Equity Residential (EQR) 10-Q 30 Oct 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 25, 2019
Document And Entity Information [Line Items]
Entity Registrant Name	EQUITY RESIDENTIAL
Entity Central Index Key	0000906107
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	EQR
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		371,354,411
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	1-12252
Entity Tax Identification Number	13-3675988
Entity Address, Address Line One	Two North Riverside Plaza
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60606
City Area Code	312
Local Phone Number	474-1300
Entity Incorporation, State or Country Code	MD
Title of 12(b) Security	Common Shares of Beneficial Interest, $0.01 Par Value (Equity Residential)
Security Exchange Name	NYSE
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
ERPOP [Member]
Document And Entity Information [Line Items]
Entity Registrant Name	ERP OPERATING LIMITED PARTNERSHIP
Entity Central Index Key	0000931182
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
No Trading Symbol Flag	true
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	0-24920
Entity Tax Identification Number	36-3894853
Entity Address, Address Line One	Two North Riverside Plaza
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60606
City Area Code	312
Local Phone Number	474-1300
Entity Incorporation, State or Country Code	IL
Title of 12(b) Security	7.57% Notes due August 15, 2026 (ERP Operating Limited Partnership)
Security Exchange Name	NYSE
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes

CONSOLIDATED BALANCE SHEETS (Un

CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
ASSETS
Land	$ 5,955,121	$ 5,875,803
Depreciable property	21,168,255	20,435,901
Projects under development	143,434	109,409
Land held for development	91,017	89,909
Investment in real estate	27,357,827	26,511,022
Accumulated depreciation	(7,171,876)	(6,696,281)
Investment in real estate, net	20,185,951	19,814,741
Investments in unconsolidated entities	52,474	58,349
Cash and cash equivalents	28,777	47,442
Restricted deposits	55,819	68,871
Right-of-use assets	481,044	0
Other assets	249,991	404,806
Total assets	21,054,056	20,394,209
Liabilities:
Mortgage notes payable, net	1,962,471	2,385,470
Notes, net	6,675,084	5,933,286
Line of credit and commercial paper	354,381	499,183
Accounts payable and accrued expenses	151,680	102,471
Accrued interest payable	73,747	62,622
Lease liabilities	333,312	0
Other liabilities	312,849	358,563
Security deposits	70,398	67,258
Distributions payable	218,136	206,601
Total liabilities	10,152,058	9,615,454
Commitments and contingencies
Redeemable Noncontrolling Interests – Operating Partnership	494,999	379,106
Shareholders' equity:
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 745,600 shares issued and outstanding as of September 30, 2019 and December 31, 2018	37,280	37,280
Common Shares of beneficial interest, $0.01 par value; 1,000,000,000 shares authorized; 371,327,332 shares issued and outstanding as of September 30, 2019 and 369,405,161 shares issued and outstanding as of December 31, 2018	3,713	3,694
Paid in capital	8,917,312	8,935,453
Retained earnings	1,308,423	1,261,763
Accumulated other comprehensive income (loss)	(84,092)	(64,986)
Total shareholders’ equity	10,182,636	10,173,204
Noncontrolling Interests:
Operating Partnership	226,065	228,738
Partially Owned Properties	(1,702)	(2,293)
Total Noncontrolling Interests	224,363	226,445
Total equity	10,406,999	10,399,649
Total liabilities and equity/capital	$ 21,054,056	$ 20,394,209

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (Unaudited) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	100,000,000	100,000,000
Preferred Stock, Shares Issued	745,600	745,600
Preferred Stock, Shares Outstanding	745,600	745,600
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	1,000,000,000	1,000,000,000
Common Stock, Shares, Issued	371,327,332	369,405,161
Common Stock, Shares, Outstanding	371,327,332	369,405,161

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
REVENUES
Rental income	$ 685,120	$ 652,677	$ 2,016,796	$ 1,925,128
Fee and asset management	$ 25	$ 190	$ 360	$ 563
Type of Revenue [Extensible List]	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember
Total revenues	$ 685,145	$ 652,867	$ 2,017,156	$ 1,925,691
EXPENSES
Property and maintenance	114,966	110,541	338,497	322,487
Real estate taxes and insurance	87,546	87,388	270,434	268,784
Property management	21,940	22,247	72,705	69,175
General and administrative	11,417	12,640	41,127	41,420
Depreciation	211,478	194,618	616,201	583,869
Total expenses	447,347	427,434	1,338,964	1,285,735
Net gain (loss) on sales of real estate properties	130,565	114,672	269,400	256,834
Impairment		(702)		(702)
Operating income	368,363	339,403	947,592	896,088
Interest and other income	631	7,864	2,221	14,860
Other expenses	(2,813)	(7,661)	(11,205)	(14,871)
Interest:
Expense incurred, net	(85,936)	(111,219)	(289,776)	(321,454)
Amortization of deferred financing costs	(2,881)	(3,276)	(8,664)	(9,054)
Income before income and other taxes, income (loss) from investments in unconsolidated entities and net gain (loss) on sales of land parcels	277,364	225,111	640,168	565,569
Income and other tax (expense) benefit	(265)	(280)	(749)	(767)
Income (loss) from investments in unconsolidated entities	(1,152)	(985)	66,906	(2,993)
Net gain (loss) on sales of land parcels	1,899		2,077	995
Net income	277,846	223,846	708,402	562,804
Net (income) loss attributable to Noncontrolling Interests:
Operating Partnership	(9,910)	(8,159)	(25,339)	(20,517)
Partially Owned Properties	(830)	(750)	(2,450)	(1,939)
Net income attributable to controlling interests	267,106	214,937	680,613	540,348
Preferred distributions	(773)	(773)	(2,318)	(2,318)
Net income available to Common Shares	$ 266,333	$ 214,164	$ 678,295	$ 538,030
Earnings per share – basic:
Net income available to Common Shares	$ 0.72	$ 0.58	$ 1.83	$ 1.46
Weighted average Common Shares outstanding	370,768	368,028	370,227	367,920
Earnings per share – diluted:
Net income available to Common Shares	$ 0.71	$ 0.58	$ 1.82	$ 1.46
Weighted average Common Shares outstanding	386,896	383,884	386,177	383,433

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Comprehensive income:
Net income	$ 277,846	$ 223,846	$ 708,402	$ 562,804
Other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period		12,026	(33,765)	24,021
Losses reclassified into earnings from other comprehensive income	5,757	4,595	14,659	13,902
Other comprehensive income (loss)	5,757	16,621	(19,106)	37,923
Comprehensive income	283,603	240,467	689,296	600,727
Comprehensive (income) attributable to Noncontrolling Interests	(10,946)	(9,519)	(27,096)	(23,848)
Comprehensive income attributable to controlling interests	$ 272,657	$ 230,948	$ 662,200	$ 576,879

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 708,402	$ 562,804
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	616,201	583,869
Amortization of deferred financing costs	8,664	9,054
Amortization of above/below market lease intangibles	(53)	3,294
Amortization of discounts and premiums on debt	10,137	21,360
Amortization of deferred settlements on derivative instruments	14,650	13,893
Amortization of right-of-use assets	9,966
Impairment		702
Write-off of pursuit costs	4,098	3,125
(Income) loss from investments in unconsolidated entities	(66,906)	2,993
Distributions from unconsolidated entities – return on capital	2,486	1,885
Net (gain) loss on sales of real estate properties	(269,400)	(256,834)
Net (gain) loss on sales of land parcels	(2,077)	(995)
Net (gain) loss on debt extinguishment	3,381	22,110
Compensation paid with Company Common Shares	20,777	22,270
Changes in assets and liabilities:
(Increase) decrease in other assets	(20,871)	(18,550)
Increase (decrease) in accounts payable and accrued expenses	57,822	58,756
Increase (decrease) in accrued interest payable	11,125	11,097
Increase (decrease) in other liabilities	(15,578)	1,190
Increase (decrease) in security deposits	3,140	2,168
Increase (decrease) in lease liabilities	(1,784)
Net cash provided by operating activities	1,094,180	1,044,191
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in real estate – acquisitions	(1,147,236)	(708,092)
Investment in real estate – development/other	(137,238)	(101,573)
Capital expenditures to real estate	(128,335)	(138,119)
Non-real estate capital additions	(2,139)	(3,155)
Interest capitalized for real estate under development	(4,801)	(4,547)
Proceeds from disposition of real estate, net	692,649	691,526
Investments in unconsolidated entities	(9,073)	(4,860)
Distributions from unconsolidated entities – return of capital	78,262
Purchase of investment securities and other investments	(269)
Net cash provided by (used for) investing activities	(658,180)	(268,820)
CASH FLOWS FROM FINANCING ACTIVITIES:
Debt financing costs	(12,025)	(4,355)
Mortgage notes payable, net:
Proceeds	295,713
Lump sum payoffs	(723,021)	(847,939)
Scheduled principal repayments	(4,883)	(4,938)
Notes, net:
Proceeds	1,194,468	497,010
Lump sum payoffs	(450,000)
Line of credit and commercial paper:
Line of credit proceeds	5,850,000	1,635,000
Line of credit repayments	(5,850,000)	(1,635,000)
Commercial paper proceeds	13,341,198	9,624,610
Commercial paper repayments	(13,486,000)	(9,425,000)
Proceeds from (payments on) settlement of derivative instruments	(41,616)	1,638
Proceeds from Employee Share Purchase Plan (ESPP)	2,323	3,074
Proceeds from exercise of options	67,066	6,000
Payment of offering costs	(789)	(27)
Other financing activities, net	(49)	(48)
Contributions – Noncontrolling Interests – Partially Owned Properties	4,594	125
Contributions – Noncontrolling Interests – Operating Partnership		1
Distributions:
Common Shares	(620,391)	(583,184)
Preferred Shares	(2,318)	(2,318)
Noncontrolling Interests – Operating Partnership	(22,202)	(21,040)
Noncontrolling Interests – Partially Owned Properties	(6,404)	(8,882)
Net cash provided by (used for) financing activities	(467,717)	(787,383)
Net increase (decrease) in cash and cash equivalents and restricted deposits	(31,717)	(12,012)
Cash and cash equivalents and restricted deposits, beginning of period	116,313	100,762
Cash and cash equivalents and restricted deposits, end of period	84,596	88,750
Cash and cash equivalents	28,777	32,995
Restricted deposits	55,819	55,755
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized	246,410	268,966
Net cash paid for income and other taxes	918	934
Amortization of deferred financing costs:
Other assets	1,808	1,809
Mortgage notes payable, net	3,529	4,197
Notes, net	3,387	3,048
Investment in real estate, net	(60)
Amortization of discounts and premiums on debt:
Mortgage notes payable, net	8,017	19,394
Notes, net	2,120	1,966
Amortization of deferred settlements on derivative instruments:
Other liabilities	(9)	(9)
Accumulated other comprehensive income	14,659	13,902
Write-off of pursuit costs:
Investment in real estate, net	4,042	3,079
Other assets	48	13
Accounts payable and accrued expenses	8	33
(Income) loss from investments in unconsolidated entities:
Investments in unconsolidated entities	(67,900)	1,973
Other liabilities	994	1,020
Realized/unrealized (gain) loss on derivative instruments:
Other assets	2,002	(24,021)
Notes, net	2,277	(1,491)
Other liabilities	29,486	1,491
Accumulated other comprehensive income	(33,765)	24,021
Investments in unconsolidated entities:
Investments in unconsolidated entities	(6,973)	(3,180)
Other liabilities	(2,100)	(1,680)
Debt financing costs:
Other assets	145
Mortgage notes payable, net	(2,354)
Notes, net	(10,454)	(4,355)
Other liabilities	638
Right-of-use assets and lease liabilities initial measurement and reclassifications:
Right-of-use assets	(491,010)
Other assets	184,116
Lease liabilities	335,096
Other liabilities	(28,202)
Mortgage Notes Payable, Net [Member]
Mortgage notes payable, net:
Net gain (loss) on debt extinguishment	$ (3,381)	$ (22,110)

