Erp Operating LTD Partnership 10-Q 6 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 31, 2015
Entity Registrant Name	EQUITY RESIDENTIAL
Entity Central Index Key	906,107
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
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		364,082,263
OPERATING PARTNERSHIP
Entity Registrant Name	ERP OPERATING LIMITED PARTNERSHIP
Entity Central Index Key	931,182
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
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 (Un

CONSOLIDATED BALANCE SHEETS (Unaudited) - Class of Stock [Domain] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Investment in real estate
Land	$ 6,374,779	$ 6,295,404
Depreciable property	20,290,324	19,851,504
Projects under development	1,240,244	1,343,919
Land held for development	127,559	184,556
Investment in real estate	28,032,906	27,675,383
Real Estate Investment Property, Accumulated Depreciation	(5,736,913)	(5,432,805)
Investment in real estate, net	22,295,993	22,242,578
Cash and cash equivalents	92,109	40,080
Investments in unconsolidated entities	94,718	105,434
Deposits - restricted	103,508	72,303
Escrow deposits - mortgage	52,862	48,085
Deferred financing costs, net	59,605	58,380
Other assets	383,035	383,754
Total assets	23,081,830	22,950,614
Liabilities:
Mortgage notes payable	4,952,579	5,086,515
Notes, net	5,875,328	5,425,346
Line of credit and commercial paper	0	333,000
Accounts payable and accrued expenses	193,096	153,590
Accrued interest payable	87,131	89,540
Other liabilities	355,632	389,915
Security deposits	76,112	75,633
Distributions payable	209,041	188,566
Total liabilities	11,748,919	11,742,105
Redeemable Noncontrolling Interests - Operating Partnership	488,178	500,733
Shareholders' equity:
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 803,600 shares issued and outstanding as of June 30, 2015 and 1,000,000 shares issued and outstanding as of December 31, 2014	40,180	50,000
Common Shares of beneficial interest, $0.01 par value; 1,000,000,000 shares authorized; 364,050,890 shares issued and outstanding as of June 30, 2015 and 362,855,454 shares issued and outstanding as of December 31, 2014	3,641	3,629
Paid in capital	8,607,889	8,536,340
Retained earnings	2,012,909	1,950,639
Accumulated other comprehensive (loss)	(163,855)	(172,152)
Total shareholders' equity	10,500,764	10,368,456
Noncontrolling Interests:
Operating Partnership	221,601	214,411
Noncontrolling Interests - Partially Owned Properties	122,368	124,909
Total Noncontrolling Interests	343,969	339,320
Total equity	10,844,733	10,707,776
Total liabilities and equity	$ 23,081,830	$ 22,950,614

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (Unaudited) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
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	803,600	1,000,000
Preferred Shares of beneficial interest, shares outstanding	803,600	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	364,050,890	362,855,454
Common Shares of beneficial interest, shares outstanding	364,050,890	362,855,454

CONSOLIDATED BALANCE SHEETS OF

CONSOLIDATED BALANCE SHEETS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Investment in real estate
Land	$ 6,374,779	$ 6,295,404
Depreciable property	20,290,324	19,851,504
Projects under development	1,240,244	1,343,919
Land held for development	127,559	184,556
Investment in real estate	28,032,906	27,675,383
Real Estate Investment Property, Accumulated Depreciation	(5,736,913)	(5,432,805)
Investment in real estate, net	22,295,993	22,242,578
Cash and cash equivalents	92,109	40,080
Investments in unconsolidated entities	94,718	105,434
Deposits - restricted	103,508	72,303
Escrow deposits - mortgage	52,862	48,085
Deferred financing costs, net	59,605	58,380
Other assets	383,035	383,754
Total assets	23,081,830	22,950,614
Liabilities:
Mortgage notes payable	4,952,579	5,086,515
Notes, net	5,875,328	5,425,346
Line of credit and commercial paper	0	333,000
Accounts payable and accrued expenses	193,096	153,590
Accrued interest payable	87,131	89,540
Other liabilities	355,632	389,915
Security deposits	76,112	75,633
Distributions payable	209,041	188,566
Total liabilities	11,748,919	11,742,105
Partners’ Capital:
Accumulated other comprehensive (loss)	(163,855)	(172,152)
Noncontrolling Interests - Partially Owned Properties	122,368	124,909
Total liabilities and equity	23,081,830	22,950,614
OPERATING PARTNERSHIP
Investment in real estate
Land	6,374,779	6,295,404
Depreciable property	20,290,324	19,851,504
Projects under development	1,240,244	1,343,919
Land held for development	127,559	184,556
Investment in real estate	28,032,906	27,675,383
Real Estate Investment Property, Accumulated Depreciation	(5,736,913)	(5,432,805)
Investment in real estate, net	22,295,993	22,242,578
Cash and cash equivalents	92,109	40,080
Investments in unconsolidated entities	94,718	105,434
Deposits - restricted	103,508	72,303
Escrow deposits - mortgage	52,862	48,085
Deferred financing costs, net	59,605	58,380
Other assets	383,035	383,754
Total assets	23,081,830	22,950,614
Liabilities:
Mortgage notes payable	4,952,579	5,086,515
Notes, net	5,875,328	5,425,346
Line of credit and commercial paper	0	333,000
Accounts payable and accrued expenses	193,096	153,590
Accrued interest payable	87,131	89,540
Other liabilities	355,632	389,915
Security deposits	76,112	75,633
Distributions payable	209,041	188,566
Total liabilities	$ 11,748,919	$ 11,742,105
Commitments and contingencies
Redeemable Limited Partners	$ 488,178	$ 500,733
Partners’ Capital:
Preferred Units	40,180	50,000
General Partner	10,624,439	10,490,608
Limited Partners	221,601	214,411
Accumulated other comprehensive (loss)	(163,855)	(172,152)
Total partners’ capital	10,722,365	10,582,867
Noncontrolling Interests - Partially Owned Properties	122,368	124,909
Total capital	10,844,733	10,707,776
Total liabilities and equity	$ 23,081,830	$ 22,950,614

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - Scenario, Unspecified [Domain] - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
REVENUES
Rental income	$ 676,508	$ 649,766	$ 1,341,114	$ 1,280,491
Fee and asset management	2,604	2,802	4,369	5,519
Total revenues	679,112	652,568	1,345,483	1,286,010
EXPENSES
Property and maintenance	118,005	115,382	242,565	240,948
Real estate taxes and insurance	83,119	83,055	169,551	165,149
Property management	20,518	20,555	41,962	42,673
Fee and asset management	1,274	1,378	2,595	3,040
Depreciation	194,282	190,136	388,803	375,303
General and administrative	15,730	13,752	35,652	31,328
Total expenses	432,928	424,258	881,128	858,441
Operating Income	246,184	228,310	464,355	427,569
Interest and other income	6,481	2,032	6,650	2,637
Other expenses	(1,770)	(1,539)	(1,700)	(2,203)
Interest:
Expense incurred, net	(110,795)	(115,924)	(219,417)	(228,973)
Amortization of deferred financing costs	(2,538)	(3,134)	(5,127)	(5,926)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations	137,562	109,745	244,761	193,104
Income and other tax (expense) benefit	(326)	(646)	(369)	(886)
Income (loss) from investments in unconsolidated entities	12,466	(7,616)	15,429	(9,025)
Net gain on sales of real estate properties	148,802	14,903	228,753	14,903
Net (loss) gain on sales of land parcels	0	824	(1)	794
Income from continuing operations	298,504	117,210	488,573	198,890
Discontinued operations, net	114	510	269	1,562
Net income	298,618	117,720	488,842	200,452
Net (income) attributable to Noncontrolling Interests:
Net (income) attributable to Noncontrolling Interests - Operating Partnership	(11,354)	(4,442)	(18,413)	(7,535)
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	(844)	(588)	(1,487)	(1,092)
Net income attributable to controlling interests	286,420	112,690	468,942	191,825
Preferred distributions	(833)	(1,036)	(1,724)	(2,072)
Premium on redemption of Preferred Shares	0	0	(2,789)	0
Net income available to Common Shares	$ 285,587	$ 111,654	$ 464,429	$ 189,753
Earnings per share - basic:
Income from continuing operations available to Common Shares	$ 0.79	$ 0.31	$ 1.28	$ 0.52
Net income available to Common Shares	$ 0.79	$ 0.31	$ 1.28	$ 0.53
Weighted average Common Shares outstanding	363,476	360,809	363,288	360,641
Earnings per share - diluted:
Income from continuing operations available to Common Shares	$ 0.78	$ 0.31	$ 1.27	$ 0.52
Net income available to Common Shares	$ 0.78	$ 0.31	$ 1.27	$ 0.52
Weighted average Common Shares outstanding	380,491	377,118	380,346	376,780
Distributions declared per Common Share outstanding	$ 0.5525	$ 0.50	$ 1.105	$ 1

CONSOLIDATED STATEMENTS OF OPE6

CONSOLIDATED STATEMENTS OF OPERATIONS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
REVENUES
Rental income	$ 676,508	$ 649,766	$ 1,341,114	$ 1,280,491
Fee and asset management	2,604	2,802	4,369	5,519
Total revenues	679,112	652,568	1,345,483	1,286,010
EXPENSES
Property and maintenance	118,005	115,382	242,565	240,948
Real estate taxes and insurance	83,119	83,055	169,551	165,149
Property management	20,518	20,555	41,962	42,673
Fee and asset management	1,274	1,378	2,595	3,040
Depreciation	194,282	190,136	388,803	375,303
General and administrative	15,730	13,752	35,652	31,328
Total expenses	432,928	424,258	881,128	858,441
Operating Income	246,184	228,310	464,355	427,569
Interest and other income	6,481	2,032	6,650	2,637
Other expenses	(1,770)	(1,539)	(1,700)	(2,203)
Interest:
Expense incurred, net	(110,795)	(115,924)	(219,417)	(228,973)
Amortization of deferred financing costs	(2,538)	(3,134)	(5,127)	(5,926)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations	137,562	109,745	244,761	193,104
Income and other tax (expense) benefit	(326)	(646)	(369)	(886)
Income (loss) from investments in unconsolidated entities	12,466	(7,616)	15,429	(9,025)
Net gain on sales of real estate properties	148,802	14,903	228,753	14,903
Net (loss) gain on sales of land parcels	0	824	(1)	794
Income from continuing operations	298,504	117,210	488,573	198,890
Discontinued operations, net	114	510	269	1,562
Net income	298,618	117,720	488,842	200,452
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	(844)	(588)	(1,487)	(1,092)
Net income attributable to controlling interests	286,420	112,690	468,942	191,825
ALLOCATION OF NET INCOME:
Premium on redemption of Preference Units	$ 0	$ 0	$ 2,789	$ 0
Earnings per Unit - basic:
Income from continuing operations available to Units	$ 0.79	$ 0.31	$ 1.28	$ 0.52
Net income available to Units	0.79	0.31	1.28	0.53
Earnings per Unit - diluted:
Income from continuing operations available to Units	0.78	0.31	1.27	0.52
Net income available to Units	$ 0.78	$ 0.31	$ 1.27	$ 0.52
OPERATING PARTNERSHIP
REVENUES
Rental income	$ 676,508	$ 649,766	$ 1,341,114	$ 1,280,491
Fee and asset management	2,604	2,802	4,369	5,519
Total revenues	679,112	652,568	1,345,483	1,286,010
EXPENSES
Property and maintenance	118,005	115,382	242,565	240,948
Real estate taxes and insurance	83,119	83,055	169,551	165,149
Property management	20,518	20,555	41,962	42,673
Fee and asset management	1,274	1,378	2,595	3,040
Depreciation	194,282	190,136	388,803	375,303
General and administrative	15,730	13,752	35,652	31,328
Total expenses	432,928	424,258	881,128	858,441
Operating Income	246,184	228,310	464,355	427,569
Interest and other income	6,481	2,032	6,650	2,637
Other expenses	(1,770)	(1,539)	(1,700)	(2,203)
Interest:
Expense incurred, net	(110,795)	(115,924)	(219,417)	(228,973)
Amortization of deferred financing costs	(2,538)	(3,134)	(5,127)	(5,926)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations	137,562	109,745	244,761	193,104
Income and other tax (expense) benefit	(326)	(646)	(369)	(886)
Income (loss) from investments in unconsolidated entities	12,466	(7,616)	15,429	(9,025)
Net gain on sales of real estate properties	148,802	14,903	228,753	14,903
Net (loss) gain on sales of land parcels	0	824	(1)	794
Income from continuing operations	298,504	117,210	488,573	198,890
Discontinued operations, net	114	510	269	1,562
Net income	298,618	117,720	488,842	200,452
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	(844)	(588)	(1,487)	(1,092)
Net income attributable to controlling interests	297,774	117,132	487,355	199,360
ALLOCATION OF NET INCOME:
Preference Units	833	1,036	1,724	2,072
Premium on redemption of Preference Units	0	0	2,789	0
General Partner	285,587	111,654	464,429	189,753
Limited Partners	11,354	4,442	18,413	7,535
Net income available to Units	$ 296,941	$ 116,096	$ 482,842	$ 197,288
Earnings per Unit - basic:
Income from continuing operations available to Units	$ 0.79	$ 0.31	$ 1.28	$ 0.52
Net income available to Units	$ 0.79	$ 0.31	$ 1.28	$ 0.53
Weighted average Units outstanding	377,063	374,551	376,880	374,377
Earnings per Unit - diluted:
Income from continuing operations available to Units	$ 0.78	$ 0.31	$ 1.27	$ 0.52
Net income available to Units	$ 0.78	$ 0.31	$ 1.27	$ 0.52
Weighted average Units outstanding	380,491	377,118	380,346	376,780
Distributions declared per Unit outstanding	$ 0.5525	$ 0.50	$ 1.105	$ 1

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - Scenario, Unspecified [Domain] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Comprehensive income:
Net income	$ 298,618	$ 117,720	$ 488,842	$ 200,452
Other comprehensive (loss) income – derivative instruments:
Unrealized holding (losses) gains arising during the period	11,676	(9,929)	(112)	(21,881)
Losses reclassified into earnings from other comprehensive income	4,573	4,206	8,911	8,335
Other comprehensive (loss) income – foreign currency:
Currency translation adjustments arising during the period	(82)	1,627	(502)	1,718
Other comprehensive income (loss)	16,167	(4,096)	8,297	(11,828)
Comprehensive income	314,785	113,624	497,139	188,624
Comprehensive (income) attributable to Noncontrolling Interests	(12,817)	(4,873)	(20,219)	(8,175)
Comprehensive income attributable to controlling interests	$ 301,968	$ 108,751	$ 476,920	$ 180,449

CONSOLIDATED STATEMENTS OF COM8

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Comprehensive income:
Net income	$ 298,618	$ 117,720	$ 488,842	$ 200,452
Other comprehensive (loss) income – derivative instruments:
Unrealized holding (losses) gains arising during the period	11,676	(9,929)	(112)	(21,881)
Losses reclassified into earnings from other comprehensive income	4,573	4,206	8,911	8,335
Other comprehensive (loss) income – foreign currency:
Currency translation adjustments arising during the period	(82)	1,627	(502)	1,718
Other comprehensive income (loss)	16,167	(4,096)	8,297	(11,828)
Comprehensive income	314,785	113,624	497,139	188,624
Comprehensive (income) attributable to Noncontrolling Interests – Partially Owned Properties	(12,817)	(4,873)	(20,219)	(8,175)
Comprehensive income attributable to controlling interests	301,968	108,751	476,920	180,449
OPERATING PARTNERSHIP
Comprehensive income:
Net income	298,618	117,720	488,842	200,452
Other comprehensive (loss) income – derivative instruments:
Unrealized holding (losses) gains arising during the period	11,676	(9,929)	(112)	(21,881)
Losses reclassified into earnings from other comprehensive income	4,573	4,206	8,911	8,335
Other comprehensive (loss) income – foreign currency:
Currency translation adjustments arising during the period	(82)	1,627	(502)	1,718
Other comprehensive income (loss)	16,167	(4,096)	8,297	(11,828)
Comprehensive income	314,785	113,624	497,139	188,624
Comprehensive (income) attributable to Noncontrolling Interests – Partially Owned Properties	(844)	(588)	(1,487)	(1,092)
Comprehensive income attributable to controlling interests	$ 313,941	$ 113,036	$ 495,652	$ 187,532

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - Scenario, Unspecified [Domain] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 488,842	$ 200,452
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	388,803	375,303
Amortization of deferred financing costs	5,127	5,926
Amortization of above/below market leases	1,691	1,530
Amortization of discounts and premiums on debt	(5,611)	(5,876)
Amortization of deferred settlements on derivative instruments	8,751	8,068
Write-off of pursuit costs	1,651	1,492
(Income) loss from investments in unconsolidated entities	(15,429)	9,025
Distributions from unconsolidated entities - return on capital	2,193	2,390
Net (gain) on sale of investment securities	(387)	(57)
Net (gain) on sales of real estate properties	(228,753)	(14,903)
Net loss (gain) on sales of land parcels	1	(794)
Net (gain) on sales of discontinued operations	0	(224)
Unrealized loss (gain) on derivative instruments	51	(90)
Compensation paid with Company Common Shares	24,017	21,905
Changes in assets and liabilities:
(Increase) in deposits – restricted	(288)	(1,820)
(Increase) decrease in mortgage deposits	(382)	187
(Increase) in other assets	(4,553)	(7,745)
Increase in accounts payable and accrued expenses	22,350	38,951
(Decrease) increase in accrued interest payable	(2,409)	80
(Decrease) in other liabilities	(11,097)	(17,237)
Increase in security deposits	479	2,916
Net cash provided by operating activities	675,047	619,479
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in real estate – acquisitions	(136,995)	(265,466)
Investment in real estate - development/other	(324,343)	(245,657)
Capital expenditures to real estate	(81,962)	(76,912)
Non-real estate capital additions	(1,955)	(1,818)
Interest capitalized for real estate and unconsolidated entities under development	(30,432)	(25,037)
Proceeds from disposition of real estate, net	379,863	48,359
Investments in unconsolidated entities	(4,786)	(9,554)
Distributions from unconsolidated entities - return of capital	26,147	64,669
Proceeds from sale of investment securities	387	57
(Increase) decrease in deposits on real estate acquisitions and investments, net	(31,247)	20,979
(Increase) decrease in mortgage deposits	(226)	760
Net cash (used for) investing activities	(205,549)	(489,620)
CASH FLOWS FROM FINANCING ACTIVITIES:
Debt financing costs	(6,352)	(10,881)
Mortgage Deposits	(4,169)	(3,580)
Mortgage notes payable:
Lump sum payoffs	(121,488)	(3,064)
Scheduled principal repayments	(5,028)	(6,000)
Notes, net:
Proceeds	746,391	1,194,277
Lump sum payoffs	(300,000)	(750,000)
Line of credit and commercial paper:
Line of credit proceeds	3,553,000	3,374,000
Line of credit repayments	(3,886,000)	(3,489,000)
Commercial paper proceeds	2,266,924	0
Commercial paper repayments	(2,267,500)	0
(Payments on) settlement of derivative instruments	(13,938)	(733)
Proceeds from Employee Stock Purchase Plan (ESPP)	2,610	2,218
Proceeds from exercise of options	33,984	25,685
Common Shares repurchased and retired	0	(1,777)
Partial redemption of 8.29% Series K Cumulative Redeemable	(9,820)	0
Premium on redemption of Preferred Shares	(2,789)	0
Payment of offering costs	(40)	0
Other financing activities, net	(33)	(33)
Acquisition of Noncontrolling Interests - Partially Owned Properties	0	(5,501)
Contributions - Noncontrolling Interests - Partially Owned Properties	0	5,684
Contributions - Noncontrolling Interests - Operating Partnership	1	3
Distributions:
Common Shares	(382,441)	(414,843)
Preferred Shares	(1,724)	(2,072)
Noncontrolling Interests – Operating Partnership	(15,062)	(16,405)
Noncontrolling Interests – Partially Owned Properties	(3,995)	(5,239)
Net Cash (used for) Financing Activities	(417,469)	(107,261)
Net increase in cash and cash equivalents	52,029	22,598
Cash and cash equivalents, beginning of period	40,080	53,534
Cash and cash equivalents, end of period	92,109	76,132
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized	218,965	226,785
Net cash paid for income and other taxes	895	843
Amortization of discounts and premiums on debt:
Mortgage notes payable	(7,420)	(7,011)
Notes, net	1,233	1,135
Line of credit and commercial paper	576	0
Amortization of deferred settlements on derivative instruments:
Other liabilities	(160)	(267)
Losses reclassified into earnings from other comprehensive income	8,911	8,335
Write-off of pursuit costs [Abstract]
Write-off of pursuit costs - investment in real estate, net	1,260	1,435
Deposits – restricted	330	0
Write-off of pursuit costs - other assets	61	57
(Income) Loss From Investments In Unconsolidated Entities [Abstract]
(Income) loss from investment in unconsolidated entities	(16,767)	7,354
Other Liabilities Loss From Investments in unconsolidated entities	1,338	1,671
Distributions from unconsolidated entities return on capital [Abstract]
Distributions from unconsolidated entities investments in unconsolidated entities	2,125	2,285
Distributions from unconsolidated entities other liabilities	68	105
Unrealized loss (gain) on derivative instruments:
Other assets	(3,873)	10,611
Notes, net	2,358	1,452
Other liabilities	1,678	9,728
Unrealized holding (losses) gains arising during the period	(112)	(21,881)
Interest capitalized for real estate and unconsolidated entities under development:
Investment in real estate, net	(30,432)	(25,002)
Investments in unconsolidated entities	0	(35)
Investments in unconsolidated entities [Abstract]
Investments in unconsolidated entities	(1,291)	(2,354)
Investments in unconsolidated entities other liabilities	(3,495)	(7,200)
Other:
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	$ 502	$ (1,718)

