income per Unit – diluted (1)		366,150			317,265			373,547			318,773
	Net income per Unit – basic		$	4.87		$	1.53		$	1.05		$	0.73
Net income per Unit – diluted		$	4.87		$	1.52		$	1.05		$	0.72
Net income per Unit – basic:
(Loss) income from continuing operations available to Units		$	(0.644	)	$	0.15		$	(0.035	)	$	0.269
Discontinued operations, net		5.515			1.384			1.08			0.456
Net income per Unit – basic		$	4.871		$	1.534		$	1.045		$	0.725
Net income per Unit – diluted (1):
(Loss) income from continuing operations available to Units		$	(0.644	)	$	0.149		$	(0.035	)	$	0.267
Discontinued operations, net		5.515			1.37			1.08			0.452
Net income per Unit – diluted		$	4.871		$	1.519		$	1.045		$	0.719
-1	Potential Units issuable from the assumed exercise/vesting of the Company's long-term compensation shares/units are automatically anti-dilutive and therefore excluded from the diluted earnings per Unit calculation as the Operating Partnership had a loss from continuing operations for the nine months and quarters ended September 30, 2013.

Discontinued_Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2013
Discontinued Operations and Disposal Groups [Abstract]	'
Discontinued Operations	'
	11	Discontinued Operations
	The Company has presented separately as discontinued operations in all periods the results of operations for all consolidated assets disposed of and all properties held for sale, if any.
	The components of discontinued operations are outlined below and include the results of operations for the respective periods that the Company owned such assets during the nine months and quarters ended September 30, 2013 and 2012 (amounts in thousands).
			Nine Months Ended September 30,						Quarter Ended September 30,
			2013			2012			2013			2012
	REVENUES
	Rental income		$	110,986		$	334,968		$	8,418		$	108,459
	Total revenues		110,986			334,968			8,418			108,459
	EXPENSES (1)
	Property and maintenance		33,181			79,482			3,272			25,608
	Real estate taxes and insurance		10,578			29,599			396			11,480
	Property management		1			211			—			70
	Depreciation		31,976			94,792			2,273			29,497
	General and administrative		76			87			3			44
	Total expenses		75,812			204,171			5,944			66,699
	Discontinued operating income		35,174			130,797			2,474			41,760
	Interest and other income		156			81			65			34
	Other expenses		(3		)	(170		)	—			(23		)
	Interest (2):
	Expense incurred, net		(1,276		)	(3,357		)	(18		)	(995		)
	Amortization of deferred financing costs		(228		)	(119		)	—			(27		)
	Income and other tax (expense) benefit		(503		)	23			(40		)	(1		)
	Discontinued operations		33,320			127,255			2,481			40,748
	Net gain on sales of discontinued operations		1,990,577			307,447			401,703			103,394
	Discontinued operations, net		$	2,023,897		$	434,702		$	404,184		$	144,142
	-1	Includes expenses paid in the current period for properties sold in prior periods related to the Company’s period of ownership.
	-2	Includes only interest expense specific to secured mortgage notes payable for properties sold.
	For the properties sold during the nine months ended September 30, 2013, the investment in real estate, net of accumulated depreciation, and the mortgage notes payable balances at December 31, 2012 were $2.0 billion and $34.4 million, respectively.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies [Abstract]	'
Commitments and Contingencies	'
	12	Commitments and Contingencies
	The Company, as an owner of real estate, is subject to various Federal, state and local environmental laws. Compliance by the Company with existing laws has not had a material adverse effect on the Company. However, the Company cannot predict the impact of new or changed laws or regulations on its current properties or on properties that it may acquire in the future.
	The Company is party to a housing discrimination lawsuit brought by a non-profit civil rights organization in April 2006 in the U.S. District Court for the District of Maryland. The suit alleges that the Company designed and built approximately 300 of its properties in violation of the accessibility requirements of the Fair Housing Act and Americans With Disabilities Act. The suit seeks actual and punitive damages, injunctive relief (including modification of non-compliant properties), costs and attorneys’ fees. The Company believes it has a number of viable defenses, including that a majority of the named properties were completed before the operative dates of the statutes in question and/or were not designed or built by the Company. Accordingly, the Company is defending the suit vigorously. Due to the pendency of the Company’s defenses and the uncertainty of many other critical factual and legal issues, it is not possible to determine or predict the outcome of the suit or a possible loss or a range of loss, and no amounts have been accrued at September 30, 2013. While no assurances can be given, the Company does not believe that the suit, if adversely determined, would have a material adverse effect on the Company.
	The Company does not believe there is any other litigation pending or threatened against it that, individually or in the aggregate, may reasonably be expected to have a material adverse effect on the Company.
	As of September 30, 2013, the Company has 13 consolidated projects (including 400 Park Avenue South in New York City which the Company is jointly developing with Toll Brothers that is discussed below and Park Aire in which the Company acquired a 95% interest in connection with the Archstone transaction that is discussed in Note 6) totaling 3,327 apartment units in various stages of development with commitments to fund of approximately $608.7 million and estimated completion dates ranging through June 30, 2016, as well as other completed development projects that are in various stages of lease up or are stabilized. Some of the projects are being developed solely by the Company, while others are being co-developed with various third party development partners. The development venture agreements with these partners are primarily deal-specific, with differing terms regarding profit-sharing, equity contributions, returns on investment, buy-sell agreements and other customary provisions. The Company is the "general" or "managing" partner of the development venture.
	As of September 30, 2013, the Company has three unconsolidated projects totaling 1,012 apartment units under development with estimated completion dates ranging through September 30, 2014, as well as one completed development project that is currently in lease up. These projects are all being co-developed with various third party development partners. The development venture agreements with these partners are primarily deal-specific, with differing terms regarding profit-sharing, equity contributions, returns on investment, buy-sell agreements and other customary provisions. The Company currently has no further funding obligations for Domain,  Nexus Sawgrass and San Norterra. While the Company is the managing member of the Domain and Nexus Sawgrass joint ventures, is responsible for constructing both projects and has given certain construction cost overrun guarantees, the joint venture partner has significant participating rights and has active involvement in and oversight of the ongoing projects. The Domain and Nexus Sawgrass buy-sell arrangements contain provisions that provide the right, but not the obligation, for the Company to acquire the partner’s interests or sell its interests at any time following the occurrence of certain pre-defined events (including at stabilization) described in the development venture agreements. The respective partner for San Norterra and Parkside at Emeryville is the “general” or “managing” partner of the development venture and the Company does not have substantive kick-out or participating rights. The Company has given a repayment guaranty on the construction loan for Parkside at Emeryville of 50% of the outstanding balance, up to a maximum of $19.7 million, and has given certain construction cost overrun guarantees.
	In December 2011, the Company and Toll Brothers (NYSE: TOL) jointly acquired a vacant land parcel at 400 Park Avenue South in New York City. The Company's and Toll Brothers' allocated portions of the purchase price were approximately $76.1 million and $57.9 million, respectively. The Company is the managing member and Toll Brothers does not have substantive kick-out or participating rights. Until the core and shell of the building is complete, the building and land will be owned jointly and are required to be consolidated on the Company's balance sheet. Thereafter, the Company will solely own and control the rental portion of the building (floors 2-22) and Toll Brothers will solely own and control the for sale portion of the building (floors 23-40). Once the core and shell are complete, the Toll Brothers' portion of the property will be deconsolidated from the Company's balance sheet. The acquisition was financed through contributions by the Company and Toll Brothers of approximately $102.5 million and $75.7 million, respectively, which included the land purchase noted above, restricted deposits and taxes and fees. As of September 30, 2013, the Company's and Toll Brothers' consolidated contributions to the joint venture were approximately $259.1 million, of which Toll Brothers' noncontrolling interest balance totaled $95.5 million.

Reportable_Segments

Reportable Segments	9 Months Ended
	Sep. 30, 2013
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]	'
Segment Reporting Disclosure [Text Block]	'
	13	Reportable Segments
	Operating segments are defined as components of an enterprise that engage in business activities from which they may earn revenues and incur expenses and about which discrete financial information is available that is evaluated regularly by the chief operating decision maker. The chief operating decision maker decides how resources are allocated and assesses performance on a recurring basis at least quarterly.
	The Company’s primary business is the acquisition, development and management of multifamily residential properties, which includes the generation of rental and other related income through the leasing of apartment units to residents. The chief operating decision maker evaluates the Company's operating performance geographically by market and both on a same store and non-same store basis. The Company’s operating segments (geographic markets) have been aggregated into four reportable segments based upon the geographic region in which they are located.
	The Company’s fee and asset management and development (including its partially owned properties) activities are other business activities that do not constitute an operating segment and as such, have been aggregated in the "Other" category in the tables presented below.
	All revenues are from external customers and there is no customer who contributed 10% or more of the Company’s total revenues during the nine months and quarters ended September 30, 2013 and 2012, respectively.
	The primary financial measure for the Company’s rental real estate segment is net operating income (“NOI”), which represents rental income less: 1) property and maintenance expense; 2) real estate taxes and insurance expense; and 3) property management expense (all as reflected in the accompanying consolidated statements of operations and comprehensive income). The Company believes that NOI is helpful to investors as a supplemental measure of its operating performance because it is a direct measure of the actual operating results of the Company’s apartment communities. Current year NOI is compared to prior year NOI and current year budgeted NOI as a measure of financial performance. The following tables present NOI for each segment from our rental real estate specific to continuing operations for the nine months and quarters ended September 30, 2013 and 2012, respectively, as well as total assets and capital expenditures at September 30, 2013 (amounts in thousands):
			Nine Months Ended September 30, 2013
			Northeast			Northwest			Southeast			Southwest			Other (3)			Total
	Rental income:
	Same store (1)		$	555,391		$	303,680		$	175,039		$	295,216		$	—		$	1,329,326
	Non-same store/other (2) (3)		263,745			99,689			1,785			51,492			3,337			420,048
	Total rental income		819,136			403,369			176,824			346,708			3,337			1,749,374
	Operating expenses:
	Same store (1)		198,068			101,982			66,013			96,446			—			462,509
	Non-same store/other (2) (3)		86,820			34,352			696			21,656			9,341			152,865
	Total operating expenses		284,888			136,334			66,709			118,102			9,341			615,374
	NOI:
	Same store (1)		357,323			201,698			109,026			198,770			—			866,817
	Non-same store/other (2) (3)		176,925			65,337			1,089			29,836			(6,004		)	267,183
	Total NOI		$	534,248		$	267,035		$	110,115		$	228,606		$	(6,004	)	$	1,134,000
	Total assets		$	11,499,130		$	4,540,404		$	1,513,074		$	3,578,742		$	2,680,081		$	23,811,431
	Capital expenditures		$	39,331		$	23,793		$	13,270		$	15,360		$	5,112		$	96,866
	-1	Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2012, less properties subsequently sold, which represented 81,099 apartment units.
	-2	Non-same store primarily includes properties acquired after January 1, 2012, plus any properties in lease-up and not stabilized as of January 1, 2012.
	-3	Other includes development and other corporate operations.
			Nine Months Ended September 30, 2012
			Northeast			Northwest			Southeast			Southwest			Other (3)			Total
	Rental income:
	Same store (1)		$	535,830		$	282,586		$	167,561		$	283,899		$	—		$	1,269,876
	Non-same store/other (2) (3)		15,876			8,049			—			1,793			(163		)	25,555
	Total rental income		551,706			290,635			167,561			285,692			(163		)	1,295,431
	Operating expenses:
	Same store (1)		190,979			98,616			64,878			93,127			—			447,600
	Non-same store/other (2) (3)		6,170			2,581			—			617			14,443			23,811
	Total operating expenses		197,149			101,197			64,878			93,744			14,443			471,411
	NOI:
	Same store (1)		344,851			183,970			102,683			190,772			—			822,276
	Non-same store/other (2) (3)		9,706			5,468			—			1,176			(14,606		)	1,744
	Total NOI		$	354,557		$	189,438		$	102,683		$	191,948		$	(14,606	)	$	824,020
	-1	Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2012, less properties subsequently sold, which represented 81,099 apartment units.
	-2	Non-same store primarily includes properties acquired after January 1, 2012, plus any properties in lease-up and not stabilized as of January 1, 2012.
	-3	Other includes development and other corporate operations.
			Quarter Ended September 30, 2013
			Northeast			Northwest			Southeast			Southwest			Other (3)			Total
	Rental income:
	Same store (1)		$	196,089		$	107,340		$	59,170		$	101,008		$	—		$	463,607
	Non-same store/other (2) (3)		101,001			38,862			768			21,470			1,172			163,273
	Total rental income		297,090			146,202			59,938			122,478			1,172			626,880
	Operating expenses:
	Same store (1)		68,044			35,784			22,619			32,855			—			159,302
	Non-same store/other (2) (3)		34,191			13,296			289			8,801			(1,117		)	55,460
	Total operating expenses		102,235			49,080			22,908			41,656			(1,117		)	214,762
	NOI:
	Same store (1)		128,045			71,556			36,551			68,153			—			304,305
	Non-same store/other (2) (3)		66,810			25,566			479			12,669			2,289			107,813
	Total NOI		$	194,855		$	97,122		$	37,030		$	80,822		$	2,289		$	412,118
	-1	Same store primarily includes all properties acquired or completed and stabilized prior to July 1, 2012, less properties subsequently sold, which represented 82,553 apartment units.
	-2	Non-same store primarily includes properties acquired after July 1, 2012, plus any properties in lease-up and not stabilized as of July 1, 2012.
	-3	Other includes development and other corporate operations.
			Quarter Ended September 30, 2012
			Northeast			Northwest			Southeast			Southwest			Other (3)			Total
	Rental income:
	Same store (1)		$	190,648		$	100,280		$	56,987		$	97,606		$	—		$	445,521
Non-same store/other (2) (3)		1,658			1,305			—			284			(121		)	3,126
Total rental income		192,306			101,585			56,987			97,890			(121		)	448,647
Operating expenses:
Same store (1)		65,758			34,443			22,435			31,814			—			154,450
Non-same store/other (2) (3)		994			235			—			52			2,508			3,789
Total operating expenses		66,752			34,678			22,435			31,866			2,508			158,239
NOI:
Same store (1)		124,890			65,837			34,552			65,792			—			291,071
Non-same store/other (2) (3)		664			1,070			—			232			(2,629		)	(663		)
Total NOI		$	125,554		$	66,907		$	34,552		$	66,024		$	(2,629	)	$	290,408
-1	Same store primarily includes all properties acquired or completed and stabilized prior to July 1, 2012, less properties subsequently sold, which represented 82,553 apartment units.
-2	Non-same store primarily includes properties acquired after July 1, 2012, plus any properties in lease-up and not stabilized as of July 1, 2012.
-3	Other includes development and other corporate operations.
Note: Markets/Metro Areas included in the above geographic segments are as follows:
(a)	Northeast – New England (excluding Boston), Boston, New York and Washington DC.
(b)	Northwest – Denver, San Francisco, Seattle and Tacoma.
(c)	Southeast – Atlanta, Orlando and South Florida.
(d)	Southwest – Inland Empire, Los Angeles, Orange County, Phoenix and San Diego.
The following table presents a reconciliation of NOI from our rental real estate specific to continuing operations for the nine months and quarters ended September 30, 2013 and 2012, respectively (amounts in thousands):
		Nine Months Ended September 30,						Quarter Ended September 30,
		2013			2012			2013			2012
Rental income		$	1,749,374		$	1,295,431		$	626,880		$	448,647
Property and maintenance expense		(333,202		)	(254,009		)	(119,632		)	(86,682		)
Real estate taxes and insurance expense		(218,777		)	(154,633		)	(76,255		)	(53,064		)
Property management expense		(63,395		)	(62,769		)	(18,875		)	(18,493		)
Total operating expenses		(615,374		)	(471,411		)	(214,762		)	(158,239		)
Net operating income		$	1,134,000		$	824,020		$	412,118		$	290,408