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) - USD ($) $ in Thousands	Total	PREFERRED SHARES	COMMON SHARES, $0.01 PAR VALUE	PAID IN CAPITAL	RETAINED EARNINGS	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	DISTRIBUTIONS	OPERATING PARTNERSHIP	PARTIALLY OWNED PROPERTIES
Balance, beginning of year at Dec. 31, 2017		$ 37,280	$ 3,680	$ 8,886,586	$ 1,403,530	$ (88,612)
Balance, beginning of year at Dec. 31, 2017								$ 226,691	$ 4,708
COMMON SHARES, $0.01 PAR VALUE
Conversion of OP Units into Common Shares				356
Exercise of share options			2	5,998
Employee Share Purchase Plan (ESPP)			1	3,073
Share-based employee compensation expense:
Restricted shares			1	6,803
Share options				9,206
ESPP discount				604
Offering costs				(27)
Supplemental Executive Retirement Plan (SERP)				(533)
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	$ 14,361			(14,361)
Adjustment for Noncontrolling Interests ownership in Operating Partnership				2,619				(2,619)
PAID IN CAPITAL
Conversion of OP Units into Common Shares				356
Exercise of share options			2	5,998
Employee Share Purchase Plan (ESPP)			1	3,073
RETAINED EARNINGS
Net income attributable to controlling interests	540,348				540,348
Common Share distributions					(596,735)
Preferred Share distributions					(2,318)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period	24,021					24,021
Losses reclassified into earnings from other comprehensive income	(13,902)					13,902
DISTRIBUTIONS
Distributions declared per Common Share outstanding							$ 1.62
NONCONTROLLING INTERESTS
Issuance of restricted units to Noncontrolling Interests								1
Conversion of OP Units into Common Shares				356
Equity compensation associated with Noncontrolling Interests								11,074
Net income	562,804
Distributions to Noncontrolling Interests								(21,560)	(8,930)
Change in carrying value of Redeemable Noncontrolling Interests - Operating Partnership	(77)							77
Adjustment for Noncontrolling Interests ownership in Operating Partnership				2,619				(2,619)
Conversion of OP Units held by Noncontrolling Interests into OP Units held by General Partner								(356)
Net income attributable to Noncontrolling Interests	20,517							20,517	1,939
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	20,517							20,517	1,939
Contributions by Noncontrolling Interests									125
Distributions to Noncontrolling Interests								(21,560)	(8,930)
Balance, end of period at Sep. 30, 2018		37,280	3,684	8,900,324	1,344,825	(50,689)
Balance, end of period at Sep. 30, 2018								233,825	(2,158)
Balance, beginning of year at Jun. 30, 2018		37,280	3,683	8,905,184	1,329,600	(67,310)
Balance, beginning of year at Jun. 30, 2018								232,995	(1,646)
COMMON SHARES, $0.01 PAR VALUE
Conversion of OP Units into Common Shares				25
Exercise of share options			1	3,382
Employee Share Purchase Plan (ESPP)				893
Share-based employee compensation expense:
Restricted shares				1,641
Share options				670
ESPP discount				204
Supplemental Executive Retirement Plan (SERP)				5
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership				(14,189)
Adjustment for Noncontrolling Interests ownership in Operating Partnership				2,509				(2,509)
PAID IN CAPITAL
Conversion of OP Units into Common Shares				25
Exercise of share options			1	3,382
Employee Share Purchase Plan (ESPP)				893
RETAINED EARNINGS
Net income attributable to controlling interests	214,937				214,937
Common Share distributions					(198,939)
Preferred Share distributions					(773)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period	12,026					12,026
Losses reclassified into earnings from other comprehensive income	(4,595)					4,595
DISTRIBUTIONS
Distributions declared per Common Share outstanding							0.54
NONCONTROLLING INTERESTS
Conversion of OP Units into Common Shares				25
Equity compensation associated with Noncontrolling Interests								2,958
Net income	223,846
Distributions to Noncontrolling Interests								(7,186)	(1,262)
Change in carrying value of Redeemable Noncontrolling Interests - Operating Partnership								(567)
Adjustment for Noncontrolling Interests ownership in Operating Partnership				2,509				(2,509)
Conversion of OP Units held by Noncontrolling Interests into OP Units held by General Partner								(25)
Net income attributable to Noncontrolling Interests	8,159							8,159	750
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	8,159							8,159	750
Distributions to Noncontrolling Interests								(7,186)	(1,262)
Balance, end of period at Sep. 30, 2018		37,280	3,684	8,900,324	1,344,825	(50,689)
Balance, end of period at Sep. 30, 2018								233,825	(2,158)
Balance, beginning of year at Dec. 31, 2018	10,173,204	37,280	3,694	8,935,453	1,261,763	(64,986)
Balance, beginning of year at Dec. 31, 2018	226,445							228,738	(2,293)
COMMON SHARES, $0.01 PAR VALUE
Conversion of OP Units into Common Shares			3	9,840
Exercise of share options			14	67,052
Employee Share Purchase Plan (ESPP)				2,323
Share-based employee compensation expense:
Restricted shares			2	10,302
Share options				2,185
ESPP discount				502
Offering costs				(789)
Supplemental Executive Retirement Plan (SERP)				(1,539)
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	114,936			(114,936)
Adjustment for Noncontrolling Interests ownership in Operating Partnership				6,919				(6,919)
PAID IN CAPITAL
Conversion of OP Units into Common Shares			3	9,840
Exercise of share options			14	67,052
Employee Share Purchase Plan (ESPP)				2,323
RETAINED EARNINGS
Net income attributable to controlling interests	680,613				680,613
Common Share distributions					(631,635)
Preferred Share distributions					(2,318)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period	(33,765)					(33,765)
Losses reclassified into earnings from other comprehensive income	(14,659)					14,659
DISTRIBUTIONS
Distributions declared per Common Share outstanding							1.7025
NONCONTROLLING INTERESTS
Conversion of OP Units into Common Shares			3	9,840
Equity compensation associated with Noncontrolling Interests								12,200
Net income	708,402
Distributions to Noncontrolling Interests								(22,493)	(6,453)
Change in carrying value of Redeemable Noncontrolling Interests - Operating Partnership	957							(957)
Adjustment for Noncontrolling Interests ownership in Operating Partnership				6,919				(6,919)
Conversion of OP Units held by Noncontrolling Interests into OP Units held by General Partner								(9,843)
Net income attributable to Noncontrolling Interests	25,339							25,339	2,450
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	25,339							25,339	2,450
Contributions by Noncontrolling Interests									4,594
Distributions to Noncontrolling Interests								(22,493)	(6,453)
Balance, end of period at Sep. 30, 2019	10,182,636	37,280	3,713	8,917,312	1,308,423	(84,092)
Balance, end of period at Sep. 30, 2019	224,363							226,065	(1,702)
Balance, beginning of year at Jun. 30, 2019		37,280	3,708	8,949,581	1,252,809	(89,849)
Balance, beginning of year at Jun. 30, 2019								227,320	(1,298)
COMMON SHARES, $0.01 PAR VALUE
Conversion of OP Units into Common Shares			1	4,971
Exercise of share options			4	18,575
Employee Share Purchase Plan (ESPP)				671
Share-based employee compensation expense:
Restricted shares				2,322
Share options				503
ESPP discount				137
Offering costs				(634)
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership				(57,962)
Adjustment for Noncontrolling Interests ownership in Operating Partnership				(852)				852
PAID IN CAPITAL
Conversion of OP Units into Common Shares			1	4,971
Exercise of share options			4	18,575
Employee Share Purchase Plan (ESPP)				671
RETAINED EARNINGS
Net income attributable to controlling interests	267,106				267,106
Common Share distributions					(210,719)
Preferred Share distributions					(773)
Accumulated other comprehensive income (loss) – derivative instruments:
Losses reclassified into earnings from other comprehensive income	(5,757)					5,757
DISTRIBUTIONS
Distributions declared per Common Share outstanding							$ 0.5675
NONCONTROLLING INTERESTS
Conversion of OP Units into Common Shares			1	4,971
Equity compensation associated with Noncontrolling Interests								1,371
Net income	277,846
Distributions to Noncontrolling Interests								(7,414)	(1,234)
Change in carrying value of Redeemable Noncontrolling Interests - Operating Partnership								(1,002)
Adjustment for Noncontrolling Interests ownership in Operating Partnership				(852)				852
Conversion of OP Units held by Noncontrolling Interests into OP Units held by General Partner								(4,972)
Net income attributable to Noncontrolling Interests	9,910							9,910	830
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	9,910							9,910	830
Distributions to Noncontrolling Interests								(7,414)	(1,234)
Balance, end of period at Sep. 30, 2019	10,182,636	$ 37,280	$ 3,713	$ 8,917,312	$ 1,308,423	$ (84,092)
Balance, end of period at Sep. 30, 2019	$ 224,363							$ 226,065	$ (1,702)

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Statement Of Stockholders Equity [Abstract]
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01	$ 0.01

CONSOLIDATED BALANCE SHEETS OF

CONSOLIDATED BALANCE SHEETS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
ASSETS
Land	$ 5,955,121	$ 5,875,803
Depreciable property	21,168,255	20,435,901
Projects under development	143,434	109,409
Land held for development	91,017	89,909
Investment in real estate	27,357,827	26,511,022
Accumulated depreciation	(7,171,876)	(6,696,281)
Investment in real estate, net	20,185,951	19,814,741
Investments in unconsolidated entities	52,474	58,349
Cash and cash equivalents	28,777	47,442
Restricted deposits	55,819	68,871
Right-of-use assets	481,044	0
Other assets	249,991	404,806
Total assets	21,054,056	20,394,209
Liabilities:
Mortgage notes payable, net	1,962,471	2,385,470
Notes, net	6,675,084	5,933,286
Line of credit and commercial paper	354,381	499,183
Accounts payable and accrued expenses	151,680	102,471
Accrued interest payable	73,747	62,622
Lease liabilities	333,312	0
Other liabilities	312,849	358,563
Security deposits	70,398	67,258
Distributions payable	218,136	206,601
Total liabilities	10,152,058	9,615,454
Commitments and contingencies
Partners’ Capital:
Accumulated other comprehensive income (loss)	(84,092)	(64,986)
Noncontrolling Interests – Partially Owned Properties	(1,702)	(2,293)
Total liabilities and equity/capital	21,054,056	20,394,209
ERPOP [Member]
ASSETS
Land	5,955,121	5,875,803
Depreciable property	21,168,255	20,435,901
Projects under development	143,434	109,409
Land held for development	91,017	89,909
Investment in real estate	27,357,827	26,511,022
Accumulated depreciation	(7,171,876)	(6,696,281)
Investment in real estate, net	20,185,951	19,814,741
Investments in unconsolidated entities	52,474	58,349
Cash and cash equivalents	28,777	47,442
Restricted deposits	55,819	68,871
Right-of-use assets	481,044
Other assets	249,991	404,806
Total assets	21,054,056	20,394,209
Liabilities:
Mortgage notes payable, net	1,962,471	2,385,470
Notes, net	6,675,084	5,933,286
Line of credit and commercial paper	354,381	499,183
Accounts payable and accrued expenses	151,680	102,471
Accrued interest payable	73,747	62,622
Lease liabilities	333,312
Other liabilities	312,849	358,563
Security deposits	70,398	67,258
Distributions payable	218,136	206,601
Total liabilities	10,152,058	9,615,454
Commitments and contingencies
Redeemable Limited Partners	494,999	379,106
Partners’ Capital:
Preference Units	37,280	37,280
General Partner	10,229,448	10,200,910
Limited Partners	226,065	228,738
Accumulated other comprehensive income (loss)	(84,092)	(64,986)
Total partners’ capital	10,408,701	10,401,942
Noncontrolling Interests – Partially Owned Properties	(1,702)	(2,293)
Total capital	10,406,999	10,399,649
Total liabilities and equity/capital	$ 21,054,056	$ 20,394,209

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
REVENUES
Rental income	$ 685,120	$ 652,677	$ 2,016,796	$ 1,925,128
Fee and asset management	$ 25	$ 190	$ 360	$ 563
Type of Revenue [Extensible List]	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember
Total revenues	$ 685,145	$ 652,867	$ 2,017,156	$ 1,925,691
EXPENSES
Property and maintenance	114,966	110,541	338,497	322,487
Real estate taxes and insurance	87,546	87,388	270,434	268,784
Property management	21,940	22,247	72,705	69,175
General and administrative	11,417	12,640	41,127	41,420
Depreciation	211,478	194,618	616,201	583,869
Total expenses	447,347	427,434	1,338,964	1,285,735
Net gain (loss) on sales of real estate properties	130,565	114,672	269,400	256,834
Impairment		(702)		(702)
Operating income	368,363	339,403	947,592	896,088
Interest and other income	631	7,864	2,221	14,860
Other expenses	(2,813)	(7,661)	(11,205)	(14,871)
Interest:
Expense incurred, net	(85,936)	(111,219)	(289,776)	(321,454)
Amortization of deferred financing costs	(2,881)	(3,276)	(8,664)	(9,054)
Income before income and other taxes, income (loss) from investments in unconsolidated entities and net gain (loss) on sales of land parcels	277,364	225,111	640,168	565,569
Income and other tax (expense) benefit	(265)	(280)	(749)	(767)
Income (loss) from investments in unconsolidated entities	(1,152)	(985)	66,906	(2,993)
Net gain (loss) on sales of land parcels	1,899		2,077	995
Net income	277,846	223,846	708,402	562,804
Partially Owned Properties	(830)	(750)	(2,450)	(1,939)
Net income attributable to controlling interests	$ 267,106	$ 214,937	$ 680,613	$ 540,348
Earnings per Unit – basic:
Net income available to Units	$ 0.72	$ 0.58	$ 1.83	$ 1.46
Earnings per Unit – diluted:
Net income available to Units	$ 0.71	$ 0.58	$ 1.82	$ 1.46
Weighted average Units outstanding	386,896	383,884	386,177	383,433
ERPOP [Member]
REVENUES
Rental income	$ 685,120	$ 652,677	$ 2,016,796	$ 1,925,128
Fee and asset management	$ 25	$ 190	$ 360	$ 563
Type of Revenue [Extensible List]	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember
Total revenues	$ 685,145	$ 652,867	$ 2,017,156	$ 1,925,691
EXPENSES
Property and maintenance	114,966	110,541	338,497	322,487
Real estate taxes and insurance	87,546	87,388	270,434	268,784
Property management	21,940	22,247	72,705	69,175
General and administrative	11,417	12,640	41,127	41,420
Depreciation	211,478	194,618	616,201	583,869
Total expenses	447,347	427,434	1,338,964	1,285,735
Net gain (loss) on sales of real estate properties	130,565	114,672	269,400	256,834
Impairment		(702)		(702)
Operating income	368,363	339,403	947,592	896,088
Interest and other income	631	7,864	2,221	14,860
Other expenses	(2,813)	(7,661)	(11,205)	(14,871)
Interest:
Expense incurred, net	(85,936)	(111,219)	(289,776)	(321,454)
Amortization of deferred financing costs	(2,881)	(3,276)	(8,664)	(9,054)
Income before income and other taxes, income (loss) from investments in unconsolidated entities and net gain (loss) on sales of land parcels	277,364	225,111	640,168	565,569
Income and other tax (expense) benefit	(265)	(280)	(749)	(767)
Income (loss) from investments in unconsolidated entities	(1,152)	(985)	66,906	(2,993)
Net gain (loss) on sales of land parcels	1,899		2,077	995
Net income	277,846	223,846	708,402	562,804
Partially Owned Properties	(830)	(750)	(2,450)	(1,939)
Net income attributable to controlling interests	277,016	223,096	705,952	560,865
ALLOCATION OF NET INCOME:
Preference Units	773	773	2,318	2,318
General Partner	266,333	214,164	678,295	538,030
Limited Partners	9,910	8,159	25,339	20,517
Net income available to Units	$ 276,243	$ 222,323	$ 703,634	$ 558,547
Earnings per Unit – basic:
Net income available to Units	$ 0.72	$ 0.58	$ 1.83	$ 1.46
Weighted average Units outstanding	383,709	380,912	383,142	380,791
Earnings per Unit – diluted:
Net income available to Units	$ 0.71	$ 0.58	$ 1.82	$ 1.46
Weighted average Units outstanding	386,896	383,884	386,177	383,433