CONSOLIDATED STATEMENTS OF CA10

CONSOLIDATED STATEMENTS OF CASH FLOWS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 488,842	$ 200,452
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	388,803	375,303
Amortization of deferred financing costs	5,127	5,926
Amortization of above/below market leases	1,691	1,530
Amortization of discounts and premiums on debt	(5,611)	(5,876)
Amortization of deferred settlements on derivative instruments	8,751	8,068
Write-off of pursuit costs	1,651	1,492
(Income) loss from investments in unconsolidated entities	(15,429)	9,025
Distributions from unconsolidated entities - return on capital	2,193	2,390
Net (gain) on sale of investment securities	(387)	(57)
Net (gain) on sales of real estate properties	(228,753)	(14,903)
Net (gain) on sales of discontinued operations	0	(224)
Unrealized loss (gain) on derivative instruments	51	(90)
Compensation paid with Company Common Shares	24,017	21,905
Changes in assets and liabilities:
(Increase) in deposits – restricted	(288)	(1,820)
(Increase) decrease in mortgage deposits	(382)	187
(Increase) in other assets	(4,553)	(7,745)
Increase in accounts payable and accrued expenses	22,350	38,951
(Decrease) increase in accrued interest payable	(2,409)	80
(Decrease) in other liabilities	(11,097)	(17,237)
Increase in security deposits	479	2,916
Net cash provided by operating activities	675,047	619,479
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in real estate - acquisitions	(136,995)	(265,466)
Investment in real estate - development/other	(324,343)	(245,657)
Capital expenditures to real estate	(81,962)	(76,912)
Non-real estate capital additions	(1,955)	(1,818)
Interest capitalized for real estate and unconsolidated entities under development	(30,432)	(25,037)
Proceeds from disposition of real estate, net	379,863	48,359
Investments in unconsolidated entities	(4,786)	(9,554)
Distributions from unconsolidated entities - return of capital	26,147	64,669
Proceeds from sale of investment securities	387	57
(Increase) decrease in deposits on real estate acquisitions and investments, net	(31,247)	20,979
(Increase) decrease in mortgage deposits	(226)	760
Net cash (used for) investing activities	(205,549)	(489,620)
CASH FLOWS FROM FINANCING ACTIVITIES:
Debt financing costs	(6,352)	(10,881)
Mortgage Deposits	(4,169)	(3,580)
Mortgage notes payable:
Scheduled principal repayments	(5,028)	(6,000)
Notes, net:
Proceeds	746,391	1,194,277
Lump sum payoffs	(300,000)	(750,000)
Line of credit and commercial paper:
Line of credit proceeds	3,553,000	3,374,000
Line of credit repayments	(3,886,000)	(3,489,000)
Commercial paper proceeds	2,266,924	0
Commercial paper repayments	(2,267,500)	0
(Payments on) settlement of derivative instruments	(13,938)	(733)
Proceeds from exercise of options	33,984	25,685
Partial redemption of 8.29% Series K Cumulative Redeemable	(9,820)	0
Premium on redemption of Preference Units	(2,789)	0
Payment of offering costs	(40)	0
Other financing activities, net	(33)	(33)
Acquisition of Noncontrolling Interests - Partially Owned Properties	0	(5,501)
Contributions - Noncontrolling Interests - Partially Owned Properties	0	5,684
Contributions - Limited Partners	1	3
Distributions:
Noncontrolling Interests – Partially Owned Properties	(3,995)	(5,239)
Net Cash (used for) Financing Activities	(417,469)	(107,261)
Net increase in cash and cash equivalents	52,029	22,598
Cash and cash equivalents, beginning of period	40,080	53,534
Cash and cash equivalents, end of period	92,109	76,132
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized	218,965	226,785
Net cash paid for income and other taxes	895	843
Amortization of discounts and premiums on debt:
Mortgage notes payable	7,420	7,011
Notes, net	1,233	1,135
Line of credit and commercial paper	576	0
Amortization of deferred settlements on derivative instruments:
Other liabilities	(160)	(267)
Losses reclassified into earnings from other comprehensive income	8,911	8,335
Write-off of pursuit costs [Abstract]
Write-off of pursuit costs - investment in real estate, net	1,260	1,435
Deposits – restricted	330	0
Write-off of pursuit costs - other assets	61	57
(Income) Loss From Investments In Unconsolidated Entities [Abstract]
(Income) loss from investment in unconsolidated entities	(16,767)	7,354
Other Liabilities Loss From Investments in unconsolidated entities	1,338	1,671
Distributions from unconsolidated entities return on capital [Abstract]
Distributions from unconsolidated entities investments in unconsolidated entities	2,125	2,285
Distributions from unconsolidated entities other liabilities	68	105
Unrealized loss (gain) on derivative instruments:
Other assets	(3,873)	10,611
Notes, net	2,358	1,452
Other liabilities	1,678	9,728
Unrealized holding (losses) gains arising during the period	(112)	(21,881)
Interest capitalized for real estate and unconsolidated entities under development:
Investment in real estate, net	(30,432)	(25,002)
Investments in unconsolidated entities	0	(35)
Investments in unconsolidated entities [Abstract]
Investments in unconsolidated entities	1,291	2,354
Investments in unconsolidated entities other liabilities	3,495	7,200
Other:
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	502	(1,718)
OPERATING PARTNERSHIP
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	488,842	200,452
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	388,803	375,303
Amortization of deferred financing costs	5,127	5,926
Amortization of above/below market leases	1,691	1,530
Amortization of discounts and premiums on debt	(5,611)	(5,876)
Amortization of deferred settlements on derivative instruments	8,751	8,068
Write-off of pursuit costs	1,651	1,492
(Income) loss from investments in unconsolidated entities	(15,429)	9,025
Distributions from unconsolidated entities - return on capital	2,193	2,390
Net (gain) on sale of investment securities	(387)	(57)
Net (gain) on sales of real estate properties	(228,753)	(14,903)
Net loss (gain) on sales of land parcels	1	(794)
Net (gain) on sales of discontinued operations	0	(224)
Unrealized loss (gain) on derivative instruments	51	(90)
Compensation paid with Company Common Shares	24,017	21,905
Changes in assets and liabilities:
(Increase) in deposits – restricted	(288)	(1,820)
(Increase) decrease in mortgage deposits	(382)	187
(Increase) in other assets	(4,553)	(7,745)
Increase in accounts payable and accrued expenses	22,350	38,951
(Decrease) increase in accrued interest payable	(2,409)	80
(Decrease) in other liabilities	(11,097)	(17,237)
Increase in security deposits	479	2,916
Net cash provided by operating activities	675,047	619,479
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in real estate - acquisitions	(136,995)	(265,466)
Investment in real estate - development/other	(324,343)	(245,657)
Capital expenditures to real estate	(81,962)	(76,912)
Non-real estate capital additions	(1,955)	(1,818)
Interest capitalized for real estate and unconsolidated entities under development	(30,432)	(25,037)
Proceeds from disposition of real estate, net	379,863	48,359
Investments in unconsolidated entities	(4,786)	(9,554)
Distributions from unconsolidated entities - return of capital	26,147	64,669
Proceeds from sale of investment securities	387	57
(Increase) decrease in deposits on real estate acquisitions and investments, net	(31,247)	20,979
(Increase) decrease in mortgage deposits	(226)	760
Net cash (used for) investing activities	(205,549)	(489,620)
CASH FLOWS FROM FINANCING ACTIVITIES:
Debt financing costs	(6,352)	(10,881)
Mortgage Deposits	(4,169)	(3,580)
Mortgage notes payable:
Lump sum payoffs	(121,488)	(3,064)
Scheduled principal repayments	(5,028)	(6,000)
Notes, net:
Proceeds	746,391	1,194,277
Lump sum payoffs	(300,000)	(750,000)
Line of credit and commercial paper:
Line of credit proceeds	3,553,000	3,374,000
Line of credit repayments	(3,886,000)	(3,489,000)
Commercial paper proceeds	2,266,924	0
Commercial paper repayments	(2,267,500)	0
(Payments on) settlement of derivative instruments	(13,938)	(733)
EQR's Employee Share Purchase Plan (ESPP)	2,610	2,218
Proceeds from exercise of options	33,984	25,685
OP Units repurchased and retired	0	(1,777)
Partial redemption of 8.29% Series K Cumulative Redeemable	(9,820)	0
Premium on redemption of Preference Units	(2,789)	0
Payment of offering costs	(40)	0
Other financing activities, net	(33)	(33)
Acquisition of Noncontrolling Interests - Partially Owned Properties	0	(5,501)
Contributions - Noncontrolling Interests - Partially Owned Properties	0	5,684
Contributions - Limited Partners	1	3
Distributions:
OP Units - General Partner	(382,441)	(414,843)
Preference Units	(1,724)	(2,072)
OP Units - Limited Partners	(15,062)	(16,405)
Noncontrolling Interests – Partially Owned Properties	(3,995)	(5,239)
Net Cash (used for) Financing Activities	(417,469)	(107,261)
Net increase in cash and cash equivalents	52,029	22,598
Cash and cash equivalents, beginning of period	40,080	53,534
Cash and cash equivalents, end of period	92,109	76,132
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized	218,965	226,785
Net cash paid for income and other taxes	895	843
Amortization of discounts and premiums on debt:
Mortgage notes payable	(7,420)	(7,011)
Notes, net	1,233	1,135
Line of credit and commercial paper	576	0
Amortization of deferred settlements on derivative instruments:
Other liabilities	(160)	(267)
Losses reclassified into earnings from other comprehensive income	8,911	8,335
Write-off of pursuit costs [Abstract]
Write-off of pursuit costs - investment in real estate, net	1,260	1,435
Deposits – restricted	330	0
Write-off of pursuit costs - other assets	61	57
(Income) Loss From Investments In Unconsolidated Entities [Abstract]
(Income) loss from investment in unconsolidated entities	(16,767)	7,354
Other Liabilities Loss From Investments in unconsolidated entities	1,338	1,671
Distributions from unconsolidated entities return on capital [Abstract]
Distributions from unconsolidated entities investments in unconsolidated entities	2,125	2,285
Distributions from unconsolidated entities other liabilities	68	105
Unrealized loss (gain) on derivative instruments:
Other assets	(3,873)	10,611
Notes, net	2,358	1,452
Other liabilities	1,678	9,728
Unrealized holding (losses) gains arising during the period	(112)	(21,881)
Interest capitalized for real estate and unconsolidated entities under development:
Investment in real estate, net	(30,432)	(25,002)
Investments in unconsolidated entities	0	(35)
Investments in unconsolidated entities [Abstract]
Investments in unconsolidated entities	(1,291)	(2,354)
Investments in unconsolidated entities other liabilities	(3,495)	(7,200)
Other:
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	$ 502	$ (1,718)

CONSOLIDATED STATEMENT OF CHANG

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (Unaudited) - Class of Stock [Domain] - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Total	PREFERRED SHARES	COMMON SHARES, $0.01 PAR VALUE	Additional Paid-in Capital [Member]	RETAINED EARNINGS	Accumulated Other Comprehensive (Loss)	OPERATING PARTNERSHIP	Partially Owned Properties [Member]
Beginning Balance, Parent at Dec. 31, 2014	$ 10,368,456	$ 50,000	$ 3,629	$ 8,536,340	$ 1,950,639	$ (172,152)
Beginning Balance, Noncontrolling Interest at Dec. 31, 2014	339,320						$ 214,411	$ 124,909
Preferred Shares [Abstract]
Partial redemption of 8.29% Series K Cumulative Redeemable	(9,820)	(9,820)
Common Share Issuance:
Conversion of OP Units into Common Shares			2	4,117			(4,119)
Exercise of share options			8	33,976
EQR's Employee Share Purchase Plan (ESPP)				2,610
Conversion of restricted shares to restricted units				(70)			70
Share-based employee compensation expense:
Restricted Shares			2	10,343
Share options				2,028
ESPP discount				533
Offering costs				(40)
Supplemental Executive Retirement Plan (SERP)				(2,227)
Change in market value of Redeemable Noncontrolling Interests - Operating Partnership	(13,966)			13,966
Adjustment for Noncontrolling Interests ownership in Operating Partnership				6,313			(6,313)
Net income attributable to controlling interests	468,942				468,942
Common Share distributions					(402,159)
Preferred Share distributions					(1,724)
Premium on redemption of Preferred Shares	(2,789)				(2,789)
Other comprehensive (loss) income – derivative instruments:
Unrealized holding (losses) arising during the period	(112)					(112)
Losses reclassified into earnings from other comprehensive income	(8,911)					8,911
Currency translation adjustments arising during the period	(502)					(502)
Issuance of restricted units to Noncontrolling Interests							1
Equity Compensation associated with Noncontrolling Interests							16,368
Net (income) attributable to Noncontrolling Interests - Operating Partnership	(18,413)						18,413
Distributions to Noncontrolling Interests							(15,819)	(4,028)
Change in carrying value	1,411						(1,411)
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	1,487							1,487
Ending Balance, Parent at Jun. 30, 2015	10,500,764	$ 40,180	$ 3,641	$ 8,607,889	$ 2,012,909	$ (163,855)
Ending Balance, Noncontrolling Interest at Jun. 30, 2015	$ 343,969						$ 221,601	$ 122,368

CONSOLIDATED STATEMENT OF CHA12

CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Total	PREFERRED UNITS	General Partner [Member]	Limited Partner [Member]	Accumulated Other Comprehensive (Loss)	Partially Owned Properties [Member]
Balance, beginning of year at Dec. 31, 2014		$ 50,000	$ 10,490,608	$ 214,411	$ (172,152)
Balance, beginning of year - Noncontrolling Interest at Dec. 31, 2014						$ 124,909
Partial redemption of 8.29% Series K Cumulative Redeemable	$ (9,820)	(9,820)
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner			4,119	(4,119)
Exercise of EQR share options			33,984
EQR's Employee Share Purchase Plan (ESPP)			2,610
Conversion of restricted shares to restricted units			(70)	70
Share-based employee compensation expense:
EQR restricted shares			10,345
EQR share options			2,028
EQR ESPP discount			533
Net income available to Units - General Partner			464,429
OP Units - General Partner distributions			(402,159)
Offering costs			(40)
Supplemental Executive Retirement Plan (SERP)			(2,227)
Change in market value of Redeemable Limited Partners			13,966
Adjustment for Limited Partners ownership in Operating Partnership			6,313	(6,313)
Issuance of restricted units to Noncontrolling Interests				1
Equity compensation associated with Units - Limited Partners				16,368
Net income available to Units - Limited Partners				18,413
Units Limited Partners Distributions				(15,819)
Change in carrying value				(1,411)
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	1,487					1,487
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders						(4,028)
Other comprehensive (loss) income – derivative instruments:
Unrealized holding (losses) arising during the period	(112)				(112)
Losses reclassified into earnings from other comprehensive income	(8,911)				8,911
Currency translation adjustments arising during the period	$ (502)				(502)
Balance, end of period at Jun. 30, 2015		$ 40,180	$ 10,624,439	$ 221,601	$ (163,855)
Balance, end of period - Noncontrolling Interest at Jun. 30, 2015						$ 122,368

Business

Business	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 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 public 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 June 30, 2015 , the Company, directly or indirectly through investments in title holding entities, owned all or a portion of 388 properties located in 12 states and the District of Columbia consisting of 108,430 apartment units. The ownership breakdown includes (table does not include various uncompleted development properties): Properties Apartment Wholly Owned Properties 361 97,438 Master-Leased Properties – Consolidated 3 853 Partially Owned Properties – Consolidated 19 3,771 Partially Owned Properties – Unconsolidated 3 1,281 Military Housing 2 5,087 388 108,430

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2015
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. These reclassifications did not have an impact on net income previously reported. Operating results for the six months ended June 30, 2015 are not necessarily indicative of the results that may be expected for the year ending December 31, 2015 . 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, 2014 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, 2014 . 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 suspended interest deductions, net operating losses, differing depreciable lives on capitalized assets and the timing of expense recognition for certain accrued liabilities. As of June 30, 2015 , 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. Recent Accounting Pronouncements In April 2014, the Financial Accounting Standards Board (the "FASB") issued new guidance for reporting discontinued operations. Only disposals representing a strategic shift in operations that has a major effect on a company’s operations and financial results will be presented as discontinued operations. Companies are required to expand their disclosures about discontinued operations to provide more information on the assets, liabilities, income and expenses of the discontinued operations. Companies are also required to disclose the pre-tax income attributable to a disposal of a significant part of a company that does not qualify for discontinued operations reporting. Application of this guidance is prospective from the date of adoption and early adoption was permitted, but only for disposals (or classifications as held for sale) that had not been reported in financial statements previously issued. The new standard was effective January 1, 2015, but the Company early adopted it as allowed effective January 1, 2014. Adoption of this standard resulted in and will likely continue to result in substantially fewer of the Company's dispositions meeting the discontinued operations qualifications. See Note 11 for further discussion. In May 2014, the FASB issued a comprehensive new revenue recognition standard entitled Revenue from Contracts with Customers that will supersede nearly all existing revenue recognition guidance. The new standard specifically excludes lease contracts. The new standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. Companies will likely need to use more judgment and make more estimates than under current revenue recognition guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration, if any, to include in the transaction price and allocating the transaction price to each separate performance obligation. The new standard will be effective for the Company beginning on January 1, 2018 and early adoption will be permitted beginning on January 1, 2017. The new standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of adoption. The Company has not yet selected a transition method and is currently evaluating the impact of adopting the new standard on its consolidated results of operations and financial position. In August 2014, the FASB issued a new standard that will explicitly require management to assess an entity's ability to continue as a going concern and to provide related footnote disclosures in certain circumstances. In connection with each annual and interim period, management will assess whether there is substantial doubt about an entity's ability to continue as a going concern within one year after the issuance date. Disclosures will be required if conditions give rise to substantial doubt. However, to determine the specific disclosures, management will need to assess whether its plans will alleviate substantial doubt. The new standard is effective for the annual period ending after December 15, 2016. The Company does not expect that this will have a material effect on its consolidated results of operations or financial position. In February 2015, the FASB issued new consolidation guidance which makes changes to both the variable interest model and the voting model. Among other changes, the new standard specifically eliminates the presumption in the current voting model that a general partner controls a limited partnership or similar entity unless that presumption can be overcome. Generally, only a single limited partner that is able to exercise substantive kick-out rights will consolidate. The new standard will be effective for the Company beginning on January 1, 2016 and early adoption is permitted, including adoption in an interim period. The new standard must be applied using a modified retrospective approach by recording a cumulative-effect adjustment to equity/capital as of the beginning of the period of adoption or retrospectively to each period presented. The Company has not yet selected a transition method and is currently evaluating the impact of adopting the new standard on its consolidated results of operations and financial position. In April 2015, the FASB issued a new standard which requires companies to present debt financing costs as a direct deduction from the carrying amount of the associated debt liability rather than as an asset, consistent with the presentation of debt discounts on the consolidated balance sheets. The new standard will be effective for the Company beginning on January 1, 2016 and early adoption is permitted. The new standard must be applied retrospectively to all prior periods presented in the consolidated financial statements. The Company does not expect that this will have a material effect on its consolidated results of operations or financial position. Other The Company is the controlling partner in various consolidated partnerships owning 19 properties and 3,771 apartment units and various completed and uncompleted development properties having a noncontrolling interest book value of $122.4 million at June 30, 2015 . 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 $11.1 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 June 30, 2015 , the Company estimates the value of Noncontrolling Interest distributions for these six properties would have been approximately $68.3 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 June 30, 2015 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.