Subsequent_EventsOther

Subsequent Events/Other	9 Months Ended
	Sep. 30, 2013
Subsequent Events Other [Abstract]	'
Subsequent Events/Other	'
	14	Subsequent Events/Other
	Subsequent Events
	Subsequent to September 30, 2013, the Company:
	•	Obtained $896.9 million of new mortgage loan proceeds, inclusive of an $800.0 million secured loan from a large insurance company which matures on November 10, 2023, is interest only and carries a fixed interest rate of 4.21%;
	•	Repaid $963.5 million outstanding of 5.883% mortgage debt assumed as part of the Archstone transaction prior to the November 1, 2014 maturity date;
	•	Repaid $825.0 million of $1.27 billion in mortgage debt assumed as part of the Archstone transaction, with the approximate $440.0 million balance remaining outstanding, continuing to mature in November 2017 and continuing to carry a fixed interest rate of 6.256%; and
	•	Sold the remainder of its investment securities, receiving proceeds of approximately $1.7 million, and recorded a $1.3 million realized gain on sale.
	In conjunction with the early debt extinguishment activity discussed above, the Company incurred cash prepayment costs of approximately $150.0 million and a net charge to earnings of approximately $43.0 million after consideration of the write-off of Archstone-related debt premiums.
	Other
	During the nine months ended September 30, 2013 and 2012, the Company incurred charges of $0.2 million and $6.9 million, respectively, related to property acquisition costs, such as survey, title and legal fees, on the acquisition of operating properties (excluding the Archstone transaction) and $4.0 million and $6.1 million, respectively, related to the write-off of various pursuit and out-of-pocket costs for terminated acquisition, disposition and development transactions. These costs, totaling $4.2 million and $13.0 million, respectively, are included in other expenses in the accompanying consolidated statements of operations and comprehensive income. See Note 4 for details on the property acquisition costs related to the Archstone transaction.
	During the nine months ended September 30, 2012, the Company settled a dispute with the owners of a land parcel for $4.2 million, which is included in other expenses in the accompanying consolidated statements of operations and comprehensive income.
	In June 2012, the Company received $150.0 million in Archstone-related termination fees subject to certain contingencies. Consistent with the resolution of these contingencies, the Company recognized $70.0 million of these fees as interest and other income in July 2012 and recognized the remaining $80.0 million as interest and other income in October 2012.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2013
Summary of Significant Accounting Policies [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) and certain reclassifications considered necessary for a fair presentation have been included. Certain reclassifications have been made to the prior period financial statements in order to conform to the current year presentation. Operating results for the nine months ended September 30, 2013 are not necessarily indicative of the results that may be expected for the year ending December 31, 2013.
	In preparation of the Company’s financial statements in conformity with accounting principles generally accepted in the United States, management makes estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.
	The balance sheets at December 31, 2012 have been derived from the audited financial statements at that date but do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.
	For further information, including definitions of capitalized terms not defined herein, refer to the consolidated financial statements and footnotes thereto included in the Company’s and the Operating Partnership's annual report on Form 10-K for the year ended December 31, 2012.
Real Estate Assets And Depreciation Of Investment In Real Estate [Policy Text Block]	'
	Real Estate Assets and Depreciation of Investment in Real Estate
	Effective for business combinations on or after January 1, 2009, an acquiring entity is required to recognize all assets acquired and liabilities assumed in a transaction at the acquisition-date fair value with limited exceptions. In addition, an acquiring entity is required to expense acquisition-related costs as incurred, value noncontrolling interests at fair value at the acquisition date and expense restructuring costs associated with an acquired business.
	The Company allocates the purchase price of properties to net tangible and identified intangible assets acquired based on their fair values. In making estimates of fair values for purposes of allocating purchase price, the Company utilizes a number of sources, including independent appraisals that may be obtained in connection with the acquisition or financing of the respective property, our own analysis of recently acquired and existing comparable properties in our portfolio and other market data. The Company also considers information obtained about each property as a result of its pre-acquisition due diligence, marketing and leasing activities in estimating the fair value of the tangible and intangible assets/liabilities acquired. The Company allocates the purchase price of acquired real estate to various components as follows:
	•	Land – Based on actual purchase price adjusted to fair value (as necessary) if acquired separately or market research/comparables if acquired with an operating property.
	•	Furniture, Fixtures and Equipment – Ranges between $3,000 and $13,000 per apartment unit acquired as an estimate of the fair value of the appliances and fixtures inside an apartment unit. The per-apartment unit amount applied depends on the type of apartment building acquired. Depreciation is calculated on the straight-line method over an estimated useful life of five to ten years.
	•	Lease Intangibles – The Company considers the value of acquired in-place leases and above/below market leases and the amortization period is the average remaining term of each respective acquired lease. In-place residential leases' average term at acquisition approximates six months. See Note 4 for more information on above and below market leases.
	•	Other Intangible Assets – The Company considers whether it has acquired other intangible assets, including any customer relationship intangibles and the amortization period is the estimated useful life of the acquired intangible asset.
	•	Building – Based on the fair value determined on an “as-if vacant” basis. Depreciation is calculated on the straight-line method over an estimated useful life of thirty years.
	•	Site Improvements – Based on replacement cost, which approximates fair value. Depreciation is calculated on the straight-line method over an estimated useful life of eight years.
	•	Long-Term Debt – The Company calculates the fair value by discounting the remaining contractual cash flows on each instrument at the current market rate for those borrowings.
Income and Other Taxes	'
	Income and Other Taxes
	Due to the structure of EQR as a REIT and the nature of the operations of its operating properties, no provision for federal income taxes has been made at the EQR level. In addition, ERPOP generally is not liable for federal income taxes as the partners recognize their proportionate share of income or loss in their tax returns; therefore no provision for federal income taxes has been made at the ERPOP level. Historically, the Company has generally only incurred certain state and local income, excise and franchise taxes. The Company has elected Taxable REIT Subsidiary (“TRS”) status for certain of its corporate subsidiaries and as a result, these entities will incur both federal and state income taxes on any taxable income of such entities after consideration of any net operating losses.
	Deferred tax assets and liabilities applicable to the TRS are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. These assets and liabilities are measured using enacted tax rates for which the temporary differences are expected to be recovered or settled. The effects of changes in tax rates on deferred tax assets and liabilities are recognized in earnings in the period enacted. The Company’s deferred tax assets are generally the result of tax affected amortization of goodwill, differing depreciable lives on capitalized assets and the timing of expense recognition for certain accrued liabilities. As of September 30, 2013, the Company has recorded a deferred tax asset, which is fully offset by a valuation allowance due to the uncertainty in forecasting future TRS taxable income.
Other	'
	Other
	The Company is the controlling partner in various consolidated partnerships owning 19 properties and 3,752 apartment units and various completed and uncompleted development properties having a noncontrolling interest book value of $110.6 million at September 30, 2013. The Company is required to make certain disclosures regarding noncontrolling interests in consolidated limited-life subsidiaries. Of the consolidated entities described above, the Company is the controlling partner in limited-life partnerships owning six properties having a noncontrolling interest deficit balance of $8.5 million. These six partnership agreements contain provisions that require the partnerships to be liquidated through the sale of their assets upon reaching a date specified in each respective partnership agreement. The Company, as controlling partner, has an obligation to cause the property owning partnerships to distribute the proceeds of liquidation to the Noncontrolling Interests in these Partially Owned Properties only to the extent that the net proceeds received by the partnerships from the sale of their assets warrant a distribution based on the partnership agreements. As of September 30, 2013, the Company estimates the value of Noncontrolling Interest distributions for these six properties would have been approximately $46.8 million (“Settlement Value”) had the partnerships been liquidated. This Settlement Value is based on estimated third party consideration realized by the partnerships upon disposition of the six Partially Owned Properties and is net of all other assets and liabilities, including yield maintenance on the mortgages encumbering the properties, that would have been due on September 30, 2013 had those mortgages been prepaid. Due to, among other things, the inherent uncertainty in the sale of real estate assets, the amount of any potential distribution to the Noncontrolling Interests in the Company's Partially Owned Properties is subject to change. To the extent that the partnerships' underlying assets are worth less than the underlying liabilities, the Company has no obligation to remit any consideration to the Noncontrolling Interests in these Partially Owned Properties.
	Effective January 1, 2012, companies are required to separately disclose the amounts and reasons for any transfers of assets and liabilities into and out of Level 1 and Level 2 of the fair value hierarchy. For fair value measurements using significant unobservable inputs (Level 3), companies are required to disclose quantitative information about the significant unobservable inputs used for all Level 3 measurements and a description of the Company's valuation processes in determining fair value. In addition, companies are required to provide a qualitative discussion about the sensitivity of recurring Level 3 measurements to changes in the unobservable inputs disclosed, including the interrelationship between inputs. Companies are also required to disclose information about when the current use of a non-financial asset measured at fair value differs from its highest and best use and the hierarchy classification for items whose fair value is not recorded on the balance sheet but is disclosed in the notes. This does not have a material effect on the Company's consolidated results of operations or financial position. See Notes 4 and 9 for further discussion.
	Effective January 1, 2013, companies are required to report, in one place, information about reclassifications out of accumulated other comprehensive income ("AOCI"). Companies will also be required to report changes in AOCI balances. For significant items reclassified out of AOCI to net income in their entirety in the same reporting period, reporting is required about the effect of the reclassifications on the respective line items in the statement where net income is presented. For items that are not reclassified to net income in their entirety in the same reporting period, a cross reference to other disclosures currently required under US GAAP is required in the notes. This does not have a material effect on the Company's consolidated results of operations or financial position. See Note 9 for further discussion.

Business_Tables

Business (Tables)	9 Months Ended
	Sep. 30, 2013
Business [Abstract]	'
Property/Unit schedule	'
		Properties	Apartment
			Units
	Wholly Owned Properties	363	99,192
	Master-Leased Properties – Consolidated	3	853
	Partially Owned Properties – Consolidated	19	3,752
	Partially Owned Properties – Unconsolidated	2	837
	Military Housing	2	5,161
		389	109,795

Equity_Capital_and_Other_Inter1

Equity, Capital and Other Interests (Tables)	9 Months Ended
	Sep. 30, 2013
Common shares and units rollforward	'
	The following tables present the changes in the Company’s issued and outstanding Common Shares and “Units” (which includes OP Units and Long-Term Incentive Plan (“LTIP”) Units) for the nine months ended September 30, 2013:
			2013
	Common Shares
	Common Shares outstanding at January 1,		325,054,654
	Common Shares Issued:
	Conversion of OP Units		47,939
	Issuance of Common Shares		34,468,085
	Exercise of share options		530,847
	Employee Share Purchase Plan (ESPP)		63,788
	Restricted share grants, net		230,646
	Common Shares outstanding at September 30,		360,395,959
	Units
	Units outstanding at January 1,		13,968,758
	LTIP Units, net		279,557
	Conversion of OP Units to Common Shares		(47,939	)
	Units outstanding at September 30,		14,200,376
	Total Common Shares and Units outstanding at September 30,		374,596,335
	Units Ownership Interest in Operating Partnership		3.8	%
Redeemable Noncontrolling Interest [Table Text Block]	'
	The following table presents the change in the redemption value of the Redeemable Noncontrolling Interests – Operating Partnership for the nine months ended September 30, 2013 (amounts in thousands):
			2013
	Balance at January 1,		$	398,372
	Change in market value		(69,344		)
	Change in carrying value		47,029
	Balance at September 30,		$	376,057
Schedule Of Preferred Stock [Table Text Block]	'
	The following table presents the Company’s issued and outstanding Preferred Shares as of September 30, 2013 and December 31, 2012:
							Amounts in thousands
			Redemption		Annual		September 30,		December 31,
			Date (1)		Dividend per		2013		2012
					Share (2)
	Preferred Shares of beneficial interest, $0.01 par value;
	100,000,000 shares authorized:
	8.29% Series K Cumulative Redeemable Preferred; liquidation		12/10/26			$4.14	$	50,000	$	50,000
	value $50 per share; 1,000,000 shares issued and outstanding
	at September 30, 2013 and December 31, 2012
							$	50,000	$	50,000
	-1	On or after the redemption date, redeemable preferred shares may be redeemed for cash at the option of the Company, in whole or in part, at a redemption price equal to the liquidation price per share, plus accrued and unpaid distributions, if any.
	-2	Dividends on Preferred Shares are payable quarterly.
Limited Partner [Member]	'
Common shares and units rollforward	'
	The following tables present the changes in the Operating Partnership’s issued and outstanding Units and in the limited partners’ Units for the nine months ended September 30, 2013:
			2013
	General and Limited Partner Units
	General and Limited Partner Units outstanding at January 1,		339,023,412
	Issued to General Partner:
	Issuance of OP Units		34,468,085
	Exercise of EQR share options		530,847
	EQR’s Employee Share Purchase Plan (ESPP)		63,788
	EQR's restricted share grants, net		230,646
	Issued to Limited Partners:
	LTIP Units, net		279,557
	General and Limited Partner Units outstanding at September 30,		374,596,335
	Limited Partner Units
	Limited Partner Units outstanding at January 1,		13,968,758
	Limited Partner LTIP Units, net		279,557
	Conversion of Limited Partner OP Units to EQR Common Shares		(47,939	)
	Limited Partner Units outstanding at September 30,		14,200,376
	Limited Partner Units Ownership Interest in Operating Partnership		3.8	%
Redeemable Noncontrolling Interest [Table Text Block]	'
	The following table presents the change in the redemption value of the Redeemable Limited Partners for the nine months ended September 30, 2013 (amounts in thousands):
			2013
	Balance at January 1,		$	398,372
	Change in market value		(69,344		)
	Change in carrying value		47,029
	Balance at September 30,		$	376,057
Schedule Of Preferred Stock [Table Text Block]	'
	The following table presents the Operating Partnership’s issued and outstanding “Preference Units” as of September 30, 2013 and December 31, 2012:
							Amounts in thousands
			Redemption		Annual		September 30,		December 31,
			Date (1)		Dividend per		2013		2012
					Unit (2)
	Preference Units:
	8.29% Series K Cumulative Redeemable Preference Units;		12/10/26			$4.14	$	50,000	$	50,000
	liquidation value $50 per unit; 1,000,000 units issued and
	outstanding at September 30, 2013 and December 31, 2012
							$	50,000	$	50,000
	-1	On or after the redemption date, redeemable preference units may be redeemed for cash at the option of the Operating Partnership, in whole or in part, at a redemption price equal to the liquidation price per unit, plus accrued and unpaid distributions, if any, in conjunction with the concurrent redemption of the corresponding Company Preferred Shares.
	-2	Dividends on Preference Units are payable quarterly.

Real_Estate_Tables

Real Estate (Tables)	9 Months Ended
	Sep. 30, 2013
Schedule of Real Estate Investments And Accumlated Depreciation [Table Text Block}	'
	The following table summarizes the carrying amounts for the Company’s investment in real estate (at cost) as of September 30, 2013 and December 31, 2012 (amounts in thousands):
		September 30,				December 31,
		2013				2012
	Land	$	6,201,333			$	4,554,912
	Depreciable property:
	Buildings and improvements	17,555,388				14,135,740
	Furniture, fixtures and equipment	1,196,410				1,343,765
	In-Place lease intangibles	503,159				232,439
	Projects under development:
	Land	280,718				210,632
	Construction-in-progress	498,335				177,118
	Land held for development:
	Land	435,227				294,868
	Construction-in-progress	70,267				58,955
	Investment in real estate	26,740,837				21,008,429
	Accumulated depreciation	(4,654,594		)		(4,912,221		)
	Investment in real estate, net	$	22,086,243			$	16,096,208
Schedule of Finite-Lived Intangible Assets [Table Text Block]	'
	The following table summarizes the carrying amounts for the Company's above and below market ground and retail lease intangibles as of September 30, 2013 (amounts in thousands):
	Description	Balance Sheet Location		Value
	Assets
	Ground lease intangibles – below market	Other Assets		$	178,251
	Retail lease intangibles – above market	Other Assets		2,310
	Lease intangible assets			180,561
	Accumulated amortization			(3,221		)
	Lease intangible assets, net			$	177,340
	Liabilities
	Ground lease intangibles – above market	Other Liabilities		$	2,400
	Retail lease intangibles – below market	Other Liabilities		7,790
	Lease intangible liabilities			10,190
	Accumulated amortization			(993		)
	Lease intangible liabilities, net			$	9,197
Schedule of Expected Amortization Expense [Table Text Block]	'
	The following table provides a summary of the aggregate amortization expense for above and below market ground lease intangibles and retail lease intangibles for each of the next five years (amounts in thousands):
		Remaining
		2013				2014				2015			2016			2017			2018
	Ground lease intangibles	$	1,080			$	4,321			$	4,321		$	4,321		$	4,321		$	4,321
	Retail lease intangibles	(218		)		(1,144		)		(1,150		)	(1,042		)	(674		)	(205		)
	Total	$	862			$	3,177			$	3,171		$	3,279		$	3,647		$	4,116
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	'
	The following table summarizes the acquisition date fair values of the assets acquired and liabilities assumed, which the Company determined using Level 1, Level 2 and Level 3 inputs (amounts in thousands):
	Land	$	2,239,000
	Depreciable property:
	Buildings and improvements	5,832,554
	Furniture, fixtures and equipment	61,470
	In-Place lease intangibles	304,830
	Projects under development	36,583
	Land held for development	239,898
	Investments in unconsolidated entities	188,139
	Other assets	196,310
	Other liabilities	(112,369		)
	Net assets acquired	$	8,986,415
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Text Block]	'
	The following table summarizes the acquisition date fair values of the above and below market ground and retail lease intangibles, which we determined using Level 2 and Level 3 inputs (amounts in thousands):
	Description	Balance Sheet Location		Fair Value
	Ground lease intangibles – below market	Other Assets		$	178,251
	Retail lease intangibles – above market	Other Assets		2,310
	Ground lease intangibles – above market	Other Liabilities		2,400
	Retail lease intangibles – below market	Other Liabilities		8,040
Business Acquisition, Pro Forma Information [Table Text Block]	'
	The following table illustrates the effect on net income, earnings per share – basic and earnings per share – diluted as if the Company had consummated the Archstone Acquisition as of January 1, 2012:
		Nine Months Ended September 30,								Quarter Ended September 30,
		2013				2012				2013			2012
		(Amounts in thousands, except per share amounts)
	Total revenues	$	1,854,509			$	1,726,304			$	629,446		$	596,734
	Income (loss) from continuing operations (1)	132,592				(179,574		)		84,978			107,024
	Discontinued operations, net	2,024,346				434,253				403,181			145,145
	Net income	2,156,938				254,679				488,159			252,169
	Net income available to Common Shares	2,070,153				232,053				468,959			234,471
	Earnings per share - basic:
	Net income available to Common Shares	$	5.76			$	0.65			$	1.3		$	0.66
	Weighted average Common Shares outstanding (2)	359,611				356,434				359,811			357,654
	Earnings per share - diluted (1):
	Net income available to Common Shares	$	5.74			$	0.65			$	1.3		$	0.66
	Weighted average Common Shares outstanding (2)	375,808				356,434				375,883			375,091
Acquired Properties Table Text Block	'
	In addition to the Archstone acquisition described above, during the nine months ended September 30, 2013, the Company acquired the entire equity interest in the following from unaffiliated parties (purchase price in thousands):
		Properties			Apartment Units			Purchase Price
	Rental Properties – Consolidated	1			322			$	91,500
	Land Parcel (one)	—			—			16,500
	Total	1			322			$	108,000
Disposed Properties Table	'
	During the nine months ended September 30, 2013, the Company disposed of the following to unaffiliated parties (sales price in thousands):
		Properties			Apartment Units			Sales Price
	Consolidated:
	Rental Properties	92			28,328			$	4,362,689
	Land Parcels (six)	—			—			77,650
	Other (1)	—			—			30,734
	Unconsolidated:
	Land Parcel (one) (2)	—			—			26,350
	Total	92			28,328			$	4,497,423
	(1) Represents a 97,000 square foot commercial building adjacent to our Harbor Steps apartment property in downtown Seattle that was acquired in 2011.
	(2) Sales price listed is the gross sales price. EQR's share of the net sales proceeds approximated 25%.
Partnership Interest [Member]	'
Business Acquisition, Pro Forma Information [Table Text Block]	'
	The following table illustrates the effect on net income, earnings per Unit – basic and earnings per Unit – diluted as if the Operating Partnership had consummated the Archstone Acquisition as of January 1, 2012:
		Nine Months Ended September 30,								Quarter Ended September 30,
		2013				2012				2013			2012
		(Amounts in thousands, except per Unit amounts)
	Total revenues	$	1,854,509			$	1,726,304			$	629,446		$	596,734
	Income (loss) from continuing operations (1)	132,592				(179,574		)		84,978			107,024
	Discontinued operations, net	2,024,346				434,253				403,181			145,145
	Net income	2,156,938				254,679				488,159			252,169
	Net income available to Units	2,155,736				242,962				487,433			245,725
	Earnings per Unit - basic:
	Net income available to Units	$	5.76			$	0.65			$	1.3		$	0.66
	Weighted average Units outstanding (2)	373,347				370,250				373,547			371,831
	Earnings per Unit - diluted (1):
	Net income available to Units	$	5.74			$	0.65			$	1.3		$	0.66
	Weighted average Units outstanding (2)	375,808				370,250				375,883			375,091