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Comprehensive income:
Net income	$ 277,846	$ 223,846	$ 708,402	$ 562,804
Other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period		12,026	(33,765)	24,021
Losses reclassified into earnings from other comprehensive income	5,757	4,595	14,659	13,902
Other comprehensive income (loss)	5,757	16,621	(19,106)	37,923
Comprehensive income	283,603	240,467	689,296	600,727
Comprehensive (income) attributable to Noncontrolling Interests – Partially Owned Properties	(10,946)	(9,519)	(27,096)	(23,848)
Comprehensive income attributable to controlling interests	272,657	230,948	662,200	576,879
ERPOP [Member]
Comprehensive income:
Net income	277,846	223,846	708,402	562,804
Other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period		12,026	(33,765)	24,021
Losses reclassified into earnings from other comprehensive income	5,757	4,595	14,659	13,902
Other comprehensive income (loss)	5,757	16,621	(19,106)	37,923
Comprehensive income	283,603	240,467	689,296	600,727
Comprehensive (income) attributable to Noncontrolling Interests – Partially Owned Properties	(830)	(750)	(2,450)	(1,939)
Comprehensive income attributable to controlling interests	$ 282,773	$ 239,717	$ 686,846	$ 598,788

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 708,402	$ 562,804
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	616,201	583,869
Amortization of deferred financing costs	8,664	9,054
Amortization of above/below market lease intangibles	(53)	3,294
Amortization of discounts and premiums on debt	10,137	21,360
Amortization of deferred settlements on derivative instruments	14,650	13,893
Amortization of right-of-use assets	9,966
Impairment		702
Write-off of pursuit costs	4,098	3,125
(Income) loss from investments in unconsolidated entities	(66,906)	2,993
Distributions from unconsolidated entities – return on capital	2,486	1,885
Net (gain) loss on sales of real estate properties	(269,400)	(256,834)
Net (gain) loss on sales of land parcels	(2,077)	(995)
Net (gain) loss on debt extinguishment	3,381	22,110
Compensation paid with Company Common Shares	20,777	22,270
Changes in assets and liabilities:
(Increase) decrease in other assets	(20,871)	(18,550)
Increase (decrease) in accounts payable and accrued expenses	57,822	58,756
Increase (decrease) in accrued interest payable	11,125	11,097
Increase (decrease) in lease liabilities	(1,784)
Increase (decrease) in other liabilities	(15,578)	1,190
Increase (decrease) in security deposits	3,140	2,168
Net cash provided by operating activities	1,094,180	1,044,191
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in real estate – acquisitions	(1,147,236)	(708,092)
Investment in real estate – development/other	(137,238)	(101,573)
Capital expenditures to real estate	(128,335)	(138,119)
Non-real estate capital additions	(2,139)	(3,155)
Interest capitalized for real estate under development	(4,801)	(4,547)
Proceeds from disposition of real estate, net	692,649	691,526
Investments in unconsolidated entities	(9,073)	(4,860)
Distributions from unconsolidated entities – return of capital	78,262
Purchase of investment securities and other investments	(269)
Net cash provided by (used for) investing activities	(658,180)	(268,820)
CASH FLOWS FROM FINANCING ACTIVITIES:
Debt financing costs	(12,025)	(4,355)
Mortgage notes payable, net:
Proceeds	295,713
Lump sum payoffs	(723,021)	(847,939)
Scheduled principal repayments	(4,883)	(4,938)
Notes, net:
Proceeds	1,194,468	497,010
Lump sum payoffs	(450,000)
Line of credit and commercial paper:
Line of credit proceeds	5,850,000	1,635,000
Line of credit repayments	(5,850,000)	(1,635,000)
Commercial paper proceeds	13,341,198	9,624,610
Commercial paper repayments	(13,486,000)	(9,425,000)
Proceeds from (payments on) settlement of derivative instruments	(41,616)	1,638
Proceeds from Employee Share Purchase Plan (ESPP)	2,323	3,074
Proceeds from exercise of EQR options	67,066	6,000
Payment of offering costs	(789)	(27)
Other financing activities, net	(49)	(48)
Contributions – Noncontrolling Interests – Partially Owned Properties	4,594	125
Contributions – Limited Partners		1
Distributions:
OP Units – General Partner	(620,391)	(583,184)
Preference Units	(2,318)	(2,318)
OP Units – Limited Partners	(22,202)	(21,040)
Noncontrolling Interests – Partially Owned Properties	(6,404)	(8,882)
Net cash provided by (used for) financing activities	(467,717)	(787,383)
Net increase (decrease) in cash and cash equivalents and restricted deposits	(31,717)	(12,012)
Cash and cash equivalents and restricted deposits, beginning of period	116,313	100,762
Cash and cash equivalents and restricted deposits, end of period	84,596	88,750
Cash and cash equivalents	28,777	32,995
Restricted deposits	55,819	55,755
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized	246,410	268,966
Net cash paid for income and other taxes	918	934
Amortization of deferred financing costs:
Investment in real estate, net	60
Other assets	1,808	1,809
Mortgage notes payable, net	3,529	4,197
Notes, net	3,387	3,048
Amortization of discounts and premiums on debt:
Mortgage notes payable, net	8,017	19,394
Notes, net	2,120	1,966
Amortization of deferred settlements on derivative instruments:
Other liabilities	(9)	(9)
Accumulated other comprehensive income	14,659	13,902
Write-off of pursuit costs:
Investment in real estate, net	4,042	3,079
Other assets	48	13
Accounts payable and accrued expenses	8	33
(Income) loss from investments in unconsolidated entities:
Investments in unconsolidated entities	(67,900)	1,973
Other liabilities	994	1,020
Realized/unrealized (gain) loss on derivative instruments:
Other assets	2,002	(24,021)
Notes, net	2,277	(1,491)
Other liabilities	29,486	1,491
Accumulated other comprehensive income	(33,765)	24,021
Investments in unconsolidated entities:
Investments in unconsolidated entities	(6,973)	(3,180)
Other liabilities	(2,100)	(1,680)
Debt financing costs:
Other assets	145
Mortgage notes payable, net	(2,354)
Notes, net	(10,454)	(4,355)
Other liabilities	638
Right-of-use assets and lease liabilities initial measurement and reclassifications:
Right-of-use assets	(491,010)
Other assets	184,116
Lease liabilities	335,096
Other liabilities	(28,202)
Mortgage Notes Payable, Net [Member]
Mortgage notes payable, net:
Net gain (loss) on debt extinguishment	(3,381)	(22,110)
ERPOP [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	708,402	562,804
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	616,201	583,869
Amortization of deferred financing costs	8,664	9,054
Amortization of above/below market lease intangibles	(53)	3,294
Amortization of discounts and premiums on debt	10,137	21,360
Amortization of deferred settlements on derivative instruments	14,650	13,893
Amortization of right-of-use assets	9,966
Impairment		702
Write-off of pursuit costs	4,098	3,125
(Income) loss from investments in unconsolidated entities	(66,906)	2,993
Distributions from unconsolidated entities – return on capital	2,486	1,885
Net (gain) loss on sales of real estate properties	(269,400)	(256,834)
Net (gain) loss on sales of land parcels	(2,077)	(995)
Net (gain) loss on debt extinguishment	3,381	22,110
Compensation paid with Company Common Shares	20,777	22,270
Changes in assets and liabilities:
(Increase) decrease in other assets	(20,871)	(18,550)
Increase (decrease) in accounts payable and accrued expenses	57,822	58,756
Increase (decrease) in accrued interest payable	11,125	11,097
Increase (decrease) in lease liabilities	(1,784)
Increase (decrease) in other liabilities	(15,578)	1,190
Increase (decrease) in security deposits	3,140	2,168
Net cash provided by operating activities	1,094,180	1,044,191
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in real estate – acquisitions	(1,147,236)	(708,092)
Investment in real estate – development/other	(137,238)	(101,573)
Capital expenditures to real estate	(128,335)	(138,119)
Non-real estate capital additions	(2,139)	(3,155)
Interest capitalized for real estate under development	(4,801)	(4,547)
Proceeds from disposition of real estate, net	692,649	691,526
Investments in unconsolidated entities	(9,073)	(4,860)
Distributions from unconsolidated entities – return of capital	78,262
Purchase of investment securities and other investments	(269)
Net cash provided by (used for) investing activities	(658,180)	(268,820)
CASH FLOWS FROM FINANCING ACTIVITIES:
Debt financing costs	(12,025)	(4,355)
Mortgage notes payable, net:
Proceeds	295,713
Lump sum payoffs	(723,021)	(847,939)
Scheduled principal repayments	(4,883)	(4,938)
Notes, net:
Proceeds	1,194,468	497,010
Lump sum payoffs	(450,000)
Line of credit and commercial paper:
Line of credit proceeds	5,850,000	1,635,000
Line of credit repayments	(5,850,000)	(1,635,000)
Commercial paper proceeds	13,341,198	9,624,610
Commercial paper repayments	(13,486,000)	(9,425,000)
Proceeds from (payments on) settlement of derivative instruments	(41,616)	1,638
Proceeds from Employee Share Purchase Plan (ESPP)	2,323	3,074
Proceeds from exercise of EQR options	67,066	6,000
Payment of offering costs	(789)	(27)
Other financing activities, net	(49)	(48)
Contributions – Noncontrolling Interests – Partially Owned Properties	4,594	125
Contributions – Limited Partners		1
Distributions:
OP Units – General Partner	(620,391)	(583,184)
Preference Units	(2,318)	(2,318)
OP Units – Limited Partners	(22,202)	(21,040)
Noncontrolling Interests – Partially Owned Properties	(6,404)	(8,882)
Net cash provided by (used for) financing activities	(467,717)	(787,383)
Net increase (decrease) in cash and cash equivalents and restricted deposits	(31,717)	(12,012)
Cash and cash equivalents and restricted deposits, beginning of period	116,313	100,762
Cash and cash equivalents and restricted deposits, end of period	84,596	88,750
Cash and cash equivalents	28,777	32,995
Restricted deposits	55,819	55,755
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized	246,410	268,966
Net cash paid for income and other taxes	918	934
Amortization of deferred financing costs:
Investment in real estate, net	(60)
Other assets	1,808	1,809
Mortgage notes payable, net	3,529	4,197
Notes, net	3,387	3,048
Amortization of discounts and premiums on debt:
Mortgage notes payable, net	8,017	19,394
Notes, net	2,120	1,966
Amortization of deferred settlements on derivative instruments:
Other liabilities	(9)	(9)
Accumulated other comprehensive income	14,659	13,902
Write-off of pursuit costs:
Investment in real estate, net	4,042	3,079
Other assets	48	13
Accounts payable and accrued expenses	8	33
(Income) loss from investments in unconsolidated entities:
Investments in unconsolidated entities	(67,900)	1,973
Other liabilities	994	1,020
Realized/unrealized (gain) loss on derivative instruments:
Other assets	2,002	(24,021)
Notes, net	2,277	(1,491)
Other liabilities	29,486	1,491
Accumulated other comprehensive income	(33,765)	24,021
Investments in unconsolidated entities:
Investments in unconsolidated entities	(6,973)	(3,180)
Other liabilities	(2,100)	(1,680)
Debt financing costs:
Other assets	145
Mortgage notes payable, net	(2,354)
Notes, net	(10,454)	(4,355)
Other liabilities	638
Right-of-use assets and lease liabilities initial measurement and reclassifications:
Right-of-use assets	(491,010)
Other assets	184,116
Lease liabilities	335,096
Other liabilities	(28,202)
ERPOP [Member] | Mortgage Notes Payable, Net [Member]
Mortgage notes payable, net:
Net gain (loss) on debt extinguishment	$ (3,381)	$ (22,110)