Equity, Capital and Other Inter

Equity, Capital and Other Interests	6 Months Ended
	Jun. 30, 2015
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 restricted units (formerly known as Long-Term Incentive Plan (“LTIP”) Units)) for the six months ended June 30, 2015 : 2015 Common Shares Common Shares outstanding at January 1, 362,855,454 Common Shares Issued: Conversion of OP Units 171,353 Exercise of share options 814,827 Employee Share Purchase Plan (ESPP) 40,873 Restricted share grants, net 169,667 Common Shares Other: Conversion of restricted shares to restricted units (1,284 ) Common Shares outstanding at June 30, 364,050,890 Units Units outstanding at January 1, 14,298,691 Restricted units, net 337,505 Conversion of restricted shares to restricted units 1,284 Conversion of OP Units to Common Shares (171,353 ) Units outstanding at June 30, 14,466,127 Total Common Shares and Units outstanding at June 30, 378,517,017 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 restricted units, are collectively referred to as the “Noncontrolling Interests – Operating Partnership”. Subject to certain exceptions (including the “book-up” requirements of restricted 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 June 30, 2015 and December 31, 2014 . 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 June 30, 2015 , the Redeemable Noncontrolling Interests – Operating Partnership have a redemption value of approximately $488.2 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 changes in the redemption value of the Redeemable Noncontrolling Interests – Operating Partnership for the six months ended June 30, 2015 (amounts in thousands): 2015 Balance at January 1, $ 500,733 Change in market value (13,966 ) Change in carrying value 1,411 Balance at June 30, $ 488,178 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 June 30, 2015 and December 31, 2014: Amounts in thousands Redemption Annual June 30, December 31, Preferred Shares of beneficial interest, $0.01 par value; 8.29% Series K Cumulative Redeemable Preferred; liquidation 12/10/26 $4.145 $ 40,180 $ 50,000 $ 40,180 $ 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. (3) Effective January 26, 2015, the Company repurchased and retired 196,400 Series K Preferred Shares with a par value of $9.82 million for total cash consideration of approximately $12.7 million . As a result of this partial redemption, the Company incurred a cash charge of approximately $2.8 million which was recorded as a premium on the redemption of Preferred Shares. 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 six months ended June 30, 2015 : 2015 General and Limited Partner Units General and Limited Partner Units outstanding at January 1, 377,154,145 Issued to General Partner: Exercise of EQR share options 814,827 EQR’s Employee Share Purchase Plan (ESPP) 40,873 EQR's restricted share grants, net 169,667 Issued to Limited Partners: Restricted units, net 337,505 General and Limited Partner Units outstanding at June 30, 378,517,017 Limited Partner Units Limited Partner Units outstanding at January 1, 14,298,691 Limited Partner restricted units, net 337,505 Conversion of EQR restricted shares to restricted units 1,284 Conversion of Limited Partner OP Units to EQR Common Shares (171,353 ) Limited Partner Units outstanding at June 30, 14,466,127 Limited Partner Units Ownership Interest in Operating Partnership 3.8 % The Limited Partners of the Operating Partnership as of June 30, 2015 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 restricted units. Subject to certain exceptions (including the “book-up” requirements of restricted 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 June 30, 2015 and December 31, 2014 . 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 June 30, 2015 , the Redeemable Limited Partner Units have a redemption value of approximately $488.2 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 changes in the redemption value of the Redeemable Limited Partners for the six months ended June 30, 2015 (amounts in thousands): 2015 Balance at January 1, $ 500,733 Change in market value (13,966 ) Change in carrying value 1,411 Balance at June 30, $ 488,178 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 June 30, 2015 and December 31, 2014 : Amounts in thousands Redemption Date (1) Annual June 30, December 31, Preference Units: 8.29% Series K Cumulative Redeemable Preference Units; 12/10/26 $4.145 $ 40,180 $ 50,000 $ 40,180 $ 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. (3) Effective January 26, 2015, the Operating Partnership repurchased and retired 196,400 Series K Preference Units with a par value of $9.82 million for total cash consideration of approximately $12.7 million , in conjunction with the concurrent redemption of the corresponding Company Preferred Shares. As a result of this partial redemption, the Operating Partnership incurred a cash charge of approximately $2.8 million which was recorded as a premium on the redemption of Preference Units. Other In September 2009, the Company announced the establishment of an At-The-Market (“ATM”) share offering program which would allow EQR to sell Common Shares from time to time 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). On July 30, 2013, the Board of Trustees 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 not issued any shares under this program since September 14, 2012. 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 six months ended June 30, 2015 . As of June 30, 2015 , EQR has remaining authorization to repurchase an additional 12,968,760 of its shares.

Real Estate

Real Estate	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and December 31, 2014 (amounts in thousands): June 30, December 31, Land $ 6,374,779 $ 6,295,404 Depreciable property: Buildings and improvements 18,328,935 17,974,337 Furniture, fixtures and equipment 1,446,235 1,365,276 In-Place lease intangibles 515,154 511,891 Projects under development: Land 406,251 466,764 Construction-in-progress 833,993 877,155 Land held for development: Land 97,387 145,366 Construction-in-progress 30,172 39,190 Investment in real estate 28,032,906 27,675,383 Accumulated depreciation (5,736,913 ) (5,432,805 ) Investment in real estate, net $ 22,295,993 $ 22,242,578 The following table summarizes the carrying amounts for the Company's above and below market ground and retail lease intangibles as of June 30, 2015 and December 31, 2014 (amounts in thousands): Description Balance Sheet Location June 30, December 31, Assets Ground lease intangibles – below market Other Assets $ 178,251 $ 178,251 Retail lease intangibles – above market Other Assets 1,260 1,260 Lease intangible assets 179,511 179,511 Accumulated amortization (11,185 ) (8,913 ) Lease intangible assets, net $ 168,326 $ 170,598 Liabilities Ground lease intangibles – above market Other Liabilities $ 2,400 $ 2,400 Retail lease intangibles – below market Other Liabilities 5,270 5,270 Lease intangible liabilities 7,670 7,670 Accumulated amortization (2,839 ) (2,258 ) Lease intangible liabilities, net $ 4,831 $ 5,412 During the six months ended June 30, 2015 and 2014, the Company amortized approximately $2.2 million and $2.2 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 $0.5 million and $0.6 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. During the quarters ended June 30, 2015 and 2014, the Company amortized approximately $1.1 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 $0.3 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 2.8 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 2015 2016 2017 2018 2019 2020 Ground lease intangibles $ 2,161 $ 4,321 $ 4,321 $ 4,321 $ 4,321 $ 4,321 Retail lease intangibles (469 ) (896 ) (540 ) (71 ) (71 ) (71 ) Total $ 1,692 $ 3,425 $ 3,781 $ 4,250 $ 4,250 $ 4,250 During the six months ended June 30, 2015 , the Company acquired the entire equity interest in the following from unaffiliated parties (purchase price in thousands): Properties Apartment Units Purchase Price Rental Properties 1 202 $ 130,275 Land Parcel (one) — — 5,968 Total 1 202 $ 136,243 During the six months ended June 30, 2015 , the Company disposed of the following to unaffiliated parties (sales price in thousands): Properties Apartment Units Sales Price Rental Properties (1) 6 1,377 $ 386,662 Total 6 1,377 $ 386,662 (1) Includes a 193,230 square foot medical office building adjacent to our Longfellow Place property in Boston with a sales price of approximately $123.3 million . The Company recognized a net gain on sales of real estate properties of approximately $228.8 million on the above sales.

Commitments to Acquire_Dispose

Commitments to Acquire/Dispose of Real Estate	6 Months Ended
	Jun. 30, 2015
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 separate agreements to acquire the following (purchase price in thousands): Properties Apartment Units Purchase Price Land Parcels (two) — — $ 21,832 Other — 2 6,000 Total — 2 $ 27,832 The Company has entered into separate agreements to dispose of the following (sales price in thousands): Properties Apartment Units Sales Price Rental Properties 2 522 $ 104,838 Land Parcels (three) — — 29,900 Total 2 522 $ 134,738 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	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 (amounts in thousands except for project and apartment unit amounts): Consolidated Unconsolidated Development Projects Held for Operating Total Operating Total Total projects (1) — 19 19 3 3 Total apartment units (1) — 3,771 3,771 1,281 1,281 Balance sheet information at 6/30/15 (at 100%): ASSETS Investment in real estate $ 351,977 $ 686,120 $ 1,038,097 $ 290,442 $ 290,442 Accumulated depreciation (2,339 ) (205,554 ) (207,893 ) (24,471 ) (24,471 ) Investment in real estate, net 349,638 480,566 830,204 265,971 265,971 Cash and cash equivalents — 17,482 17,482 8,793 8,793 Investments in unconsolidated entities — 50,771 50,771 — — Deposits – restricted 11,609 345 11,954 273 273 Deferred financing costs, net — 1,963 1,963 7 7 Other assets 6,988 25,959 32,947 703 703 Total assets $ 368,235 $ 577,086 $ 945,321 $ 275,747 $ 275,747 LIABILITIES AND EQUITY/CAPITAL Mortgage notes payable (2) $ — $ 360,654 $ 360,654 $ 175,135 $ 175,135 Accounts payable & accrued expenses 5,756 1,939 7,695 1,486 1,486 Accrued interest payable — 1,266 1,266 691 691 Other liabilities 615 819 1,434 325 325 Security deposits 589 2,002 2,591 592 592 Total liabilities 6,960 366,680 373,640 178,229 178,229 Noncontrolling Interests – Partially Owned 117,350 5,018 122,368 90,878 90,878 Company equity/General and Limited 243,925 205,388 449,313 6,640 6,640 Total equity/capital 361,275 210,406 571,681 97,518 97,518 Total liabilities and equity/capital $ 368,235 $ 577,086 $ 945,321 $ 275,747 $ 275,747 Consolidated Unconsolidated Development Projects Held for Operating Operating Total Total Operating information for the six months ended 6/30/15 (at 100%): Operating revenue $ 1,103 $ 46,071 $ 47,174 $ 15,918 $ 15,918 Operating expenses 851 13,545 14,396 5,388 5,388 Net operating income 252 32,526 32,778 10,530 10,530 Depreciation 2,339 11,073 13,412 6,159 6,159 General and administrative/other 1 41 42 119 119 Operating (loss) income (2,088 ) 21,412 19,324 4,252 4,252 Interest and other income — 5 5 — — Other expenses — (50 ) (50 ) — — Interest: Expense incurred, net — (7,786 ) (7,786 ) (4,697 ) (4,697 ) Amortization of deferred financing costs — (177 ) (177 ) (1 ) (1 ) (Loss) income before income and other taxes and (loss) (2,088 ) 13,404 11,316 (446 ) (446 ) Income and other tax (expense) benefit — (35 ) (35 ) (18 ) (18 ) (Loss) from investments in unconsolidated entities — (739 ) (739 ) — — Net (loss) income $ (2,088 ) $ 12,630 $ 10,542 $ (464 ) $ (464 ) (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. Note: The above tables exclude the Company's interests in unconsolidated joint ventures entered into with AvalonBay Communities, Inc. (“AVB”) in connection with the acquisition of certain real estate related assets from Archstone Enterprise LP (such assets are referred to herein as "Archstone"). These ventures own certain non-core Archstone assets that are held for sale and succeeded to certain residual Archstone liabilities/litigation, as well as responsibility for tax protection arrangements and third-party preferred interests in former Archstone subsidiaries. The preferred interests had an aggregate liquidation value of $71.2 million at June 30, 2015 . 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 an aggregate noncontrolling interest book value of $122.4 million at June 30, 2015 . The Company does not have any variable interest entities. Operating Properties On February 27, 2013, in conjunction with the acquisition of Archstone, the Company acquired an interest in the Wisconsin Place joint venture. This project contains 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 entire 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. On February 27, 2013, in conjunction with the acquisition of Archstone, the Company acquired an interest in the Waterton Tenside joint venture. 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 $29.7 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. 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 each of these entities. These projects are now unconsolidated. Details of these projects follow: • Nexus Sawgrass – This development project was completed and stabilized during the quarter ended September 30, 2014 . Total project costs were approximately $78.6 million and construction was predominantly funded with a long-term, non-recourse secured loan from the partner. The mortgage loan has a current unconsolidated outstanding balance of $48.6 million , bears interest at 5.60% and matures January 1, 2021 . • Domain – This development project was completed and stabilized during the quarter ended March 31, 2015 . Total project costs were approximately $155.8 million and construction was predominantly funded with a long-term, non-recourse secured loan from the partner. The mortgage loan has a current unconsolidated outstanding balance of $96.8 million , bears interest at 5.75% and matures January 1, 2022 . While the Company is the managing member of both of the joint ventures, was responsible for constructing both of the projects and had 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. Development Project Prism at Park Ave South – 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 master condominium association has been legally established, 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 June 30, 2015 , the Company's and Toll Brothers' consolidated contributions to the joint venture were approximately $342.2 million , of which Toll Brothers' noncontrolling interest balance totaled $117.4 million . See Note 14 for additional discussion. Other On February 27, 2013, in connection with the acquisition of Archstone, 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, such as interests in a two property portfolio of apartment buildings and succeeded to certain residual Archstone liabilities/litigation. The Residual JV is owned 60% by the Company and 40% by AVB and the Company's initial investment was $147.6 million . The Residual JV 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 Residual JV is unconsolidated and recorded using the equity method of accounting. During the six months ended June 30, 2015 , the Company received approximately $26.1 million in distributions from the Residual JV as a result of the winddown/sale of remaining assets owned by the Residual JV and a partial litigation settlement received by the Residual JV. The Company's pro rata share of the distributions related to the winddown of the German dispositions that occurred in 2014 was approximately $2.3 million during the six months ended June 30, 2015 and $100.8 million cumulatively since the acquisition of Archstone. The Company's pro rata share of the proceeds related to the sale of certain remaining assets owned by the Residual JV and the partial litigation settlement received by the Residual JV were approximately $17.2 million and $6.6 million , respectively. On February 27, 2013, in connection with the acquisition of Archstone, 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. At June 30, 2015 , the remaining preferred interests had an aggregate liquidation value of $71.2 million , our share of which is included in other liabilities in the accompanying consolidated balance sheets. Obligations of the Legacy JV are borne 60% by the Company and 40% by AVB. The Legacy JV 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 Legacy JV is unconsolidated and recorded using the equity method of accounting.

Deposits - Restricted

Deposits - Restricted	6 Months Ended
	Jun. 30, 2015
Deposits - Restricted [Abstract]
Restricted Cash And Cash Equivalents Disclosure [Text Block]	7. Deposits – Restricted and Escrow Deposits – Mortgage The following table presents the Company’s restricted deposits as of June 30, 2015 and December 31, 2014 (amounts in thousands): June 30, December 31, Tax-deferred (1031) exchange proceeds $ 40,383 $ — Earnest money on pending acquisitions 2,210 580 Restricted deposits on real estate investments 13,605 24,701 Resident security and utility deposits 46,976 46,516 Other 334 506 Totals $ 103,508 $ 72,303 The following table presents the Company’s escrow deposits as of June 30, 2015 and December 31, 2014 (amounts in thousands): June 30, December 31, Real estate taxes and insurance $ 2,617 $ 2,235 Replacement reserves 3,657 3,431 Mortgage principal reserves/sinking funds 45,736 41,567 Other 852 852 Totals $ 52,862 $ 48,085

Debt

Debt	6 Months Ended
	Jun. 30, 2015
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 revolving credit facility up to the maximum amount and for the full term of the facility. Mortgage Notes Payable As of June 30, 2015 , the Company had outstanding mortgage debt of approximately $5.0 billion . During the six months ended June 30, 2015 , the Company repaid $126.5 million of mortgage loans. The Company recorded $0.1 million of write-offs of unamortized deferred financing costs during the six months ended June 30, 2015 as additional interest expense related to debt extinguishment of mortgages. The Company also recorded $1.4 million of write-offs of net unamortized premiums during the six months ended June 30, 2015 as a reduction of interest expense related to debt extinguishment of mortgages. As of June 30, 2015 , the Company had $700.5 million of secured debt subject to third party credit enhancement. As of June 30, 2015 , scheduled maturities for the Company’s outstanding mortgage indebtedness were at various dates through May 1, 2061 . At June 30, 2015 , the interest rate range on the Company’s mortgage debt was 0.04% to 7.25% . During the six months ended June 30, 2015 , the weighted average interest rate on the Company’s mortgage debt was 4.20% . Notes As of June 30, 2015 , the Company had outstanding unsecured notes of approximately $5.9 billion . During the six months ended June 30, 2015 , the Company: ▪ Repaid $300.0 million of 6.584% unsecured notes at maturity; ▪ Issued $450.0 million of ten-year 3.375% fixed rate public notes, receiving net proceeds of $447.5 million before underwriting fees, hedge termination costs and other expenses, at an all-in effective interest rate of 3.81% after termination of various forward starting swaps in conjunction with the issuance (see Note 9 for further discussion); and ▪ Issued $300.0 million of thirty-year 4.50% fixed rate public notes, receiving net proceeds of $298.9 million before underwriting fees and other expenses, at an all-in effective interest rate of 4.55% . As of June 30, 2015 , scheduled maturities for the Company’s outstanding notes were at various dates through June 1, 2045 . At June 30, 2015 , the interest rate range on the Company’s notes was 2.375% to 7.57% . During the six months ended June 30, 2015 , the weighted average interest rate on the Company’s notes was 4.99% . Line of Credit and Commercial Paper 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 facility will generally be LIBOR plus a spread (currently 0.95% ) 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. As of June 30, 2015 , the amount available on the revolving credit facility was $2.46 billion (net of $41.7 million which was restricted/dedicated to support letters of credit). During the six months ended June 30, 2015 , the weighted average interest rate on the revolving credit facility was 1.06% . On February 2, 2015, the Company entered into an unsecured commercial paper note program in the United States. The Company may borrow up to a maximum of $500.0 million on this program subject to market conditions. The notes will be sold under customary terms in the United States commercial paper note market and will rank pari passu with all of the Company's other unsecured senior indebtedness. The notes bear interest at various floating rates with a weighted average of 0.57% for the six months ended June 30, 2015 . No amounts were outstanding at June 30, 2015 .