Commitments_to_AcquireDispose_1

Commitments to Acquire/Dispose of Real Estate (Tables)	9 Months Ended
	Sep. 30, 2013
Commitments to Acquire Dispose of Real Estate [Abstract]	'
Real Estate to be Acquired Table Text Block	'
	The Company has entered into a separate agreement to acquire the following (purchase price in thousands):
		Properties	Apartment Units	Purchase Price
	Land Parcel (one)	—	—	$	12,500
	Total	—	—	$	12,500
Disposed Properties Table Text Block	'
	he Company has entered into a separate agreement to dispose of the following (sales price in thousands):
		Properties	Apartment Units	Sales Price
	Land Parcel (one)	—	—	$	27,000
	Total	—	—	$	27,000

Investments_in_Partially_Owned1

Investments in Partially Owned Entities (Tables)	9 Months Ended
	Sep. 30, 2013
Investments in Partially Owned Entities [Abstract]	'
Partially Owned Property Balance Sheet Schedule [Table Text Block]	'
	The following tables and information summarize the Company’s investments in partially owned entities as of September 30, 2013 (amounts in thousands except for project and apartment unit amounts):
		Consolidated									Unconsolidated
		Development Projects									Development Projects
		Held for			Operating			Total			Held for			Completed, Not Stabilized (3)			Operating			Total
		and/or Under									and/or Under
		Development									Development
	Total projects (1)	—			19			19			—			1			1			2
	Total apartment units (1)	—			3,752			3,752			—			501			336			837
	Balance sheet information at 9/30/13 (at 100%):
	ASSETS
	Investment in real estate	$	308,893		$	672,958		$	981,851		$	238,872		$	77,292		$	55,369		$	371,533
	Accumulated depreciation	—			(167,457		)	(167,457		)	(84		)	—			(4,165		)	(4,249		)
	Investment in real estate, net	308,893			505,501			814,394			238,788			77,292			51,204			367,284
	Cash and cash equivalents	4,253			17,659			21,912			1,153			317			1,357			2,827
	Investments in unconsolidated entities	—			55,040			55,040			—			—			—			—
	Deposits – restricted	43,631			206			43,837			—			—			—			—
	Deferred financing costs, net	—			2,521			2,521			—			5			5			10
	Other assets	5,781			27,170			32,951			333			5			1,038			1,376
	Total assets	$	362,558		$	608,097		$	970,655		$	240,274		$	77,619		$	53,604		$	371,497
	LIABILITIES AND EQUITY/CAPITAL
	Mortgage notes payable (2)	$	—		$	358,730		$	358,730		$	118,723		$	45,217		$	30,550		$	194,490
	Accounts payable & accrued expenses	27,052			2,495			29,547			13,781			2,864			(143		)	16,502
	Accrued interest payable	—			1,259			1,259			432			208			—			640
	Other liabilities	1,045			1,254			2,299			365			156			1,345			1,866
	Security deposits	1			1,821			1,822			94			75			18			187
	Total liabilities	28,098			365,559			393,657			133,395			48,520			31,770			213,685
	Noncontrolling Interests - Partially Owned	98,126			12,509			110,635			78,556			23,205			20,450			122,211
	Properties/Partners' equity
	Company equity/General and Limited	236,334			230,029			466,363			28,323			5,894			1,384			35,601
	Partners' Capital
	Total equity/capital	334,460			242,538			576,998			106,879			29,099			21,834			157,812
	Total liabilities and equity/capital	$	362,558		$	608,097		$	970,655		$	240,274		$	77,619		$	53,604		$	371,497
Partially Owned Property Income Statement Schedule [Table Text Block]	'
		Consolidated									Unconsolidated
		Development Projects									Development Projects
		Held for									Held for						Operating
		and/or Under									and/or Under			Completed, Not Stabilized (3)
		Development			Operating			Total			Development									Total
	Operating information for the nine months ended 9/30/13 (at 100%):
	Operating revenue	$	12		$	59,666		$	59,678		$	1,305		$	1,861		$	3,173		$	6,339
	Operating expenses	407			18,458			18,865			1,141			1,023			1,402			3,566
	Net operating (loss) income	(395		)	41,208			40,813			164			838			1,771			2,773
	Depreciation	—			26,478			26,478			84			—			4,165			4,249
	General and administrative/other	520			79			599			23			—			141			164
	Operating (loss) income	(915		)	14,651			13,736			57			838			(2,535		)	(1,640		)
	Interest and other income	2			3			5			—			—			10			10
	Other expenses	(334		)	(4		)	(338		)	—			—			—			—
	Interest:
	Expense incurred, net	(2		)	(10,615		)	(10,617		)	(152		)	(501		)	(658		)	(1,311		)
	Amortization of deferred financing costs	—			(216		)	(216		)	—			—			(1		)	(1		)
	(Loss) income before income and other taxes, (loss)	(1,249		)	3,819			2,570			(95		)	337			(3,184		)	(2,942		)
	from investments in unconsolidated entities, net
	(loss) gain on sales of land parcels and
	discontinued operations
	Income and other tax (expense) benefit	(11		)	(56		)	(67		)	—			—			—			—
	(Loss) from investments in unconsolidated entities	—			(1,010		)	(1,010		)	—			—			—			—
	Net (loss) on sales of land parcels	(17		)	—			(17		)	—			—			—			—
	Net gain on sales of discontinued operations	—			26,673			26,673			—			—			—			—
	Net (loss) income	$	(1,277	)	$	29,426		$	28,149		$	(95	)	$	337		$	(3,184	)	$	(2,942	)
	-1	Project and apartment unit counts exclude all uncompleted development projects until those projects are substantially completed.
	-2	All debt is non-recourse to the Company with the exception of 50% of the current $5.7 million outstanding debt balance on one unconsolidated development project.
	-3	Projects included here are substantially complete. However, they may still require additional exterior and interior work for all units to be available for leasing.
	Note:	The above tables exclude the Company's interests in unconsolidated joint ventures entered into with AVB in connection with the Archstone transaction. These ventures own certain non-core Archstone assets that are held for sale and succeeded to certain residual Archstone liabilities, such as liability for various employment-related matters as well as responsibility for tax protection arrangements and third-party preferred interests in former Archstone subsidiaries. The preferred interests have an aggregate liquidation value of $88.3 million at September 30, 2013. The ventures are owned 60% by the Company and 40% by AVB.

Deposits_Restricted_Tables

Deposits - Restricted (Tables)	9 Months Ended
	Sep. 30, 2013
Deposits - Restricted [Abstract]	'
Schedule of Restricted Cash and Cash Equivalents [Table Text Block]	'
	The following table presents the Company’s restricted deposits as of September 30, 2013 and December 31, 2012 (amounts in thousands):
		September 30,		December 31,
		2013		2012
	Tax–deferred (1031) exchange proceeds	$	—	$	152,182
	Earnest money on pending acquisitions	350		5,613
	Restricted deposits on real estate investments	53,764		44,209
	Resident security and utility deposits	44,255		44,199
	Other	505		4,239
	Totals	$	98,874	$	250,442

Derivative_and_Other_Fair_Valu1

Derivative and Other Fair Value Instruments (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Derivative Instrument Table	'
	The following table summarizes the Company’s consolidated derivative instruments at September 30, 2013 (dollar amounts are in thousands):
		Forward
		Starting
		Swaps (1)
	Current Notional Balance	$	400,000
	Lowest Possible Notional	$	400,000
	Highest Possible Notional	$	400,000
	Lowest Interest Rate	2.125		%
	Highest Interest Rate	3.23		%
	Earliest Maturity Date	2024
	Latest Maturity Date	2024
Schedule of Location and Amount of Financial Instruments on Balanace Sheet	'
	The following tables provide a summary of the fair value measurements for each major category of assets and liabilities measured at fair value on a recurring basis and the location within the accompanying Consolidated Balance Sheets at September 30, 2013 and December 31, 2012, respectively (amounts in thousands):
							Fair Value Measurements at Reporting Date Using
	Description	Balance Sheet		9/30/13			Quoted Prices in			Significant  Other				Significant
		Location					Active Markets for			Observable Inputs				Unobservable Inputs
							Identical Assets/Liabilities			(Level 2)				(Level  3)
							(Level 1)
	Assets
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Forward Starting Swaps	Other Assets		$	12,132		$	—		$	12,132			$	—
	Supplemental Executive Retirement Plan	Other Assets		78,629			78,629			—				—
	Available-for-Sale Investment Securities	Other Assets		1,675			1,675			—				—
	Total			$	92,436		$	80,304		$	12,132			$	—
	Liabilities
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Forward Starting Swaps	Other Liabilities		$	3,456		$	—		$	3,456			$	—
	Supplemental Executive Retirement Plan	Other Liabilities		78,629			78,629			—				—
	Total			$	82,085		$	78,629		$	3,456			$	—
	Redeemable Noncontrolling Interests –
	Operating Partnership/Redeemable
	Limited Partners	Mezzanine		$	376,057		$	—		$	376,057			$	—
							Fair Value Measurements at Reporting Date Using
	Description	Balance Sheet		12/31/12			Quoted Prices in			Significant  Other				Significant
		Location					Active Markets for			Observable Inputs				Unobservable Inputs
							Identical Assets/Liabilities			(Level 2)				(Level  3)
							(Level 1)
	Assets
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Fair Value Hedges	Other Assets		$	1,524		$	—		$	1,524			$	—
	Supplemental Executive Retirement Plan	Other Assets		70,655			70,655			—				—
	Available-for-Sale Investment Securities	Other Assets		2,214			2,214			—				—
	Total			$	74,393		$	72,869		$	1,524			$	—
	Liabilities
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Forward Starting Swaps	Other Liabilities		$	44,050		$	—		$	44,050			$	—
	Supplemental Executive Retirement Plan	Other Liabilities		70,655			70,655			—				—
	Total			$	114,705		$	70,655		$	44,050			$	—
	Redeemable Noncontrolling Interests –
	Operating Partnership/Redeemable
	Limited Partners	Mezzanine		$	398,372		$	—		$	398,372			$	—
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Table Text Block]	'
	The following tables provide a summary of the effect of fair value hedges on the Company’s accompanying Consolidated Statements of Operations and Comprehensive Income for the nine months ended September 30, 2013 and 2012, respectively (amounts in thousands):
	30-Sep-13	Location of		Amount of			Hedged Item		Income Statement	Amount of
	Type of Fair Value Hedge	Gain/(Loss)		Gain/(Loss)					Location of	Gain/(Loss)
		Recognized in		Recognized in					Hedged	Recognized in
		Income		Income					Item Gain/(Loss)	Income
		on Derivative		on Derivative						on Hedged Item
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Interest Rate Swaps	Interest expense		$	(1,524	)	Fixed rate debt		Interest expense	$	1,524
	Total			$	(1,524	)				$	1,524
	30-Sep-12	Location of		Amount of			Hedged Item		Income Statement	Amount of
	Type of Fair Value Hedge	Gain/(Loss)		Gain/(Loss)					Location of	Gain/(Loss)
		Recognized in		Recognized in					Hedged	Recognized in
		Income		Income					Item Gain/(Loss)	Income
		on Derivative		on Derivative						on Hedged Item
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Interest Rate Swaps	Interest expense		$	(5,934	)	Fixed rate debt		Interest expense	$	5,934
	Total			$	(5,934	)				$	5,934
Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	'
	The following tables provide a summary of the effect of cash flow hedges on the Company’s accompanying Consolidated Statements of Operations and Comprehensive Income for the nine months ended September 30, 2013 and 2012, respectively (amounts in thousands):
		Effective Portion								Ineffective Portion
	30-Sep-13	Amount of				Location of Gain/	Amount of Gain/			Location of		Amount of Gain/
	Type of Cash Flow Hedge	Gain/(Loss)				(Loss)	(Loss)			Gain/(Loss)		(Loss)
		Recognized in OCI				Reclassified from	Reclassified from			Recognized in		Reclassified from
		on Derivative				Accumulated	Accumulated			Income		Accumulated
						OCI	OCI			on Derivative		OCI
						into Income	into Income					into Income
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Forward Starting Swaps/Treasury Locks	$	8,737			Interest expense	$	(16,084	)	N/A		$	—
	Total	$	8,737				$	(16,084	)			$	—
		Effective Portion								Ineffective Portion
	30-Sep-12	Amount of				Location of Gain/	Amount of Gain/			Location of		Amount of Gain/
	Type of Cash Flow Hedge	Gain/(Loss)				(Loss)	(Loss)			Gain/(Loss)		(Loss)
		Recognized in OCI				Reclassified from	Reclassified from			Recognized in		Reclassified from
		on Derivative				Accumulated	Accumulated			Income		Accumulated
						OCI	OCI			on Derivative		OCI
						into Income	into Income					into Income
	Derivatives designated as hedging instruments:
	Interest Rate Contracts:
	Forward Starting Swaps/Treasury Locks	$	(12,337	)		Interest expense	$	(10,907	)	N/A		$	—
	Total	$	(12,337	)			$	(10,907	)			$	—
Available-for-sale Securities [Table Text Block]	'
	The following tables set forth the maturity, amortized cost, gross unrealized gains and losses, book/fair value and interest and other income of the various investment securities held as of September 30, 2013 and December 31, 2012, respectively (amounts in thousands):
				Other Assets
	30-Sep-13	Maturity		Amortized			Unrealized			Unrealized				Book/		Interest and
	Security			Cost			Gains			Losses				Fair Value		Other Income
	Available-for-Sale Investment Securities	N/A		$	412		$	1,263		$	—			$	1,675	$	830
	Total			$	412		$	1,263		$	—			$	1,675	$	830
				Other Assets
	31-Dec-12	Maturity		Amortized			Unrealized			Unrealized				Book/		Interest and
	Security			Cost			Gains			Losses				Fair Value		Other Income
	Available-for-Sale Investment Securities	N/A		$	675		$	1,539		$	—			$	2,214	$	—
	Total			$	675		$	1,539		$	—			$	2,214	$	—

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2013
Schedule of Calculation of Numerator and Denominator in Earnings Per Share [Table Text Block]	'
	The following tables set forth the computation of net income per share – basic and net income per share – diluted for the Company (amounts in thousands except per share amounts):
			Nine Months Ended September 30,						Quarter Ended September 30,
			2013			2012			2013			2012
	Numerator for net income per share – basic:
	(Loss) income from continuing operations		$	(234,414	)	$	62,103		$	(12,467	)	$	92,181
	Allocation to Noncontrolling Interests – Operating Partnership, net		9,402			(2,128		)	483			(3,895		)
	Net loss (income) attributable to Noncontrolling Interests – Partially		1,101			(457		)	311			312
	Owned Properties
	Preferred distributions		(3,109		)	(9,319		)	(1,037		)	(2,386		)
	Premium on redemption of Preferred Shares		—			(5,150		)	—			(5,150		)
	(Loss) income from continuing operations available to Common Shares,		(227,020		)	45,049			(12,710		)	81,062
	net of Noncontrolling Interests
	Discontinued operations, net of Noncontrolling Interests		1,943,548			415,184			388,865			137,541
	Numerator for net income per share – basic		$	1,716,528		$	460,233		$	376,155		$	218,603
	Numerator for net income per share – diluted (1):
	(Loss) income from continuing operations					$	62,103					$	92,181
	Net loss (income) attributable to Noncontrolling Interests – Partially					(457		)				312
	Owned Properties
	Preferred distributions					(9,319		)				(2,386		)
	Premium on redemption of Preferred Shares					(5,150		)				(5,150		)
	(Loss) income from continuing operations available to Common Shares					47,177						84,957
	Discontinued operations, net					434,702						144,142
	Numerator for net income per share – diluted (1)		$	1,716,528		$	481,879		$	376,155		$	229,099
	Denominator for net income per share – basic and diluted (1):
	Denominator for net income per share – basic		352,414			300,116			359,811			301,336
	Effect of dilutive securities:
	OP Units					13,816						14,177
	Long-term compensation shares/units					3,333						3,260
	Denominator for net income per share – diluted (1)		352,414			317,265			359,811			318,773
	Net income per share – basic		$	4.87		$	1.53		$	1.05		$	0.73
	Net income per share – diluted		$	4.87		$	1.52		$	1.05		$	0.72
	Net income per share – basic:
	(Loss) income from continuing operations available to Common Shares,		$	(0.644	)	$	0.15		$	(0.035	)	$	0.269
	net of Noncontrolling Interests
	Discontinued operations, net of Noncontrolling Interests		5.515			1.384			1.08			0.456
	Net income per share – basic		$	4.871		$	1.534		$	1.045		$	0.725
	Net income per share – diluted (1):
	(Loss) income from continuing operations available to Common Shares		$	(0.644	)	$	0.149		$	(0.035	)	$	0.267
	Discontinued operations, net		5.515			1.37			1.08			0.452
	Net income per share – diluted		$	4.871		$	1.519		$	1.045		$	0.719
	-1	Potential common shares issuable from the assumed conversion of OP Units and the exercise/vesting of long-term compensation shares/units are automatically anti-dilutive and therefore excluded from the diluted earnings per share calculation as the Company had a loss from continuing operations for the nine months and quarters ended September 30, 2013.
Operating Partnership [Member]	'
Schedule of Calculation of Numerator and Denominator in Earnings Per Share [Table Text Block]	'
	The following tables set forth the computation of net income per Unit – basic and net income per Unit – diluted for the Operating Partnership (amounts in thousands except per Unit amounts):
			Nine Months Ended September 30,						Quarter Ended September 30,
			2013			2012			2013			2012
	Numerator for net income per Unit – basic and diluted (1):
	(Loss) income from continuing operations		$	(234,414	)	$	62,103		$	(12,467	)	$	92,181
	Net loss (income) attributable to Noncontrolling Interests – Partially		1,101			(457		)	311			312
	Owned Properties
	Allocation to Preference Units		(3,109		)	(9,319		)	(1,037		)	(2,386		)
	Allocation to premium on redemption of Preference Units		—			(5,150		)	—			(5,150		)
	(Loss) income from continuing operations available to Units		(236,422		)	47,177			(13,193		)	84,957
	Discontinued operations, net		2,023,897			434,702			404,184			144,142
	Numerator for net income per Unit – basic and diluted (1)		$	1,787,475		$	481,879		$	390,991		$	229,099
	Denominator for net income per Unit – basic and diluted (1):
	Denominator for net income per Unit – basic		366,150			313,932			373,547			315,513
	Effect of dilutive securities:
	Dilution for Units issuable upon assumed exercise/vesting of the					3,333						3,260
	Company's long-term compensation shares/units
	Denominator for net income per Unit – diluted (1)		366,150			317,265			373,547			318,773
	Net income per Unit – basic		$	4.87		$	1.53		$	1.05		$	0.73
	Net income per Unit – diluted		$	4.87		$	1.52		$	1.05		$	0.72
	Net income per Unit – basic:
	(Loss) income from continuing operations available to Units		$	(0.644	)	$	0.15		$	(0.035	)	$	0.269
	Discontinued operations, net		5.515			1.384			1.08			0.456
	Net income per Unit – basic		$	4.871		$	1.534		$	1.045		$	0.725
	Net income per Unit – diluted (1):
	(Loss) income from continuing operations available to Units		$	(0.644	)	$	0.149		$	(0.035	)	$	0.267
	Discontinued operations, net		5.515			1.37			1.08			0.452
	Net income per Unit – diluted		$	4.871		$	1.519		$	1.045		$	0.719
	-1	Potential Units issuable from the assumed exercise/vesting of the Company's long-term compensation shares/units are automatically anti-dilutive and therefore excluded from the diluted earnings per Unit calculation as the Operating Partnership had a loss from continuing operations for the nine months and quarters ended September 30, 2013.