CONSOLIDATED STATEMENTS OF CH_3

CONSOLIDATED STATEMENTS OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) $ in Thousands	Total	ERPOP [Member]	PREFERRED SHARESERPOP [Member]	General Partner [Member]	General Partner [Member]ERPOP [Member]	Limited PartnerERPOP [Member]	ACCUMULATED OTHER COMPREHENSIVE (LOSS) [Member]ERPOP [Member]	DISTRIBUTIONS	Partially Owned PropertiesERPOP [Member]
Balance, beginning of year at Dec. 31, 2017			$ 37,280		$ 10,293,796	$ 226,691	$ (88,612)
Balance, beginning of year at Dec. 31, 2017									$ 4,708
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner					356	(356)
Exercise of EQR share options					6,000
EQR's Employee Share Purchase Plan (ESPP)				$ 3,074
Share-based employee compensation expense:
EQR restricted shares					6,804
EQR share options					9,206
EQR ESPP discount					604
Net income available to Units - General Partner		$ 538,030			538,030
OP Units General Partner distributions					(596,735)
Offering costs					(27)
Supplemental Executive Retirement Plan (SERP)					(533)
Change in market value of Redeemable Limited Partners					(14,361)
Adjustment for Limited Partners ownership in Operating Partnership					2,619	(2,619)
LIMITED PARTNERS
Issuance of restricted units to Limited Partners						1
Conversion of OP Units held by Limited Partners into OP Units held by General Partner					356	(356)
Equity compensation associated with Units - Limited Partners						11,074
Net income available to Units - Limited Partners		20,517				20,517
Units - Limited Partners distributions						(21,560)
Change in carrying value of Redeemable Limited Partners						77
Adjustment for Limited Partners ownership in Operating Partnership					2,619	(2,619)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period	$ 24,021	24,021					24,021
Losses reclassified into earnings from other comprehensive income	(13,902)	(13,902)					13,902
NONCONTROLLING INTERESTS PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	562,804	562,804							1,939
Contributions by Noncontrolling Interests									125
Distributions to Noncontrolling Interests									(8,930)
Balance, end of period at Sep. 30, 2018			37,280		10,248,833	233,825	(50,689)
Balance, end of period at Sep. 30, 2018									(2,158)
DISTRIBUTIONS
Distributions declared per Unit outstanding								$ 1.62
Balance, beginning of year at Jun. 30, 2018			37,280		10,238,467	232,995	(67,310)
Balance, beginning of year at Jun. 30, 2018									(1,646)
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner					25	(25)
Exercise of EQR share options					3,383
EQR's Employee Share Purchase Plan (ESPP)				893
Share-based employee compensation expense:
EQR restricted shares					1,641
EQR share options					670
EQR ESPP discount					204
Net income available to Units - General Partner		214,164			214,164
OP Units General Partner distributions					(198,939)
Supplemental Executive Retirement Plan (SERP)					5
Change in market value of Redeemable Limited Partners					(14,189)
Adjustment for Limited Partners ownership in Operating Partnership					2,509	(2,509)
LIMITED PARTNERS
Conversion of OP Units held by Limited Partners into OP Units held by General Partner					25	(25)
Equity compensation associated with Units - Limited Partners						2,958
Net income available to Units - Limited Partners		8,159				8,159
Units - Limited Partners distributions						(7,186)
Change in carrying value of Redeemable Limited Partners						(567)
Adjustment for Limited Partners ownership in Operating Partnership					2,509	(2,509)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period	12,026	12,026					12,026
Losses reclassified into earnings from other comprehensive income	(4,595)	(4,595)					4,595
NONCONTROLLING INTERESTS PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	223,846	223,846							750
Distributions to Noncontrolling Interests									(1,262)
Balance, end of period at Sep. 30, 2018			37,280		10,248,833	233,825	(50,689)
Balance, end of period at Sep. 30, 2018									(2,158)
DISTRIBUTIONS
Distributions declared per Unit outstanding								0.54
Balance, beginning of year at Dec. 31, 2018			37,280		10,200,910	228,738	(64,986)
Balance, beginning of year at Dec. 31, 2018									(2,293)
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner					9,843	(9,843)
Exercise of EQR share options					67,066
EQR's Employee Share Purchase Plan (ESPP)				2,323
Share-based employee compensation expense:
EQR restricted shares					10,304
EQR share options					2,185
EQR ESPP discount					502
Net income available to Units - General Partner		678,295			678,295
OP Units General Partner distributions					(631,635)
Offering costs					(789)
Supplemental Executive Retirement Plan (SERP)					(1,539)
Change in market value of Redeemable Limited Partners					(114,936)
Adjustment for Limited Partners ownership in Operating Partnership					6,919	(6,919)
LIMITED PARTNERS
Conversion of OP Units held by Limited Partners into OP Units held by General Partner					9,843	(9,843)
Equity compensation associated with Units - Limited Partners						12,200
Net income available to Units - Limited Partners		25,339				25,339
Units - Limited Partners distributions						(22,493)
Change in carrying value of Redeemable Limited Partners						(957)
Adjustment for Limited Partners ownership in Operating Partnership					6,919	(6,919)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period	(33,765)	(33,765)					(33,765)
Losses reclassified into earnings from other comprehensive income	(14,659)	(14,659)					14,659
NONCONTROLLING INTERESTS PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	708,402	708,402							2,450
Contributions by Noncontrolling Interests									4,594
Distributions to Noncontrolling Interests									(6,453)
Balance, end of period at Sep. 30, 2019			37,280		10,229,448	226,065	(84,092)
Balance, end of period at Sep. 30, 2019									(1,702)
DISTRIBUTIONS
Distributions declared per Unit outstanding								1.7025
Balance, beginning of year at Jun. 30, 2019			37,280		10,206,098	227,320	(89,849)
Balance, beginning of year at Jun. 30, 2019									(1,298)
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner					4,972	(4,972)
Exercise of EQR share options					18,579
EQR's Employee Share Purchase Plan (ESPP)				$ 671
Share-based employee compensation expense:
EQR restricted shares					2,322
EQR share options					503
EQR ESPP discount					137
Net income available to Units - General Partner		266,333			266,333
OP Units General Partner distributions					(210,719)
Offering costs					(634)
Change in market value of Redeemable Limited Partners					(57,962)
Adjustment for Limited Partners ownership in Operating Partnership					(852)	852
LIMITED PARTNERS
Conversion of OP Units held by Limited Partners into OP Units held by General Partner					4,972	(4,972)
Equity compensation associated with Units - Limited Partners						1,371
Net income available to Units - Limited Partners		9,910				9,910
Units - Limited Partners distributions						(7,414)
Change in carrying value of Redeemable Limited Partners						(1,002)
Adjustment for Limited Partners ownership in Operating Partnership					(852)	852
Accumulated other comprehensive income (loss) – derivative instruments:
Losses reclassified into earnings from other comprehensive income	(5,757)	(5,757)					5,757
NONCONTROLLING INTERESTS PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	$ 277,846	$ 277,846							830
Distributions to Noncontrolling Interests									(1,234)
Balance, end of period at Sep. 30, 2019			$ 37,280		$ 10,229,448	$ 226,065	$ (84,092)
Balance, end of period at Sep. 30, 2019									$ (1,702)
DISTRIBUTIONS
Distributions declared per Unit outstanding								$ 0.5675

Business

Business	9 Months Ended
	Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Business	1. Business Equity Residential (“EQR”) is an S&P 500 company focused on the acquisition, development and management of rental apartment properties located in urban and high-density suburban communities, a business that is conducted on its behalf by ERP Operating Limited Partnership (“ERPOP”). EQR is a Maryland real estate investment trust (“REIT”) formed in March 1993 and ERPOP is an Illinois limited partnership formed in May 1993. ERPOP. ERPOP. EQR is the general partner of, and as of September 30, 2019 owned an approximate 96.4% ownership interest in, ERPOP. All of the Company’s property ownership, development and related business operations are conducted through the Operating Partnership ERPOP. ERPOP, As of September 30, 2019, the Company, directly or indirectly through investments in title holding entities, owned all or a portion of 308 properties located in 10 states and the District of Columbia consisting of 80,299 apartment units. The ownership breakdown includes (table does not include various uncompleted development properties): Properties Apartment Units Wholly Owned Properties 290 76,602 Master-Leased Properties – Consolidated 1 162 Partially Owned Properties – Consolidated 17 3,535 308 80,299

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Summary Of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. 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 nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019. 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, 2018 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, 2018 . 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 may incur both federal and state income taxes on any taxable income of such entities after consideration of any net operating losses. In December 2017, H.R. 1, informally titled the Tax Cuts and Jobs Act (the “Tax Act”), became law. As of September 30, 2019, the Tax Act did not have a material impact on our REIT or subsidiary entities, our ability to continue to qualify as a REIT or on our results of operations. Recently Issued Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“ FASB”) Recently Adopted Accounting Pronouncements In FASB Revenue from Contracts with Customers For the remaining approximately 6% of rental income that is subject to the revenue recognition standard, the Company’s disaggregated revenue streams are disclosed in the table included in the Company’s and the Operating Partnership’s Annual Report on Form 10-K for the year ended December 31, 2018 and are comparable with the percentage of rental income for the nine months and quarter ended September 30, 2019. These revenue streams have the same timing and pattern of revenue recognition across our reportable segments, with consistent allocations between the leasing and revenue recognition standards. Additionally, as part of the revenue recognition standard, the FASB issued amendments related to partial sales of real estate. Adoption of the partial sales standard did not result in a change of accounting for the Company related to its disposition process. We concluded that the Company’s typical dispositions will continue to meet the criteria for sale and associated profit recognition under both standards. In • Lessors – Leases are accounted for using an approach that is substantially equivalent to existing guidance for operating, sales-type and financing leases, but aligned with the revenue recognition standard. Lessors are required to allocate lease payments to separate lease and non-lease components of each lease agreement, with the non-lease com ponents evaluated under the revenue recognition standard. • Lessees – Leases are accounted for using a dual approach, classifying leases as either operating or finance based on the principle of whether or not the lease is effectively a financed purchase of the leased asset by the lessee. This classification determines whether the lease expense is recognized on a straight-line basis over the term of the lease (for operating leases) or based on an effective interest method (for finance leases). A lessee is also required to record a right-of-use asset and a lease liability on its balance sheet for all leases with a term of greater than 12 months regardless of their classification as operating or finance leases. Leases with a term of 12 months or less are accounted for similar to existing guidance for operating leases. The Company adopted this standard as required effective January 1, 2019 using a modified retrospective method and the Company applied the guidance as of the adoption date and elected certain practical expedients, as described below. The standard impacted our consolidated balance sheets but did not impact our consolidated statements of operations. Right-of-use (“ROU”) assets and lease liabilities where the Company is the lessee were recognized for various corporate office leases and ground leases. The Company recorded ROU assets and related lease liabilities to its opening balance sheet upon adoption on January 1, 2019 of $434.2 million and $278.3 million, respectively. The Company calculated the net present value of the lease liabilities on January 1, 2019 and reclassed the following amounts from other assets and other liabilities to record our initial ROU assets (amounts in thousands): January 1, 2019 Balance Sheet Reclass: Initial lease liabilities $ 278,287 Reclassifications: Prepaid ground leases 17,886 Other Assets Ground lease intangibles – below market, net 166,230 Other Assets Ground lease intangibles – above market, net (2,110 ) Other Liabilities Straight-line rent liabilities (1) (26,092 ) Other Liabilities Initial right-of-use assets $ 434,201 (1) Straight-line rent liabilities relate to corporate office leases and certain ground leases. The Company elected the practical expedient to not reassess the classification of existing operating leases. As of January 1, 2019, any new or modified ground leases may be classified as financing leases unless they meet certain conditions. When there is a material lease modification, the Company is required to reassess the classification and remeasure the lease liability. In July 2018, the FASB issued an amendment to the leases standard, which includes a practical expedient that provides lessors an option not to separate lease and non-lease components when certain criteria are met and instead account for those components as a single component under the leases standard. The amendment also provides a transition option that permits the application of the new guidance as of the adoption date rather than to all periods presented. The Company elected the practical expedient to account for both its lease and non-lease components as a single component under the leases standard and elected the new transition option as of the date of adoption effective January 1, 2019. See Note 8 for additional discussion regarding the new lease standard. In August 2017, the FASB issued a final standard which makes changes to the hedge accounting model to enable entities to better portray their risk management activities in the financial statements. The standard expands an entity’s ability to hedge nonfinancial and financial risk components, reduces complexity in fair value hedges of interest rate risk and eases certain documentation and assessment requirements. The standard also eliminates the requirement to separately measure and report hedge ineffectiveness and generally requires the entire change in the fair value of any hedging instrument to be presented in the same income statement line as the hedged instrument. The Company adopted this standard as required effective January 1, 2019 and it did not have a material effect on its consolidated results of operations or financial position.