Derivative and Other Fair Value

Derivative and Other Fair Value Instruments	6 Months Ended
	Jun. 30, 2015
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. 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. 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 sheets. 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 debt (including its line of credit) were calculated using indicative rates provided by lenders of similar loans in the case of mortgage notes payable and the private unsecured debt (including its line of credit) and quoted market prices for each underlying issuance in the case of the public unsecured notes. The carrying values of the Company’s mortgage notes payable and unsecured notes were approximately $5.0 billion and $5.9 billion , respectively, at June 30, 2015 . The fair values of the Company’s mortgage notes payable and unsecured notes were approximately $4.9 billion (Level 2) and $6.1 billion (Level 2), respectively, at June 30, 2015 . The carrying values of the Company's mortgage notes payable and unsecured debt (including its line of credit) were approximately $5.1 billion and $5.8 billion , respectively, at December 31, 2014 . The fair values of the Company’s mortgage notes payable and unsecured debt (including its line of credit) were approximately $5.1 billion (Level 2) and $6.1 billion (Level 2), respectively, at December 31, 2014 . The fair values of the Company’s financial instruments (other than mortgage notes payable, unsecured notes, line of credit and derivative instruments), including cash and cash equivalents and other financial instruments, approximate their carrying or contract values. The following table summarizes the Company’s consolidated derivative instruments at June 30, 2015 (dollar amounts are in thousands): Fair Value Current Notional Balance $ 450,000 Lowest Possible Notional $ 450,000 Highest Possible Notional $ 450,000 Lowest Interest Rate 2.375 % Highest Interest Rate 2.375 % Earliest Maturity Date 2019 Latest Maturity Date 2019 (1) Fair Value Hedges – Converts outstanding fixed rate unsecured notes ( $450.0 million 2.375% notes due July 1, 2019 ) to a floating interest rate of 90-Day LIBOR plus 0.61% . 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 June 30, 2015 and December 31, 2014 , respectively (amounts in thousands): Fair Value Measurements at Reporting Date Using Description Balance Sheet Location 6/30/2015 Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Derivatives designated as hedging instruments: Interest Rate Contracts: Fair Value Hedges Other Assets $ 3,955 $ — $ 3,955 $ — Supplemental Executive Retirement Plan Other Assets 99,641 99,641 — — Total $ 103,596 $ 99,641 $ 3,955 $ — Liabilities Supplemental Executive Retirement Plan Other Liabilities $ 99,641 $ 99,641 $ — $ — Total $ 99,641 $ 99,641 $ — $ — Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners Mezzanine $ 488,178 $ — $ 488,178 $ — Fair Value Measurements at Reporting Date Using Description Balance Sheet Location 12/31/2014 Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Derivatives designated as hedging instruments: Interest Rate Contracts: Fair Value Hedges Other Assets $ 1,597 $ — $ 1,597 $ — Forward Starting Swaps Other Assets 332 — 332 — Supplemental Executive Retirement Plan Other Assets 104,463 104,463 — — Total $ 106,392 $ 104,463 $ 1,929 $ — Liabilities Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps Other Liabilities $ 14,104 $ — $ 14,104 $ — Supplemental Executive Retirement Plan Other Liabilities 104,463 104,463 — — Total $ 118,567 $ 104,463 $ 14,104 $ — Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners Mezzanine $ 500,733 $ — $ 500,733 $ — 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 six months ended June 30, 2015 and 2014 , respectively (amounts in thousands): June 30, 2015 Type of Fair Value Hedge Location of Gain/(Loss) Recognized in Income on Derivative Amount of Gain/(Loss) Recognized in Income on Derivative Hedged Item Income Statement Location of Hedged Item Gain/(Loss) Amount of Gain/(Loss) Recognized in Income on Hedged Item Derivatives designated as hedging instruments: Interest Rate Contracts: Interest Rate Swaps Interest expense $ 2,358 Fixed rate debt Interest expense $ (2,358 ) Total $ 2,358 $ (2,358 ) June 30, 2014 Type of Fair Value Hedge Location of Derivative Amount of Derivative Hedged Item Income Statement Amount of Gain/(Loss) Recognized in Income on Hedged Item Derivatives designated as hedging instruments: Interest Rate Contracts: Interest Rate Swaps Interest expense $ 1,452 Fixed rate debt Interest expense $ (1,452 ) Total $ 1,452 $ (1,452 ) 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 six months ended June 30, 2015 and 2014 , respectively (amounts in thousands): Effective Portion Ineffective Portion June 30, 2015 Type of Cash Flow Hedge Amount of Gain/(Loss) Recognized in OCI on Derivative Location of Gain/ (Loss) Reclassified from Accumulated OCI into Income Amount of Gain/ Location of Gain/(Loss) Recognized in Income on Derivative Amount of Gain/ Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps $ (142 ) Interest expense $ (8,911 ) Interest expense $ (30 ) Total $ (142 ) $ (8,911 ) $ (30 ) Effective Portion Ineffective Portion June 30, 2014 Type of Cash Flow Hedge Amount of Gain/(Loss) Recognized in OCI on Derivative Location of Gain/ (Loss) Reclassified from Accumulated OCI into Income Amount of Gain/ Location of Gain/(Loss) Recognized in Income on Derivative Amount of Gain/ Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps $ (21,790 ) Interest expense $ (8,335 ) Interest expense $ 91 Total $ (21,790 ) $ (8,335 ) $ 91 As of June 30, 2015 and December 31, 2014 , there were approximately $163.4 million and $172.2 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 June 30, 2015 , the Company may recognize an estimated $23.8 million of accumulated other comprehensive (loss) as additional interest expense during the twelve months ending June 30, 2016 . In May 2015, the Company paid a net $15.1 million to settle nine forward starting ten-year swaps in conjunction with the issuance of $450.0 million of ten-year fixed rate public notes. The ineffective portion of approximately $30,000 and accrued interest of approximately $1.2 million were recorded as increases to interest expense. The remaining amount of approximately $13.9 million will be deferred as a component of accumulated other comprehensive (loss) and recognized as an increase to interest expense over the first 9 years and 10.5 months of the notes.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2015
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): Six Months Ended June 30, Quarter Ended June 30, 2015 2014 2015 2014 Numerator for net income per share – basic: Income from continuing operations $ 488,573 $ 198,890 $ 298,504 $ 117,210 Allocation to Noncontrolling Interests – Operating Partnership, net (18,403 ) (7,475 ) (11,350 ) (4,422 ) Net (income) attributable to Noncontrolling Interests – Partially Owned Properties (1,487 ) (1,092 ) (844 ) (588 ) Preferred distributions (1,724 ) (2,072 ) (833 ) (1,036 ) Premium on redemption of Preferred Shares (2,789 ) — — — Income from continuing operations available to Common Shares, net of 464,170 188,251 285,477 111,164 Discontinued operations, net of Noncontrolling Interests 259 1,502 110 490 Numerator for net income per share – basic $ 464,429 $ 189,753 $ 285,587 $ 111,654 Numerator for net income per share – diluted: Income from continuing operations $ 488,573 $ 198,890 $ 298,504 $ 117,210 Net (income) attributable to Noncontrolling Interests – Partially Owned Properties (1,487 ) (1,092 ) (844 ) (588 ) Preferred distributions (1,724 ) (2,072 ) (833 ) (1,036 ) Premium on redemption of Preferred Shares (2,789 ) — — — Income from continuing operations available to Common Shares 482,573 195,726 296,827 115,586 Discontinued operations, net 269 1,562 114 510 Numerator for net income per share – diluted $ 482,842 $ 197,288 $ 296,941 $ 116,096 Denominator for net income per share – basic and diluted: Denominator for net income per share – basic 363,288 360,641 363,476 360,809 Effect of dilutive securities: OP Units 13,592 13,736 13,587 13,742 Long-term compensation shares/units 3,466 2,403 3,428 2,567 Denominator for net income per share – diluted 380,346 376,780 380,491 377,118 Net income per share – basic $ 1.28 $ 0.53 $ 0.79 $ 0.31 Net income per share – diluted $ 1.27 $ 0.52 $ 0.78 $ 0.31 Net income per share – basic: Income from continuing operations available to Common Shares, net of $ 1.28 $ 0.52 $ 0.79 $ 0.31 Discontinued operations, net of Noncontrolling Interests — 0.01 — — Net income per share – basic $ 1.28 $ 0.53 $ 0.79 $ 0.31 Net income per share – diluted: Income from continuing operations available to Common Shares $ 1.27 $ 0.52 $ 0.78 $ 0.31 Discontinued operations, net — — — — Net income per share – diluted $ 1.27 $ 0.52 $ 0.78 $ 0.31 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): Six Months Ended June 30, Quarter Ended June 30, 2015 2014 2015 2014 Numerator for net income per Unit – basic and diluted: Income from continuing operations $ 488,573 $ 198,890 $ 298,504 $ 117,210 Net (income) attributable to Noncontrolling Interests – Partially Owned Properties (1,487 ) (1,092 ) (844 ) (588 ) Allocation to Preference Units (1,724 ) (2,072 ) (833 ) (1,036 ) Allocation to premium on redemption of Preference Units (2,789 ) — — — Income from continuing operations available to Units 482,573 195,726 296,827 115,586 Discontinued operations, net 269 1,562 114 510 Numerator for net income per Unit – basic and diluted $ 482,842 $ 197,288 $ 296,941 $ 116,096 Denominator for net income per Unit – basic and diluted: Denominator for net income per Unit – basic 376,880 374,377 377,063 374,551 Effect of dilutive securities: Dilution for Units issuable upon assumed exercise/vesting of the Company’s 3,466 2,403 3,428 2,567 Denominator for net income per Unit – diluted 380,346 376,780 380,491 377,118 Net income per Unit – basic $ 1.28 $ 0.53 $ 0.79 $ 0.31 Net income per Unit – diluted $ 1.27 $ 0.52 $ 0.78 $ 0.31 Net income per Unit – basic: Income from continuing operations available to Units $ 1.28 $ 0.52 $ 0.79 $ 0.31 Discontinued operations, net — 0.01 — — Net income per Unit – basic $ 1.28 $ 0.53 $ 0.79 $ 0.31 Net income per Unit – diluted: Income from continuing operations available to Units $ 1.27 $ 0.52 $ 0.78 $ 0.31 Discontinued operations, net — — — — Net income per Unit – diluted $ 1.27 $ 0.52 $ 0.78 $ 0.31

Discontinued Operations

Discontinued Operations	6 Months Ended
	Jun. 30, 2015
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, for properties sold in 2013 and prior years. The amounts included in discontinued operations for the six months and quarters ended June 30, 2015 and 2014 represent trailing activity for properties sold in 2013 and prior years. None of the properties sold during the six months and quarters ended June 30, 2015 and 2014 met the new criteria for reporting discontinued operations. See Note 2 for further discussion. The components of discontinued operations are outlined below and include the results of operations for the respective periods that the Company owned such assets for properties sold in 2013 and prior years during the six months and quarters ended June 30, 2015 and 2014 (amounts in thousands). Six Months Ended June 30, Quarter Ended June 30, 2015 2014 2015 2014 REVENUES Rental income $ 338 $ 1,275 $ 177 $ 252 Total revenues 338 1,275 177 252 EXPENSES (1) Property and maintenance (67 ) (41 ) — (89 ) Real estate taxes and insurance 53 (6 ) 1 (19 ) General and administrative 71 51 65 46 Total expenses 57 4 66 (62 ) Discontinued operating income 281 1,271 111 314 Interest and other income 3 80 3 45 Income and other tax (expense) benefit (15 ) (13 ) — (2 ) Discontinued operations 269 1,338 114 357 Net gain on sales of discontinued operations — 224 — 153 Discontinued operations, net $ 269 $ 1,562 $ 114 $ 510 (1) Includes expenses paid in the current period for properties sold in prior periods related to the Company’s period of ownership.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 . 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 has established a reserve related to various litigation matters associated with its Massachusetts properties and periodically assesses the adequacy of the reserve and makes adjustments as necessary. During the six months ended June 30, 2015 , the Company recorded a reduction to the reserve of approximately $1.0 million , resulting in a total reserve of approximately $5.0 million at June 30, 2015 . While no assurances can be given, the Company does not believe that the ultimate resolution of these litigation matters, 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 June 30, 2015 , the Company has 15 consolidated projects (including Prism at Park Avenue South in New York City, which the Company is jointly developing with Toll Brothers as discussed below) totaling 5,211 apartment units in various stages of development with commitments to fund of approximately $1.1 billion and estimated completion dates ranging through September 30, 2017 , 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 ventures. As of June 30, 2015 , the Company has two completed unconsolidated development projects that are stabilized. Both projects were co-developed with the same third party development partner in different ventures. The development venture agreements with this partner are primarily deal-specific regarding profit-sharing, equity contributions, returns on investment, buy-sell agreements and other customary provisions. The Company currently has no further funding obligations related to these projects. While the Company is the managing member of both of the joint ventures, was 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 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. 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 master condominium association has been legally established, 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 June 30, 2015 , the Company's and Toll Brothers' consolidated contributions to the joint venture were approximately $342.2 million , of which Toll Brothers' noncontrolling interest balance totaled $117.4 million . See Note 14 for additional discussion.

Reportable Segments

Reportable Segments	6 Months Ended
	Jun. 30, 2015
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 located in its core markets represent its reportable segments (with the aggregation of Los Angeles, Orange County and San Diego into the Southern California reportable segment). The Company's operating segments located in its non-core markets that are not material have also been aggregated in the tables presented below. 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 six months and quarters ended June 30, 2015 and 2014 , 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 six months and quarters ended June 30, 2015 and 2014 , respectively, as well as total assets and capital expenditures at June 30, 2015 (amounts in thousands): Six Months Ended June 30, 2015 Six Months Ended June 30, 2014 Rental Income Operating Expenses NOI Rental Income Operating Expenses NOI Same store (1) Boston $ 124,419 $ 41,741 $ 82,678 $ 120,678 $ 39,725 $ 80,953 Denver 58,826 15,627 43,199 54,123 15,097 39,026 New York 234,555 89,855 144,700 225,407 87,045 138,362 San Francisco 182,399 53,957 128,442 165,343 52,964 112,379 Seattle 81,906 25,697 56,209 76,511 25,770 50,741 South Florida 99,828 36,224 63,604 94,755 35,159 59,596 Southern California 212,517 68,164 144,353 201,450 67,298 134,152 Washington D.C. 226,819 75,620 151,199 224,975 73,399 151,576 Non-core 45,829 16,906 28,923 44,092 16,596 27,496 Total same store 1,267,098 423,791 843,307 1,207,334 413,053 794,281 Non-same store/other (2) (3) Boston 3,336 882 2,454 1,819 412 1,407 New York 115 609 (494 ) — — — Seattle 9,396 2,596 6,800 1,240 657 583 South Florida 3,913 1,346 2,567 2,047 1,251 796 Southern California 35,005 12,864 22,141 19,392 8,642 10,750 Washington D.C. 10,877 3,024 7,853 7,707 2,989 4,718 Other (3) 11,374 8,966 2,408 40,952 21,766 19,186 Total non-same store/other 74,016 30,287 43,729 73,157 35,717 37,440 Total $ 1,341,114 $ 454,078 $ 887,036 $ 1,280,491 $ 448,770 $ 831,721 (1) Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2014, less properties subsequently sold, which represented 96,761 apartment units. (2) Non-same store primarily includes properties acquired after January 1, 2014, plus any properties in lease-up and not stabilized as of January 1, 2014. (3) Other includes development, other corporate operations and operations prior to sale for properties sold in 2014 and 2015 that do not meet the new discontinued operations criteria. Quarter Ended June 30, 2015 Quarter Ended June 30, 2014 Rental Income Operating Expenses NOI Rental Income Operating Expenses NOI Same store (1) Boston $ 62,556 $ 20,061 $ 42,495 $ 60,779 $ 18,442 $ 42,337 Denver 29,829 8,168 21,661 27,511 7,635 19,876 New York 118,485 44,091 74,394 114,221 41,410 72,811 San Francisco 92,549 26,854 65,695 84,082 26,354 57,728 Seattle 41,515 13,030 28,485 38,890 13,036 25,854 South Florida 50,527 18,256 32,271 47,860 17,634 30,226 Southern California 110,357 34,984 75,373 104,319 34,697 69,622 Washington D.C. 116,168 37,585 78,583 115,081 36,372 78,709 Non-core 23,212 8,097 15,115 22,190 7,935 14,255 Total same store 645,198 211,126 434,072 614,933 203,515 411,418 Non-same store/other (2) (3) Boston 2,411 652 1,759 791 202 589 New York 112 613 (501 ) — — — Seattle 4,816 1,297 3,519 1,129 511 618 South Florida 1,981 672 1,309 1,246 797 449 Southern California 14,193 5,375 8,818 7,836 4,019 3,817 Washington D.C. 3,492 910 2,582 2,287 854 1,433 Other (3) 4,305 997 3,308 21,544 9,094 12,450 Total non-same store/other 31,310 10,516 20,794 34,833 15,477 19,356 Total $ 676,508 $ 221,642 $ 454,866 $ 649,766 $ 218,992 $ 430,774 (1) Same store primarily includes all properties acquired or completed and stabilized prior to April 1, 2014, less properties subsequently sold, which represented 97,580 apartment units. (2) Non-same store primarily includes properties acquired after April 1, 2014, plus any properties in lease-up and not stabilized as of April 1, 2014. (3) Other includes development, other corporate operations and operations prior to sale for properties sold in 2014 and 2015 that do not meet the new discontinued operations criteria. Six Months Ended June 30, 2015 Total Assets Capital Expenditures Same store (1) Boston $ 1,868,144 $ 6,525 Denver 510,123 2,958 New York 4,602,213 8,365 San Francisco 2,683,829 12,676 Seattle 1,080,755 6,505 South Florida 1,118,604 7,453 Southern California 2,768,169 14,390 Washington D.C. 4,222,865 17,340 Non-core 338,125 3,101 Total same store 19,192,827 79,313 Non-same store/other (2) (3) Boston 176,247 83 New York 118,166 — Seattle 227,930 21 South Florida 66,082 22 Southern California 842,096 1,691 Washington D.C. 239,843 509 Other (3) 2,218,639 323 Total non-same store/other 3,889,003 2,649 Total $ 23,081,830 $ 81,962 (1) Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2014, less properties subsequently sold, which represented 96,761 apartment units. (2) Non-same store primarily includes properties acquired after January 1, 2014, plus any properties in lease-up and not stabilized as of January 1, 2014. (3) Other includes development, other corporate operations and capital expenditures for properties sold. Note: Markets/Metro Areas aggregated in the above Southern California and Non-core segments are as follows: (a) Southern California – Los Angeles, Orange County and San Diego. (b) Non-core – Inland Empire, CA, New England (excluding Boston) and Phoenix. The following table presents a reconciliation of NOI from our rental real estate specific to continuing operations for the six months and quarters ended June 30, 2015 and 2014 , respectively (amounts in thousands): Six Months Ended June 30, Quarter Ended June 30, 2015 2014 2015 2014 Rental income $ 1,341,114 $ 1,280,491 $ 676,508 $ 649,766 Property and maintenance expense (242,565 ) (240,948 ) (118,005 ) (115,382 ) Real estate taxes and insurance expense (169,551 ) (165,149 ) (83,119 ) (83,055 ) Property management expense (41,962 ) (42,673 ) (20,518 ) (20,555 ) Total operating expenses (454,078 ) (448,770 ) (221,642 ) (218,992 ) Net operating income $ 887,036 $ 831,721 $ 454,866 $ 430,774

Subsequent Events_Other

Subsequent Events/Other	6 Months Ended
	Jun. 30, 2015
Subsequent Events Other [Abstract]
Subsequent Events/Other	14. Subsequent Events/Other Subsequent Events Subsequent to June 30, 2015 , the Company recorded the master condominium declaration for its development project at 400 Park Avenue South in New York City with Toll Brothers. As a result, the Toll Brothers' portion of the property will be deconsolidated from the Company's balance sheet in the third quarter of 2015. Other During the six months ended June 30, 2015 and 2014 , the Company incurred charges of $0.2 million and $0.1 million , respectively, related to property acquisition costs, such as survey, title and legal fees, on the acquisition of operating properties and $1.6 million and $1.5 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 $1.8 million and $1.6 million , respectively, are included in other expenses in the accompanying consolidated statements of operations and comprehensive income. Effective January 1, 2015, the Company has revised its executive compensation program. The long-term incentive portion of the revised program will be performance based and determined by the Company’s absolute and relative total shareholder return over a three year performance period. During the six months ended June 30, 2015 , the Company expensed approximately $4.7 million under the long-term incentive portion of the revised program, of which $0.7 million and $4.0 million was recorded to property management expense and general and administrative expense, respectively. During the six months ended June 30, 2015 and 2014 , the Company received $5.8 million and $2.3 million , respectively, for the settlement of various litigation/insurance claims, which are included in interest and other income in the accompanying consolidated statements of operations and comprehensive income.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2015
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. These reclassifications did not have an impact on net income previously reported. Operating results for the six months ended June 30, 2015 are not necessarily indicative of the results that may be expected for the year ending December 31, 2015 . 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, 2014 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, 2014 .
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 suspended interest deductions, net operating losses, differing depreciable lives on capitalized assets and the timing of expense recognition for certain accrued liabilities. As of June 30, 2015 , 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.
New Accounting Pronouncements	Recent Accounting Pronouncements In April 2014, the Financial Accounting Standards Board (the "FASB") issued new guidance for reporting discontinued operations. Only disposals representing a strategic shift in operations that has a major effect on a company’s operations and financial results will be presented as discontinued operations. Companies are required to expand their disclosures about discontinued operations to provide more information on the assets, liabilities, income and expenses of the discontinued operations. Companies are also required to disclose the pre-tax income attributable to a disposal of a significant part of a company that does not qualify for discontinued operations reporting. Application of this guidance is prospective from the date of adoption and early adoption was permitted, but only for disposals (or classifications as held for sale) that had not been reported in financial statements previously issued. The new standard was effective January 1, 2015, but the Company early adopted it as allowed effective January 1, 2014. Adoption of this standard resulted in and will likely continue to result in substantially fewer of the Company's dispositions meeting the discontinued operations qualifications. See Note 11 for further discussion. In May 2014, the FASB issued a comprehensive new revenue recognition standard entitled Revenue from Contracts with Customers that will supersede nearly all existing revenue recognition guidance. The new standard specifically excludes lease contracts. The new standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. Companies will likely need to use more judgment and make more estimates than under current revenue recognition guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration, if any, to include in the transaction price and allocating the transaction price to each separate performance obligation. The new standard will be effective for the Company beginning on January 1, 2018 and early adoption will be permitted beginning on January 1, 2017. The new standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of adoption. The Company has not yet selected a transition method and is currently evaluating the impact of adopting the new standard on its consolidated results of operations and financial position. In August 2014, the FASB issued a new standard that will explicitly require management to assess an entity's ability to continue as a going concern and to provide related footnote disclosures in certain circumstances. In connection with each annual and interim period, management will assess whether there is substantial doubt about an entity's ability to continue as a going concern within one year after the issuance date. Disclosures will be required if conditions give rise to substantial doubt. However, to determine the specific disclosures, management will need to assess whether its plans will alleviate substantial doubt. The new standard is effective for the annual period ending after December 15, 2016. The Company does not expect that this will have a material effect on its consolidated results of operations or financial position. In February 2015, the FASB issued new consolidation guidance which makes changes to both the variable interest model and the voting model. Among other changes, the new standard specifically eliminates the presumption in the current voting model that a general partner controls a limited partnership or similar entity unless that presumption can be overcome. Generally, only a single limited partner that is able to exercise substantive kick-out rights will consolidate. The new standard will be effective for the Company beginning on January 1, 2016 and early adoption is permitted, including adoption in an interim period. The new standard must be applied using a modified retrospective approach by recording a cumulative-effect adjustment to equity/capital as of the beginning of the period of adoption or retrospectively to each period presented. The Company has not yet selected a transition method and is currently evaluating the impact of adopting the new standard on its consolidated results of operations and financial position. In April 2015, the FASB issued a new standard which requires companies to present debt financing costs as a direct deduction from the carrying amount of the associated debt liability rather than as an asset, consistent with the presentation of debt discounts on the consolidated balance sheets. The new standard will be effective for the Company beginning on January 1, 2016 and early adoption is permitted. The new standard must be applied retrospectively to all prior periods presented in the consolidated financial statements. The Company does not expect that this will have a material effect on its consolidated results of operations or financial position.
Other [Table Text Block]	Other The Company is the controlling partner in various consolidated partnerships owning 19 properties and 3,771 apartment units and various completed and uncompleted development properties having a noncontrolling interest book value of $122.4 million at June 30, 2015 . 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 $11.1 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 June 30, 2015 , the Company estimates the value of Noncontrolling Interest distributions for these six properties would have been approximately $68.3 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 June 30, 2015 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.