Discontinued_Operations_Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2013
Discontinued Operations and Disposal Groups [Abstract]	'
Components of discontinued operations	'
	The components of discontinued operations are outlined below and include the results of operations for the respective periods that the Company owned such assets during the nine months and quarters ended September 30, 2013 and 2012 (amounts in thousands).
			Nine Months Ended September 30,						Quarter Ended September 30,
			2013			2012			2013			2012
	REVENUES
	Rental income		$	110,986		$	334,968		$	8,418		$	108,459
	Total revenues		110,986			334,968			8,418			108,459
	EXPENSES (1)
	Property and maintenance		33,181			79,482			3,272			25,608
	Real estate taxes and insurance		10,578			29,599			396			11,480
	Property management		1			211			—			70
	Depreciation		31,976			94,792			2,273			29,497
	General and administrative		76			87			3			44
	Total expenses		75,812			204,171			5,944			66,699
	Discontinued operating income		35,174			130,797			2,474			41,760
	Interest and other income		156			81			65			34
	Other expenses		(3		)	(170		)	—			(23		)
	Interest (2):
	Expense incurred, net		(1,276		)	(3,357		)	(18		)	(995		)
	Amortization of deferred financing costs		(228		)	(119		)	—			(27		)
	Income and other tax (expense) benefit		(503		)	23			(40		)	(1		)
	Discontinued operations		33,320			127,255			2,481			40,748
	Net gain on sales of discontinued operations		1,990,577			307,447			401,703			103,394
	Discontinued operations, net		$	2,023,897		$	434,702		$	404,184		$	144,142
	-1	Includes expenses paid in the current period for properties sold in prior periods related to the Company’s period of ownership.
	-2	Includes only interest expense specific to secured mortgage notes payable for properties sold.

Reportable_Segments_Tables

Reportable Segments (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]	'
Reportable Segments Schedule	'
			Nine Months Ended September 30, 2013
			Northeast			Northwest			Southeast			Southwest			Other (3)			Total
	Rental income:
	Same store (1)		$	555,391		$	303,680		$	175,039		$	295,216		$	—		$	1,329,326
	Non-same store/other (2) (3)		263,745			99,689			1,785			51,492			3,337			420,048
	Total rental income		819,136			403,369			176,824			346,708			3,337			1,749,374
	Operating expenses:
	Same store (1)		198,068			101,982			66,013			96,446			—			462,509
	Non-same store/other (2) (3)		86,820			34,352			696			21,656			9,341			152,865
	Total operating expenses		284,888			136,334			66,709			118,102			9,341			615,374
	NOI:
	Same store (1)		357,323			201,698			109,026			198,770			—			866,817
	Non-same store/other (2) (3)		176,925			65,337			1,089			29,836			(6,004		)	267,183
	Total NOI		$	534,248		$	267,035		$	110,115		$	228,606		$	(6,004	)	$	1,134,000
	Total assets		$	11,499,130		$	4,540,404		$	1,513,074		$	3,578,742		$	2,680,081		$	23,811,431
	Capital expenditures		$	39,331		$	23,793		$	13,270		$	15,360		$	5,112		$	96,866
	-1	Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2012, less properties subsequently sold, which represented 81,099 apartment units.
	-2	Non-same store primarily includes properties acquired after January 1, 2012, plus any properties in lease-up and not stabilized as of January 1, 2012.
	-3	Other includes development and other corporate operations.
			Nine Months Ended September 30, 2012
			Northeast			Northwest			Southeast			Southwest			Other (3)			Total
	Rental income:
	Same store (1)		$	535,830		$	282,586		$	167,561		$	283,899		$	—		$	1,269,876
	Non-same store/other (2) (3)		15,876			8,049			—			1,793			(163		)	25,555
	Total rental income		551,706			290,635			167,561			285,692			(163		)	1,295,431
	Operating expenses:
	Same store (1)		190,979			98,616			64,878			93,127			—			447,600
	Non-same store/other (2) (3)		6,170			2,581			—			617			14,443			23,811
	Total operating expenses		197,149			101,197			64,878			93,744			14,443			471,411
	NOI:
	Same store (1)		344,851			183,970			102,683			190,772			—			822,276
	Non-same store/other (2) (3)		9,706			5,468			—			1,176			(14,606		)	1,744
	Total NOI		$	354,557		$	189,438		$	102,683		$	191,948		$	(14,606	)	$	824,020
	-1	Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2012, less properties subsequently sold, which represented 81,099 apartment units.
	-2	Non-same store primarily includes properties acquired after January 1, 2012, plus any properties in lease-up and not stabilized as of January 1, 2012.
	-3	Other includes development and other corporate operations.
			Quarter Ended September 30, 2013
			Northeast			Northwest			Southeast			Southwest			Other (3)			Total
	Rental income:
	Same store (1)		$	196,089		$	107,340		$	59,170		$	101,008		$	—		$	463,607
	Non-same store/other (2) (3)		101,001			38,862			768			21,470			1,172			163,273
	Total rental income		297,090			146,202			59,938			122,478			1,172			626,880
	Operating expenses:
	Same store (1)		68,044			35,784			22,619			32,855			—			159,302
	Non-same store/other (2) (3)		34,191			13,296			289			8,801			(1,117		)	55,460
	Total operating expenses		102,235			49,080			22,908			41,656			(1,117		)	214,762
	NOI:
	Same store (1)		128,045			71,556			36,551			68,153			—			304,305
	Non-same store/other (2) (3)		66,810			25,566			479			12,669			2,289			107,813
	Total NOI		$	194,855		$	97,122		$	37,030		$	80,822		$	2,289		$	412,118
	-1	Same store primarily includes all properties acquired or completed and stabilized prior to July 1, 2012, less properties subsequently sold, which represented 82,553 apartment units.
	-2	Non-same store primarily includes properties acquired after July 1, 2012, plus any properties in lease-up and not stabilized as of July 1, 2012.
	-3	Other includes development and other corporate operations.
			Quarter Ended September 30, 2012
			Northeast			Northwest			Southeast			Southwest			Other (3)			Total
	Rental income:
	Same store (1)		$	190,648		$	100,280		$	56,987		$	97,606		$	—		$	445,521
	Non-same store/other (2) (3)		1,658			1,305			—			284			(121		)	3,126
	Total rental income		192,306			101,585			56,987			97,890			(121		)	448,647
	Operating expenses:
	Same store (1)		65,758			34,443			22,435			31,814			—			154,450
	Non-same store/other (2) (3)		994			235			—			52			2,508			3,789
	Total operating expenses		66,752			34,678			22,435			31,866			2,508			158,239
NOI:
Same store (1)		124,890			65,837			34,552			65,792			—			291,071
Non-same store/other (2) (3)		664			1,070			—			232			(2,629		)	(663		)
Total NOI		$	125,554		$	66,907		$	34,552		$	66,024		$	(2,629	)	$	290,408
-1	Same store primarily includes all properties acquired or completed and stabilized prior to July 1, 2012, less properties subsequently sold, which represented 82,553 apartment units.
-2	Non-same store primarily includes properties acquired after July 1, 2012, plus any properties in lease-up and not stabilized as of July 1, 2012.
-3	Other includes development and other corporate operations.
Reconciliation of NOI	'
	The following table presents a reconciliation of NOI from our rental real estate specific to continuing operations for the nine months and quarters ended September 30, 2013 and 2012, respectively (amounts in thousands):
			Nine Months Ended September 30,						Quarter Ended September 30,
			2013			2012			2013			2012
	Rental income		$	1,749,374		$	1,295,431		$	626,880		$	448,647
	Property and maintenance expense		(333,202		)	(254,009		)	(119,632		)	(86,682		)
	Real estate taxes and insurance expense		(218,777		)	(154,633		)	(76,255		)	(53,064		)
	Property management expense		(63,395		)	(62,769		)	(18,875		)	(18,493		)
	Total operating expenses		(615,374		)	(471,411		)	(214,762		)	(158,239		)
	Net operating income		$	1,134,000		$	824,020		$	412,118		$	290,408

Business_Details

Business (Details)	Sep. 30, 2013
Noncontrolling Interest, Ownership Percentage by Parent	96.20%
Number of Real Estate Properties	389
Number of Units in Real Estate Property	109,795
Number of States in which Entity Operates	12
Property/Unit schedule	'
Wholly Owned Properties	363
Master Leased Properties Acquired	3
Partially Owned Consolidated Properties	19
Partially Owned Unconsolidated Properties	2
Military Housing Properties	2
Wholly Owned Units	99,192
Master Leased Units	853
Partially Owned Consolidated Units	3,752
Partially Owned Unconsolidated Units	837
Military Housing Units	5,161
Archstone Transaction [Member]	'
Property/Unit schedule	'
Master Leased Properties Acquired	3

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Value of furniture and fixtures minimum range	$3,000	'
Value of furniture and fixtures maximum range	13,000	'
Partially Owned Consolidated Properties	19	'
Partially Owned Consolidated Units	3,752	'
Noncontrolling Interests - Partially Owned Properties	110,635,000	77,688,000
Partially Owned Limited Life Partnership Properties	6	'
Noncontrolling Interest Balance Limited Life Partnerships	-8,500,000	'
Noncontrolling Interests Settlement Value	$46,761,561	'
Lease Intangibles, Average Term	6	'
Furniture and Fixtures [Member]	'	'
Property, Plant and Equipment, Estimated Useful Lives	'5	'
Furniture and Fixtures Maximum [Member]	'	'
Property, Plant and Equipment, Estimated Useful Lives	'10	'
Building Improvements [Member]	'	'
Property, Plant and Equipment, Estimated Useful Lives	'8	'
Building [Member]	'	'
Property, Plant and Equipment, Estimated Useful Lives	'30	'

Equity_Capital_and_Other_Inter2

Equity, Capital and Other Interests EQR Common Shares (Details)	9 Months Ended		9 Months Ended			12 Months Ended	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012
			Archstone Transaction [Member]	Limited Partner [Member]	Limited Partner [Member]	Public Offering [Member]	Limited Partner [Member]	Limited Partner [Member]
Common Shares outstanding at January 1,	360,395,959	325,054,654	'	'	'	'	'	'
Common Shares Issued:	'	'	'	'	'	'	'	'
Conversion of OP Units	47,939	'	'	'	'	'	'	'
Issuance of Common Shares	34,468,085	'	34,468,085	'	'	21,850,000	'	'
Exercise of share options	530,847	'	'	'	'	'	'	'
Employee Share Purchase Plan (ESPP)	63,788	'	'	'	'	'	'	'
Restricted Share Grants Net	230,646	'	'	'	'	'	'	'
Units	'	'	'	'	'	'	'	'
Total Units Outstanding	'	'	'	14,200,376	13,968,758	'	14,200,376	13,968,758
Issuance Of LTIPs	'	'	'	279,557	'	'	279,557	'
Shares Issued During Period Shares Conversion Of Units To Common Shares	'	'	'	-47,939	'	'	-47,939	'
Common Shares And Units Outstanding	374,596,335	'	'	'	'	'	'	'
Units Ownership Interest in Operating Partnership	3.80%	'	'	'	'	'	'	'

Equity_Capital_and_Other_Inter3

Equity, Capital and Other Interest Redeemable (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Redeemable Noncontrolling Interests - Operating Partnership	$376,057	$398,372
Change in market value	-69,344	'
Change in carrying value	47,029	'
Limited Partners Change In Redemption Value	-69,344	'
Limited Partners Change In Carrying Value	47,029	'
Partnership Interest [Member]	'	'
Redeemable Limited Partners	$376,057	$398,372

Equity_Capital_and_Other_Inter4

Equity, Capital and Other Interests Preferred (Details) (USD $)	9 Months Ended	12 Months Ended	45 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013
Class of Stock [Line Items]	'	'	'
Preferred Stock, Shares Authorized	100,000,000	100,000,000	100,000,000
Preferred Stock, Par or Stated Value Per Share	$0.01	$0.01	$0.01
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 1,000,000 shares issued and outstanding as of September 30, 2013 and December 31, 2012	$50,000	$50,000	$50,000
Series K Preferred Stock [Member]	'	'	'
Class of Stock [Line Items]	'	'	'
Preferred Stock Preference Units Issued	1,000,000	1,000,000	1,000,000
Preferred Stock Preference Units Outstanding	1,000,000	1,000,000	1,000,000
Preferred Stock Preference Units Redemption Price Per Share Unit	$50	$50	$50
Preferred Stock Preference Units Dividend Rate Percentage	8.29%	8.29%	8.29%
Preferred Stocks Preference Units Redemption Date	10-Dec-26	'	'
Annual Dividend Per Preferred Share Preference Unit	$4.14	'	'
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 1,000,000 shares issued and outstanding as of September 30, 2013 and December 31, 2012	50,000	50,000	50,000
Preference Units	50,000	50,000	50,000
Partnership Interest [Member]	'	'	'
Class of Stock [Line Items]	'	'	'
Preference Units	$50,000	$50,000	$50,000

Equity_Capital_and_Other_Inter5

Equity, Capital and Other Interests ERP Units (Details)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Capital Unit [Line Items]	'	'
Common Shares And Units Outstanding	374,596,335	'
Issuance of OP Units	34,468,085	'
Exercise of EQR share options	530,847	'
EQR's Employee Share Purchase Plan (ESPP)	63,788	'
Restricted Share Grants Net	230,646	'
Units Ownership Interest in Operating Partnership	3.80%	'
General And Limited Partner [Member]	'	'
Capital Unit [Line Items]	'	'
Common Shares And Units Outstanding	374,596,335	339,023,412
Issuance of OP Units	34,468,085	'
Exercise of EQR share options	530,847	'
EQR's Employee Share Purchase Plan (ESPP)	63,788	'
Restricted Share Grants Net	230,646	'
Issuance Of LTIPs	279,557	'
Limited Partner [Member]	'	'
Capital Unit [Line Items]	'	'
Issuance Of LTIPs	279,557	'
Shares Issued During Period Shares Conversion Of Units To Common Shares	-47,939	'
Total Units Outstanding	14,200,376	13,968,758

Equity_Capital_and_Other_Inter6

Equity, Capital and Other Interests Text (Details) (USD $)	6 Months Ended	9 Months Ended			12 Months Ended
	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012
				Archstone Transaction [Member]	Public Offering [Member]
Stock Repurchased and Retired During Period, Shares	'	0	'	'	'
Issuance of Common Shares	'	34,468,085	'	34,468,085	21,850,000
Stock Issued During Period, Value, New Issues	'	'	'	$1,900,000,000	$1,200,000,000
Average Price Per Common Share Issued	'	'	'	$55.99	$54.75
Units Issued During Period New Issues	'	'	'	34,468,085	21,850,000
Payments of Stock Issuance Costs	'	954,000	2,860,000	'	35,900,000
Common Stock Capital Shares Reserved For Future Issuance Under Share Offering Program	'	17,000,000	'	'	'
Common Shares Added To Atm Program	'	5,687,478	'	'	'
Additional Common Shares Authorized	'	13,000,000	'	'	'
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$464,600,000	'	'	'	'
Stock Repurchase Program, Number of Shares Authorized to be Repurchased	'	13,000,000	'	'	'