Equity, Capital and Other Inter

Equity, Capital and Other Interests	9 Months Ended
	Sep. 30, 2019
Equity Capital And Other Interests [Abstract]
Equity, Capital and Other Interests	3. Equity, Capital and Other 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) for the nine months ended September 30, 2019 and 2018: 2019 2018 Common Shares Common Shares outstanding at January 1, 369,405,161 368,018,082 Common Shares Issued: Conversion of OP Units 294,400 12,510 Exercise of share options 1,430,048 194,796 Employee Share Purchase Plan (ESPP) 37,263 61,321 Restricted share grants, net 160,460 122,877 Common Shares outstanding at September 30, 371,327,332 368,409,586 Units Units outstanding at January 1, 13,904,035 13,768,438 Restricted unit grants, net 140,055 267,074 Conversion of OP Units to Common Shares (294,400 ) (12,510 ) Units outstanding at September 30, 13,749,690 14,023,002 Total Common Shares and Units outstanding at September 30, 385,077,022 382,432,588 Units Ownership Interest in Operating Partnership 3.6 % 3.7 % 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 law, Instruments that require settlement in registered shares cannot be classified in permanent equity as it is not always completely within an issuer’s control to deliver registered shares. Therefore, settlement in cash is assumed and that responsibility for settlement in cash is deemed to fall to the Operating Partnership as the primary source of cash for EQR, resulting in presentation in the mezzanine section of the balance sheet. The Redeemable Noncontrolling Interests – Operating Partnership are adjusted to the greater of carrying value or fair market value based on the Common Share price of EQR at the end of each respective reporting period. EQR has the ability to deliver unregistered Common Shares for the remaining portion of the Noncontrolling Interests – Operating Partnership Units that are classified in permanent equity at September 30, 2019 and December 31, 2018. The The 2019 2018 Balance at January 1, $ 379,106 $ 366,955 Change in market value 114,936 14,361 Change in carrying value 957 (77 ) Balance at September 30, $ 494,999 $ 381,239 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 100,000,000 The Amounts in thousands Annual Call Dividend Per September 30, December 31, Date (1) Share (2) 2019 2018 Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized: 8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of September 30, 2019 and December 31, 2018 12/10/26 $ 4.145 $ 37,280 $ 37,280 $ 37,280 $ 37,280 (1) On or after the call date, redeemable preferred shares may be redeemed for cash at the option of the Company, in whole or in part, at a redemption price equal to the liquidation price per share, plus accrued and unpaid distributions, if any. (2) Dividends on Preferred Shares are payable quarterly. Capital and Redeemable Limited Partners of ERP Operating Limited Partnership The following tables present the changes in the Operating Partnership’s issued and outstanding Units and in the limited partners’ Units for the nine months ended September 30, 2019 and 2018: 2019 2018 General and Limited Partner Units General and Limited Partner Units outstanding at January 1, 383,309,196 381,786,520 Issued to General Partner: Exercise of EQR share options 1,430,048 194,796 EQR’s Employee Share Purchase Plan (ESPP) 37,263 61,321 EQR’s restricted share grants, net 160,460 122,877 Issued to Limited Partners: Restricted unit grants, net 140,055 267,074 General and Limited Partner Units outstanding at September 30, 385,077,022 382,432,588 Limited Partner Units Limited Partner Units outstanding at January 1, 13,904,035 13,768,438 Limited Partner restricted unit grants, net 140,055 267,074 Conversion of Limited Partner OP Units to EQR Common Shares (294,400 ) (12,510 ) Limited Partner Units outstanding at September 30, 13,749,690 14,023,002 Limited Partner Units Ownership Interest in Operating Partnership 3.6 % 3.7 % The Limited Partners of the Operating Partnership as of September 30, 2019 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 cannot be classified in permanent equity as it is not always completely within an issuer’s control to deliver registered shares. Therefore, settlement in cash is assumed and that responsibility for settlement in cash is deemed to fall to the Operating Partnership as the primary source of cash for EQR, resulting in presentation in the mezzanine section of the balance sheet. The Redeemable Limited Partner Units are adjusted to the greater of carrying value or fair market value based on the Common Share price of EQR at the end of each respective reporting period. EQR has the ability to deliver unregistered Common Shares for the remaining portion of the Limited Partner Units that are classified in permanent equity at September 30, 2019 . The carrying value of the Redeemable Limited Partner Units is allocated based on the number of Redeemable Limited Partner The following table presents the changes in the redemption value of the Redeemable Limited Partners for the nine months ended September 30, 2019 and 2018 (amounts in thousands): 2019 2018 Balance at January 1, $ 379,106 $ 366,955 Change in market value 114,936 14,361 Change in carrying value 957 (77 ) Balance at September 30, $ 494,999 $ 381,239 EQR contributes all net proceeds from its various equity offerings (including proceeds from exercise of options for Common ERPOP. The December 31, 2018 Amounts in thousands Annual Call Dividend Per September 30, December 31, Date (1) Unit (2) 2019 2018 Preference Units: 8.29% Series K Cumulative Redeemable Preference Units; liquidation value $50 per unit; 745,600 units issued and outstanding as of September 30, 2019 and December 31, 2018 12/10/26 $ 4.145 $ 37,280 $ 37,280 $ 37,280 $ 37,280 (1) On or after the call date, redeemable preference units may be redeemed for cash at the option of the Operating Partnership, in whole or in part, at a redemption price equal to the liquidation price per unit, plus accrued and unpaid distributions, if any, in conjunction with the concurrent redemption of the corresponding Company Preferred Shares. (2) Dividends on Preference Units are payable quarterly. Other EQR and ERPOP currently have an active universal shelf registration statement for the issuance of equity and debt securities that automatically became effective upon filing with the SEC in June 2019 and expires in June 2022. Per the terms of ERPOP’s partnership agreement, EQR contributes the net proceeds of 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) or preference units (on a one-for-one preferred share per preference unit basis). The Company has an At-The-Market (“ATM”) The Company may repurchase up to 13.0 million Common Shares under its share repurchase program. No open market repurchases have occurred since 2008, and no repurchases of any kind have occurred since February 2014. As of September 30, 2019, EQR has remaining authorization to repurchase up to 13.0 million of its shares under the repurchase program.

Real Estate

Real Estate	9 Months Ended
	Sep. 30, 2019
Real Estate [Abstract]
Real Estate	4. Real Estate The following table summarizes the carrying amounts for the Company’s investment in real estate (at cost) as of September 30, 2019 and December 31, 2018 (amounts in thousands): September 30, 2019 December 31, 2018 Land $ 5,955,121 $ 5,875,803 Depreciable property: Buildings and improvements 18,796,370 18,232,625 Furniture, fixtures and equipment 1,875,121 1,722,231 In-Place lease intangibles 496,764 481,045 Projects under development: Land 23,531 25,429 Construction-in-progress 119,903 83,980 Land held for development: Land 64,660 61,038 Construction-in-progress 26,357 28,871 Investment in real estate 27,357,827 26,511,022 Accumulated depreciation (7,171,876 ) (6,696,281 ) Investment in real estate, net $ 20,185,951 $ 19,814,741 During the nine months ended September 30, 2019, the Company acquired the following from unaffiliated parties (purchase price in thousands): Properties Apartment Units Purchase Price Rental Properties – Consolidated (1) 10 2,728 $ 1,124,580 Land Parcels (three) (2) — — 19,832 Total 10 2,728 $ 1,144,412 (1) Purchase price includes an allocation of approximately $193.4 million to land and $933.3 million to depreciable property (inclusive of capitalized closing costs). (2) Purchase price includes an allocation of approximately $16.7 million to vacant land and $3.8 million to construction-in-progress (inclusive of capitalized closing costs). Land parcels include entry into one long-term ground lease for a land project under development in the Washington D.C. market. See Notes 6 and 8 for additional discussion. During the nine months ended September 30, 2019, the Company disposed of the following to unaffiliated parties (sales price in thousands): Properties Apartment Units Sales Price Rental Properties – Consolidated 9 1,202 $ 706,675 Rental Properties – Unconsolidated (1) 2 945 394,500 Land Parcels (one) — — 1,900 Total 11 2,147 $ 1,103,075 ( 1 ) The Company owned a 20% interest in both unconsolidated rental properties. Sales price listed is the gross sales price. The Company received net sales proceeds of approximately $78.3 million. The Company recognized a net gain on sales of real estate properties of approximately $269.4 million, a net gain on sales of unconsolidated entities of approximately $69.5 million and a net gain on sales of land parcels of approximately $2.1 million on the above sales.

Commitments to Acquire_Dispose

Commitments to Acquire/Dispose of Real Estate	9 Months Ended
	Sep. 30, 2019
Commitments To Acquire Dispose Of Real Estate [Abstract]
Commitments to Acquire/Dispose of Real Estate	5. Commitments to Acquire/Dispose of Real The Company has not entered into any agreements to acquire rental properties or land parcels as of the date of filing. The Company has entered into separate agreements to dispose of the following (sales price in thousands): Properties Apartment Units Sales Price Rental Properties – Consolidated 1 939 $ 254,000 Land Parcels (three) — — 55,350 Total 1 939 $ 309,350 The closing of pending transactions is subject to certain conditions and restrictions; therefore, there can be no assurance that the transactions will be consummated or that the final terms will not differ in material respects from any agreements summarized above. See Note 14 for discussion of the properties acquired or disposed of, if any, subsequent to September 30, 2019.

Investments in Partially Owned

Investments in Partially Owned Entities	9 Months Ended
	Sep. 30, 2019
Investments In Partially Owned Entities [Abstract]
Investments in Partially Owned Entities	6. Investments in Partially Owned The Consolidated Variable Interest Entities (“VIEs”) In accordance with accounting standards for consolidation of VIEs, the Company consolidates ERPOP on EQR’s financial statements. As the sole general partner of ERPOP, EQR has exclusive control of ERPOP’s day-to-day management. The limited partners are not able to exercise substantive kick-out or participating rights. As a result, ERPOP qualifies as a VIE. EQR has a controlling financial interest in ERPOP and, thus, is ERPOP’s primary beneficiary. EQR has the power to direct the activities of ERPOP that most significantly impact ERPOP’s economic performance as well as the obligation to absorb losses or the right to receive benefits from ERPOP that could potentially be significant to ERPOP. The Company has various equity interests in certain joint ventures owning 17 properties containing 3,535 apartment units. The Company is the general partner or managing member of these joint ventures and is responsible for managing the operations and affairs of the joint ventures as well as making all decisions regarding the businesses of the joint ventures. The limited partners or non-managing members are not able to exercise substantive kick-out or participating rights. As a result, the joint ventures qualify as VIEs. The Company has a controlling financial interest in the VIEs and, thus, is the VIEs’ primary beneficiary. The Company has both the power to direct the activities of the VIEs that most significantly impact the VIEs’ economic performance as well as the obligation to absorb losses or the right to receive benefits from the VIEs that could potentially be significant to the VIEs. As a result, the joint ventures are required to be consolidated on the Company’s financial statements. During the nine months ended September 30, 2019, the Company entered into a consolidated joint venture which is owned 90% by the Company and 10% by its joint venture partner, who is the general partner and developer. The joint venture has been deemed to be a VIE and is consolidated due to the Company being the primary beneficiary. The joint venture owns a land parcel which it is currently developing into a multifamily rental property. The consolidated assets and liabilities related to the VIEs discussed above were approximately $711.5 million and $325.5 million, respectively, at September 30, 2019 Investments in Unconsolidated Entities The following table and information summarizes the Company’s investments in unconsolidated entities, which are accounted for under the equity method of accounting as the requirements for consolidation are not met, as of September 30, 2019 and December 31, 2018 (amounts in thousands except for ownership percentage): September 30, 2019 December 31, 2018 Ownership Percentage Investments in Unconsolidated Entities: Wisconsin Place Developer (VIE) (1) $ 40,896 $ 42,365 33.3% Operating Properties (Non-VIE) (2) — 10,494 20.0% Real Estate Technology/Other 11,578 5,490 Varies Investments in Unconsolidated Entities $ 52,474 $ 58,349 (1) Represents an unconsolidated interest in an entity that owns the land underlying one of the consolidated joint venture properties noted above and owns and operates a related parking facility. The joint venture, as a limited partner, does not have substantive kick-out or participating rights in the entity. As a result, the entity qualifies as a VIE. The joint venture does not have a controlling financial interest in the VIE and is not the VIE’s primary beneficiary. The joint venture does not have the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance or the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. As a result, the entity that owns the land and owns and operates the parking facility is unconsolidated and recorded using the equity method of accounting. (2) Includes two joint ventures under separate agreements with the same partner totaling 945 apartment units as of December 31, 2018. During the nine months ended September 30, 2019, the Company and its joint venture partner sold both properties under separate agreements to unaffiliated parties. See Note 4 for additional discussion.