Business (Tables)

Business (Tables)	6 Months Ended
	Jun. 30, 2015
Business [Abstract]
Schedule of Real Estate Properties	The ownership breakdown includes (table does not include various uncompleted development properties): Properties Apartment Wholly Owned Properties 361 97,438 Master-Leased Properties – Consolidated 3 853 Partially Owned Properties – Consolidated 19 3,771 Partially Owned Properties – Unconsolidated 3 1,281 Military Housing 2 5,087 388 108,430

Equity, Capital and Other Int29

Equity, Capital and Other Interests (Tables)	6 Months Ended
	Jun. 30, 2015
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 restricted units (formerly known as Long-Term Incentive Plan (“LTIP”) Units)) for the six months ended June 30, 2015 : 2015 Common Shares Common Shares outstanding at January 1, 362,855,454 Common Shares Issued: Conversion of OP Units 171,353 Exercise of share options 814,827 Employee Share Purchase Plan (ESPP) 40,873 Restricted share grants, net 169,667 Common Shares Other: Conversion of restricted shares to restricted units (1,284 ) Common Shares outstanding at June 30, 364,050,890 Units Units outstanding at January 1, 14,298,691 Restricted units, net 337,505 Conversion of restricted shares to restricted units 1,284 Conversion of OP Units to Common Shares (171,353 ) Units outstanding at June 30, 14,466,127 Total Common Shares and Units outstanding at June 30, 378,517,017 Units Ownership Interest in Operating Partnership 3.8 %
Redeemable Noncontrolling Interest [Table Text Block]	The following table presents the changes in the redemption value of the Redeemable Noncontrolling Interests – Operating Partnership for the six months ended June 30, 2015 (amounts in thousands): 2015 Balance at January 1, $ 500,733 Change in market value (13,966 ) Change in carrying value 1,411 Balance at June 30, $ 488,178
Schedule Of Preferred Stock [Table Text Block]	The following table presents the Company’s issued and outstanding Preferred Shares as of June 30, 2015 and December 31, 2014: Amounts in thousands Redemption Annual June 30, December 31, Preferred Shares of beneficial interest, $0.01 par value; 8.29% Series K Cumulative Redeemable Preferred; liquidation 12/10/26 $4.145 $ 40,180 $ 50,000 $ 40,180 $ 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. (3) Effective January 26, 2015, the Company repurchased and retired 196,400 Series K Preferred Shares with a par value of $9.82 million for total cash consideration of approximately $12.7 million . As a result of this partial redemption, the Company incurred a cash charge of approximately $2.8 million which was recorded as a premium on the redemption of Preferred Shares.
Limited Partner [Member]
Redeemable Noncontrolling Interest [Table Text Block]	The following table presents the changes in the redemption value of the Redeemable Limited Partners for the six months ended June 30, 2015 (amounts in thousands): 2015 Balance at January 1, $ 500,733 Change in market value (13,966 ) Change in carrying value 1,411 Balance at June 30, $ 488,178
Schedule Of Preferred Stock [Table Text Block]	The following table presents the Operating Partnership’s issued and outstanding “Preference Units” as of June 30, 2015 and December 31, 2014 : Amounts in thousands Redemption Date (1) Annual June 30, December 31, Preference Units: 8.29% Series K Cumulative Redeemable Preference Units; 12/10/26 $4.145 $ 40,180 $ 50,000 $ 40,180 $ 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. (3) Effective January 26, 2015, the Operating Partnership repurchased and retired 196,400 Series K Preference Units with a par value of $9.82 million for total cash consideration of approximately $12.7 million , in conjunction with the concurrent redemption of the corresponding Company Preferred Shares. As a result of this partial redemption, the Operating Partnership incurred a cash charge of approximately $2.8 million which was recorded as a premium on the redemption of Preference Units.
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 six months ended June 30, 2015 : 2015 General and Limited Partner Units General and Limited Partner Units outstanding at January 1, 377,154,145 Issued to General Partner: Exercise of EQR share options 814,827 EQR’s Employee Share Purchase Plan (ESPP) 40,873 EQR's restricted share grants, net 169,667 Issued to Limited Partners: Restricted units, net 337,505 General and Limited Partner Units outstanding at June 30, 378,517,017 Limited Partner Units Limited Partner Units outstanding at January 1, 14,298,691 Limited Partner restricted units, net 337,505 Conversion of EQR restricted shares to restricted units 1,284 Conversion of Limited Partner OP Units to EQR Common Shares (171,353 ) Limited Partner Units outstanding at June 30, 14,466,127 Limited Partner Units Ownership Interest in Operating Partnership 3.8 %

Real Estate (Tables)

Real Estate (Tables)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and December 31, 2014 (amounts in thousands): June 30, December 31, Land $ 6,374,779 $ 6,295,404 Depreciable property: Buildings and improvements 18,328,935 17,974,337 Furniture, fixtures and equipment 1,446,235 1,365,276 In-Place lease intangibles 515,154 511,891 Projects under development: Land 406,251 466,764 Construction-in-progress 833,993 877,155 Land held for development: Land 97,387 145,366 Construction-in-progress 30,172 39,190 Investment in real estate 28,032,906 27,675,383 Accumulated depreciation (5,736,913 ) (5,432,805 ) Investment in real estate, net $ 22,295,993 $ 22,242,578
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 June 30, 2015 and December 31, 2014 (amounts in thousands): Description Balance Sheet Location June 30, December 31, Assets Ground lease intangibles – below market Other Assets $ 178,251 $ 178,251 Retail lease intangibles – above market Other Assets 1,260 1,260 Lease intangible assets 179,511 179,511 Accumulated amortization (11,185 ) (8,913 ) Lease intangible assets, net $ 168,326 $ 170,598 Liabilities Ground lease intangibles – above market Other Liabilities $ 2,400 $ 2,400 Retail lease intangibles – below market Other Liabilities 5,270 5,270 Lease intangible liabilities 7,670 7,670 Accumulated amortization (2,839 ) (2,258 ) Lease intangible liabilities, net $ 4,831 $ 5,412
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 2015 2016 2017 2018 2019 2020 Ground lease intangibles $ 2,161 $ 4,321 $ 4,321 $ 4,321 $ 4,321 $ 4,321 Retail lease intangibles (469 ) (896 ) (540 ) (71 ) (71 ) (71 ) Total $ 1,692 $ 3,425 $ 3,781 $ 4,250 $ 4,250 $ 4,250
Acquired and Disposed Properties [Table Text Block]	During the six months ended June 30, 2015 , the Company acquired the entire equity interest in the following from unaffiliated parties (purchase price in thousands): Properties Apartment Units Purchase Price Rental Properties 1 202 $ 130,275 Land Parcel (one) — — 5,968 Total 1 202 $ 136,243 During the six months ended June 30, 2015 , the Company disposed of the following to unaffiliated parties (sales price in thousands): Properties Apartment Units Sales Price Rental Properties (1) 6 1,377 $ 386,662 Total 6 1,377 $ 386,662 (1) Includes a 193,230 square foot medical office building adjacent to our Longfellow Place property in Boston with a sales price of approximately $123.3 million .

Commitments to Acquire_Dispos31

Commitments to Acquire/Dispose of Real Estate (Tables)	6 Months Ended
	Jun. 30, 2015
Commitments to Acquire Dispose of Real Estate [Abstract]
Real Estate to be Acquired Table Text Block	The Company has entered into separate agreements to acquire the following (purchase price in thousands): Properties Apartment Units Purchase Price Land Parcels (two) — — $ 21,832 Other — 2 6,000 Total — 2 $ 27,832
Real Estate To Be Disposed Of Text Block	The Company has entered into separate agreements to dispose of the following (sales price in thousands): Properties Apartment Units Sales Price Rental Properties 2 522 $ 104,838 Land Parcels (three) — — 29,900 Total 2 522 $ 134,738

Investments in Partially Owne32

Investments in Partially Owned Entities (Tables)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 (amounts in thousands except for project and apartment unit amounts): Consolidated Unconsolidated Development Projects Held for Operating Total Operating Total Total projects (1) — 19 19 3 3 Total apartment units (1) — 3,771 3,771 1,281 1,281 Balance sheet information at 6/30/15 (at 100%): ASSETS Investment in real estate $ 351,977 $ 686,120 $ 1,038,097 $ 290,442 $ 290,442 Accumulated depreciation (2,339 ) (205,554 ) (207,893 ) (24,471 ) (24,471 ) Investment in real estate, net 349,638 480,566 830,204 265,971 265,971 Cash and cash equivalents — 17,482 17,482 8,793 8,793 Investments in unconsolidated entities — 50,771 50,771 — — Deposits – restricted 11,609 345 11,954 273 273 Deferred financing costs, net — 1,963 1,963 7 7 Other assets 6,988 25,959 32,947 703 703 Total assets $ 368,235 $ 577,086 $ 945,321 $ 275,747 $ 275,747 LIABILITIES AND EQUITY/CAPITAL Mortgage notes payable (2) $ — $ 360,654 $ 360,654 $ 175,135 $ 175,135 Accounts payable & accrued expenses 5,756 1,939 7,695 1,486 1,486 Accrued interest payable — 1,266 1,266 691 691 Other liabilities 615 819 1,434 325 325 Security deposits 589 2,002 2,591 592 592 Total liabilities 6,960 366,680 373,640 178,229 178,229 Noncontrolling Interests – Partially Owned 117,350 5,018 122,368 90,878 90,878 Company equity/General and Limited 243,925 205,388 449,313 6,640 6,640 Total equity/capital 361,275 210,406 571,681 97,518 97,518 Total liabilities and equity/capital $ 368,235 $ 577,086 $ 945,321 $ 275,747 $ 275,747
Partially Owned Property Income Statement Schedule [Table Text Block]	Consolidated Unconsolidated Development Projects Held for Operating Operating Total Total Operating information for the six months ended 6/30/15 (at 100%): Operating revenue $ 1,103 $ 46,071 $ 47,174 $ 15,918 $ 15,918 Operating expenses 851 13,545 14,396 5,388 5,388 Net operating income 252 32,526 32,778 10,530 10,530 Depreciation 2,339 11,073 13,412 6,159 6,159 General and administrative/other 1 41 42 119 119 Operating (loss) income (2,088 ) 21,412 19,324 4,252 4,252 Interest and other income — 5 5 — — Other expenses — (50 ) (50 ) — — Interest: Expense incurred, net — (7,786 ) (7,786 ) (4,697 ) (4,697 ) Amortization of deferred financing costs — (177 ) (177 ) (1 ) (1 ) (Loss) income before income and other taxes and (loss) (2,088 ) 13,404 11,316 (446 ) (446 ) Income and other tax (expense) benefit — (35 ) (35 ) (18 ) (18 ) (Loss) from investments in unconsolidated entities — (739 ) (739 ) — — Net (loss) income $ (2,088 ) $ 12,630 $ 10,542 $ (464 ) $ (464 ) (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. Note: The above tables exclude the Company's interests in unconsolidated joint ventures entered into with AvalonBay Communities, Inc. (“AVB”) in connection with the acquisition of certain real estate related assets from Archstone Enterprise LP (such assets are referred to herein as "Archstone"). These ventures own certain non-core Archstone assets that are held for sale and succeeded to certain residual Archstone liabilities/litigation, as well as responsibility for tax protection arrangements and third-party preferred interests in former Archstone subsidiaries. The preferred interests had an aggregate liquidation value of $71.2 million at June 30, 2015 . The ventures are owned 60% by the Company and 40% by AVB.

Deposits - Restricted (Tables)

Deposits - Restricted (Tables)	6 Months Ended
	Jun. 30, 2015
Deposits - Restricted [Abstract]
Schedule of Restricted Cash and Cash Equivalents [Table Text Block]	The following table presents the Company’s restricted deposits as of June 30, 2015 and December 31, 2014 (amounts in thousands): June 30, December 31, Tax-deferred (1031) exchange proceeds $ 40,383 $ — Earnest money on pending acquisitions 2,210 580 Restricted deposits on real estate investments 13,605 24,701 Resident security and utility deposits 46,976 46,516 Other 334 506 Totals $ 103,508 $ 72,303
Escrow Deposits [Text Block]	The following table presents the Company’s escrow deposits as of June 30, 2015 and December 31, 2014 (amounts in thousands): June 30, December 31, Real estate taxes and insurance $ 2,617 $ 2,235 Replacement reserves 3,657 3,431 Mortgage principal reserves/sinking funds 45,736 41,567 Other 852 852 Totals $ 52,862 $ 48,085

Derivative and Other Fair Val34

Derivative and Other Fair Value Instruments (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Derivative Instrument Table	The following table summarizes the Company’s consolidated derivative instruments at June 30, 2015 (dollar amounts are in thousands): Fair Value Current Notional Balance $ 450,000 Lowest Possible Notional $ 450,000 Highest Possible Notional $ 450,000 Lowest Interest Rate 2.375 % Highest Interest Rate 2.375 % Earliest Maturity Date 2019 Latest Maturity Date 2019 (1) Fair Value Hedges – Converts outstanding fixed rate unsecured notes ( $450.0 million 2.375% notes due July 1, 2019 ) to a floating interest rate of 90-Day LIBOR plus 0.61% .
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 June 30, 2015 and December 31, 2014 , respectively (amounts in thousands): Fair Value Measurements at Reporting Date Using Description Balance Sheet Location 6/30/2015 Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Derivatives designated as hedging instruments: Interest Rate Contracts: Fair Value Hedges Other Assets $ 3,955 $ — $ 3,955 $ — Supplemental Executive Retirement Plan Other Assets 99,641 99,641 — — Total $ 103,596 $ 99,641 $ 3,955 $ — Liabilities Supplemental Executive Retirement Plan Other Liabilities $ 99,641 $ 99,641 $ — $ — Total $ 99,641 $ 99,641 $ — $ — Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners Mezzanine $ 488,178 $ — $ 488,178 $ — Fair Value Measurements at Reporting Date Using Description Balance Sheet Location 12/31/2014 Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Derivatives designated as hedging instruments: Interest Rate Contracts: Fair Value Hedges Other Assets $ 1,597 $ — $ 1,597 $ — Forward Starting Swaps Other Assets 332 — 332 — Supplemental Executive Retirement Plan Other Assets 104,463 104,463 — — Total $ 106,392 $ 104,463 $ 1,929 $ — Liabilities Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps Other Liabilities $ 14,104 $ — $ 14,104 $ — Supplemental Executive Retirement Plan Other Liabilities 104,463 104,463 — — Total $ 118,567 $ 104,463 $ 14,104 $ — Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners Mezzanine $ 500,733 $ — $ 500,733 $ —
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 six months ended June 30, 2015 and 2014 , respectively (amounts in thousands): June 30, 2015 Type of Fair Value Hedge Location of Gain/(Loss) Recognized in Income on Derivative Amount of Gain/(Loss) Recognized in Income on Derivative Hedged Item Income Statement Location of Hedged Item Gain/(Loss) Amount of Gain/(Loss) Recognized in Income on Hedged Item Derivatives designated as hedging instruments: Interest Rate Contracts: Interest Rate Swaps Interest expense $ 2,358 Fixed rate debt Interest expense $ (2,358 ) Total $ 2,358 $ (2,358 ) June 30, 2014 Type of Fair Value Hedge Location of Derivative Amount of Derivative Hedged Item Income Statement Amount of Gain/(Loss) Recognized in Income on Hedged Item Derivatives designated as hedging instruments: Interest Rate Contracts: Interest Rate Swaps Interest expense $ 1,452 Fixed rate debt Interest expense $ (1,452 ) Total $ 1,452 $ (1,452 )
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 six months ended June 30, 2015 and 2014 , respectively (amounts in thousands): Effective Portion Ineffective Portion June 30, 2015 Type of Cash Flow Hedge Amount of Gain/(Loss) Recognized in OCI on Derivative Location of Gain/ (Loss) Reclassified from Accumulated OCI into Income Amount of Gain/ Location of Gain/(Loss) Recognized in Income on Derivative Amount of Gain/ Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps $ (142 ) Interest expense $ (8,911 ) Interest expense $ (30 ) Total $ (142 ) $ (8,911 ) $ (30 ) Effective Portion Ineffective Portion June 30, 2014 Type of Cash Flow Hedge Amount of Gain/(Loss) Recognized in OCI on Derivative Location of Gain/ (Loss) Reclassified from Accumulated OCI into Income Amount of Gain/ Location of Gain/(Loss) Recognized in Income on Derivative Amount of Gain/ Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps $ (21,790 ) Interest expense $ (8,335 ) Interest expense $ 91 Total $ (21,790 ) $ (8,335 ) $ 91