Real_Estate_Details

Real Estate (Details) (USD $)	3 Months Ended		9 Months Ended		45 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012
Land	$6,201,333,000	'	$6,201,333,000	'	$6,201,333,000	$4,554,912,000
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Investment Building and Building Improvements	17,555,388,000	'	17,555,388,000	'	17,555,388,000	14,135,740,000
Fixtures and Equipment, Gross	1,196,410,000	'	1,196,410,000	'	1,196,410,000	1,343,765,000
Finite-Lived Intangible Assets, Gross	503,159,000	'	503,159,000	'	503,159,000	232,439,000
Projects under development	779,053,000	'	779,053,000	'	779,053,000	387,750,000
Land held for development	505,494,000	'	505,494,000	'	505,494,000	353,823,000
Real Estate Investment Property, at Cost	26,740,837,000	'	26,740,837,000	'	26,740,837,000	21,008,429,000
Real Estate Investment Property, Accumulated Depreciation	-4,654,594,000	'	-4,654,594,000	'	-4,654,594,000	-4,912,221,000
Investment in real estate, net	22,086,243,000	'	22,086,243,000	'	22,086,243,000	16,096,208,000
Ground Lease Intangibles Below Market	178,251,000	'	178,251,000	'	178,251,000	'
Retail Lease Intangibles Above Market	2,310,000	'	2,310,000	'	2,310,000	'
Lease Intangible Assets	180,561,000	'	180,561,000	'	180,561,000	'
Lease Intangible Assets, Net	177,340,000	'	177,340,000	'	177,340,000	'
Ground Lease Intangibles Above Market	2,400,000	'	2,400,000	'	2,400,000	'
Retail Lease Intangibles Below Market	7,790,000	'	7,790,000	'	7,790,000	'
Lease Intangible Liabilities	10,190,000	'	10,190,000	'	10,190,000	'
Amortization Of Intangible Liabilities	-993,000	'	-993,000	'	-993,000	'
Lease Intangible Liabilities, net	9,197,000	'	9,197,000	'	9,197,000	'
Ground Lease Amortization	1,100,000	'	2,500,000	'	'	'
Retail Lease Amortization	100,000	'	300,000	'	'	'
Weighted Average Ground Lease Amortization Period	49.8	'	49.8	'	49.8	'
Weighted Average Retail Lease Amortization Period	5.3	'	5.3	'	5.3	'
Properties acquired	'	'	1	'	'	'
Property Units Acquired	'	'	322	'	'	'
Master Leased Properties Acquired	3	'	3	'	3	'
Payments to Acquire Businesses, Net of Cash Acquired	'	'	4,000,875,000	0	'	'
Mortgage notes payable	6,230,675,000	'	6,230,675,000	'	6,230,675,000	3,898,369,000
Issuance of Common Shares	'	'	34,468,085	'	'	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	'	34,100,000	'	'	'
Mark-to-Market Debt Premiums	'	'	127,900,000	'	'	'
Number of Properties Subject to Ground Leases	9	'	9	'	9	'
Business Combination, Acquisition Related Costs	'	'	200,000	6,900,000	95,400,000	'
Payments of Financing Costs	'	'	-18,254,000	-4,599,000	'	'
Merger Expenses	182,000	87,000	19,741,000	1,921,000	81,900,000	'
(Loss) from investments in unconsolidated entities due to merger expenses	-1,771,000	0	-54,781,000	0	'	'
Business Acquisition, Pro Forma Revenue	629,446,000	596,734,000	1,854,509,000	1,726,304,000	'	'
Business Acquisition, Proforma Income Loss From Continuing Operations	84,978,000	107,024,000	132,592,000	-179,574,000	'	'
Business Acquisition, Proforma Income Loss From Discontinued Operations Net Of Tax	403,181,000	145,145,000	2,024,346,000	434,253,000	'	'
Business Acquisition, Pro Forma Net Income (Loss)	488,159,000	252,169,000	2,156,938,000	254,679,000	'	'
Business Acquisition, Proforma Net Income Available to Common Shares	468,959,000	234,471,000	2,070,153,000	232,053,000	'	'
Business Acquisition, Pro Forma Earnings Per Share, Basic	$1.30	$0.66	$5.76	$0.65	'	'
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$1.30	$0.66	$5.74	$0.65	'	'
Business Acquisition, Proforma Weighted Average Common Shares Basic	359,811,000	357,654,000	359,611,000	356,434,000	'	'
Business Acquisition, Proforma Weighted Average Number Of Shares Diluted	375,883,000	375,091,000	375,808,000	356,434,000	'	'
Consolidated Properties [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Uncompleted Development Properties Acquired	2	'	2	'	2	'
Archstone [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Amortization of Intangible Assets	-3,221,000	'	-3,221,000	'	-3,221,000	'
Payments to Acquire Businesses, Net of Cash Acquired	'	'	4,000,000,000	'	'	'
Mortgage notes payable	2,000,000,000	'	2,000,000,000	'	2,000,000,000	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	'	3,100,000,000	'	'	'
Business Acquisition, Purchase Price Allocation, Land	2,239,000,000	'	2,239,000,000	'	2,239,000,000	'
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets	304,830,000	'	304,830,000	'	304,830,000	'
Business Combination Purchase Price Allocation Projects Under Development	36,583,000	'	36,583,000	'	36,583,000	'
Business Combination Purchase Price Allocation Land Held for Development	239,898,000	'	239,898,000	'	239,898,000	'
Business Combination Purchase Price Allocation Investments in Unconsolidated Entities	188,139,000	'	188,139,000	'	188,139,000	'
Business Acquisition, Purchase Price Allocation, Other Assets	196,310,000	'	196,310,000	'	196,310,000	'
Business Acquisition, Purchase Price Allocation, Other Liabilities	-112,369,000	'	-112,369,000	'	-112,369,000	'
Payments of Financing Costs	'	'	2,500,000	'	13,500,000	'
Merger Expenses	'	'	'	1,921,000	'	'
Severance Costs	'	'	53,600,000	'	'	'
2013 [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Ground Lease Intangibles Amortization	1,080,000	'	1,080,000	'	1,080,000	'
Retail Lease Intangibles Amortization	-218,000	'	-218,000	'	-218,000	'
Total Above And Below Market Ground Lease Intangibles And Retail Lease Intangibles	862,000	'	862,000	'	862,000	'
2014 [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Ground Lease Intangibles Amortization	4,321,000	'	4,321,000	'	4,321,000	'
Retail Lease Intangibles Amortization	-1,144,000	'	-1,144,000	'	-1,144,000	'
Total Above And Below Market Ground Lease Intangibles And Retail Lease Intangibles	3,177,000	'	3,177,000	'	3,177,000	'
2015 [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Ground Lease Intangibles Amortization	4,321,000	'	4,321,000	'	4,321,000	'
Retail Lease Intangibles Amortization	-1,150,000	'	-1,150,000	'	-1,150,000	'
Total Above And Below Market Ground Lease Intangibles And Retail Lease Intangibles	3,171,000	'	3,171,000	'	3,171,000	'
2016 [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Ground Lease Intangibles Amortization	4,321,000	'	4,321,000	'	4,321,000	'
Retail Lease Intangibles Amortization	-1,042,000	'	-1,042,000	'	-1,042,000	'
Total Above And Below Market Ground Lease Intangibles And Retail Lease Intangibles	3,279,000	'	3,279,000	'	3,279,000	'
2017 [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Ground Lease Intangibles Amortization	4,321,000	'	4,321,000	'	4,321,000	'
Retail Lease Intangibles Amortization	-674,000	'	-674,000	'	-674,000	'
Total Above And Below Market Ground Lease Intangibles And Retail Lease Intangibles	3,647,000	'	3,647,000	'	3,647,000	'
2018 [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Ground Lease Intangibles Amortization	4,321,000	'	4,321,000	'	4,321,000	'
Retail Lease Intangibles Amortization	-205,000	'	-205,000	'	-205,000	'
Total Above And Below Market Ground Lease Intangibles And Retail Lease Intangibles	4,116,000	'	4,116,000	'	4,116,000	'
Investment Banking and Legal/Accounting Fees [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Merger Expenses	'	'	19,700,000	'	'	'
Building and Building Improvements [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	5,832,554,000	'	5,832,554,000	'	5,832,554,000	'
Furniture and Fixtures [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	61,470,000	'	61,470,000	'	61,470,000	'
Archstone Transaction [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Ground Lease Intangibles Below Market	178,251,000	'	178,251,000	'	178,251,000	'
Retail Lease Intangibles Above Market	2,310,000	'	2,310,000	'	2,310,000	'
Ground Lease Intangibles Above Market	2,400,000	'	2,400,000	'	2,400,000	'
Retail Lease Intangibles Below Market	8,040,000	'	8,040,000	'	8,040,000	'
Business Acquisition, Percentage of Voting Interests Acquired	60.00%	'	60.00%	'	60.00%	'
Properties acquired	'	'	71	'	'	'
Partially Owned Properties Acquired Properties	1	'	1	'	1	'
Partially Owned Units Acquired Units	432	'	432	'	432	'
Partially Owned Unconsolidated Properties Acquired	1	'	1	'	1	'
Partially Owned Unconsolidated Units Acquired	336	'	336	'	336	'
Master Leased Properties Acquired	3	'	3	'	3	'
Master Leased Units Acquired	853	'	853	'	853	'
Uncompleted Development Properties Acquired	4	'	4	'	4	'
Uncompleted Development Units Acquired	964	'	964	'	964	'
Land parcels acquired	'	'	14	'	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	8,986,415,000	'	8,986,415,000	'	8,986,415,000	'
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	153,500,000	'	358,000,000	'	'	'
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	104,200,000	'	244,200,000	'	'	'
Unconsolidated Properties [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Uncompleted Development Properties Acquired	2	'	2	'	2	'
Projects under development [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Land Under Development	280,718,000	'	280,718,000	'	280,718,000	210,632,000
Projects under development	498,335,000	'	498,335,000	'	498,335,000	177,118,000
Land held for development [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Projects under development	70,267,000	'	70,267,000	'	70,267,000	58,955,000
Land held for development	435,227,000	'	435,227,000	'	435,227,000	294,868,000
Archstone Transaction [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Property Units Acquired	'	'	20,160	'	'	'
OPERATING PARTNERSHIP	'	'	'	'	'	'
Land	6,201,333,000	'	6,201,333,000	'	6,201,333,000	4,554,912,000
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Projects under development	779,053,000	'	779,053,000	'	779,053,000	387,750,000
Land held for development	505,494,000	'	505,494,000	'	505,494,000	353,823,000
Real Estate Investment Property, at Cost	26,740,837,000	'	26,740,837,000	'	26,740,837,000	21,008,429,000
Real Estate Investment Property, Accumulated Depreciation	-4,654,594,000	'	-4,654,594,000	'	-4,654,594,000	-4,912,221,000
Investment in real estate, net	22,086,243,000	'	22,086,243,000	'	22,086,243,000	16,096,208,000
Payments to Acquire Businesses, Net of Cash Acquired	'	'	4,000,875,000	0	'	'
Mortgage notes payable	6,230,675,000	'	6,230,675,000	'	6,230,675,000	3,898,369,000
Payments of Financing Costs	'	'	-18,254,000	-4,599,000	'	'
Merger Expenses	182,000	87,000	19,741,000	1,921,000	'	'
(Loss) from investments in unconsolidated entities due to merger expenses	-1,771,000	0	-54,781,000	0	'	'
Business Acquisition, Pro Forma Revenue	629,446,000	596,734,000	1,854,509,000	1,726,304,000	'	'
Business Acquisition, Proforma Income Loss From Continuing Operations	84,978,000	107,024,000	132,592,000	-179,574,000	'	'
Business Acquisition, Proforma Income Loss From Discontinued Operations Net Of Tax	403,181,000	145,145,000	2,024,346,000	434,253,000	'	'
Business Acquisition, Pro Forma Net Income (Loss)	488,159,000	252,169,000	2,156,938,000	254,679,000	'	'
Business Acquisition, Proforma Net Income Available to Units	487,433,000	245,725,000	2,155,736,000	242,962,000	'	'
Business Acquisition, Pro Forma Earnings Per Share, Basic	$1.30	$0.66	$5.76	$0.65	'	'
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$1.30	$0.66	$5.74	$0.65	'	'
Business Acquisition, Proforma Weighted Average Limited Partnership And General Partnership Units Outstanding Basic	373,547,000	371,831,000	373,347,000	370,250,000	'	'
Business Acquisition, Proforma Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	375,883,000	375,091,000	375,808,000	370,250,000	'	'
Archstone Transaction [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Issuance of Common Shares	'	'	34,468,085	'	'	'
Stock Issued During Period, Value, New Issues	'	'	1,900,000,000	'	'	'
Average Price Per Common Share Issued	'	'	$55.99	'	'	'
DelayedDrawTermLoan [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Term Loan Principal Amount	$750,000,000	'	$750,000,000	'	$750,000,000	'
Land [Member]	'	'	'	'	'	'
Property, Plant and Equipment, Gross [Abstract]	'	'	'	'	'	'
Property Units Acquired	'	'	0	'	'	'
Land parcels acquired	'	'	1	'	'	'

Real_Estate_Details_2

Real Estate (Details 2) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Properties acquired	'	'	1	'
Property Units Acquired	'	'	322	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$108,000,000	'	$108,000,000	'
Disposed Properties	'	'	92	'
Disposed Units	'	'	28,328	'
Proceeds From Sale Of Property	'	'	4,497,423,000	'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	401,703,000	103,394,000	1,990,577,000	307,447,000
Net gain (loss) on sales of land parcels	-2,437,000	0	12,179,000	0
Consolidated Rental Properties [Member]	'	'	'	'
Properties acquired	'	'	1	'
Property Units Acquired	'	'	322	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	91,500,000	'	91,500,000	'
Disposed Properties	'	'	92	'
Disposed Units	'	'	28,328	'
Proceeds From Sale Of Property	'	'	4,362,689,000	'
Land [Member]	'	'	'	'
Property Units Acquired	'	'	0	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	16,500,000	'	16,500,000	'
Proceeds From Sale Of Property	'	'	77,650,000	'
Land parcels acquired	'	'	1	'
Disposed Land Parcels	'	'	6	'
Unconsolidated Land Parcel Disposition	'	'	1	'
Commercial Real Estate [Member]	'	'	'	'
Proceeds From Sale Of Property	'	'	30,734,000	'
Commercial Properties Disposed	'	'	1	'
Unconsolidated Institutional Joint Ventures [Member]	'	'	'	'
Proceeds From Sale Of Property	'	'	$26,350,000	'

Commitments_to_AcquireDispose_2

Commitments to Acquire/Dispose of Real Estate (Details) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Commitments to Acquire Real Estate	'
Properties Acquired-Total	0
Rental Units Acquired - Total	0
Purchase Price - Total	$12,500
Commitments to Dispose of Real Estate	'
Properties Disposed - Total	0
Rental Units Disposed-Total	0
Sales Price For Commitments To Dispose	27,000
Land Parcel [Member]	'
Commitments to Acquire Real Estate	'
Purchase Price - Total	12,500
Land Parcels Contracted to be Acquired	1
Land Parcel [Member]	'
Commitments to Dispose of Real Estate	'
Sales Price For Commitments To Dispose	$27,000
Land Parcels Contracted to be Disposed	1