Restricted Deposits

Restricted Deposits	9 Months Ended
	Sep. 30, 2019
Deposits Restricted [Abstract]
Restricted Deposits	7. Restricted Deposits The following table presents the Company’s restricted deposits as of September 30, 2019 and December 31, 2018 (amounts in thousands): September 30, 2019 December 31, 2018 Mortgage escrow deposits: Real estate taxes and insurance $ — $ 876 Replacement reserves 8,523 8,641 Mortgage principal reserves/sinking funds 8,758 9,754 Other — 852 Mortgage escrow deposits 17,281 20,123 Restricted cash: Earnest money on pending acquisitions — 5,000 Restricted deposits on real estate investments 665 540 Resident security and utility deposits 36,888 35,659 Other 985 7,549 Restricted cash 38,538 48,748 Restricted deposits $ 55,819 $ 68,871

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	8 . Leases Lessor Accounting The Company is the lessor for its residential and retail leases (including commercial leases) and these leases will continue to be accounted for as operating leases under the new standard as described in Note 2. Therefore, the Company did not have significant changes in the accounting for its lease revenues. For the nine months ended September 30, 2019, approximately 97.1% of the Company’s total lease revenue is generated from residential apartment leases that are generally for twelve months or less in length. The residential apartment leases may include lease income related to such items as parking, storage and pet rent that the Company treats as a single lease component because the amenities cannot be leased on their own and the timing and pattern of revenue recognition are the same. The collection of lease payments at lease commencement is probable and therefore the Company subsequently recognizes lease income over the lease term on a straight-line basis. Residential leases are renewable upon consent of both parties on an annual or monthly basis. For the nine months ended September 30, 2019, approximately 2.9% of the Company’s total lease revenue is generated by retail leases that are generally for terms ranging between 5-10 years. The retail leases generally consist of ground floor retail spaces and master-leased parking garages that serve as additional amenities for our residents. The retail leases may include lease income related to such items as parking and storage rent that the Company treats as a single lease component because the amenities cannot be leased on their own and the timing and pattern of revenue recognition are the same. The collection of lease payments at lease commencement is probable and therefore the Company subsequently recognizes lease income over the lease term on a straight-line basis. Retail leases are renewable with market-based renewal options. The Company elected the practical expedient to account for both its lease and non-lease components (specifically common area maintenance charges) as a single lease component under the leases standard. The following table presents the lease income types relating to lease payments for residential and retail leases for the nine months and quarter ended September 30, 2019 (amounts in thousands): Nine Months Ended September 30, 2019 Quarter Ended September 30, 2019 Lease Income Type Residential Leases Retail Leases Total Residential Leases Retail Leases Total Residential and retail rent $ 1,801,749 $ 54,616 $ 1,856,365 $ 611,020 $ 18,453 $ 629,473 Parking rent 27,874 259 28,133 9,405 100 9,505 Storage rent 2,796 51 2,847 940 20 960 Pet rent 8,714 — 8,714 2,916 — 2,916 Total lease revenue (1) $ 1,841,133 $ 54,926 $ 1,896,059 $ 624,281 $ 18,573 $ 642,854 (1) Excludes other rental income of $120.7 million for the nine months ended September 30, 2019 and $42.2 million for the quarter ended September 30, 2019, which is accounted for under the revenue recognition standard. Lessee Accounting The Company is the lessee under various corporate office and ground leases for which the Company recognized ROU assets and related lease liabilities effective January 1, 2019. The following table presents the Company’s ROU assets and related lease liabilities as of September 30, 2019 (amounts in thousands): 2019 Right-of-use assets: Corporate office leases $ 43,739 Ground leases (finance) 23,201 Ground leases (operating) 414,104 Right-of-use assets $ 481,044 Lease liabilities: Corporate office leases $ 45,237 Ground leases (finance) 23,210 Ground leases (operating) 264,865 Lease liabilities $ 333,312 As the standard requires the recognition of a liability for the lease obligation, discount rates are used to determine the net present value of the lease payments. The discount rate for the lease is the rate implicit in the lease or, if that rate cannot be readily determined, the incremental borrowing rate. As the Company does not know the amount of the lessors’ initial direct costs, it cannot readily determine the rate implicit in the lease and instead must apply the incremental borrowing rate. The Company has estimated the discount rate ranges of 3.3% to 3.9% for corporate office leases and 4.4% to 5.5% for ground leases at adoption. Since the Company’s credit backs the corporate office lease obligations and the lease terms are generally ten years or less, the discount rate range was estimated by using the Company’s borrowing rates for actual pricing data. The discount rate range for ground leases takes into account various factors, including the longer life of the ground leases, and was estimated by using the Company’s borrowing rates for actual pricing data through 30 years and other long-term market rates. Corporate office leases The Company leases nine corporate offices with remaining lease terms of one to 23 years (inclusive of applicable extension options). The Company’s corporate office leases continue to be accounted for as operating leases under the new standard. During the quarter ended September 30, 2019, the Company modified two office leases that continue to be classified as operating leases and recorded an additional lease liability and ROU asset at initial remeasurement of approximately $29.1 million. The Company leases its corporate headquarters from an entity affiliated with EQR’s Chairman of the Board of Trustees. The lease term expires on November 30, 2032 and contains two five-year extension options. The amount incurred for such office space for the nine months and quarter ended September 30, 2019 was approximately $2.0 million and $0.7 million, respectively. The Company believes this amount approximates market rates for such rental space. Ground leases The Company maintains long-term ground leases for 14 operating properties and one project under development with lease expiration dates ranging from 2042 through 2113 (inclusive of applicable purchase options). The Company owns the building and improvements. Based on its election of the package of practical expedients, the Company was not required to reassess the classification of existing ground leases and therefore the 14 operating property leases continue to be accounted for as operating leases. During the quarter ended September 30, 2019, the Company entered into a new ground lease for a project under development that is being accounted for as a finance lease and recorded an initial lease liability and ROU asset of approximately $23.2 million. Additional disclosures The following table illustrates the quantitative disclosures for lessees as of and for the nine months and quarter ended September 30, 2019 (amounts in thousands): Nine Months Ended September 30, 2019 Quarter Ended September 30, 2019 Lease cost: Finance lease cost: Amortization of right-of-use assets $ — $ — Interest on lease liabilities (capitalized) 55 55 Operating lease cost: Corporate office leases 2,753 935 Ground leases 16,650 5,550 Short-term lease cost: Corporate office leases 168 56 Ground leases — — Variable lease cost: Corporate office leases 1,130 361 Ground leases 2,575 880 Total lease cost $ 23,331 $ 7,837 The following table illustrates the quantitative disclosures for lessees as of and for the nine months ended September 30, 2019 (amounts in thousands): September 30, 2019 Other information: Cash paid for amounts included in the measurement of lease liabilities: Investing cash flows from finance leases (capitalized) $ 47 Operating cash flows from operating leases: Corporate office leases $ 4,128 Ground leases $ 12,035 ROU assets obtained in exchange for new finance lease liabilities $ 23,201 ROU assets obtained in exchange for new operating lease liabilities: Corporate office leases $ 45,791 Ground leases $ 422,018 Weighted-average remaining lease term – finance leases 19.9 years Weighted-average remaining lease term – operating leases: Corporate office leases 19.2 years Ground leases 56.4 years Weighted-average discount rate – finance leases 3.0 % Weighted-average discount rate – operating leases: Corporate office leases 3.2 % Ground leases 5.0 % The following table summarizes the Company’s undiscounted cash flows for contractual obligations for minimum rent payments/receipts under operating and financing leases for the next five years and thereafter as of September 30, 2019: (Payments)/Receipts Due by Year (in thousands) Remaining 2019 2020 2021 2022 2023 2024 Thereafter Total Finance Leases: Minimum Rent Payments (a) $ (141 ) $ (567 ) $ (578 ) $ (590 ) $ (601 ) $ (614 ) $ (33,850 ) $ (36,941 ) Operating Leases: Minimum Rent Payments (a) $ (4,175 ) $ (16,840 ) $ (16,862 ) $ (16,602 ) $ (16,687 ) $ (17,014 ) $ (977,238 ) $ (1,065,418 ) Minimum Rent Receipts (b) $ 16,194 $ 63,409 $ 60,140 $ 56,624 $ 49,150 $ 41,950 $ 149,208 $ 436,675 (a) Minimum basic rent due for corporate office leases and base rent due on ground leases where the Company is the lessee. (b) Minimum basic rent receipts due for various retail space where the Company is the lessor. Excludes residential leases due to their short-term nature. The following table provides a reconciliation of lease liabilities from our undiscounted cash flows for minimum rent payments as of September 30, 2019 (amounts in thousands): 2019 Total minimum rent payments $ 1,102,359 Less: Lease discount 769,047 Lease liabilities $ 333,312

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	9 . Debt EQR Mortgage Notes Payable As of September 30, 2019, the Company had outstanding mortgage debt of approximately $2.0 billion. During the nine months ended September 30, 2019, the Company: • Obtained $288.1 million in 3.94% fixed rate mortgage debt held in a Fannie Mae loan pool maturing on March 1, 2029; • Obtained $7.6 million in variable rate construction mortgage debt that is non-recourse to the Company maturing on June 25, 2022 (total commitment of $67.6 million); • Repaid $132.6 million of tax-exempt variable rate mortgage bonds maturing in 2032 through 2036; • Repaid $ 5.9 2032 2035 • Repaid $500.0 million of 5.78% mortgage debt held in a Freddie Mac loan pool at par prior to the July 1, 2020 maturity date; • Repaid $84.5 million of 4.79% mortgage debt maturing in 2053 and incurred a prepayment penalty of $3.4 million; and • Repaid $4.9 million of scheduled principal repayments on various mortgage debt. The Company recorded $2.3 million of write-offs of unamortized deferred financing costs during the nine months ended September 30, 2019 as additional interest expense related to debt extinguishment of mortgages. The Company also recorded $6.2 million of write-offs of net unamortized discounts during the nine months ended September 30, 2019 as additional interest expense related to debt extinguishment of mortgages. As of September 30, 2019, the Company had $301.7 million of secured debt (primarily tax-exempt bonds) subject to third party credit enhancement. As Notes As of September 30, 2019, the Company had outstanding unsecured notes of approximately $6.7 billion. During the nine months ended September 30, 2019, the Company: • Issued $600.0 million of ten-year 3.00% unsecured notes, receiving net proceeds of approximately $597.5 million before underwriting fees, hedge termination costs and other expenses; • Issued $600.0 million of ten-year 2.50% unsecured notes, receiving net proceeds of approximately $597.0 million before underwriting fees and other expenses; and • Repaid $450.0 million of 2.375% unsecured notes at maturity. The fair value interest rate swaps matured in conjunction with the maturity of the notes that converted the fixed rate of 2.375% to a floating interest rate of 90-Day LIBOR plus 0.61%. As September 30, 2019 The Company’s unsecured public debt contains certain financial and operating covenants including, among other things, maintenance of certain financial ratios. The Company was in compliance with its unsecured public debt covenants for the nine months ended September 30, 2019. Line of Credit and Commercial Paper The Company has a $2.0 billion unsecured revolving credit facility maturing January 10, 2022. The Company has the ability to increase available borrowings by an additional $750.0 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 0.825%), or based on bids received from the lending group, and the Company pays an annual facility fee (currently ). Both the spread and the facility fee are dependent on the Company’s senior unsecured credit rating. The Company has an T he Company limits its utilization of the revolving credit facility in order to maintain liquidity to support its $500.0 million commercial paper program along with certain other obligations. The following table presents the availability on the Company’s unsecured revolving credit facility as of September 30, 2019 (amounts in thousands): September 30, 2019 Unsecured revolving credit facility commitment $ 2,000,000 Commercial paper balance outstanding (355,000 ) Unsecured revolving credit facility balance outstanding — Other restricted amounts (100,929 ) Unsecured revolving credit facility availability $ 1,544,071 Other In 2017, the Company executed a letter of credit facility with a third party financial institution which is not backed or collateralized by borrowings on the Company’s unsecured revolving credit facility. As of September 30, 2019, there was $9.0 million in letters of credit outstanding on this facility.

Derivative and Other Fair Value

Derivative and Other Fair Value Instruments	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Derivative and Other Fair Value Instruments	10 . Derivative and Other Fair Value 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 commodity prices in the daily operations of the business. A • 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 The Company’s derivative positions are valued using models developed by the respective counterparty as well as models applied internally by the Company that use as their inputs 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 commercial paper and line of credit, if applicable) 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 commercial paper and line of credit, if applicable) and quoted market prices for each underlying issuance in the case of the public unsecured notes. The fair values of the Company’s financial instruments (other than mortgage notes payable, unsecured notes, commercial paper, line of credit and derivative instruments), including cash and cash equivalents and other financial instruments, approximate their carrying or contract value. The September 30, 2019 December 31, 2018 Carrying Value Estimated Fair Value (Level 2) Carrying Value Estimated Fair Value (Level 2) Mortgage notes payable, net $ 1,962,471 $ 1,961,120 $ 2,385,470 $ 2,352,502 Unsecured debt, net 7,029,465 7,599,742 6,432,469 6,481,426 Total debt, net $ 8,991,936 $ 9,560,862 $ 8,817,939 $ 8,833,928 The Fair Value Measurements at Reporting Date Using Description Balance Sheet Location 9/30/2019 Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Supplemental Executive Retirement Plan Other Assets $ 146,542 $ 146,542 $ — $ — Liabilities Supplemental Executive Retirement Plan Other Liabilities $ 146,542 $ 146,542 $ — $ — Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners Mezzanine $ 494,999 $ — $ 494,999 $ — Fair Value Measurements at Reporting Date Using Description Balance Sheet Location 12/31/2018 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: Forward Starting Swaps Other Assets $ 2,000 $ — $ 2,000 $ — Supplemental Executive Retirement Plan Other Assets 134,088 134,088 — — Total $ 136,088 $ 134,088 $ 2,000 $ — Liabilities Derivatives designated as hedging instruments: Interest Rate Contracts: Fair Value Hedges Other Liabilities $ 2,277 $ — $ 2,277 $ — Forward Starting Swaps Other Liabilities 9,851 — 9,851 — Supplemental Executive Retirement Plan Other Liabilities 134,088 134,088 — — Total $ 146,216 $ 134,088 $ 12,128 $ — Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners Mezzanine $ 379,106 $ — $ 379,106 $ — The September 30, 2019 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 $ 2,277 Fixed rate debt Interest expense $ (2,277 ) Total $ 2,277 $ (2,277 ) September 30, 2018 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 $ (1,491 ) Fixed rate debt Interest expense $ 1,491 Total $ (1,491 ) $ 1,491 The Effective Portion September 30, 2019 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/(Loss) Reclassified from Accumulated OCI into Income Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps $ (33,765 ) Interest expense $ (14,659 ) Total $ (33,765 ) $ (14,659 ) Effective Portion Ineffective Portion September 30, 2018 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/(Loss) Reclassified from Accumulated OCI into Income Location of Gain/(Loss) Recognized in Income on Derivative Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps $ 24,021 Interest expense $ (13,902 ) N/A $ — Total $ 24,021 $ (13,902 ) $ — As September 30, 2019 In June 2019, the Company paid approximately $41.8 million to settle ten forward starting swaps in conjunction with the issuance of $600.0 million of ten-year unsecured public notes. The accrued interest of approximately $0.2 million was recorded as an increase to interest expense. The remaining $41.6 million will be deferred as a component of accumulated other comprehensive income (loss) and will be recognized as an increase to interest expense over the first nine years and eleven months of the notes. In July 2019, six fair value interest rate swaps matured in conjunction with the maturity of the $450.0 million of 2.375% unsecured notes.