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2015
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): Six Months Ended June 30, Quarter Ended June 30, 2015 2014 2015 2014 Numerator for net income per share – basic: Income from continuing operations $ 488,573 $ 198,890 $ 298,504 $ 117,210 Allocation to Noncontrolling Interests – Operating Partnership, net (18,403 ) (7,475 ) (11,350 ) (4,422 ) Net (income) attributable to Noncontrolling Interests – Partially Owned Properties (1,487 ) (1,092 ) (844 ) (588 ) Preferred distributions (1,724 ) (2,072 ) (833 ) (1,036 ) Premium on redemption of Preferred Shares (2,789 ) — — — Income from continuing operations available to Common Shares, net of 464,170 188,251 285,477 111,164 Discontinued operations, net of Noncontrolling Interests 259 1,502 110 490 Numerator for net income per share – basic $ 464,429 $ 189,753 $ 285,587 $ 111,654 Numerator for net income per share – diluted: Income from continuing operations $ 488,573 $ 198,890 $ 298,504 $ 117,210 Net (income) attributable to Noncontrolling Interests – Partially Owned Properties (1,487 ) (1,092 ) (844 ) (588 ) Preferred distributions (1,724 ) (2,072 ) (833 ) (1,036 ) Premium on redemption of Preferred Shares (2,789 ) — — — Income from continuing operations available to Common Shares 482,573 195,726 296,827 115,586 Discontinued operations, net 269 1,562 114 510 Numerator for net income per share – diluted $ 482,842 $ 197,288 $ 296,941 $ 116,096 Denominator for net income per share – basic and diluted: Denominator for net income per share – basic 363,288 360,641 363,476 360,809 Effect of dilutive securities: OP Units 13,592 13,736 13,587 13,742 Long-term compensation shares/units 3,466 2,403 3,428 2,567 Denominator for net income per share – diluted 380,346 376,780 380,491 377,118 Net income per share – basic $ 1.28 $ 0.53 $ 0.79 $ 0.31 Net income per share – diluted $ 1.27 $ 0.52 $ 0.78 $ 0.31 Net income per share – basic: Income from continuing operations available to Common Shares, net of $ 1.28 $ 0.52 $ 0.79 $ 0.31 Discontinued operations, net of Noncontrolling Interests — 0.01 — — Net income per share – basic $ 1.28 $ 0.53 $ 0.79 $ 0.31 Net income per share – diluted: Income from continuing operations available to Common Shares $ 1.27 $ 0.52 $ 0.78 $ 0.31 Discontinued operations, net — — — — Net income per share – diluted $ 1.27 $ 0.52 $ 0.78 $ 0.31
OPERATING PARTNERSHIP
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): Six Months Ended June 30, Quarter Ended June 30, 2015 2014 2015 2014 Numerator for net income per Unit – basic and diluted: Income from continuing operations $ 488,573 $ 198,890 $ 298,504 $ 117,210 Net (income) attributable to Noncontrolling Interests – Partially Owned Properties (1,487 ) (1,092 ) (844 ) (588 ) Allocation to Preference Units (1,724 ) (2,072 ) (833 ) (1,036 ) Allocation to premium on redemption of Preference Units (2,789 ) — — — Income from continuing operations available to Units 482,573 195,726 296,827 115,586 Discontinued operations, net 269 1,562 114 510 Numerator for net income per Unit – basic and diluted $ 482,842 $ 197,288 $ 296,941 $ 116,096 Denominator for net income per Unit – basic and diluted: Denominator for net income per Unit – basic 376,880 374,377 377,063 374,551 Effect of dilutive securities: Dilution for Units issuable upon assumed exercise/vesting of the Company’s 3,466 2,403 3,428 2,567 Denominator for net income per Unit – diluted 380,346 376,780 380,491 377,118 Net income per Unit – basic $ 1.28 $ 0.53 $ 0.79 $ 0.31 Net income per Unit – diluted $ 1.27 $ 0.52 $ 0.78 $ 0.31 Net income per Unit – basic: Income from continuing operations available to Units $ 1.28 $ 0.52 $ 0.79 $ 0.31 Discontinued operations, net — 0.01 — — Net income per Unit – basic $ 1.28 $ 0.53 $ 0.79 $ 0.31 Net income per Unit – diluted: Income from continuing operations available to Units $ 1.27 $ 0.52 $ 0.78 $ 0.31 Discontinued operations, net — — — — Net income per Unit – diluted $ 1.27 $ 0.52 $ 0.78 $ 0.31

Discontinued Operations (Tables

Discontinued Operations (Tables)	6 Months Ended
	Jun. 30, 2015
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 for properties sold in 2013 and prior years during the six months and quarters ended June 30, 2015 and 2014 (amounts in thousands). Six Months Ended June 30, Quarter Ended June 30, 2015 2014 2015 2014 REVENUES Rental income $ 338 $ 1,275 $ 177 $ 252 Total revenues 338 1,275 177 252 EXPENSES (1) Property and maintenance (67 ) (41 ) — (89 ) Real estate taxes and insurance 53 (6 ) 1 (19 ) General and administrative 71 51 65 46 Total expenses 57 4 66 (62 ) Discontinued operating income 281 1,271 111 314 Interest and other income 3 80 3 45 Income and other tax (expense) benefit (15 ) (13 ) — (2 ) Discontinued operations 269 1,338 114 357 Net gain on sales of discontinued operations — 224 — 153 Discontinued operations, net $ 269 $ 1,562 $ 114 $ 510 (1) Includes expenses paid in the current period for properties sold in prior periods related to the Company’s period of ownership.

Reportable Segments (Tables)

Reportable Segments (Tables)	6 Months Ended
	Jun. 30, 2015
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Reportable Segments Schedule	The following tables present NOI for each segment from our rental real estate specific to continuing operations for the six months and quarters ended June 30, 2015 and 2014 , respectively, as well as total assets and capital expenditures at June 30, 2015 (amounts in thousands): Six Months Ended June 30, 2015 Six Months Ended June 30, 2014 Rental Income Operating Expenses NOI Rental Income Operating Expenses NOI Same store (1) Boston $ 124,419 $ 41,741 $ 82,678 $ 120,678 $ 39,725 $ 80,953 Denver 58,826 15,627 43,199 54,123 15,097 39,026 New York 234,555 89,855 144,700 225,407 87,045 138,362 San Francisco 182,399 53,957 128,442 165,343 52,964 112,379 Seattle 81,906 25,697 56,209 76,511 25,770 50,741 South Florida 99,828 36,224 63,604 94,755 35,159 59,596 Southern California 212,517 68,164 144,353 201,450 67,298 134,152 Washington D.C. 226,819 75,620 151,199 224,975 73,399 151,576 Non-core 45,829 16,906 28,923 44,092 16,596 27,496 Total same store 1,267,098 423,791 843,307 1,207,334 413,053 794,281 Non-same store/other (2) (3) Boston 3,336 882 2,454 1,819 412 1,407 New York 115 609 (494 ) — — — Seattle 9,396 2,596 6,800 1,240 657 583 South Florida 3,913 1,346 2,567 2,047 1,251 796 Southern California 35,005 12,864 22,141 19,392 8,642 10,750 Washington D.C. 10,877 3,024 7,853 7,707 2,989 4,718 Other (3) 11,374 8,966 2,408 40,952 21,766 19,186 Total non-same store/other 74,016 30,287 43,729 73,157 35,717 37,440 Total $ 1,341,114 $ 454,078 $ 887,036 $ 1,280,491 $ 448,770 $ 831,721 (1) Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2014, less properties subsequently sold, which represented 96,761 apartment units. (2) Non-same store primarily includes properties acquired after January 1, 2014, plus any properties in lease-up and not stabilized as of January 1, 2014. (3) Other includes development, other corporate operations and operations prior to sale for properties sold in 2014 and 2015 that do not meet the new discontinued operations criteria. Quarter Ended June 30, 2015 Quarter Ended June 30, 2014 Rental Income Operating Expenses NOI Rental Income Operating Expenses NOI Same store (1) Boston $ 62,556 $ 20,061 $ 42,495 $ 60,779 $ 18,442 $ 42,337 Denver 29,829 8,168 21,661 27,511 7,635 19,876 New York 118,485 44,091 74,394 114,221 41,410 72,811 San Francisco 92,549 26,854 65,695 84,082 26,354 57,728 Seattle 41,515 13,030 28,485 38,890 13,036 25,854 South Florida 50,527 18,256 32,271 47,860 17,634 30,226 Southern California 110,357 34,984 75,373 104,319 34,697 69,622 Washington D.C. 116,168 37,585 78,583 115,081 36,372 78,709 Non-core 23,212 8,097 15,115 22,190 7,935 14,255 Total same store 645,198 211,126 434,072 614,933 203,515 411,418 Non-same store/other (2) (3) Boston 2,411 652 1,759 791 202 589 New York 112 613 (501 ) — — — Seattle 4,816 1,297 3,519 1,129 511 618 South Florida 1,981 672 1,309 1,246 797 449 Southern California 14,193 5,375 8,818 7,836 4,019 3,817 Washington D.C. 3,492 910 2,582 2,287 854 1,433 Other (3) 4,305 997 3,308 21,544 9,094 12,450 Total non-same store/other 31,310 10,516 20,794 34,833 15,477 19,356 Total $ 676,508 $ 221,642 $ 454,866 $ 649,766 $ 218,992 $ 430,774 (1) Same store primarily includes all properties acquired or completed and stabilized prior to April 1, 2014, less properties subsequently sold, which represented 97,580 apartment units. (2) Non-same store primarily includes properties acquired after April 1, 2014, plus any properties in lease-up and not stabilized as of April 1, 2014. (3) Other includes development, other corporate operations and operations prior to sale for properties sold in 2014 and 2015 that do not meet the new discontinued operations criteria. Six Months Ended June 30, 2015 Total Assets Capital Expenditures Same store (1) Boston $ 1,868,144 $ 6,525 Denver 510,123 2,958 New York 4,602,213 8,365 San Francisco 2,683,829 12,676 Seattle 1,080,755 6,505 South Florida 1,118,604 7,453 Southern California 2,768,169 14,390 Washington D.C. 4,222,865 17,340 Non-core 338,125 3,101 Total same store 19,192,827 79,313 Non-same store/other (2) (3) Boston 176,247 83 New York 118,166 — Seattle 227,930 21 South Florida 66,082 22 Southern California 842,096 1,691 Washington D.C. 239,843 509 Other (3) 2,218,639 323 Total non-same store/other 3,889,003 2,649 Total $ 23,081,830 $ 81,962 (1) Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2014, less properties subsequently sold, which represented 96,761 apartment units. (2) Non-same store primarily includes properties acquired after January 1, 2014, plus any properties in lease-up and not stabilized as of January 1, 2014. (3) Other includes development, other corporate operations and capital expenditures for properties sold.
Reconciliation of NOI	The following table presents a reconciliation of NOI from our rental real estate specific to continuing operations for the six months and quarters ended June 30, 2015 and 2014 , respectively (amounts in thousands): Six Months Ended June 30, Quarter Ended June 30, 2015 2014 2015 2014 Rental income $ 1,341,114 $ 1,280,491 $ 676,508 $ 649,766 Property and maintenance expense (242,565 ) (240,948 ) (118,005 ) (115,382 ) Real estate taxes and insurance expense (169,551 ) (165,149 ) (83,119 ) (83,055 ) Property management expense (41,962 ) (42,673 ) (20,518 ) (20,555 ) Total operating expenses (454,078 ) (448,770 ) (221,642 ) (218,992 ) Net operating income $ 887,036 $ 831,721 $ 454,866 $ 430,774

Business (Details)

Business (Details)	Jun. 30, 2015
Noncontrolling Interest, Ownership Percentage by Parent	96.20%
Number of Real Estate Properties	388
Number of States in which Entity Operates	12
Number of Units in Real Estate Property	108,430
Consolidated Properties [Member]
Number of Real Estate Properties	361
Number of Units in Real Estate Property	97,438
Master-Leased Properties [Member]
Number of Real Estate Properties	3
Number of Units in Real Estate Property	853
Partially Owned Properties [Member]
Number of Real Estate Properties	19
Number of Units in Real Estate Property	3,771
Unconsolidated Properties [Member]
Number of Real Estate Properties	3
Number of Units in Real Estate Property	1,281
Military Housing [Member]
Number of Real Estate Properties	2
Number of Units in Real Estate Property	5,087

Summary of Significant Accoun39

Summary of Significant Accounting Policies (Details) $ in Thousands	Jun. 30, 2015USD ($)	Dec. 31, 2014USD ($)
Number of Real Estate Properties	388
Number of Units in Real Estate Property	108,430
Noncontrolling Interests - Partially Owned Properties	$ 122,368	$ 124,909
Partially Owned Properties [Member]
Number of Real Estate Properties	19
Number of Units in Real Estate Property	3,771
Limited Life Partnership Properties [Member]
Number of Real Estate Properties	6
Noncontrolling Interests - Partially Owned Properties	$ 11,092
Noncontrolling Interests Settlement Value	$ 68,300

Equity, Capital and Other Int40

Equity, Capital and Other Interests EQR Common Shares (Details) - shares	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Common Shares of beneficial interest, shares outstanding	364,050,890	362,855,454
Common Shares Issued:
Conversion of OP Units	171,353
Exercise of share options	814,827
Employee Share Purchase Plan (ESPP)	40,873
Restricted Share Grants, net	169,667
Conversion of restricted shares to restricted units	(1,284)
Units
Common Shares And Units Outstanding	378,517,017
Units Ownership Interest in Operating Partnership	3.80%
Limited Partner [Member]
Limited Partners' Capital Account, Units Outstanding	14,466,127	14,298,691
Common Shares Issued:
Conversion of OP Units	(171,353)
Conversion of restricted shares to restricted units	1,284
Units
Restricted units, net	337,505

Equity, Capital and Other Int41

Equity, Capital and Other Interests Redeemable (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Redeemable Noncontrolling Interests Operating Partnership	$ 488,178	$ 500,733
Change in market value of Redeemable Noncontrolling Interests - Operating Partnership	(13,966)
Change in carrying value	1,411
OPERATING PARTNERSHIP
Limited Partners Change In Redemption Value	(13,966)
Limited Partners Change In Carrying Value	1,411
Redeemable Limited Partners	$ 488,178	$ 500,733

Equity, Capital and Other Int42

Equity, Capital and Other Interests Preferred (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Class of Stock [Line Items]
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 803,600 shares issued and outstanding as of June 30, 2015 and 1,000,000 shares issued and outstanding as of December 31, 2014	$ 40,180		$ 40,180		$ 50,000
Partial redemption of 8.29% Series K Cumulative Redeemable			9,820	$ 0
Premium on redemption of Preference Units	0	$ 0	2,789	0
OPERATING PARTNERSHIP
Class of Stock [Line Items]
Partial redemption of 8.29% Series K Cumulative Redeemable			9,820	0
Premium on redemption of Preference Units	0	$ 0	2,789	$ 0
Preferred Units	$ 40,180		$ 40,180		$ 50,000
Series K Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock Preference Units Dividend Rate Percentage			8.29%		8.29%
Preferred Stock Preference Units Redemption Price Per Share Unit	$ 50		$ 50		$ 50
Preferred Stock Preference Units Issued	803,600		803,600		1,000,000
Preferred Stock Preference Units Outstanding	803,600		803,600		1,000,000
Preferred Stocks Preference Units Redemption Date			Dec. 10, 2026
Annual Dividend Per Preferred Share Preference Unit			$ 4.145
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 803,600 shares issued and outstanding as of June 30, 2015 and 1,000,000 shares issued and outstanding as of December 31, 2014	$ 40,180		$ 40,180		$ 50,000
Preferred Stock Preference Units Repurchased and Retired			196,400
Partial redemption of 8.29% Series K Cumulative Redeemable			$ 9,820
Payments For Repurchase Of Preferred Stock Preference Units			12,700
Premium on redemption of Preference Units			$ 2,789
Series K Preferred Stock [Member] | OPERATING PARTNERSHIP
Class of Stock [Line Items]
Preferred Stock Preference Units Dividend Rate Percentage			8.29%		8.29%
Preferred Stock Preference Units Redemption Price Per Share Unit	$ 50		$ 50		$ 50
Preferred Stock Preference Units Issued	803,600		803,600		1,000,000
Preferred Stock Preference Units Outstanding	803,600		803,600		1,000,000
Preferred Stocks Preference Units Redemption Date			Dec. 10, 2026
Annual Dividend Per Preferred Share Preference Unit			$ 4.145
Preferred Units	$ 40,180		$ 40,180		$ 50,000

Equity, Capital and Other Int43

Equity, Capital and Other Interests ERP Units (Details) - shares	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Capital Unit [Line Items]
Common Shares And Units Outstanding	378,517,017
Exercise of EQR share options	814,827
EQR's Employee Share Purchase Plan (ESPP)	40,873
Restricted Share Grants, net	169,667
Conversion of restricted shares to restricted units	(1,284)
Shares Issued During Period Shares Conversion Of Units To Common Shares	171,353
Units Ownership Interest in Operating Partnership	3.80%
Limited Partner [Member]
Capital Unit [Line Items]
Limited Partners' Capital Account, Units Outstanding	14,466,127	14,298,691
Restricted units, net	337,505
Conversion of restricted shares to restricted units	1,284
Shares Issued During Period Shares Conversion Of Units To Common Shares	(171,353)
General And Limited Partner [Member]
Capital Unit [Line Items]
Common Shares And Units Outstanding	378,517,017	377,154,145
Exercise of EQR share options	814,827
EQR's Employee Share Purchase Plan (ESPP)	40,873
Restricted Share Grants, net	169,667
Restricted units, net	337,505

Equity, Capital and Other Int44

Equity, Capital and Other Interests Text (Details) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
Preferred Stock, Shares Authorized	100,000,000	100,000,000
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Additional Common Shares Authorized	13,000,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased	13,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	12,968,760

Real Estate (Details)

Real Estate (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Land	$ 6,374,779		$ 6,374,779		$ 6,295,404
Property, Plant and Equipment, Gross [Abstract]
Investment Building and Building Improvements	18,328,935		18,328,935		17,974,337
Fixtures and Equipment, Gross	1,446,235		1,446,235		1,365,276
Finite-Lived Intangible Asset, Acquired-in-Place Leases	515,154		515,154		511,891
Projects under development -CIP	1,240,244		1,240,244		1,343,919
Land Available for Development	127,559		127,559		184,556
Investment in real estate	28,032,906		28,032,906		27,675,383
Real Estate Investment Property, Accumulated Depreciation	(5,736,913)		(5,736,913)		(5,432,805)
Investment in real estate, net	22,295,993		22,295,993		22,242,578
Finite-Lived Intangible Assets, Gross	179,511		179,511		179,511
Amortization of Intangible Assets	(11,185)		(11,185)		(8,913)
Lease Intangible Assets, Net	168,326		168,326		170,598
Lease Intangible Liabilities	7,670		7,670		7,670
Amortization Of Intangible Liabilities	(2,839)		(2,839)		(2,258)
Lease Intangible Liabilities, net	$ 4,831		4,831		5,412
Amortization of above/below market leases			$ 1,691	$ 1,530
Weighted Average Ground Lease Amortization Period	49.8		49.8
Weighted Average Retail Lease Amortization Period	2.8		2.8
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	$ 1,692		$ 1,692
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	3,425		3,425
Finite-Lived Intangible Assets, Amortization Expense, Year Two	3,781		3,781
Finite-Lived Intangible Assets, Amortization Expense, Year Three	4,250		4,250
Finite-Lived Intangible Assets, Amortization Expense, Year Four	4,250		4,250
Finite-Lived Intangible Assets, Amortization Expense, Year Five	4,250		4,250
Retail Site [Member]
Property, Plant and Equipment, Gross [Abstract]
Amortization of above/below market leases	300	$ 300	500	600
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	(469)		(469)
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	(896)		(896)
Finite-Lived Intangible Assets, Amortization Expense, Year Two	(540)		(540)
Finite-Lived Intangible Assets, Amortization Expense, Year Three	(71)		(71)
Finite-Lived Intangible Assets, Amortization Expense, Year Four	(71)		(71)
Finite-Lived Intangible Assets, Amortization Expense, Year Five	(71)		(71)
Assets [Member]
Property, Plant and Equipment, Gross [Abstract]
Below Market Lease, Gross	178,251		178,251		178,251
Finite-Lived Intangible Asset, Off-market Lease, Favorable, Gross	1,260		1,260		1,260
Liability [Member]
Property, Plant and Equipment, Gross [Abstract]
Below Market Lease, Gross	5,270		5,270		5,270
Off-market Lease, Unfavorable	2,400		2,400		2,400
Ground Lease [Member]
Property, Plant and Equipment, Gross [Abstract]
Amortization of above/below market leases	1,100	$ 1,100	2,200	$ 2,200
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	2,161		2,161
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	4,321		4,321
Finite-Lived Intangible Assets, Amortization Expense, Year Two	4,321		4,321
Finite-Lived Intangible Assets, Amortization Expense, Year Three	4,321		4,321
Finite-Lived Intangible Assets, Amortization Expense, Year Four	4,321		4,321
Finite-Lived Intangible Assets, Amortization Expense, Year Five	4,321		4,321
Projects under development [Member]
Property, Plant and Equipment, Gross [Abstract]
Projects under development - Land	406,251		406,251		466,764
Projects under development -CIP	833,993		833,993		877,155
Land held for development [Member]
Property, Plant and Equipment, Gross [Abstract]
Projects under development -CIP	30,172		30,172		39,190
Land Available for Development	$ 97,387		$ 97,387		$ 145,366

Real Estate (Details 2)