Investments_in_Partially_Owned2

Investments in Partially Owned Entities (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 08, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Consolidated Properties	'	19	'	19	'	'	'
Partially Owned Unconsolidated Properties	'	2	'	2	'	'	'
Partially Owned Consolidated Units	'	3,752	'	3,752	'	'	'
Partially Owned Unconsolidated Units	'	837	'	837	'	'	'
ASSETS	'	'	'	'	'	'	'
Real Estate Investment Property, at Cost	'	$26,740,837,000	'	$26,740,837,000	'	$21,008,429,000	'
Real Estate Investment Property, Accumulated Depreciation	'	-4,654,594,000	'	-4,654,594,000	'	-4,912,221,000	'
Investment in real estate, net	'	22,086,243,000	'	22,086,243,000	'	16,096,208,000	'
Cash and Cash Equivalents, at Carrying Value	'	972,761,000	45,623,000	972,761,000	45,623,000	612,590,000	383,921,000
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	165,898,000	'	165,898,000	'	17,877,000	'
Restricted Cash and Cash Equivalents	'	98,874,000	'	98,874,000	'	250,442,000	'
Deferred Finance Costs, Net	'	66,775,000	'	66,775,000	'	44,382,000	'
Other Assets	'	379,979,000	'	379,979,000	'	170,372,000	'
Total assets	'	23,811,431,000	'	23,811,431,000	'	17,201,000,000	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	6,230,675,000	'	6,230,675,000	'	3,898,369,000	'
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	'	166,939,000	'	166,939,000	'	38,372,000	'
Interest Payable	'	85,353,000	'	85,353,000	'	76,223,000	'
Other Liabilities	'	331,797,000	'	331,797,000	'	304,518,000	'
Security Deposit Liability	'	71,462,000	'	71,462,000	'	66,988,000	'
Total liabilities	'	12,512,584,000	'	12,512,584,000	'	9,275,521,000	'
Noncontrolling Interests Partially Owned Properties	'	110,635,000	'	110,635,000	'	77,688,000	'
Total liabilities and equity	'	23,811,431,000	'	23,811,431,000	'	17,201,000,000	'
Partially Owned Property Income Statement Schedule	'	'	'	'	'	'	'
Operating revenue	'	629,446,000	451,699,000	1,756,773,000	1,302,759,000	'	'
Depreciation	'	277,336,000	139,337,000	798,121,000	422,148,000	'	'
General and Administrative Expense	'	14,438,000	10,083,000	47,018,000	37,162,000	'	'
Operating Income	'	121,394,000	142,932,000	291,521,000	368,443,000	'	'
Interest and Other Income	'	816,000	70,087,000	1,320,000	70,514,000	'	'
Interest:	'	'	'	'	'	'	'
Interest Expense, Debt	'	120,035,000	113,222,000	437,452,000	345,476,000	'	'
Amortization of Financing Costs	'	4,335,000	3,320,000	15,636,000	10,265,000	'	'
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	'	-6,328,000	92,406,000	-187,518,000	62,708,000	'	'
Income and other tax (expense) benefit	'	-493,000	-222,000	-1,326,000	-602,000	'	'
(Loss) from investments in unconsolidated entities due to operations	'	-1,454,000	-3,000	-2,984,000	-3,000	'	'
Net gain (loss) on sales of land parcels	'	-2,437,000	0	12,179,000	0	'	'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	'	401,703,000	103,394,000	1,990,577,000	307,447,000	'	'
Net income	'	391,717,000	236,323,000	1,789,483,000	496,805,000	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Joint Venture Partner Ownership Percentage	'	80.00%	'	80.00%	'	'	'
Equity Method Investment, Ownership Percentage	'	20.00%	'	20.00%	'	'	'
Variable Interest Entity, Consolidated, Carrying Amount, Assets	'	5,000,000	'	5,000,000	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	5.88%	'	'	'	'	'	'
Debt Instrument, Maturity Date	1-Nov-14	'	'	1-Sep-14	'	'	'
Preferred Interests	'	'	'	65,000,000	'	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	'	108,000,000	'	108,000,000	'	'	'
Investment in Joint Venture	'	259,138,385	'	259,138,385	'	'	'
Number of Joint Ventures	'	2	'	2	'	'	'
Partners Payments To Acquire Equity Method Investments	'	'	'	40,100,000	'	'	'
Consolidated Development Projects Held for and or Under Development [Member]	'	'	'	'	'	'	'
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Consolidated Properties	'	0	'	0	'	'	'
Partially Owned Consolidated Units	'	0	'	0	'	'	'
ASSETS	'	'	'	'	'	'	'
Real Estate Investment Property, at Cost	'	308,893,000	'	308,893,000	'	'	'
Real Estate Investment Property, Accumulated Depreciation	'	0	'	0	'	'	'
Investment in real estate, net	'	308,893,000	'	308,893,000	'	'	'
Cash and Cash Equivalents, at Carrying Value	'	4,253,000	'	4,253,000	'	'	'
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	0	'	0	'	'	'
Restricted Cash and Cash Equivalents	'	43,631,000	'	43,631,000	'	'	'
Deferred Finance Costs, Net	'	0	'	0	'	'	'
Other Assets	'	5,781,000	'	5,781,000	'	'	'
Total assets	'	362,558,000	'	362,558,000	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	0	'	0	'	'	'
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	'	27,052,000	'	27,052,000	'	'	'
Interest Payable	'	0	'	0	'	'	'
Other Liabilities	'	1,045,000	'	1,045,000	'	'	'
Security Deposit Liability	'	1,000	'	1,000	'	'	'
Total liabilities	'	28,098,000	'	28,098,000	'	'	'
Noncontrolling Interests Partially Owned Properties	'	98,126,000	'	98,126,000	'	'	'
Parent Equity Interest	'	236,334,000	'	236,334,000	'	'	'
Total Equity Interest	'	334,460,000	'	334,460,000	'	'	'
Total liabilities and equity	'	362,558,000	'	362,558,000	'	'	'
Partially Owned Property Income Statement Schedule	'	'	'	'	'	'	'
Operating revenue	'	'	'	12,000	'	'	'
Operating Expenses	'	'	'	407,000	'	'	'
Gross Profit	'	'	'	-395,000	'	'	'
Depreciation	'	'	'	0	'	'	'
General and Administrative Expense	'	'	'	520,000	'	'	'
Operating Income	'	'	'	-915,000	'	'	'
Interest and Other Income	'	'	'	2,000	'	'	'
Other Nonoperating Income (Expense)	'	'	'	-334,000	'	'	'
Interest:	'	'	'	'	'	'	'
Interest Expense, Debt	'	'	'	-2,000	'	'	'
Amortization of Financing Costs	'	'	'	0	'	'	'
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	'	'	'	-1,249,000	'	'	'
Income and other tax (expense) benefit	'	'	'	-11,000	'	'	'
(Loss) from investments in unconsolidated entities due to operations	'	'	'	0	'	'	'
Net gain (loss) on sales of land parcels	'	'	'	-17,000	'	'	'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	'	'	'	0	'	'	'
Net income	'	'	'	-1,277,000	'	'	'
Consolidated Operating [Domain]	'	'	'	'	'	'	'
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Consolidated Properties	'	19	'	19	'	'	'
Partially Owned Consolidated Units	'	3,752	'	3,752	'	'	'
ASSETS	'	'	'	'	'	'	'
Real Estate Investment Property, at Cost	'	672,958,000	'	672,958,000	'	'	'
Real Estate Investment Property, Accumulated Depreciation	'	-167,457,000	'	-167,457,000	'	'	'
Investment in real estate, net	'	505,501,000	'	505,501,000	'	'	'
Cash and Cash Equivalents, at Carrying Value	'	17,659,000	'	17,659,000	'	'	'
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	55,040,000	'	55,040,000	'	'	'
Restricted Cash and Cash Equivalents	'	206,000	'	206,000	'	'	'
Deferred Finance Costs, Net	'	2,521,000	'	2,521,000	'	'	'
Other Assets	'	27,170,000	'	27,170,000	'	'	'
Total assets	'	608,097,000	'	608,097,000	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	358,730,000	'	358,730,000	'	'	'
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	'	2,495,000	'	2,495,000	'	'	'
Interest Payable	'	1,259,000	'	1,259,000	'	'	'
Other Liabilities	'	1,254,000	'	1,254,000	'	'	'
Security Deposit Liability	'	1,821,000	'	1,821,000	'	'	'
Total liabilities	'	365,559,000	'	365,559,000	'	'	'
Noncontrolling Interests Partially Owned Properties	'	12,509,000	'	12,509,000	'	'	'
Parent Equity Interest	'	230,029,000	'	230,029,000	'	'	'
Total Equity Interest	'	242,538,000	'	242,538,000	'	'	'
Total liabilities and equity	'	608,097,000	'	608,097,000	'	'	'
Partially Owned Property Income Statement Schedule	'	'	'	'	'	'	'
Operating revenue	'	'	'	59,666,000	'	'	'
Operating Expenses	'	'	'	18,458,000	'	'	'
Gross Profit	'	'	'	41,208,000	'	'	'
Depreciation	'	'	'	26,478,000	'	'	'
General and Administrative Expense	'	'	'	79,000	'	'	'
Operating Income	'	'	'	14,651,000	'	'	'
Interest and Other Income	'	'	'	3,000	'	'	'
Other Nonoperating Income (Expense)	'	'	'	-4,000	'	'	'
Interest:	'	'	'	'	'	'	'
Interest Expense, Debt	'	'	'	-10,615,000	'	'	'
Amortization of Financing Costs	'	'	'	-216,000	'	'	'
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	'	'	'	3,819,000	'	'	'
Income and other tax (expense) benefit	'	'	'	-56,000	'	'	'
(Loss) from investments in unconsolidated entities due to operations	'	'	'	-1,010,000	'	'	'
Net gain (loss) on sales of land parcels	'	'	'	0	'	'	'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	'	'	'	26,673,000	'	'	'
Net income	'	'	'	29,426,000	'	'	'
Consolidated Total [Domain]	'	'	'	'	'	'	'
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Consolidated Properties	'	19	'	19	'	'	'
Partially Owned Consolidated Units	'	3,752	'	3,752	'	'	'
ASSETS	'	'	'	'	'	'	'
Real Estate Investment Property, at Cost	'	981,851,000	'	981,851,000	'	'	'
Real Estate Investment Property, Accumulated Depreciation	'	-167,457,000	'	-167,457,000	'	'	'
Investment in real estate, net	'	814,394,000	'	814,394,000	'	'	'
Cash and Cash Equivalents, at Carrying Value	'	21,912,000	'	21,912,000	'	'	'
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	55,040,000	'	55,040,000	'	'	'
Restricted Cash and Cash Equivalents	'	43,837,000	'	43,837,000	'	'	'
Deferred Finance Costs, Net	'	2,521,000	'	2,521,000	'	'	'
Other Assets	'	32,951,000	'	32,951,000	'	'	'
Total assets	'	970,655,000	'	970,655,000	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	358,730,000	'	358,730,000	'	'	'
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	'	29,547,000	'	29,547,000	'	'	'
Interest Payable	'	1,259,000	'	1,259,000	'	'	'
Other Liabilities	'	2,299,000	'	2,299,000	'	'	'
Security Deposit Liability	'	1,822,000	'	1,822,000	'	'	'
Total liabilities	'	393,657,000	'	393,657,000	'	'	'
Noncontrolling Interests Partially Owned Properties	'	110,635,000	'	110,635,000	'	'	'
Parent Equity Interest	'	466,363,000	'	466,363,000	'	'	'
Total Equity Interest	'	576,998,000	'	576,998,000	'	'	'
Total liabilities and equity	'	970,655,000	'	970,655,000	'	'	'
Partially Owned Property Income Statement Schedule	'	'	'	'	'	'	'
Operating revenue	'	'	'	59,678,000	'	'	'
Operating Expenses	'	'	'	18,865,000	'	'	'
Gross Profit	'	'	'	40,813,000	'	'	'
Depreciation	'	'	'	26,478,000	'	'	'
General and Administrative Expense	'	'	'	599,000	'	'	'
Operating Income	'	'	'	13,736,000	'	'	'
Interest and Other Income	'	'	'	5,000	'	'	'
Other Nonoperating Income (Expense)	'	'	'	-338,000	'	'	'
Interest:	'	'	'	'	'	'	'
Interest Expense, Debt	'	'	'	-10,617,000	'	'	'
Amortization of Financing Costs	'	'	'	-216,000	'	'	'
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	'	'	'	2,570,000	'	'	'
Income and other tax (expense) benefit	'	'	'	-67,000	'	'	'
(Loss) from investments in unconsolidated entities due to operations	'	'	'	-1,010,000	'	'	'
Net gain (loss) on sales of land parcels	'	'	'	-17,000	'	'	'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	'	'	'	26,673,000	'	'	'
Net income	'	'	'	28,149,000	'	'	'
Unconsolidated Development Projects Held for and or Under Development [Domain]	'	'	'	'	'	'	'
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Unconsolidated Properties	'	0	'	0	'	'	'
Partially Owned Unconsolidated Units	'	0	'	0	'	'	'
ASSETS	'	'	'	'	'	'	'
Real Estate Investment Property, at Cost	'	238,872,000	'	238,872,000	'	'	'
Real Estate Investment Property, Accumulated Depreciation	'	-84,000	'	-84,000	'	'	'
Investment in real estate, net	'	238,788,000	'	238,788,000	'	'	'
Cash and Cash Equivalents, at Carrying Value	'	1,153,000	'	1,153,000	'	'	'
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	0	'	0	'	'	'
Restricted Cash and Cash Equivalents	'	0	'	0	'	'	'
Deferred Finance Costs, Net	'	0	'	0	'	'	'
Other Assets	'	333,000	'	333,000	'	'	'
Total assets	'	240,274,000	'	240,274,000	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	118,723,000	'	118,723,000	'	'	'
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	'	13,781,000	'	13,781,000	'	'	'
Interest Payable	'	432,000	'	432,000	'	'	'
Other Liabilities	'	365,000	'	365,000	'	'	'
Security Deposit Liability	'	94,000	'	94,000	'	'	'
Total liabilities	'	133,395,000	'	133,395,000	'	'	'
Noncontrolling Interests Partially Owned Properties	'	78,556,000	'	78,556,000	'	'	'
Parent Equity Interest	'	28,323,000	'	28,323,000	'	'	'
Total Equity Interest	'	106,879,000	'	106,879,000	'	'	'
Total liabilities and equity	'	240,274,000	'	240,274,000	'	'	'
Partially Owned Property Income Statement Schedule	'	'	'	'	'	'	'
Operating revenue	'	'	'	1,305,000	'	'	'
Operating Expenses	'	'	'	1,141,000	'	'	'
Gross Profit	'	'	'	164,000	'	'	'
Depreciation	'	'	'	84,000	'	'	'
General and Administrative Expense	'	'	'	23,000	'	'	'
Operating Income	'	'	'	57,000	'	'	'
Interest and Other Income	'	'	'	0	'	'	'
Other Nonoperating Income (Expense)	'	'	'	0	'	'	'
Interest:	'	'	'	'	'	'	'
Interest Expense, Debt	'	'	'	-152,000	'	'	'
Amortization of Financing Costs	'	'	'	0	'	'	'
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	'	'	'	-95,000	'	'	'
Income and other tax (expense) benefit	'	'	'	0	'	'	'
(Loss) from investments in unconsolidated entities due to operations	'	'	'	0	'	'	'
Net gain (loss) on sales of land parcels	'	'	'	0	'	'	'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	'	'	'	0	'	'	'
Net income	'	'	'	-95,000	'	'	'
Unconsolidated Completed, Not Stabilized [Domain]	'	'	'	'	'	'	'
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Unconsolidated Properties	'	1	'	1	'	'	'
Partially Owned Unconsolidated Units	'	501	'	501	'	'	'
ASSETS	'	'	'	'	'	'	'
Real Estate Investment Property, at Cost	'	77,292,000	'	77,292,000	'	'	'
Real Estate Investment Property, Accumulated Depreciation	'	0	'	0	'	'	'
Investment in real estate, net	'	77,292,000	'	77,292,000	'	'	'
Cash and Cash Equivalents, at Carrying Value	'	317,000	'	317,000	'	'	'
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	0	'	0	'	'	'
Restricted Cash and Cash Equivalents	'	0	'	0	'	'	'
Deferred Finance Costs, Net	'	5,000	'	5,000	'	'	'
Other Assets	'	5,000	'	5,000	'	'	'
Total assets	'	77,619,000	'	77,619,000	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	45,217,000	'	45,217,000	'	'	'
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	'	2,864,000	'	2,864,000	'	'	'
Interest Payable	'	208,000	'	208,000	'	'	'
Other Liabilities	'	156,000	'	156,000	'	'	'
Security Deposit Liability	'	75,000	'	75,000	'	'	'
Total liabilities	'	48,520,000	'	48,520,000	'	'	'
Noncontrolling Interests Partially Owned Properties	'	23,205,000	'	23,205,000	'	'	'
Parent Equity Interest	'	5,894,000	'	5,894,000	'	'	'
Total Equity Interest	'	29,099,000	'	29,099,000	'	'	'
Total liabilities and equity	'	77,619,000	'	77,619,000	'	'	'
Partially Owned Property Income Statement Schedule	'	'	'	'	'	'	'
Operating revenue	'	'	'	1,861,000	'	'	'
Operating Expenses	'	'	'	1,023,000	'	'	'
Gross Profit	'	'	'	838,000	'	'	'
Depreciation	'	'	'	0	'	'	'
General and Administrative Expense	'	'	'	0	'	'	'
Operating Income	'	'	'	838,000	'	'	'
Interest and Other Income	'	'	'	0	'	'	'
Other Nonoperating Income (Expense)	'	'	'	0	'	'	'
Interest:	'	'	'	'	'	'	'
Interest Expense, Debt	'	'	'	-501,000	'	'	'
Amortization of Financing Costs	'	'	'	0	'	'	'
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	'	'	'	337,000	'	'	'
Income and other tax (expense) benefit	'	'	'	0	'	'	'
(Loss) from investments in unconsolidated entities due to operations	'	'	'	0	'	'	'
Net gain (loss) on sales of land parcels	'	'	'	0	'	'	'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	'	'	'	0	'	'	'
Net income	'	'	'	337,000	'	'	'
Unconsolidated Operating [Domain]	'	'	'	'	'	'	'
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Unconsolidated Properties	'	1	'	1	'	'	'
Partially Owned Unconsolidated Units	'	336	'	336	'	'	'
ASSETS	'	'	'	'	'	'	'
Real Estate Investment Property, at Cost	'	55,369,000	'	55,369,000	'	'	'
Real Estate Investment Property, Accumulated Depreciation	'	-4,165,000	'	-4,165,000	'	'	'
Investment in real estate, net	'	51,204,000	'	51,204,000	'	'	'
Cash and Cash Equivalents, at Carrying Value	'	1,357,000	'	1,357,000	'	'	'
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	0	'	0	'	'	'
Restricted Cash and Cash Equivalents	'	0	'	0	'	'	'
Deferred Finance Costs, Net	'	5,000	'	5,000	'	'	'
Other Assets	'	1,038,000	'	1,038,000	'	'	'
Total assets	'	53,604,000	'	53,604,000	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	30,550,000	'	30,550,000	'	'	'
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	'	-143,000	'	-143,000	'	'	'
Interest Payable	'	0	'	0	'	'	'
Other Liabilities	'	1,345,000	'	1,345,000	'	'	'
Security Deposit Liability	'	18,000	'	18,000	'	'	'
Total liabilities	'	31,770,000	'	31,770,000	'	'	'
Noncontrolling Interests Partially Owned Properties	'	20,450,000	'	20,450,000	'	'	'
Parent Equity Interest	'	1,384,000	'	1,384,000	'	'	'
Total Equity Interest	'	21,834,000	'	21,834,000	'	'	'
Total liabilities and equity	'	53,604,000	'	53,604,000	'	'	'
Partially Owned Property Income Statement Schedule	'	'	'	'	'	'	'
Operating revenue	'	'	'	3,173,000	'	'	'
Operating Expenses	'	'	'	1,402,000	'	'	'
Gross Profit	'	'	'	1,771,000	'	'	'
Depreciation	'	'	'	4,165,000	'	'	'
General and Administrative Expense	'	'	'	141,000	'	'	'
Operating Income	'	'	'	-2,535,000	'	'	'
Interest and Other Income	'	'	'	10,000	'	'	'
Other Nonoperating Income (Expense)	'	'	'	0	'	'	'
Interest:	'	'	'	'	'	'	'
Interest Expense, Debt	'	'	'	-658,000	'	'	'
Amortization of Financing Costs	'	'	'	-1,000	'	'	'
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	'	'	'	-3,184,000	'	'	'
Income and other tax (expense) benefit	'	'	'	0	'	'	'
(Loss) from investments in unconsolidated entities due to operations	'	'	'	0	'	'	'
Net gain (loss) on sales of land parcels	'	'	'	0	'	'	'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	'	'	'	0	'	'	'
Net income	'	'	'	-3,184,000	'	'	'
Unconsolidated Total [Domain]	'	'	'	'	'	'	'
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Unconsolidated Properties	'	2	'	2	'	'	'
Partially Owned Unconsolidated Units	'	837	'	837	'	'	'
ASSETS	'	'	'	'	'	'	'
Real Estate Investment Property, at Cost	'	371,533,000	'	371,533,000	'	'	'
Real Estate Investment Property, Accumulated Depreciation	'	-4,249,000	'	-4,249,000	'	'	'
Investment in real estate, net	'	367,284,000	'	367,284,000	'	'	'
Cash and Cash Equivalents, at Carrying Value	'	2,827,000	'	2,827,000	'	'	'
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	0	'	0	'	'	'
Restricted Cash and Cash Equivalents	'	0	'	0	'	'	'
Deferred Finance Costs, Net	'	10,000	'	10,000	'	'	'
Other Assets	'	1,376,000	'	1,376,000	'	'	'
Total assets	'	371,497,000	'	371,497,000	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	194,490,000	'	194,490,000	'	'	'
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	'	16,502,000	'	16,502,000	'	'	'
Interest Payable	'	640,000	'	640,000	'	'	'
Other Liabilities	'	1,866,000	'	1,866,000	'	'	'
Security Deposit Liability	'	187,000	'	187,000	'	'	'
Total liabilities	'	213,685,000	'	213,685,000	'	'	'
Noncontrolling Interests Partially Owned Properties	'	122,211,000	'	122,211,000	'	'	'
Parent Equity Interest	'	35,601,000	'	35,601,000	'	'	'
Total Equity Interest	'	157,812,000	'	157,812,000	'	'	'
Total liabilities and equity	'	371,497,000	'	371,497,000	'	'	'
Partially Owned Property Income Statement Schedule	'	'	'	'	'	'	'
Operating revenue	'	'	'	6,339,000	'	'	'
Operating Expenses	'	'	'	3,566,000	'	'	'
Gross Profit	'	'	'	2,773,000	'	'	'
Depreciation	'	'	'	4,249,000	'	'	'
General and Administrative Expense	'	'	'	164,000	'	'	'
Operating Income	'	'	'	-1,640,000	'	'	'
Interest and Other Income	'	'	'	10,000	'	'	'
Other Nonoperating Income (Expense)	'	'	'	0	'	'	'
Interest:	'	'	'	'	'	'	'
Interest Expense, Debt	'	'	'	-1,311,000	'	'	'
Amortization of Financing Costs	'	'	'	-1,000	'	'	'
(Loss) income before income and other taxes, (loss) from investments in unconsolidated entities, net gain (loss) on sales of unconsolidated entities and land parcels and discontinued operations	'	'	'	-2,942,000	'	'	'
Income and other tax (expense) benefit	'	'	'	0	'	'	'
(Loss) from investments in unconsolidated entities due to operations	'	'	'	0	'	'	'
Net gain (loss) on sales of land parcels	'	'	'	0	'	'	'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	'	'	'	0	'	'	'
Net income	'	'	'	-2,942,000	'	'	'
Residual JV [Domain]	'	'	'	'	'	'	'
ASSETS	'	'	'	'	'	'	'
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	105,100,000	'	105,100,000	'	'	'
Joint Venture Partner [Member]	'	'	'	'	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Noncontrolling Interests Partially Owned Properties	'	95,528,824	'	95,528,824	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Land purchase price	'	57,900,000	'	57,900,000	'	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	'	75,700,000	'	75,700,000	'	'	'
Company's Portion [Member]	'	'	'	'	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Land purchase price	'	76,100,000	'	76,100,000	'	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	'	102,500,000	'	102,500,000	'	'	'
Nexus Sawgrass [Member]	'	'	'	'	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	45,200,000	'	45,200,000	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Project Cost	'	78,200,000	'	78,200,000	'	'	'
Maximum Debt Commitment	'	48,700,000	'	48,700,000	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	5.60%	'	5.60%	'	'	'
Debt Instrument, Maturity Date	'	'	'	1-Jan-21	'	'	'
Domain [Member]	'	'	'	'	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	82,200,000	'	82,200,000	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Project Cost	'	154,600,000	'	154,600,000	'	'	'
Maximum Debt Commitment	'	98,600,000	'	98,600,000	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	5.75%	'	5.75%	'	'	'
Debt Instrument, Maturity Date	'	'	'	1-Jan-22	'	'	'
Archstone Transaction [Member]	'	'	'	'	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Liquidation Value Preferred Interests	'	88,300,000	'	88,300,000	'	'	'
Business Acquisition, Percentage of Voting Interests Acquired	'	60.00%	'	60.00%	'	'	'
Joint Venture Partner Ownership Percentage	'	40.00%	'	40.00%	'	'	'
Company's Portion [Member]	'	'	'	'	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Preferred Interests	'	'	'	39,000,000	'	'	'
Enclave at Wellington [Domain]	'	'	'	'	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Business Acquisition, Percentage of Voting Interests Acquired	'	95.00%	'	95.00%	'	'	'
Partially Owned Consolidated Properties	'	268	'	268	'	'	'
Initial Basis of Land, Consolidated	'	26,200,000	'	26,200,000	'	'	'
Project Cost	'	50,000,000	'	50,000,000	'	'	'
East Palmetto Park [Domain]	'	'	'	'	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Business Acquisition, Percentage of Voting Interests Acquired	'	90.00%	'	90.00%	'	'	'
Partially Owned Consolidated Properties	'	377	'	377	'	'	'
Initial Basis of Land, Consolidated	'	20,200,000	'	20,200,000	'	'	'
Wisconsin Place [Domain]	'	'	'	'	'	'	'
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Consolidated Units	'	432	'	432	'	'	'
ASSETS	'	'	'	'	'	'	'
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	'	56,500,000	'	56,500,000	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Business Acquisition, Percentage of Voting Interests Acquired	'	75.00%	'	75.00%	'	'	'
Initial Basis of Land, Consolidated	'	198,500,000	'	198,500,000	'	'	'
San Norterra [Domain]	'	'	'	'	'	'	'
Variable Interest Entity [Line Items]	'	'	'	'	'	'	'
Debt Instrument, Description of Variable Rate Basis	'	'	'	'LIBOR plus 2.00%	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	30,800,000	'	30,800,000	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Equity Method Investment, Ownership Percentage	'	85.00%	'	85.00%	'	'	'
Project Cost	'	56,300,000	'	56,300,000	'	'	'
Partially Owned Unconsolidated Units To Be Developed	'	388	'	388	'	'	'
Initial Basis of Land, Unconsolidated	'	-16,900,000	'	-16,900,000	'	'	'
Maximum Debt Commitment	'	34,800,000	'	34,800,000	'	'	'
Debt Instrument, Maturity Date	'	'	'	6-Jan-15	'	'	'
Waterton Tenside [Domain]	'	'	'	'	'	'	'
Partially Owned Property Balance Sheet Schedule	'	'	'	'	'	'	'
Partially Owned Unconsolidated Units	'	336	'	336	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	30,600,000	'	30,600,000	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Equity Method Investment, Ownership Percentage	'	20.00%	'	20.00%	'	'	'
Initial Basis of Land, Unconsolidated	'	-5,100,000	'	-5,100,000	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	3.66%	'	3.66%	'	'	'
Debt Instrument, Maturity Date	'	'	'	1-Dec-18	'	'	'
Parkside at Emeryville [Domain]	'	'	'	'	'	'	'
Variable Interest Entity [Line Items]	'	'	'	'	'	'	'
Debt Instrument, Description of Variable Rate Basis	'	'	'	'LIBOR plus 2.25%	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Secured Debt	'	5,700,000	'	5,700,000	'	'	'
Investments In Partially Owned Entities (Textuals) [Abstract]	'	'	'	'	'	'	'
Equity Method Investment, Ownership Percentage	'	5.00%	'	5.00%	'	'	'
Project Cost	'	75,000,000	'	75,000,000	'	'	'
Partially Owned Unconsolidated Units To Be Developed	'	180	'	180	'	'	'
Initial Basis of Land, Unconsolidated	'	2,100,000	'	2,100,000	'	'	'
Maximum Debt Commitment	'	39,500,000	'	39,500,000	'	'	'
Debt Instrument, Maturity Date	'	'	'	14-Aug-15	'	'	'
Unconsolidated Project Under Development Commitment Fund	'	$19,700,000	'	$19,700,000	'	'	'
London Interbank Offered Rate (LIBOR) [Member]	'	'	'	'	'	'	'
Variable Interest Entity [Line Items]	'	'	'	'	'	'	'
Debt Instrument, Description of Variable Rate Basis	'	'	'	'LIBOR plus 1.75%	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Debt Instrument, Basis Spread on Variable Rate	'	'	'	1.75%	'	'	'
London Interbank Offered Rate (LIBOR) [Member] | San Norterra [Domain]	'	'	'	'	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Debt Instrument, Basis Spread on Variable Rate	'	'	'	2.00%	'	'	'
London Interbank Offered Rate (LIBOR) [Member] | Parkside at Emeryville [Domain]	'	'	'	'	'	'	'
LIABILITIES AND EQUITY	'	'	'	'	'	'	'
Debt Instrument, Basis Spread on Variable Rate	'	'	'	2.25%	'	'	'