Earnings Per Share and Earnings

Earnings Per Share and Earnings Per Unit	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Share And Earnings Per Unit	1 1 . Earnings Per Share and Earnings Per Equity Residential The Nine Months Ended September 30, Quarter Ended September 30, 2019 2018 2019 2018 Numerator for net income per share – basic: Net income $ 708,402 $ 562,804 $ 277,846 $ 223,846 Allocation to Noncontrolling Interests – Operating Partnership (25,339 ) (20,517 ) (9,910 ) (8,159 ) Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties (2,450 ) (1,939 ) (830 ) (750 ) Preferred distributions (2,318 ) (2,318 ) (773 ) (773 ) Numerator for net income per share – basic $ 678,295 $ 538,030 $ 266,333 $ 214,164 Numerator for net income per share – diluted: Net income $ 708,402 $ 562,804 $ 277,846 $ 223,846 Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties (2,450 ) (1,939 ) (830 ) (750 ) Preferred distributions (2,318 ) (2,318 ) (773 ) (773 ) Numerator for net income per share – diluted $ 703,634 $ 558,547 $ 276,243 $ 222,323 Denominator for net income per share – basic and diluted: Denominator for net income per share – basic 370,227 367,920 370,768 368,028 Effect of dilutive securities: OP Units 12,915 12,871 12,941 12,884 Long-term compensation shares/units 3,035 2,642 3,187 2,972 Denominator for net income per share – diluted 386,177 383,433 386,896 383,884 Net income per share – basic $ 1.83 $ 1.46 $ 0.72 $ 0.58 Net income per share – diluted $ 1.82 $ 1.46 $ 0.71 $ 0.58 ERP Operating Limited Partnership The following tables set forth the computation of net income per Unit – basic and net income per Unit – diluted for the Operating Partnership (amounts in thousands except per Unit amounts): Nine Months Ended September 30, Quarter Ended September 30, 2019 2018 2019 2018 Numerator for net income per Unit – basic and diluted: Net income $ 708,402 $ 562,804 $ 277,846 $ 223,846 Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties (2,450 ) (1,939 ) (830 ) (750 ) Allocation to Preference Units (2,318 ) (2,318 ) (773 ) (773 ) Numerator for net income per Unit – basic and diluted $ 703,634 $ 558,547 $ 276,243 $ 222,323 Denominator for net income per Unit – basic and diluted: Denominator for net income per Unit – basic 383,142 380,791 383,709 380,912 Effect of dilutive securities: Dilution for Units issuable upon assumed exercise/vesting of the Company’s long-term compensation shares/units 3,035 2,642 3,187 2,972 Denominator for net income per Unit – diluted 386,177 383,433 386,896 383,884 Net income per Unit – basic $ 1.83 $ 1.46 $ 0.72 $ 0.58 Net income per Unit – diluted $ 1.82 $ 1.46 $ 0.71 $ 0.58

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	1 2 . 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 does not believe there is any litigation pending or threatened against it that, individually or in the aggregate, may reasonably be expected to have a material adverse effect on the Company. As of September 30, 2019, the Company has two wholly owned projects and one partially owned project totaling 824 apartment units in various stages of development with remaining commitments to fund of approximately $459.4 million (inclusive of applicable construction mortgage and joint venture partner obligations) and estimated completion dates ranging through September 30, 2021, as well as other completed development projects that are in various stages of lease-up or are stabilized. As of September 30, 2019, the Company has a joint venture agreement with a third party partner for the consolidated development of a multifamily rental property. The development commitment to fund is included in the development funding totals above. The joint venture agreement includes a

Reportable Segments

Reportable Segments	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Reportable Segments	1 3 . Reportable 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 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 geographic same store operating segments located in urban and high-density suburban communities represent its reportable segments (the recently acquired Denver properties owned by the Company are currently included in non-same store). The Company’s operating segments located in its other markets (Phoenix) that are not material have also been included in the tables presented below. The Company’s fee and asset management and development 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 The primary financial measure for the Company’s rental real estate segment is net operating income (“NOI”), which represents The Nine Months Ended September 30, Quarter Ended September 30, 2019 2018 2019 2018 Rental income $ 2,016,796 $ 1,925,128 $ 685,120 $ 652,677 Property and maintenance expense (338,497 ) (322,487 ) (114,966 ) (110,541 ) Real estate taxes and insurance expense (270,434 ) (268,784 ) (87,546 ) (87,388 ) Total operating expenses (608,931 ) (591,271 ) (202,512 ) (197,929 ) Net operating income $ 1,407,865 $ 1,333,857 $ 482,608 $ 454,748 The following tables present NOI for each segment from our rental real estate for the nine months and quarters ended September 30, 2019 and 2018, Nine Months Ended September 30, 2019 Nine Months Ended September 30, 2018 Rental Income Operating Expenses NOI Rental Income Operating Expenses NOI Same store (1) Los Angeles $ 350,841 $ 102,851 $ 247,990 $ 337,047 $ 96,431 $ 240,616 Orange County 78,522 18,583 59,939 75,595 18,434 57,161 San Diego 71,088 18,532 52,556 68,640 17,988 50,652 Subtotal - Southern California 500,451 139,966 360,485 481,282 132,853 348,429 San Francisco 359,867 87,104 272,763 346,485 84,581 261,904 Washington D.C. 330,944 101,969 228,975 323,549 100,575 222,974 New York 340,828 142,047 198,781 332,474 133,001 199,473 Boston 169,576 46,645 122,931 163,292 45,473 117,819 Seattle 154,453 41,517 112,936 150,103 42,084 108,019 Other Markets 1,560 545 1,015 1,453 503 950 Total same store 1,857,679 559,793 1,297,886 1,798,638 539,070 1,259,568 Non-same store/other (2) (3) Non-same store 136,353 43,801 92,552 69,334 25,322 44,012 Other (3) 22,764 5,337 17,427 57,156 26,879 30,277 Total non-same store/other 159,117 49,138 109,979 126,490 52,201 74,289 Totals $ 2,016,796 $ 608,931 $ 1,407,865 $ 1,925,128 $ 591,271 $ 1,333,857 (1) For the nine months ended September 30, 2019 and 2018, same store primarily includes all properties acquired or completed that were stabilized prior to January 1, 2018, less properties subsequently sold, which represented 72,979 apartment (2) For the nine months ended September 30, 2019 and 2018, non-same store primarily includes properties acquired after January 1, 2018, plus any properties in lease-up and not stabilized as of January 1, (3) Other includes development, other corporate operations and operations prior to disposition for properties sold. Quarter Ended September 30, 2019 Quarter Ended September 30, 2018 Rental Income Operating Expenses NOI Rental Income Operating Expenses NOI Same store (1) Los Angeles $ 122,506 $ 36,666 $ 85,840 $ 118,864 $ 34,683 $ 84,181 Orange County 26,636 6,382 20,254 25,599 6,203 19,396 San Diego 24,064 6,447 17,617 23,215 6,234 16,981 Subtotal - Southern California 173,206 49,495 123,711 167,678 47,120 120,558 San Francisco 127,104 31,438 95,666 122,075 30,420 91,655 Washington D.C. 111,712 34,797 76,915 108,979 34,549 74,430 New York 117,382 48,293 69,089 114,407 45,143 69,264 Boston 59,354 16,243 43,111 56,724 16,124 40,600 Seattle 60,434 16,086 44,348 58,107 16,062 42,045 Other Markets 520 168 352 484 164 320 Total same store 649,712 196,520 453,192 628,454 189,582 438,872 Non-same store/other (2) (3) Non-same store 32,171 9,676 22,495 8,160 2,785 5,375 Other (3) 3,237 (3,684 ) 6,921 16,063 5,562 10,501 Total non-same store/other 35,408 5,992 29,416 24,223 8,347 15,876 Totals $ 685,120 $ 202,512 $ 482,608 $ 652,677 $ 197,929 $ 454,748 (1) For the quarters ended September 30, 2019 and 2018, same store primarily includes all properties acquired or completed that were stabilized prior to July 1, 2018, less properties subsequently sold, which repres ented 75,290 apartment units. (2) For the quarters ended September 30, 2019 and 2018, non-same store primarily includes properties acquired after July 1, 2018, plus any properties in lease-up and not stabilized as of July 1, (3) Other includes development, other corporate operations and operations prior to disposition for properties sold. Nine Months Ended September 30, 2019 Total Assets Capital Expenditures Same store (1) Los Angeles $ 3,002,609 $ 23,301 Orange County 409,559 7,460 San Diego 394,352 3,161 Subtotal - Southern California 3,806,520 33,922 San Francisco 3,267,869 19,422 Washington D.C. 3,600,267 16,517 New York 3,915,125 17,532 Boston 1,479,159 18,191 Seattle 1,304,042 14,162 Other Markets 12,867 165 Total same store 17,385,849 119,911 Non-same store/other (2) (3) Non-same store 3,109,994 7,757 Other (3) 558,213 667 Total non-same store/other 3,668,207 8,424 Totals $ 21,054,056 $ 128,335 (1) Same store primarily includes all properties acquired or completed that were stabilized prior to January 1, 2018, less properties subsequently sold, which represented 72,979 apartment (2) Non-same store primarily includes properties acquired after January 1, 2018, plus any properties in lease-up and not stabilized as of January 1, (3) Other includes development, other corporate operations and capital expenditures for properties

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	1 4 . Subsequent Subsequent to September 30, 2019, the Company: • Repaid $20.0 million of tax-exempt variable rate mortgage bonds at maturity.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
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 nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019. 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, 2018 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, 2018 .
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 may incur both federal and state income taxes on any taxable income of such entities after consideration of any net operating losses. In December 2017, H.R. 1, informally titled the Tax Cuts and Jobs Act (the “Tax Act”), became law. As of September 30, 2019, the Tax Act did not have a material impact on our REIT or subsidiary entities, our ability to continue to qualify as a REIT or on our results of operations.
Recently Issued and Adopted Accounting Pronouncements	Recently Issued Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“ FASB”) Recently Adopted Accounting Pronouncements In FASB Revenue from Contracts with Customers For the remaining approximately 6% of rental income that is subject to the revenue recognition standard, the Company’s disaggregated revenue streams are disclosed in the table included in the Company’s and the Operating Partnership’s Annual Report on Form 10-K for the year ended December 31, 2018 and are comparable with the percentage of rental income for the nine months and quarter ended September 30, 2019. These revenue streams have the same timing and pattern of revenue recognition across our reportable segments, with consistent allocations between the leasing and revenue recognition standards. Additionally, as part of the revenue recognition standard, the FASB issued amendments related to partial sales of real estate. Adoption of the partial sales standard did not result in a change of accounting for the Company related to its disposition process. We concluded that the Company’s typical dispositions will continue to meet the criteria for sale and associated profit recognition under both standards. In • Lessors – Leases are accounted for using an approach that is substantially equivalent to existing guidance for operating, sales-type and financing leases, but aligned with the revenue recognition standard. Lessors are required to allocate lease payments to separate lease and non-lease components of each lease agreement, with the non-lease com ponents evaluated under the revenue recognition standard. • Lessees – Leases are accounted for using a dual approach, classifying leases as either operating or finance based on the principle of whether or not the lease is effectively a financed purchase of the leased asset by the lessee. This classification determines whether the lease expense is recognized on a straight-line basis over the term of the lease (for operating leases) or based on an effective interest method (for finance leases). A lessee is also required to record a right-of-use asset and a lease liability on its balance sheet for all leases with a term of greater than 12 months regardless of their classification as operating or finance leases. Leases with a term of 12 months or less are accounted for similar to existing guidance for operating leases.

Business (Tables)

Business (Tables)	9 Months Ended
	Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Ownership Breakdown	The ownership breakdown includes (table does not include various uncompleted development properties): Properties Apartment Units Wholly Owned Properties 290 76,602 Master-Leased Properties – Consolidated 1 162 Partially Owned Properties – Consolidated 17 3,535 308 80,299

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Summary Of Significant Accounting Policies [Abstract]
Schedule of Reclassification's to Initial Right-of-use Assets	The Company calculated the net present value of the lease liabilities on January 1, 2019 and reclassed the following amounts from other assets and other liabilities to record our initial ROU assets (amounts in thousands): January 1, 2019 Balance Sheet Reclass: Initial lease liabilities $ 278,287 Reclassifications: Prepaid ground leases 17,886 Other Assets Ground lease intangibles – below market, net 166,230 Other Assets Ground lease intangibles – above market, net (2,110 ) Other Liabilities Straight-line rent liabilities (1) (26,092 ) Other Liabilities Initial right-of-use assets $ 434,201 (1) Straight-line rent liabilities relate to corporate office leases and certain ground leases.