Real Estate (Details 2) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)property	Jun. 30, 2014USD ($)
Properties acquired | property			1
Property Units Acquired			202
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 136,243		$ 136,243
Disposed Properties | property			6
Disposed Units			1,377
Proceeds From Sale Of Property			$ 386,662
Net gain on sales of real estate properties	148,802	$ 14,903	$ 228,753	$ 14,903
Consolidated Rental Properties [Member]
Properties acquired | property			1
Property Units Acquired			202
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	130,275		$ 130,275
Disposed Properties | property			6
Disposed Units			1,377
Proceeds From Sale Of Property			$ 386,662
Land [Member]
Land parcels acquired | property			1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 5,968		$ 5,968
Commercial Real Estate [Member]
Proceeds From Sale Of Property			$ 123,300

Commitments to Acquire_Dispos47

Commitments to Acquire/Dispose of Real Estate (Details) - Jul. 31, 2015 $ in Thousands	USD ($)property
Commitments to Acquire Real Estate
Properties Acquired-Total | property	0
Rental Units Acquired - Total	2
Purchase Price - Total	$ 27,832
Commitments to Dispose of Real Estate
Properties Disposed - Total | property	2
Rental Units Disposed-Total	522
Sales Price For Commitments To Dispose	$ 134,738
Rental Properties Disposed of [Member]
Commitments to Dispose of Real Estate
Properties Disposed - Total | property	2
Rental Units Disposed-Total	522
Sales Price For Commitments To Dispose	$ 104,838
Land [Member]
Commitments to Dispose of Real Estate
Sales Price For Commitments To Dispose	$ 29,900
Land Parcels Contracted To Be Disposed	3
Consolidated Rental Properties [Member]
Commitments to Acquire Real Estate
Purchase Price - Total	$ 6,000
Land [Member]
Commitments to Acquire Real Estate
Purchase Price - Total	$ 21,832
Land Parcels Contracted To Be Acquired	2

Investments in Partially Owne48

Investments in Partially Owned Entities (Details) - USD ($)	3 Months Ended		6 Months Ended		28 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments In Partially Owned Entities (Textuals) [Abstract]
Joint Venture Partner Ownership Percentage	80.00%		80.00%		80.00%
Investments in unconsolidated entities	$ 94,718,000		$ 94,718,000		$ 94,718,000	$ 105,434,000
Equity Method Investment, Ownership Percentage	20.00%		20.00%		20.00%
Secured Debt	$ 4,952,579,000		$ 4,952,579,000		$ 4,952,579,000	5,086,515,000
Debt Instrument, Maturity Date			May 1, 2061
Number of Joint Ventures	2		2		2
Partners Payments To Acquire Equity Method Investments			$ 40,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 136,243,000		136,243,000		$ 136,243,000
Investment in Joint Venture	342,200,000		342,200,000		342,200,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 122,368,000		122,368,000		$ 122,368,000	124,909,000
Distributions from unconsolidated entities - return of capital			$ 26,147,000	$ 64,669,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	388		388		388
Number of Units in Real Estate Property	108,430		108,430		108,430
ASSETS
Investment in real estate	$ 28,032,906,000		$ 28,032,906,000		$ 28,032,906,000	27,675,383,000
Real Estate Investment Property, Accumulated Depreciation	(5,736,913,000)		(5,736,913,000)		(5,736,913,000)	(5,432,805,000)
Investment in real estate, net	22,295,993,000		22,295,993,000		22,295,993,000	22,242,578,000
Cash and cash equivalents	92,109,000	$ 76,132,000	92,109,000	76,132,000	92,109,000	40,080,000	$ 53,534,000
Investments in unconsolidated entities	94,718,000		94,718,000		94,718,000	105,434,000
Deposits - restricted	103,508,000		103,508,000		103,508,000	72,303,000
Deferred financing costs, net	59,605,000		59,605,000		59,605,000	58,380,000
Other Assets	383,035,000		383,035,000		383,035,000	383,754,000
Total assets	23,081,830,000		23,081,830,000		23,081,830,000	22,950,614,000
LIABILITIES AND EQUITY
Secured Debt	4,952,579,000		4,952,579,000		4,952,579,000	5,086,515,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	193,096,000		193,096,000		193,096,000	153,590,000
Accrued interest payable	87,131,000		87,131,000		87,131,000	89,540,000
Other liabilities	355,632,000		355,632,000		355,632,000	389,915,000
Security deposits	76,112,000		76,112,000		76,112,000	75,633,000
Total liabilities	11,748,919,000		11,748,919,000		11,748,919,000	11,742,105,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	122,368,000		122,368,000		122,368,000	124,909,000
Total liabilities and equity	23,081,830,000		23,081,830,000		23,081,830,000	$ 22,950,614,000
Partially Owned Property Income Statement Schedule
Operating revenue	679,112,000	652,568,000	1,345,483,000	1,286,010,000
Depreciation	194,282,000	190,136,000	388,803,000	375,303,000
General and administrative/other	15,730,000	13,752,000	35,652,000	31,328,000
Operating Income	246,184,000	228,310,000	464,355,000	427,569,000
Interest and other income	6,481,000	2,032,000	6,650,000	2,637,000
Interest:
Expense incurred, net	110,795,000	115,924,000	219,417,000	228,973,000
Amortization of deferred financing costs	(2,538,000)	(3,134,000)	(5,127,000)	(5,926,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations	137,562,000	109,745,000	244,761,000	193,104,000
Income and other tax (expense) benefit	(326,000)	(646,000)	(369,000)	(886,000)
Income (loss) from investments in unconsolidated entities	12,466,000	(7,616,000)	15,429,000	(9,025,000)
Net income	298,618,000	$ 117,720,000	488,842,000	$ 200,452,000
Consolidated Development Projects Held for and or Under Development [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	0		0		0
Secured Debt	0		0		0
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 117,350,000		$ 117,350,000		$ 117,350,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	0		0		0
Number of Units in Real Estate Property	0		0		0
ASSETS
Investment in real estate	$ 351,977,000		$ 351,977,000		$ 351,977,000
Real Estate Investment Property, Accumulated Depreciation	(2,339,000)		(2,339,000)		(2,339,000)
Investment in real estate, net	349,638,000		349,638,000		349,638,000
Cash and cash equivalents	0		0		0
Investments in unconsolidated entities	0		0		0
Deposits - restricted	11,609,000		11,609,000		11,609,000
Deferred financing costs, net	0		0		0
Other Assets	6,988,000		6,988,000		6,988,000
Total assets	368,235,000		368,235,000		368,235,000
LIABILITIES AND EQUITY
Secured Debt	0		0		0
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	5,756,000		5,756,000		5,756,000
Accrued interest payable	0		0		0
Other liabilities	615,000		615,000		615,000
Security deposits	589,000		589,000		589,000
Total liabilities	6,960,000		6,960,000		6,960,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	117,350,000		117,350,000		117,350,000
Company equity/General and Limited Partners' Capital	243,925,000		243,925,000		243,925,000
Total equity/capital	361,275,000		361,275,000		361,275,000
Total liabilities and equity	368,235,000		368,235,000		368,235,000
Partially Owned Property Income Statement Schedule
Operating revenue			1,103,000
Operating expenses			851,000
Net operating (loss) income			252,000
Depreciation			2,339,000
General and administrative/other			1,000
Operating Income			(2,088,000)
Interest and other income			0
Other expenses			0
Interest:
Expense incurred, net			0
Amortization of deferred financing costs			0
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			(2,088,000)
Income and other tax (expense) benefit			0
Income (loss) from investments in unconsolidated entities			0
Net income			(2,088,000)
Consolidated Operating [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	50,771,000		50,771,000		50,771,000
Secured Debt	360,654,000		360,654,000		360,654,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 5,018,000		$ 5,018,000		$ 5,018,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	19		19		19
Number of Units in Real Estate Property	3,771		3,771		3,771
ASSETS
Investment in real estate	$ 686,120,000		$ 686,120,000		$ 686,120,000
Real Estate Investment Property, Accumulated Depreciation	(205,554,000)		(205,554,000)		(205,554,000)
Investment in real estate, net	480,566,000		480,566,000		480,566,000
Cash and cash equivalents	17,482,000		17,482,000		17,482,000
Investments in unconsolidated entities	50,771,000		50,771,000		50,771,000
Deposits - restricted	345,000		345,000		345,000
Deferred financing costs, net	1,963,000		1,963,000		1,963,000
Other Assets	25,959,000		25,959,000		25,959,000
Total assets	577,086,000		577,086,000		577,086,000
LIABILITIES AND EQUITY
Secured Debt	360,654,000		360,654,000		360,654,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	1,939,000		1,939,000		1,939,000
Accrued interest payable	1,266,000		1,266,000		1,266,000
Other liabilities	819,000		819,000		819,000
Security deposits	2,002,000		2,002,000		2,002,000
Total liabilities	366,680,000		366,680,000		366,680,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	5,018,000		5,018,000		5,018,000
Company equity/General and Limited Partners' Capital	205,388,000		205,388,000		205,388,000
Total equity/capital	210,406,000		210,406,000		210,406,000
Total liabilities and equity	577,086,000		577,086,000		577,086,000
Partially Owned Property Income Statement Schedule
Operating revenue			46,071,000
Operating expenses			13,545,000
Net operating (loss) income			32,526,000
Depreciation			11,073,000
General and administrative/other			41,000
Operating Income			21,412,000
Interest and other income			5,000
Other expenses			(50,000)
Interest:
Expense incurred, net			(7,786,000)
Amortization of deferred financing costs			(177,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			13,404,000
Income and other tax (expense) benefit			(35,000)
Income (loss) from investments in unconsolidated entities			(739,000)
Net income			12,630,000
Consolidated Total [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	50,771,000		50,771,000		50,771,000
Secured Debt	360,654,000		360,654,000		360,654,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 122,368,000		$ 122,368,000		$ 122,368,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	19		19		19
Number of Units in Real Estate Property	3,771		3,771		3,771
ASSETS
Investment in real estate	$ 1,038,097,000		$ 1,038,097,000		$ 1,038,097,000
Real Estate Investment Property, Accumulated Depreciation	(207,893,000)		(207,893,000)		(207,893,000)
Investment in real estate, net	830,204,000		830,204,000		830,204,000
Cash and cash equivalents	17,482,000		17,482,000		17,482,000
Investments in unconsolidated entities	50,771,000		50,771,000		50,771,000
Deposits - restricted	11,954,000		11,954,000		11,954,000
Deferred financing costs, net	1,963,000		1,963,000		1,963,000
Other Assets	32,947,000		32,947,000		32,947,000
Total assets	945,321,000		945,321,000		945,321,000
LIABILITIES AND EQUITY
Secured Debt	360,654,000		360,654,000		360,654,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	7,695,000		7,695,000		7,695,000
Accrued interest payable	1,266,000		1,266,000		1,266,000
Other liabilities	1,434,000		1,434,000		1,434,000
Security deposits	2,591,000		2,591,000		2,591,000
Total liabilities	373,640,000		373,640,000		373,640,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	122,368,000		122,368,000		122,368,000
Company equity/General and Limited Partners' Capital	449,313,000		449,313,000		449,313,000
Total equity/capital	571,681,000		571,681,000		571,681,000
Total liabilities and equity	945,321,000		945,321,000		945,321,000
Partially Owned Property Income Statement Schedule
Operating revenue			47,174,000
Operating expenses			14,396,000
Net operating (loss) income			32,778,000
Depreciation			13,412,000
General and administrative/other			42,000
Operating Income			19,324,000
Interest and other income			5,000
Other expenses			(50,000)
Interest:
Expense incurred, net			(7,786,000)
Amortization of deferred financing costs			(177,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			11,316,000
Income and other tax (expense) benefit			(35,000)
Income (loss) from investments in unconsolidated entities			(739,000)
Net income			10,542,000
Unconsolidated Operating [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	0		0		0
Secured Debt	175,135,000		175,135,000		175,135,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 90,878,000		$ 90,878,000		$ 90,878,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	3		3		3
Number of Units in Real Estate Property	1,281		1,281		1,281
ASSETS
Investment in real estate	$ 290,442,000		$ 290,442,000		$ 290,442,000
Real Estate Investment Property, Accumulated Depreciation	(24,471,000)		(24,471,000)		(24,471,000)
Investment in real estate, net	265,971,000		265,971,000		265,971,000
Cash and cash equivalents	8,793,000		8,793,000		8,793,000
Investments in unconsolidated entities	0		0		0
Deposits - restricted	273,000		273,000		273,000
Deferred financing costs, net	7,000		7,000		7,000
Other Assets	703,000		703,000		703,000
Total assets	275,747,000		275,747,000		275,747,000
LIABILITIES AND EQUITY
Secured Debt	175,135,000		175,135,000		175,135,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	1,486,000		1,486,000		1,486,000
Accrued interest payable	691,000		691,000		691,000
Other liabilities	325,000		325,000		325,000
Security deposits	592,000		592,000		592,000
Total liabilities	178,229,000		178,229,000		178,229,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	90,878,000		90,878,000		90,878,000
Company equity/General and Limited Partners' Capital	6,640,000		6,640,000		6,640,000
Total equity/capital	97,518,000		97,518,000		97,518,000
Total liabilities and equity	275,747,000		275,747,000		275,747,000
Partially Owned Property Income Statement Schedule
Operating revenue			15,918,000
Operating expenses			5,388,000
Net operating (loss) income			10,530,000
Depreciation			6,159,000
General and administrative/other			119,000
Operating Income			4,252,000
Interest and other income			0
Other expenses			0
Interest:
Expense incurred, net			(4,697,000)
Amortization of deferred financing costs			(1,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			(446,000)
Income and other tax (expense) benefit			(18,000)
Income (loss) from investments in unconsolidated entities			0
Net income			(464,000)
Unconsolidated Total [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	0		0		0
Secured Debt	175,135,000		175,135,000		175,135,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 90,878,000		$ 90,878,000		$ 90,878,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	3		3		3
Number of Units in Real Estate Property	1,281		1,281		1,281
ASSETS
Investment in real estate	$ 290,442,000		$ 290,442,000		$ 290,442,000
Real Estate Investment Property, Accumulated Depreciation	(24,471,000)		(24,471,000)		(24,471,000)
Investment in real estate, net	265,971,000		265,971,000		265,971,000
Cash and cash equivalents	8,793,000		8,793,000		8,793,000
Investments in unconsolidated entities	0		0		0
Deposits - restricted	273,000		273,000		273,000
Deferred financing costs, net	7,000		7,000		7,000
Other Assets	703,000		703,000		703,000
Total assets	275,747,000		275,747,000		275,747,000
LIABILITIES AND EQUITY
Secured Debt	175,135,000		175,135,000		175,135,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	1,486,000		1,486,000		1,486,000
Accrued interest payable	691,000		691,000		691,000
Other liabilities	325,000		325,000		325,000
Security deposits	592,000		592,000		592,000
Total liabilities	178,229,000		178,229,000		178,229,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	90,878,000		90,878,000		90,878,000
Company equity/General and Limited Partners' Capital	6,640,000		6,640,000		6,640,000
Total equity/capital	97,518,000		97,518,000		97,518,000
Total liabilities and equity	275,747,000		275,747,000		275,747,000
Partially Owned Property Income Statement Schedule
Operating revenue			15,918,000
Operating expenses			5,388,000
Net operating (loss) income			10,530,000
Depreciation			6,159,000
General and administrative/other			119,000
Operating Income			4,252,000
Interest and other income			0
Other expenses			0
Interest:
Expense incurred, net			(4,697,000)
Amortization of deferred financing costs			(1,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			(446,000)
Income and other tax (expense) benefit			(18,000)
Income (loss) from investments in unconsolidated entities			0
Net income			(464,000)
Archstone Transaction [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Liquidation Value Preferred Interests	$ 71,200,000		71,200,000		71,200,000
Germany [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Distributions from unconsolidated entities - return of capital			$ 2,300,000		$ 100,800,000
Residual JV [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Business Acquisition, Percentage of Voting Interests Acquired	60.00%		60.00%		60.00%
Joint Venture Partner Ownership Percentage	40.00%		40.00%		40.00%
Investments in unconsolidated entities	$ 147,600,000		$ 147,600,000		$ 147,600,000
Distributions from unconsolidated entities - return of capital			26,100,000
ASSETS
Investments in unconsolidated entities	$ 147,600,000		147,600,000		$ 147,600,000
Residual JV [Domain] | Rental Properties Disposed of [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Distributions from unconsolidated entities - return of capital			17,200,000
Residual JV [Domain] | Settled Litigation [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Distributions from unconsolidated entities - return of capital			$ 6,600,000
Wisconsin Place [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Business Acquisition, Percentage of Voting Interests Acquired	75.00%		75.00%		75.00%
Initial Basis of Real Estate, Consolidated	$ 198,500,000		$ 198,500,000		$ 198,500,000
Investments in unconsolidated entities	$ 56,500,000		$ 56,500,000		$ 56,500,000
Partially Owned Property Balance Sheet Schedule
Number of Units in Real Estate Property	432		432		432
ASSETS
Investments in unconsolidated entities	$ 56,500,000		$ 56,500,000		$ 56,500,000
Waterton Tenside [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Equity Method Investment, Ownership Percentage	20.00%		20.00%		20.00%
Initial Basis of Real Estate, Unconsolidated	$ 5,100,000		$ 5,100,000		$ 5,100,000
Secured Debt	$ 29,700,000		$ 29,700,000		$ 29,700,000
Debt Instrument, Interest Rate, Stated Percentage	3.66%		3.66%		3.66%
Debt Instrument, Maturity Date			Dec. 1, 2018
Partially Owned Property Balance Sheet Schedule
Number of Units in Real Estate Property	336		336		336
LIABILITIES AND EQUITY
Secured Debt	$ 29,700,000		$ 29,700,000		$ 29,700,000
Joint Venture Partner [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Land purchase price	57,900,000		57,900,000		57,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	75,700,000		75,700,000		75,700,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	117,400,000		117,400,000		117,400,000
LIABILITIES AND EQUITY
Noncontrolling Interests - Partially Owned Properties/Partners' equity	117,400,000		117,400,000		117,400,000
Company's Portion [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Land purchase price	76,100,000		76,100,000		76,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	102,500,000		102,500,000		102,500,000
Nexus Sawgrass [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Secured Debt	$ 48,600,000		$ 48,600,000		$ 48,600,000
Debt Instrument, Interest Rate, Stated Percentage	5.60%		5.60%		5.60%
Debt Instrument, Maturity Date			Jan. 1, 2021
Project Cost	$ 78,600,000		$ 78,600,000		$ 78,600,000
LIABILITIES AND EQUITY
Secured Debt	48,600,000		48,600,000		48,600,000
Domain [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Secured Debt	$ 96,800,000		$ 96,800,000		$ 96,800,000
Debt Instrument, Interest Rate, Stated Percentage	5.75%		5.75%		5.75%
Debt Instrument, Maturity Date			Jan. 1, 2022
Project Cost	$ 155,800,000		$ 155,800,000		$ 155,800,000
LIABILITIES AND EQUITY
Secured Debt	$ 96,800,000		$ 96,800,000		$ 96,800,000

Deposits - Restricted (Details)

Deposits - Restricted (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Restricted Cash and Cash Equivalents Items [Line Items]
Tax-deferred (1031) exchange proceeds	$ 40,383	$ 0
Earnest money on pending acquisitions	2,210	580
Restricted deposits on real estate investments	13,605	24,701
Resident security and utility deposits	46,976	46,516
Other Restricted Cash	334	506
Restricted Cash and Cash Equivalents	103,508	72,303
Escrow deposits for real estate taxes and insurance	2,617	2,235
Replacement reserve	3,657	3,431
Mortgage principal reserves/sinking funds	45,736	41,567
Escrow deposits - other	852	852
Escrow Deposits For Mortgage And Replacement Reserves	$ 52,862	$ 48,085

Debt Mortgage Notes Payable (De

Debt Mortgage Notes Payable (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Mortgage notes payable	$ 4,952,579	$ 5,086,515
Repayments Of Long-term Debt	126,500
Write Off Of Unamortized Deferred Financing Costs	100
Write off unamortized premium discount	$ 1,400
Debt Instrument, Maturity Date	May 1, 2061
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	0.04%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	7.25%
Weighted Average Mortgage Debt Interest Rate	4.20%
Credit enhanced debt [Member]
Debt Instrument [Line Items]
Mortgage notes payable	$ 700,500

Debt Notes (Details)