Deposits_Restricted_Details

Deposits - Restricted (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Restricted Cash and Cash Equivalents Items [Line Items]	'	'
Tax Deferred Exchange Proceeds	$0	$152,182
Earnest Money On Acquisitions	350	5,613
Restricted deposits on real estate investments	53,764	44,209
Resident security and utility deposits	44,255	44,199
Other Restricted Cash	505	4,239
Restricted Cash and Cash Equivalents	$98,874	$250,442

Debt_Mortgage_Notes_Payable_De

Debt Mortgage Notes Payable (Details) (USD $)	1 Months Ended	9 Months Ended
	Nov. 08, 2013	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Debt Instrument [Line Items]	'	'	'	'
Mortgage notes payable	'	$6,230,675,000	'	$3,898,369,000
Repayments Of Mortgage Notes Payable	963,500,000	9,527,000	11,022,000	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	34,100,000	'	'
Properties Collateralized	'	1	'	'
Debt Instrument, Interest Rate, Stated Percentage	5.88%	'	'	'
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	'	0.05%	'	'
Interest rate range to maximum	'	7.25%	'	'
Debt Instrument, Maturity Date	1-Nov-14	1-Sep-14	'	'
Mark-to-Market Debt Premiums	'	127,900,000	'	'
Prepayment Penalty Charges	'	71,443,173	'	'
Unamortized Deferred Financing Costs Written Off	'	1,647,148	'	'
Write off of unamortized premium discount	'	3,250,553	'	'
Weighted Average Mortgage Debt Interest Rate	'	4.25%	'	'
London Interbank Offered Rate (LIBOR) [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Debt Instrument, Description of Variable Rate Basis	'	'LIBOR plus 1.75%	'	'
Debt Instrument, Basis Spread on Variable Rate	'	1.75%	'	'
Credit enhanced debt [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Mortgage notes payable	'	700,500,000	'	'
Secured Debt [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Repayments Of Mortgage Notes Payable	'	711,300,000	'	'
Other Debt Obligations [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	339,000,000	'	'
Properties Collateralized	'	3	'	'
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	'	0.10%	'	'
Interest rate range to maximum	'	5.24%	'	'
Debt Instrument, Maturity Date	'	1-May-61	'	'
Fannie Mae Pool 3 And 4 [Domain]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	2,200,000,000	'	'
Fannie Mae Pool 3 [Domain]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	1,200,000,000	'	'
Properties Collateralized	'	16	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	6.26%	'	'
Debt Instrument, Maturity Date	'	1-Nov-17	'	'
Fannie Mae Pool 4 [Domain]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	1,000,000,000	'	'
Properties Collateralized	'	15	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	5.88%	'	'
Debt Instrument, Maturity Date	'	1-Nov-14	'	'
Nontaxable Municipal Bonds [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	$346,600,000	'	'
Properties Collateralized	'	4	'	'
Debt Instrument, Maturity Date	'	15-Nov-36	'	'
Nontaxable Municipal Bonds [Member] | Minimum [Member] | SIFMA [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Debt Instrument, Description of Variable Rate Basis	'	'SIFMA plus 0.860%	'	'
Debt Instrument, Basis Spread on Variable Rate	'	0.86%	'	'
Nontaxable Municipal Bonds [Member] | Maximum [Member] | SIFMA [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Debt Instrument, Description of Variable Rate Basis	'	'SIFMA plus 1.402%	'	'
Debt Instrument, Basis Spread on Variable Rate	'	1.40%	'	'

Debt_Notes_Details

Debt Notes (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Nov. 08, 2013	Dec. 31, 2012
Debt Instrument [Line Items]	'	'	'	'
Notes, net	$5,476,522,000	'	'	$4,630,875,000
Repayments of Notes Payable	400,000,000	253,858,000	'	'
Proceeds from Issuance of Unsecured Debt	500,000,000	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	'	5.88%	'
Proceeds from Debt, Net of Issuance Costs	495,600,000	'	'	'
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Maximum	4.00%	'	'	'
Term Loan Facility Spread	1.20%	'	'	'
Bridge Loan Principal Amount	'	'	'	2,500,000,000
Unamortized Deferred Financing Costs Written Off	1,647,148	'	'	'
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	0.05%	'	'	'
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	7.25%	'	'	'
Debt Instrument, Maturity Date Range, End	31-Dec-26	'	'	'
Weighted Average Interest Rate	5.06%	'	'	'
Unsecured Debt [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	1.34%	'	'	'
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	7.57%	'	'	'
5.200% Notes [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Repayments of Notes Payable	400,000,000	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	5.20%	'	'	'
3.00% Notes [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	3.00%	'	'	'
DelayedDrawTermLoan [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Term Loan Principal Amount	750,000,000	'	'	'
Bridge Loan [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Unamortized Deferred Financing Costs Written Off	$2,500,000	'	'	'

Debt_Lines_of_Credit_Details

Debt Lines of Credit (Details) (USD $)	1 Months Ended	9 Months Ended
	Nov. 08, 2013	Sep. 30, 2013
Line of Credit Facility [Line Items]	'	'
Debt Instrument, Maturity Date	1-Nov-14	1-Sep-14
500.0 million ability to increase	'	$500,000,000
Line Of Credit Facility Commitment Fee	'	'15 Basis Points
A 250 billion LOC [Member] [Domain]	'	'
Line of Credit Facility [Line Items]	'	'
Unsecured revolving credit facility	'	2,500,000,000
Debt Instrument, Maturity Date	'	1-Apr-18
Remaining borrowing capacity	'	2,470,000,000
Amount restricted/dedicated to support letters of credit	'	34,899,541
Weighted Average Interest Rate Revolving Credit Facility	'	1.28%
A 175 billion LOC [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Unsecured revolving credit facility	'	$1,750,000,000
Debt Instrument, Maturity Date	'	1-Jul-14
Revolving Credit Facility [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Line Of Credit Spread	'	1.05%

Derivative_and_Other_Fair_Valu2

Derivative and Other Fair Value Instruments (Details) (Forward Starting Swaps [Member], USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Forward Starting Swaps [Member]	'
Derivative [Line Items]	'
Current Notional Balance	$400,000
Lowest Possible Notional	400,000
Highest Possible Notional	$400,000
Lowest Interest Rate	2.13%
Highest Interest Rate	3.23%
Earliest Maturity Date	'2024
Latest Maturity Date	'2024

Derivative_and_Other_Fair_Valu3

Derivative and Other Fair Value Instruments (Details 1) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Derivative asset, fair value	$12,132	$1,524
Fair Value Of Serp Investments	78,629	70,655
Other Assets, Fair Value Disclosure	1,675	2,214
Assets, Fair Value Disclosure	92,436	74,393
Derivative liability, fair value	3,456	44,050
Other Liabilities, Fair Value Disclosure	78,629	70,655
Liabilities, Fair Value Disclosure	82,085	114,705
Redeemable Noncontrolling Interest Operating Partnership Liability Fair Value Disclosure	376,057	398,372
Fair Value, Inputs, Level 1 [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative asset, fair value	0	0
Fair Value Of Serp Investments	78,629	70,655
Other Assets, Fair Value Disclosure	1,675	2,214
Assets, Fair Value Disclosure	80,304	72,869
Derivative liability, fair value	0	0
Other Liabilities, Fair Value Disclosure	78,629	70,655
Liabilities, Fair Value Disclosure	78,629	70,655
Redeemable Noncontrolling Interest Operating Partnership Liability Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative asset, fair value	12,132	1,524
Fair Value Of Serp Investments	0	0
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	12,132	1,524
Derivative liability, fair value	3,456	44,050
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	3,456	44,050
Redeemable Noncontrolling Interest Operating Partnership Liability Fair Value Disclosure	376,057	398,372
Fair Value, Inputs, Level 3 [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative asset, fair value	0	0
Fair Value Of Serp Investments	0	0
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	0	0
Derivative liability, fair value	0	0
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	0	0
Redeemable Noncontrolling Interest Operating Partnership Liability Fair Value Disclosure	$0	$0

Derivative_and_Other_Fair_Valu4

Derivative and Other Fair Value Instruments (Details 3) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Increase (Decrease) in Fair Value of Interest Rate Fair Value Hedging Instruments	($1,524)	($5,934)
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	1,524	5,934
Effective Portion - Amount of Gain/ (Loss) Recognized in OCI on Derivative	8,737	-12,337
Effective Portion - Amount of Gain/ (Loss) Reclassified from Accumulated OCI into Income	-16,084	-10,907
Ineffective Portion - Amount of Gain/ (Loss) Reclassifed from Accumulated OCI into Income	0	0
Interest Rate Swap [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Increase (Decrease) in Fair Value of Interest Rate Fair Value Hedging Instruments	-1,524	-5,934
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	1,524	5,934
Derivative, Description of Hedged Item	'Fixed rate debt	'Fixed rate debt
Forward Starting Swaps/Treasury Locks [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Effective Portion - Amount of Gain/ (Loss) Recognized in OCI on Derivative	8,737	-12,337
Effective Portion - Amount of Gain/ (Loss) Reclassified from Accumulated OCI into Income	-16,084	-10,907
Ineffective Portion - Amount of Gain/ (Loss) Reclassifed from Accumulated OCI into Income	$0	$0

Derivative_and_Other_Fair_Valu5

Derivative and Other Fair Value Instruments (Details 4) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Oct. 04, 2013	Nov. 08, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Available for Sale	'	'	'	'	'	'	'
Other assets, amortized cost	'	'	$412	'	$412	'	$675
Other assets, Unrealized Gains	'	'	'	'	1,263	'	1,539
Other assets, Unrealized Losses	'	'	'	'	0	'	0
Other assets, Book/Fair value	'	'	1,675	'	1,675	'	2,214
Interest and Other income	'	'	'	'	830	'	0
Proceeds from Sale of Available-for-sale Securities	300	-1,700	'	'	828	0	'
(Gain) Loss on Sale of Securities, Net	'	-1,300	-830	0	-830	0	'
Other Available-for-Sale Securities [Member]	'	'	'	'	'	'	'
Available for Sale	'	'	'	'	'	'	'
Other assets, amortized cost	'	'	412	'	412	'	675
Other assets, Unrealized Gains	'	'	'	'	1,263	'	1,539
Other assets, Unrealized Losses	'	'	'	'	0	'	0
Other assets, Book/Fair value	'	'	1,675	'	1,675	'	2,214
Interest and Other income	'	'	'	'	$830	'	$0

Derivative_and_Other_Fair_Valu6

Derivative and Other Fair Value Instruments (Details Textuals) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Derivative [Line Items]	'	'
Mortgage notes payable	$6,230,675,000	$3,898,369,000
Notes, net	5,476,522,000	4,630,875,000
Fair value of mortgage notes payable	6,400,000,000	4,300,000,000
Fair value of unsecured notes payable including line of credit	5,800,000,000	5,200,000,000
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	-169,866,106	-194,700,000
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	21,700,000	'
Payments for (Proceeds from) Hedge, Investing Activities	44,700,000	'
Proceeds from Issuance of Unsecured Debt	500,000,000	'
Interest Expense	700,000	'
Deferred accumulated other comprehensive (loss)	$44,000,000	'

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	($12,467)	$92,181	($234,414)	$62,103
Income (Loss) Attributable to Noncontrolling Interest	483	-3,895	9,402	-2,128
Allocation Of Net Income Loss To Noncontrolling Interests Partially Owned Properties	311	312	1,101	-457
Dividends, Preferred Stock	-1,037	-2,386	-3,109	-9,319
Redemption Premium	0	-5,150	0	-5,150
Income From Continuing Operations Available To Common Shares	'	84,957	'	47,177
Income (Loss) from Continuing Operations Attributable to Parent	-12,710	81,062	-227,020	45,049
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	388,865	137,541	1,943,548	415,184
Net Income Loss Available To Common Stockholder Basic	376,155	218,603	1,716,528	460,233
Weighted Average Number of Shares Outstanding, Basic	359,811	301,336	352,414	300,116
Dilutive Op Units	'	14,177	'	13,816
Dilutive Securities Options	'	3,260	'	3,333
Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	359,811	'	352,414	'
Earnings Per Share, Basic	$1.04	$0.73	$4.87	$1.53
Earnings Per Share, Diluted	$1.04	$0.72	$4.87	$1.52
(Loss) income from continuing operations available to Common Shares	($0.04)	$0.27	($0.64)	$0.15
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share	$1.08	$0.46	$5.51	$1.38
Income (Loss) from Continuing Operations, Per Diluted Share	($0.04)	$0.27	($0.64)	$0.15
Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share	$1.08	$0.45	$5.51	$1.37
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	404,184	144,142	2,023,897	434,702
Net Income (Loss) Available to Common Stockholders, Diluted	376,155	229,099	1,716,528	481,879
OPERATING PARTNERSHIP	'	'	'	'
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	-12,467	92,181	-234,414	62,103
Allocation Of Net Income Loss To Noncontrolling Interests Partially Owned Properties	311	312	1,101	-457
Redemption Premium	0	-5,150	0	-5,150
Dilutive Securities Options	'	3,260	'	3,333
Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	373,547	318,773	366,150	317,265
Earnings Per Share, Basic	$1.04	$0.73	$4.87	$1.53
Earnings Per Share, Diluted	$1.04	$0.72	$4.87	$1.52
(Loss) income from continuing operations available to Common Shares	($0.04)	$0.27	($0.64)	$0.15
Income (Loss) from Continuing Operations, Per Diluted Share	($0.04)	$0.27	($0.64)	$0.15
Dividend preference units	-1,037	-2,386	-3,109	-9,319
Income Loss From Continuing Operations Available To Units	-13,193	84,957	-236,422	47,177
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	404,184	144,142	2,023,897	434,702
Net Income loss available to Op unitholders basic diluted numerator	$390,991	$229,099	$1,787,475	$481,879
Weighted Average Limited Partnership and General Partnership Units Outstanding, Basic	373,547	315,513	366,150	313,932
Income (Loss) from Discontinued Operations, Net of Tax, Per Outstanding Limited Partnership and General Partnership Unit, Basic	$1.08	$0.46	$5.51	$1.38
Income Loss From Discontinued Operations Net Of Tax Per Outstanding Limited Partnership And General Partnership Diluted	$1.08	$0.45	$5.51	$1.37

Discontinued_Operations_Detail

Discontinued Operations (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012
REVENUES	'		'		'		'		'
Disposal Group Including Discontinued Operation Rental Revenue	$8,418,000		$108,459,000		$110,986,000		$334,968,000		'
Disposal Group, Including Discontinued Operation, Revenue	8,418,000		108,459,000		110,986,000		334,968,000		'
EXPENSES	'		'		'		'		'
Disposal Group Including Discontinued Operation Property And Maintenance	3,272,000	[1]	25,608,000	[1]	33,181,000	[1]	79,482,000	[1]	'
Disposal Group Including Discontinued Operation Real Estate Taxes And Insurance	396,000	[1]	11,480,000	[1]	10,578,000	[1]	29,599,000	[1]	'
Disposal Group Including Discontinued Operations Property Management	0		70,000	[1]	1,000	[1]	211,000	[1]	'
Disposal Group Including Discontinued Operation Depreciation	2,273,000	[1]	29,497,000	[1]	31,976,000	[1]	94,792,000	[1]	'
Disposal Group Including Discontinued Operation General And Administrative	3,000	[1]	44,000	[1]	76,000	[1]	87,000	[1]	'
Disposal Group, Including Discontinued Operation, Operating Expense	5,944,000	[1]	66,699,000	[1]	75,812,000	[1]	204,171,000	[1]	'
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	2,474,000		41,760,000		35,174,000		130,797,000		'
Disposal Group Including Discontinued Operation Interest And Other Income	65,000		34,000		156,000		81,000		'
Disposal Group Including Discontinued Operation Other Expenses	0		-23,000		-3,000		-170,000		'
Interest (2)	'		'		'		'		'
Expense Incurred, Net	-18,000	[2]	-995,000	[2]	-1,276,000	[2]	-3,357,000	[2]	'
Disposal Group Including Discontinued Operation Amortization Of Deferred Financing Costs	0	[2]	-27,000	[2]	-228,000	[2]	-119,000	[2]	'
Discontinued Operation, Tax Effect of Discontinued Operation	-40,000		-1,000		-503,000		23,000		'
Income Loss From Discontinued Operations	2,481,000		40,748,000		33,320,000		127,255,000		'
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	401,703,000		103,394,000		1,990,577,000		307,447,000		'
Discontinued operations, net	404,184,000		144,142,000		2,023,897,000		434,702,000		'
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net	'		'		'		'		1,964,677,220
Disposal Group Including Discontinued Operation Mortgage Notes Payable	'		'		'		'		$34,386,391
[1]	Includes expenses paid in the current period for properties sold in prior periods related to the Companybs period of ownership.
[2]	Includes only interest expense specific to secured mortgage notes payable for properties sold.

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
300 properties designed and built in violation of accessibility requirements	300	'
Projects in various stages of development	13	'
Units in various stages of development	3,327	'
Consolidated Project Under Development Commitment Fund	$608,741,000	'
Various stages of development with estimated completion dates ranging through June 30, 2016	30-Jun-16	'
Number Of Unconsolidated Projects	3	'
Number Of Apartments Units Under Development Unconsolidated Projects	1,012	'
Estimated completion period of project	30-Sep-14	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	108,000,000	'
Investment in Joint Venture	259,138,385	'
Noncontrolling Interests - Partially Owned Properties	110,635,000	77,688,000
Joint Venture Partner [Member]	'	'
Land purchase price	57,900,000	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	75,700,000	'
Noncontrolling Interests - Partially Owned Properties	95,528,824	'
Company's Portion [Member]	'	'
Land purchase price	76,100,000	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	102,500,000	'
Enclave at Wellington [Domain]	'	'
Business Acquisition, Percentage of Voting Interests Acquired	95.00%	'
Parkside at Emeryville [Domain]	'	'
Guarantor Obligations, Maximum Exposure	$19,700,000	'

Reportable_Segments_Details

Reportable Segments (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Rental income:	'	'	'	'	'
Same store	$463,607	$445,521	$1,329,326	$1,269,876	'
Non-same store/other	163,273	3,126	420,048	25,555	'
Segment Reporting Information Revenues	626,880	448,647	1,749,374	1,295,431	'
Operating expenses:	'	'	'	'	'
Same store	159,302	154,450	462,509	447,600	'
Non-same store/other	55,460	3,789	152,865	23,811	'
Total operating expenses	214,762	158,239	615,374	471,411	'
NOI:	'	'	'	'	'
Same store	304,305	291,071	866,817	822,276	'
Non-same store/other	107,813	-663	267,183	1,744	'
Total NOI	412,118	290,408	1,134,000	824,020	'
Total assets	23,811,431	'	23,811,431	'	17,201,000
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	'	'	96,866	'	'
Reportable Segments (Textuals) [Abstract]	'	'	'	'	'
Rental income	626,880	448,647	1,749,374	1,295,431	'
Cost of Property Repairs and Maintenance	-119,632	-86,682	-333,202	-254,009	'
Real Estate Taxes and Insurance	-76,255	-53,064	-218,777	-154,633	'
Property management	-18,875	-18,493	-63,395	-62,769	'
Total Operating Expenses	-214,762	-158,239	-615,374	-471,411	'
Units in same store properties	82,553	'	81,099	'	'
Northeast [Member]	'	'	'	'	'
Rental income:	'	'	'	'	'
Same store	196,089	190,648	555,391	535,830	'
Non-same store/other	101,001	1,658	263,745	15,876	'
Segment Reporting Information Revenues	297,090	192,306	819,136	551,706	'
Operating expenses:	'	'	'	'	'
Same store	68,044	65,758	198,068	190,979	'
Non-same store/other	34,191	994	86,820	6,170	'
Total operating expenses	102,235	66,752	284,888	197,149	'
NOI:	'	'	'	'	'
Same store	128,045	124,890	357,323	344,851	'
Non-same store/other	66,810	664	176,925	9,706	'
Total NOI	194,855	125,554	534,248	354,557	'
Total assets	11,499,130	'	11,499,130	'	'
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	'	'	39,331	'	'
Northwest [Member]	'	'	'	'	'
Rental income:	'	'	'	'	'
Same store	107,340	100,280	303,680	282,586	'
Non-same store/other	38,862	1,305	99,689	8,049	'
Segment Reporting Information Revenues	146,202	101,585	403,369	290,635	'
Operating expenses:	'	'	'	'	'
Same store	35,784	34,443	101,982	98,616	'
Non-same store/other	13,296	235	34,352	2,581	'
Total operating expenses	49,080	34,678	136,334	101,197	'
NOI:	'	'	'	'	'
Same store	71,556	65,837	201,698	183,970	'
Non-same store/other	25,566	1,070	65,337	5,468	'
Total NOI	97,122	66,907	267,035	189,438	'
Total assets	4,540,404	'	4,540,404	'	'
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	'	'	23,793	'	'
Southeast [Member]	'	'	'	'	'
Rental income:	'	'	'	'	'
Same store	59,170	56,987	175,039	167,561	'
Non-same store/other	768	0	1,785	0	'
Segment Reporting Information Revenues	59,938	56,987	176,824	167,561	'
Operating expenses:	'	'	'	'	'
Same store	22,619	22,435	66,013	64,878	'
Non-same store/other	289	0	696	0	'
Total operating expenses	22,908	22,435	66,709	64,878	'
NOI:	'	'	'	'	'
Same store	36,551	34,552	109,026	102,683	'
Non-same store/other	479	0	1,089	0	'
Total NOI	37,030	34,552	110,115	102,683	'
Total assets	1,513,074	'	1,513,074	'	'
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	'	'	13,270	'	'
Southwest [Member]	'	'	'	'	'
Rental income:	'	'	'	'	'
Same store	101,008	97,606	295,216	283,899	'
Non-same store/other	21,470	284	51,492	1,793	'
Segment Reporting Information Revenues	122,478	97,890	346,708	285,692	'
Operating expenses:	'	'	'	'	'
Same store	32,855	31,814	96,446	93,127	'
Non-same store/other	8,801	52	21,656	617	'
Total operating expenses	41,656	31,866	118,102	93,744	'
NOI:	'	'	'	'	'
Same store	68,153	65,792	198,770	190,772	'
Non-same store/other	12,669	232	29,836	1,176	'
Total NOI	80,822	66,024	228,606	191,948	'
Total assets	3,578,742	'	3,578,742	'	'
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	'	'	15,360	'	'
Other [Member]	'	'	'	'	'
Rental income:	'	'	'	'	'
Same store	0	0	0	0	'
Non-same store/other	1,172	-121	3,337	-163	'
Segment Reporting Information Revenues	1,172	-121	3,337	-163	'
Operating expenses:	'	'	'	'	'
Same store	0	0	0	0	'
Non-same store/other	-1,117	2,508	9,341	14,443	'
Total operating expenses	-1,117	2,508	9,341	14,443	'
NOI:	'	'	'	'	'
Same store	0	0	0	0	'
Non-same store/other	2,289	-2,629	-6,004	-14,606	'
Total NOI	2,289	-2,629	-6,004	-14,606	'
Total assets	2,680,081	'	2,680,081	'	'
Segment Reporting Information, Expenditures for Additions to Long-Lived Assets	'	'	$5,112	'	'

Subsequent_EventsOther_Details

Subsequent Events/Other (Details) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended	45 Months Ended
Share data in Millions, unless otherwise specified	Oct. 04, 2013	Nov. 08, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013
Subsequent Event [Line Items]	'	'	'	'	'	'	'	'	'
Proceeds from Issuance of Long-term Debt	'	$896,900,000	'	'	'	$5,951,000	$0	'	'
Debt Instrument, Maturity Date	'	1-Nov-14	'	'	'	1-Sep-14	'	'	'
Secured Debt	'	'	6,230,675,000	3,898,369,000	'	6,230,675,000	'	3,898,369,000	6,230,675,000
Repayments Of Mortgage Notes Payable	'	963,500,000	'	'	'	9,527,000	11,022,000	'	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	'	'	'	'	34,100,000	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	5.88%	'	'	'	'	'	'	'
Proceeds from Sale of Available-for-sale Securities	-300,000	1,700,000	'	'	'	-828,000	0	'	'
(Gain) Loss on Sale of Securities, Net	'	1,300,000	830,000	'	0	830,000	0	'	'
Common Stock Capital Shares Reserved For Future Issuance Under Share Offering Program	'	'	17	'	'	17	'	'	17
Stock Repurchase Program, Number of Shares Authorized to be Repurchased	'	'	13	'	'	13	'	'	13
Business Combination, Acquisition Related Costs	'	'	'	'	'	200,000	6,900,000	'	95,400,000
Noncash Project Abandonment Costs	'	'	'	'	'	3,969,000	6,141,000	'	'
Other Nonoperating Expense	'	'	3,986,000	'	3,984,000	7,530,000	18,587,000	'	'
Settlement Expense	'	'	'	'	'	'	4,200,000	'	'
Break Up Fee	'	'	'	80,000,000	70,000,000	'	'	150,000,000	'
Archstone [Member]	'	'	'	'	'	'	'	'	'
Subsequent Event [Line Items]	'	'	'	'	'	'	'	'	'
Secured Debt	'	'	2,000,000,000	'	'	2,000,000,000	'	'	2,000,000,000
Noncash or Part Noncash Acquisition, Debt Assumed	'	'	'	'	'	3,100,000,000	'	'	'
Other Expense [Member]	'	'	'	'	'	'	'	'	'
Subsequent Event [Line Items]	'	'	'	'	'	'	'	'	'
Other Nonoperating Expense	'	'	'	'	'	4,200,000	13,000,000	'	'
New York Life Loan [Member]	'	'	'	'	'	'	'	'	'
Subsequent Event [Line Items]	'	'	'	'	'	'	'	'	'
Proceeds from Issuance of Long-term Debt	'	800,000,000	'	'	'	'	'	'	'
Debt Instrument, Maturity Date	'	10-Nov-23	'	'	'	'	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	4.21%	'	'	'	'	'	'	'
Archstone Transaction [Member]	'	'	'	'	'	'	'	'	'
Subsequent Event [Line Items]	'	'	'	'	'	'	'	'	'
Debt Instrument, Maturity Date	'	1-Nov-17	'	'	'	'	'	'	'
Secured Debt	'	440,000,000	'	'	'	'	'	'	'
Repayments Of Mortgage Notes Payable	'	825,000,000	'	'	'	'	'	'	'
Noncash or Part Noncash Acquisition, Debt Assumed	'	'	'	'	'	$1,270,000,000	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	6.26%	'	'	'	'	'	'	'