Debt Notes (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Debt Instrument [Line Items]
Notes, net	$ 5,875,328		$ 5,425,346
Repayments of Notes Payable	$ 300,000	$ 750,000
Debt Instrument, Maturity Date Range, End	Jun. 1, 2045
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	0.04%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	7.25%
Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	2.375%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	7.57%
Weighted Average Interest Rate	4.99%
6.584% Notes [Member]
Debt Instrument [Line Items]
Repayments of Notes Payable	$ 300,000
Debt Instrument, Interest Rate, Stated Percentage	6.584%
3.375% Notes [Member] [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.375%
Proceeds from Issuance of Unsecured Debt	$ 450,000
Proceeds from Debt, Net of Issuance Costs	$ 447,500
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Maximum	3.81%
4.50% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.50%
Proceeds from Issuance of Unsecured Debt	$ 300,000
Proceeds from Debt, Net of Issuance Costs	$ 298,900
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Maximum	4.55%

Debt Line of Credit and Commerc

Debt Line of Credit and Commercial Paper (Details) - Jun. 30, 2015 - USD ($) $ in Millions	Total
Line of Credit Facility [Line Items]
Debt Instrument, Maturity Date	May 1, 2061
Debt Instrument, Basis Spread on Variable Rate	0.95%
Commercial paper, maximum borrowing capacity	$ 500
A 175 billion LOC [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility	1,750
A 250 billion LOC [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility	$ 2,500
Debt Instrument, Maturity Date	Apr. 1, 2018
500.0 million ability to increase	$ 500
Line Of Credit Facility Commitment Fee	15 Basis Points
Remaining borrowing capacity	$ 2,460
Amount restricted/dedicated to support letters of credit	$ 41.7
Weighted Average Interest Rate Revolving Credit Facility	1.06%
Commercial Paper [Member]
Line of Credit Facility [Line Items]
Weighted Average Interest Rate	0.57%
Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Description of Variable Rate Basis	LIBOR plus 0.95%

Derivative and Other Fair Val53

Derivative and Other Fair Value Instruments (Details) - Jun. 30, 2015 - USD ($) $ in Thousands	Total
Derivative [Line Items]
Debt Instrument, Maturity Date	May 1, 2061
2.375% Notes [Member]
Derivative [Line Items]
Proceeds from Issuance of Unsecured Debt	$ 450,000
Debt Instrument, Interest Rate, Stated Percentage	2.375%
Debt Instrument, Maturity Date	Jul. 1, 2019
Derivative, Variable Interest Rate	0.61%
Debt Instrument, Description of Variable Rate Basis	LIBOR plus 0.61%
Fair Value Hedging [Member]
Derivative [Line Items]
Current Notional Balance	$ 450,000
Lowest Possible Notional	450,000
Highest Possible Notional	$ 450,000
Lowest Interest Rate	2.375%
Highest Interest Rate	2.375%
Earliest Maturity Date	P2019Y0M0D
Latest Maturity Date	P2019Y0M0D

Derivative and Other Fair Val54

Derivative and Other Fair Value Instruments (Details 1) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Fair Value Of Serp Investments	$ 99,641	$ 104,463
Assets, Fair Value Disclosure	103,596	106,392
Derivative liability, fair value		14,104
Other Liabilities, Fair Value Disclosure	99,641	104,463
Liabilities, Fair Value Disclosure	99,641	118,567
Redeemable Noncontrolling Interests Operating Partnership	488,178	500,733
Fair Value, Inputs, Level 1 [Member]
Derivatives, Fair Value [Line Items]
Fair Value Of Serp Investments	99,641	104,463
Assets, Fair Value Disclosure	99,641	104,463
Derivative liability, fair value		0
Other Liabilities, Fair Value Disclosure	99,641	104,463
Liabilities, Fair Value Disclosure	99,641	104,463
Redeemable Noncontrolling Interests Operating Partnership	0	0
Fair Value, Inputs, Level 2 [Member]
Derivatives, Fair Value [Line Items]
Fair Value Of Serp Investments	0	0
Assets, Fair Value Disclosure	3,955	1,929
Derivative liability, fair value		14,104
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	0	14,104
Redeemable Noncontrolling Interests Operating Partnership	488,178	500,733
Fair Value, Inputs, Level 3 [Member]
Derivatives, Fair Value [Line Items]
Fair Value Of Serp Investments	0	0
Assets, Fair Value Disclosure	0	0
Derivative liability, fair value		0
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	0	0
Redeemable Noncontrolling Interests Operating Partnership	0	0
Fair Value Hedging [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	3,955	1,597
Fair Value Hedging [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	0	0
Fair Value Hedging [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	3,955	1,597
Fair Value Hedging [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	$ 0	0
Forward Starting Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		332
Forward Starting Swaps [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		0
Forward Starting Swaps [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		332
Forward Starting Swaps [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		$ 0

Derivative and Other Fair Val55

Derivative and Other Fair Value Instruments (Details 3) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Increase (Decrease) in Fair Value of Interest Rate Fair Value Hedging Instruments	$ 2,358	$ 1,452
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	(2,358)	(1,452)
Effective Portion - Amount of Gain/ (Loss) Recognized in OCI on Derivative	(142)	(21,790)
Effective Portion - Amount of Gain/ (Loss) Reclassified from Accumulated OCI into Income	(8,911)	(8,335)
Ineffective Portion - Amount of Gain/ (Loss) Reclassifed from Accumulated OCI into Income	(30)	91
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Increase (Decrease) in Fair Value of Interest Rate Fair Value Hedging Instruments	$ 2,358	$ 1,452
Derivative, Description of Hedged Item	Fixed rate debt	Fixed rate debt
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	$ (2,358)	$ (1,452)
Forward Starting Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Effective Portion - Amount of Gain/ (Loss) Recognized in OCI on Derivative	(142)	(21,790)
Effective Portion - Amount of Gain/ (Loss) Reclassified from Accumulated OCI into Income	(8,911)	(8,335)
Ineffective Portion - Amount of Gain/ (Loss) Reclassifed from Accumulated OCI into Income	$ (30)	$ 91

Derivative and Other Fair Val56

Derivative and Other Fair Value Instruments (Details Textuals) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Jun. 30, 2016
Derivative [Line Items]
Mortgage notes payable	$ 4,952,579		$ 5,086,515
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	(163,400)		(172,200)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net				$ 23,800
Payments for (Proceeds from) Hedge, Investing Activities	15,100
Ineffective Portion - Amount of Gain/ (Loss) Reclassifed from Accumulated OCI into Income	(30)	$ 91
Interest Expense	1,200
ChargesHedgeTerminationActivities	13,900
Unsecured Debt [Member]
Derivative [Line Items]
Unsecured Debt	5,900,000		5,800,000
Debt Instrument, Fair Value Disclosure	6,100,000		6,100,000
Secured Debt [Member]
Derivative [Line Items]
Mortgage notes payable	4,952,579
Debt Instrument, Fair Value Disclosure	4,900,000		$ 5,100,000
3.375% Notes [Member] [Member]
Derivative [Line Items]
Proceeds from Issuance of Unsecured Debt	$ 450,000

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income from continuing operations	$ 298,504	$ 117,210	$ 488,573	$ 198,890
Allocation to Noncontrolling Interests - Operating Partnership, net	(11,350)	(4,422)	(18,403)	(7,475)
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	(844)	(588)	(1,487)	(1,092)
Preferred distributions	(833)	(1,036)	(1,724)	(2,072)
Premium on redemption of Preferred Shares	0	0	(2,789)	0
Income from continuing operations available to Common Shares, net of Noncontrolling Interests	285,477	111,164	464,170	188,251
Discontinued operations, net of Noncontrolling Interests	110	490	259	1,502
Numerator for net income per share - basic	285,587	111,654	464,429	189,753
Income from continuing operations available to Common Shares	296,827	115,586	482,573	195,726
Discontinued operations, net	114	510	269	1,562
Numerator for net income per share - diluted	$ 296,941	$ 116,096	$ 482,842	$ 197,288
Denominator for net income per share - basic	363,476	360,809	363,288	360,641
Effect of dilutive securities - OP Units	13,587	13,742	13,592	13,736
Effect of dilutive securities - Long-term compensation shares/units	3,428	2,567	3,466	2,403
Denominator for net income per share - diluted	380,491	377,118	380,346	376,780
Net income per share - basic	$ 0.79	$ 0.31	$ 1.28	$ 0.53
Net income per share - diluted	0.78	0.31	1.27	0.52
Income from continuing operations available to Common Shares	0.79	0.31	1.28	0.52
Net income per share - basic - Discontinued operations, net of Noncontrolling Interests	0	0	0	0.01
Income from continuing operations available to Common Shares	0.78	0.31	1.27	0.52
Net income per share - diluted - discontinued operations, net	$ 0	$ 0	$ 0	$ 0
OPERATING PARTNERSHIP
Income from continuing operations	$ 298,504	$ 117,210	$ 488,573	$ 198,890
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	(844)	(588)	(1,487)	(1,092)
Dividend preference units	(833)	(1,036)	(1,724)	(2,072)
Premium on redemption of Preferred Shares	0	0	(2,789)	0
Discontinued operations, net	$ 114	$ 510	$ 269	$ 1,562
Effect of dilutive securities - Long-term compensation shares/units	3,428	2,567	3,466	2,403
Net income per share - basic	$ 0.79	$ 0.31	$ 1.28	$ 0.53
Net income per share - diluted	0.78	0.31	1.27	0.52
Income from continuing operations available to Common Shares	0.79	0.31	1.28	0.52
Income from continuing operations available to Common Shares	$ 0.78	$ 0.31	$ 1.27	$ 0.52
Income from continuing operations available to Units	$ 296,827	$ 115,586	$ 482,573	$ 195,726
Numerator for net income per Unit - basic and diluted	$ 296,941	$ 116,096	$ 482,842	$ 197,288
Denominator for net income per Unit - basic	377,063	374,551	376,880	374,377
Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted	380,491	377,118	380,346	376,780
Net income per Unit - basic - Discontinued operations, net	$ 0	$ 0	$ 0	$ 0.01
Net income per Unit - diluted - Discontinued operations, net	$ 0	$ 0	$ 0	$ 0

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
REVENUES
Discontinued Operations - Rental income		$ 177	$ 252	$ 338	$ 1,275
Discontinued Operations - Total revenue		177	252	338	1,275
EXPENSES (1)
Discontinued Operations - Property and maintenance	[1]	0	(89)	(67)	(41)
Discontinued Operations - Real estate taxes and insurance	[1]	1	(19)	53	(6)
Discontinued Operations - General and administrative	[1]	65	46	71	51
Discontinued Operations - Total expenses	[1]	66	(62)	57	4
Discontinued operating income		111	314	281	1,271
Discontinued Operations - Interest and other income		3	45	3	80
Discontinued Operations - Income and other tax (expense) benefit		0	(2)	(15)	(13)
Income Loss From Discontinued Operations		114	357	269	1,338
Discontinued Operation - Net gain on sales of discontinued operations		0	153	0	224
Discontinued operations, net		$ 114	$ 510	$ 269	$ 1,562
[1]	Includes expenses paid in the current period for properties sold in prior periods related to the Company’s period of ownership.

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015USD ($)	Dec. 31, 2014USD ($)
300 properties designed and built in violation of accessibility requirements	300
Loss Contingency Accrual, Period Increase (Decrease)	$ 1,000
Loss Contingency Accrual	$ 5,000
Projects in various stages of development	15
Units in various stages of development	5,211
Consolidated Project Under Development Commitment Fund	$ 1,100,000
Various stages of development with estimated completion dates ranging through September 30, 2017	Sep. 30, 2017
Number Of Unconsolidated Projects	2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 136,243
Investment in Joint Venture	342,200
Noncontrolling Interests - Partially Owned Properties	122,368	$ 124,909
Company's Portion [Member]
Land purchase price	76,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	102,500
Joint Venture Partner [Member]
Land purchase price	57,900
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	75,700
Noncontrolling Interests - Partially Owned Properties	$ 117,400

Reportable Segments (Details)

Reportable Segments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Reportable Segments
Assets	$ 23,081,830		$ 23,081,830		$ 22,950,614
Payments to Acquire Other Property, Plant, and Equipment			81,962
Rental income:
Total Rental Income	676,508	$ 649,766	1,341,114	$ 1,280,491
Operating expenses:
Total Operating Expenses	221,642	218,992	454,078	448,770
NOI:
Total NOI	$ 454,866	430,774	$ 887,036	831,721
Reportable Segments (Textuals) [Abstract]
Units in same store properties	97,580		96,761
Rental income	$ 676,508	649,766	$ 1,341,114	1,280,491
Property and maintenance expense	(118,005)	(115,382)	(242,565)	(240,948)
Real estate taxes and insurance expense	(83,119)	(83,055)	(169,551)	(165,149)
Property management expense	(20,518)	(20,555)	(41,962)	(42,673)
Total Operating Expenses	(221,642)	(218,992)	(454,078)	(448,770)
Non-same store [Domain]
Reportable Segments
Assets	3,889,003		3,889,003
Payments to Acquire Other Property, Plant, and Equipment			2,649
Same Store [Domain]
Rental income:
Same store - Rental Income	645,198	614,933	1,267,098	1,207,334
Operating expenses:
Same store - Operating Expenses	211,126	203,515	423,791	413,053
NOI:
Same store - NOI	434,072	411,418	843,307	794,281
Same Store [Domain] | Boston [Domain]
Reportable Segments
Assets	1,868,144		1,868,144
Payments to Acquire Other Property, Plant, and Equipment			6,525
Rental income:
Same store - Rental Income	62,556	60,779	124,419	120,678
Operating expenses:
Same store - Operating Expenses	20,061	18,442	41,741	39,725
NOI:
Same store - NOI	42,495	42,337	82,678	80,953
Same Store [Domain] | Denver [Domain]
Reportable Segments
Assets	510,123		510,123
Payments to Acquire Other Property, Plant, and Equipment			2,958
Rental income:
Same store - Rental Income	29,829	27,511	58,826	54,123
Operating expenses:
Same store - Operating Expenses	8,168	7,635	15,627	15,097
NOI:
Same store - NOI	21,661	19,876	43,199	39,026
Same Store [Domain] | New York [Domain]
Reportable Segments
Assets	4,602,213		4,602,213
Payments to Acquire Other Property, Plant, and Equipment			8,365
Rental income:
Same store - Rental Income	118,485	114,221	234,555	225,407
Operating expenses:
Same store - Operating Expenses	44,091	41,410	89,855	87,045
NOI:
Same store - NOI	74,394	72,811	144,700	138,362
Same Store [Domain] | San Francisco [Domain]
Reportable Segments
Assets	2,683,829		2,683,829
Payments to Acquire Other Property, Plant, and Equipment			12,676
Rental income:
Same store - Rental Income	92,549	84,082	182,399	165,343
Operating expenses:
Same store - Operating Expenses	26,854	26,354	53,957	52,964
NOI:
Same store - NOI	65,695	57,728	128,442	112,379
Same Store [Domain] | Seattle [Domain]
Reportable Segments
Assets	1,080,755		1,080,755
Payments to Acquire Other Property, Plant, and Equipment			6,505
Rental income:
Same store - Rental Income	41,515	38,890	81,906	76,511
Operating expenses:
Same store - Operating Expenses	13,030	13,036	25,697	25,770
NOI:
Same store - NOI	28,485	25,854	56,209	50,741
Same Store [Domain] | South Florida [Domain]
Reportable Segments
Assets	1,118,604		1,118,604
Payments to Acquire Other Property, Plant, and Equipment			7,453
Rental income:
Same store - Rental Income	50,527	47,860	99,828	94,755
Operating expenses:
Same store - Operating Expenses	18,256	17,634	36,224	35,159
NOI:
Same store - NOI	32,271	30,226	63,604	59,596
Same Store [Domain] | Southern California [Domain]
Reportable Segments
Assets	2,768,169		2,768,169
Payments to Acquire Other Property, Plant, and Equipment			14,390
Rental income:
Same store - Rental Income	110,357	104,319	212,517	201,450
Operating expenses:
Same store - Operating Expenses	34,984	34,697	68,164	67,298
NOI:
Same store - NOI	75,373	69,622	144,353	134,152
Same Store [Domain] | Washington DC [Domain]
Reportable Segments
Assets	4,222,865		4,222,865
Payments to Acquire Other Property, Plant, and Equipment			17,340
Rental income:
Same store - Rental Income	116,168	115,081	226,819	224,975
Operating expenses:
Same store - Operating Expenses	37,585	36,372	75,620	73,399
NOI:
Same store - NOI	78,583	78,709	151,199	151,576
Same Store [Domain] | Non-Core [Domain]
Reportable Segments
Assets	338,125		338,125
Payments to Acquire Other Property, Plant, and Equipment			3,101
Rental income:
Same store - Rental Income	23,212	22,190	45,829	44,092
Operating expenses:
Same store - Operating Expenses	8,097	7,935	16,906	16,596
NOI:
Same store - NOI	15,115	14,255	28,923	27,496
Same Store [Domain] | Same Store [Domain]
Reportable Segments
Assets	19,192,827		19,192,827
Payments to Acquire Other Property, Plant, and Equipment			79,313
Non-same store [Domain] | Boston [Domain]
Reportable Segments
Assets	176,247		176,247
Payments to Acquire Other Property, Plant, and Equipment			83
Rental income:
Non-same store - Rental Income	2,411	791	3,336	1,819
Operating expenses:
Non-same store - Operating Expenses	652	202	882	412
NOI:
Non-same store - NOI	1,759	589	2,454	1,407
Non-same store [Domain] | New York [Domain]
Reportable Segments
Assets	118,166		118,166
Payments to Acquire Other Property, Plant, and Equipment			0
Rental income:
Non-same store - Rental Income	112	0	115	0
Operating expenses:
Non-same store - Operating Expenses	613	0	609	0
NOI:
Non-same store - NOI	(501)	0	(494)	0
Non-same store [Domain] | Seattle [Domain]
Reportable Segments
Assets	227,930		227,930
Payments to Acquire Other Property, Plant, and Equipment			21
Rental income:
Non-same store - Rental Income	4,816	1,129	9,396	1,240
Operating expenses:
Non-same store - Operating Expenses	1,297	511	2,596	657
NOI:
Non-same store - NOI	3,519	618	6,800	583
Non-same store [Domain] | South Florida [Domain]
Reportable Segments
Assets	66,082		66,082
Payments to Acquire Other Property, Plant, and Equipment			22
Rental income:
Non-same store - Rental Income	1,981	1,246	3,913	2,047
Operating expenses:
Non-same store - Operating Expenses	672	797	1,346	1,251
NOI:
Non-same store - NOI	1,309	449	2,567	796
Non-same store [Domain] | Southern California [Domain]
Reportable Segments
Assets	842,096		842,096
Payments to Acquire Other Property, Plant, and Equipment			1,691
Rental income:
Non-same store - Rental Income	14,193	7,836	35,005	19,392
Operating expenses:
Non-same store - Operating Expenses	5,375	4,019	12,864	8,642
NOI:
Non-same store - NOI	8,818	3,817	22,141	10,750
Non-same store [Domain] | Washington DC [Domain]
Reportable Segments
Assets	239,843		239,843
Payments to Acquire Other Property, Plant, and Equipment			509
Rental income:
Non-same store - Rental Income	3,492	2,287	10,877	7,707
Operating expenses:
Non-same store - Operating Expenses	910	854	3,024	2,989
NOI:
Non-same store - NOI	2,582	1,433	7,853	4,718
Non-same store [Domain] | Other (3) [Domain]
Reportable Segments
Assets	2,218,639		2,218,639
Payments to Acquire Other Property, Plant, and Equipment			323
Rental income:
Non-same store - Rental Income	4,305	21,544	11,374	40,952
Operating expenses:
Non-same store - Operating Expenses	997	9,094	8,966	21,766
NOI:
Non-same store - NOI	3,308	12,450	2,408	19,186
Non-same store [Domain] | Non-same store [Domain]
Rental income:
Non-same store - Rental Income	31,310	34,833	74,016	73,157
Operating expenses:
Non-same store - Operating Expenses	10,516	15,477	30,287	35,717
NOI:
Non-same store - NOI	$ 20,794	$ 19,356	$ 43,729	$ 37,440

Subsequent Events_Other (Detail

Subsequent Events/Other (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Other [Line Items]
Business Combination, Acquisition Related Costs	$ 200	$ 100
Noncash Project Abandonment Costs	1,651	1,492
Other Expenses	1,800	1,600
Employee Benefits and Share-based Compensation	4,700
Litigation Settlement, Amount	5,800	$ 2,300
Owned Property Management Costs [Member]
Other [Line Items]
Employee Benefits and Share-based Compensation	700
General and Administrative [Member]
Other [Line Items]
Employee Benefits and Share-based Compensation	$ 4,000