Equity, Capital and Other Int_2

Equity, Capital and Other Interests (Tables)	9 Months Ended
	Sep. 30, 2019
Class Of Stock [Line Items]
Changes in Issued and Outstanding Common Shares and Units	The following tables present the changes in the Company’s issued and outstanding Common Shares and “Units” (which includes OP Units and restricted units) for the nine months ended September 30, 2019 and 2018: 2019 2018 Common Shares Common Shares outstanding at January 1, 369,405,161 368,018,082 Common Shares Issued: Conversion of OP Units 294,400 12,510 Exercise of share options 1,430,048 194,796 Employee Share Purchase Plan (ESPP) 37,263 61,321 Restricted share grants, net 160,460 122,877 Common Shares outstanding at September 30, 371,327,332 368,409,586 Units Units outstanding at January 1, 13,904,035 13,768,438 Restricted unit grants, net 140,055 267,074 Conversion of OP Units to Common Shares (294,400 ) (12,510 ) Units outstanding at September 30, 13,749,690 14,023,002 Total Common Shares and Units outstanding at September 30, 385,077,022 382,432,588 Units Ownership Interest in Operating Partnership 3.6 % 3.7 %
Changes in Redemption Value of Redeemable Noncontrolling Interests and Limited Partners Interest	The 2019 2018 Balance at January 1, $ 379,106 $ 366,955 Change in market value 114,936 14,361 Change in carrying value 957 (77 ) Balance at September 30, $ 494,999 $ 381,239
Issued and Outstanding Preferred Shares and Preference Units	The Amounts in thousands Annual Call Dividend Per September 30, December 31, Date (1) Share (2) 2019 2018 Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized: 8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of September 30, 2019 and December 31, 2018 12/10/26 $ 4.145 $ 37,280 $ 37,280 $ 37,280 $ 37,280 (1) On or after the call 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.
ERPOP [Member]
Class Of Stock [Line Items]
Changes in Issued and Outstanding Common Shares and Units	The following tables present the changes in the Operating Partnership’s issued and outstanding Units and in the limited partners’ Units for the nine months ended September 30, 2019 and 2018: 2019 2018 General and Limited Partner Units General and Limited Partner Units outstanding at January 1, 383,309,196 381,786,520 Issued to General Partner: Exercise of EQR share options 1,430,048 194,796 EQR’s Employee Share Purchase Plan (ESPP) 37,263 61,321 EQR’s restricted share grants, net 160,460 122,877 Issued to Limited Partners: Restricted unit grants, net 140,055 267,074 General and Limited Partner Units outstanding at September 30, 385,077,022 382,432,588 Limited Partner Units Limited Partner Units outstanding at January 1, 13,904,035 13,768,438 Limited Partner restricted unit grants, net 140,055 267,074 Conversion of Limited Partner OP Units to EQR Common Shares (294,400 ) (12,510 ) Limited Partner Units outstanding at September 30, 13,749,690 14,023,002 Limited Partner Units Ownership Interest in Operating Partnership 3.6 % 3.7 %
Changes in Redemption Value of Redeemable Noncontrolling Interests and Limited Partners Interest	The following table presents the changes in the redemption value of the Redeemable Limited Partners for the nine months ended September 30, 2019 and 2018 (amounts in thousands): 2019 2018 Balance at January 1, $ 379,106 $ 366,955 Change in market value 114,936 14,361 Change in carrying value 957 (77 ) Balance at September 30, $ 494,999 $ 381,239
Issued and Outstanding Preferred Shares and Preference Units	The December 31, 2018 Amounts in thousands Annual Call Dividend Per September 30, December 31, Date (1) Unit (2) 2019 2018 Preference Units: 8.29% Series K Cumulative Redeemable Preference Units; liquidation value $50 per unit; 745,600 units issued and outstanding as of September 30, 2019 and December 31, 2018 12/10/26 $ 4.145 $ 37,280 $ 37,280 $ 37,280 $ 37,280 (1) On or after the call date, redeemable preference units may be redeemed for cash at the option of the Operating Partnership, in whole or in part, at a redemption price equal to the liquidation price per unit, plus accrued and unpaid distributions, if any, in conjunction with the concurrent redemption of the corresponding Company Preferred Shares. (2) Dividends on Preference Units are payable quarterly.

Real Estate (Tables)

Real Estate (Tables)	9 Months Ended
	Sep. 30, 2019
Real Estate [Abstract]
Summary of Carrying Amounts of Investment in Real Estate	The following table summarizes the carrying amounts for the Company’s investment in real estate (at cost) as of September 30, 2019 and December 31, 2018 (amounts in thousands): September 30, 2019 December 31, 2018 Land $ 5,955,121 $ 5,875,803 Depreciable property: Buildings and improvements 18,796,370 18,232,625 Furniture, fixtures and equipment 1,875,121 1,722,231 In-Place lease intangibles 496,764 481,045 Projects under development: Land 23,531 25,429 Construction-in-progress 119,903 83,980 Land held for development: Land 64,660 61,038 Construction-in-progress 26,357 28,871 Investment in real estate 27,357,827 26,511,022 Accumulated depreciation (7,171,876 ) (6,696,281 ) Investment in real estate, net $ 20,185,951 $ 19,814,741
Acquired Properties From Unaffiliated Parties	During the nine months ended September 30, 2019, the Company acquired the following from unaffiliated parties (purchase price in thousands): Properties Apartment Units Purchase Price Rental Properties – Consolidated (1) 10 2,728 $ 1,124,580 Land Parcels (three) (2) — — 19,832 Total 10 2,728 $ 1,144,412 (1) Purchase price includes an allocation of approximately $193.4 million to land and $933.3 million to depreciable property (inclusive of capitalized closing costs). (2) Purchase price includes an allocation of approximately $16.7 million to vacant land and $3.8 million to construction-in-progress (inclusive of capitalized closing costs). Land parcels include entry into one long-term ground lease for a land project under development in the Washington D.C. market. See Notes 6 and 8 for additional discussion.
Disposed Properties to Unaffiliated Parties	During the nine months ended September 30, 2019, the Company disposed of the following to unaffiliated parties (sales price in thousands): Properties Apartment Units Sales Price Rental Properties – Consolidated 9 1,202 $ 706,675 Rental Properties – Unconsolidated (1) 2 945 394,500 Land Parcels (one) — — 1,900 Total 11 2,147 $ 1,103,075 ( 1 ) The Company owned a 20% interest in both unconsolidated rental properties. Sales price listed is the gross sales price. The Company received net sales proceeds of approximately $78.3 million.

Commitments to Acquire_Dispos_2

Commitments to Acquire/Dispose of Real Estate (Tables)	9 Months Ended
	Sep. 30, 2019
Commitments To Acquire Dispose Of Real Estate [Abstract]
Separate Agreements to Dispose	The Company has entered into separate agreements to dispose of the following (sales price in thousands): Properties Apartment Units Sales Price Rental Properties – Consolidated 1 939 $ 254,000 Land Parcels (three) — — 55,350 Total 1 939 $ 309,350

Investments in Partially Owne_2

Investments in Partially Owned Entities (Tables)	9 Months Ended
	Sep. 30, 2019
Investments In Partially Owned Entities [Abstract]
Summary of Companys Investment in Unconsolidated Entities	The following table and information summarizes the Company’s investments in unconsolidated entities, which are accounted for under the equity method of accounting as the requirements for consolidation are not met, as of September 30, 2019 and December 31, 2018 (amounts in thousands except for ownership percentage): September 30, 2019 December 31, 2018 Ownership Percentage Investments in Unconsolidated Entities: Wisconsin Place Developer (VIE) (1) $ 40,896 $ 42,365 33.3% Operating Properties (Non-VIE) (2) — 10,494 20.0% Real Estate Technology/Other 11,578 5,490 Varies Investments in Unconsolidated Entities $ 52,474 $ 58,349 (1) Represents an unconsolidated interest in an entity that owns the land underlying one of the consolidated joint venture properties noted above and owns and operates a related parking facility. The joint venture, as a limited partner, does not have substantive kick-out or participating rights in the entity. As a result, the entity qualifies as a VIE. The joint venture does not have a controlling financial interest in the VIE and is not the VIE’s primary beneficiary. The joint venture does not have the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance or the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. As a result, the entity that owns the land and owns and operates the parking facility is unconsolidated and recorded using the equity method of accounting. (2) Includes two joint ventures under separate agreements with the same partner totaling 945 apartment units as of December 31, 2018. During the nine months ended September 30, 2019, the Company and its joint venture partner sold both properties under separate agreements to unaffiliated parties. See Note 4 for additional discussion.

Restricted Deposits (Tables)

Restricted Deposits (Tables)	9 Months Ended
	Sep. 30, 2019
Deposits Restricted [Abstract]
Restricted Deposits	The following table presents the Company’s restricted deposits as of September 30, 2019 and December 31, 2018 (amounts in thousands): September 30, 2019 December 31, 2018 Mortgage escrow deposits: Real estate taxes and insurance $ — $ 876 Replacement reserves 8,523 8,641 Mortgage principal reserves/sinking funds 8,758 9,754 Other — 852 Mortgage escrow deposits 17,281 20,123 Restricted cash: Earnest money on pending acquisitions — 5,000 Restricted deposits on real estate investments 665 540 Resident security and utility deposits 36,888 35,659 Other 985 7,549 Restricted cash 38,538 48,748 Restricted deposits $ 55,819 $ 68,871

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Summary of Lease Income Types Relating to Lease Payments	The following table presents the lease income types relating to lease payments for residential and retail leases for the nine months and quarter ended September 30, 2019 (amounts in thousands): Nine Months Ended September 30, 2019 Quarter Ended September 30, 2019 Lease Income Type Residential Leases Retail Leases Total Residential Leases Retail Leases Total Residential and retail rent $ 1,801,749 $ 54,616 $ 1,856,365 $ 611,020 $ 18,453 $ 629,473 Parking rent 27,874 259 28,133 9,405 100 9,505 Storage rent 2,796 51 2,847 940 20 960 Pet rent 8,714 — 8,714 2,916 — 2,916 Total lease revenue (1) $ 1,841,133 $ 54,926 $ 1,896,059 $ 624,281 $ 18,573 $ 642,854 (1) Excludes other rental income of $120.7 million for the nine months ended September 30, 2019 and $42.2 million for the quarter ended September 30, 2019, which is accounted for under the revenue recognition standard.
Summary of Right-of-Use Assets and Related Lease Liabilities	The following table presents the Company’s ROU assets and related lease liabilities as of September 30, 2019 (amounts in thousands): 2019 Right-of-use assets: Corporate office leases $ 43,739 Ground leases (finance) 23,201 Ground leases (operating) 414,104 Right-of-use assets $ 481,044 Lease liabilities: Corporate office leases $ 45,237 Ground leases (finance) 23,210 Ground leases (operating) 264,865 Lease liabilities $ 333,312
Summary of Quantitative Disclosures for Lessees	The following table illustrates the quantitative disclosures for lessees as of and for the nine months and quarter ended September 30, 2019 (amounts in thousands): Nine Months Ended September 30, 2019 Quarter Ended September 30, 2019 Lease cost: Finance lease cost: Amortization of right-of-use assets $ — $ — Interest on lease liabilities (capitalized) 55 55 Operating lease cost: Corporate office leases 2,753 935 Ground leases 16,650 5,550 Short-term lease cost: Corporate office leases 168 56 Ground leases — — Variable lease cost: Corporate office leases 1,130 361 Ground leases 2,575 880 Total lease cost $ 23,331 $ 7,837
Summary of Quantitative Disclosures for Lessees Operating Lease Liabilities	The following table illustrates the quantitative disclosures for lessees as of and for the nine months ended September 30, 2019 (amounts in thousands): September 30, 2019 Other information: Cash paid for amounts included in the measurement of lease liabilities: Investing cash flows from finance leases (capitalized) $ 47 Operating cash flows from operating leases: Corporate office leases $ 4,128 Ground leases $ 12,035 ROU assets obtained in exchange for new finance lease liabilities $ 23,201 ROU assets obtained in exchange for new operating lease liabilities: Corporate office leases $ 45,791 Ground leases $ 422,018 Weighted-average remaining lease term – finance leases 19.9 years Weighted-average remaining lease term – operating leases: Corporate office leases 19.2 years Ground leases 56.4 years Weighted-average discount rate – finance leases 3.0 % Weighted-average discount rate – operating leases: Corporate office leases 3.2 % Ground leases 5.0 %
Summary of Undiscounted Cash Flows for Contractual Obligations for Minimum Rent Payments/Receipts	The following table summarizes the Company’s undiscounted cash flows for contractual obligations for minimum rent payments/receipts under operating and financing leases for the next five years and thereafter as of September 30, 2019: (Payments)/Receipts Due by Year (in thousands) Remaining 2019 2020 2021 2022 2023 2024 Thereafter Total Finance Leases: Minimum Rent Payments (a) $ (141 ) $ (567 ) $ (578 ) $ (590 ) $ (601 ) $ (614 ) $ (33,850 ) $ (36,941 ) Operating Leases: Minimum Rent Payments (a) $ (4,175 ) $ (16,840 ) $ (16,862 ) $ (16,602 ) $ (16,687 ) $ (17,014 ) $ (977,238 ) $ (1,065,418 ) Minimum Rent Receipts (b) $ 16,194 $ 63,409 $ 60,140 $ 56,624 $ 49,150 $ 41,950 $ 149,208 $ 436,675 (a) Minimum basic rent due for corporate office leases and base rent due on ground leases where the Company is the lessee. (b) Minimum basic rent receipts due for various retail space where the Company is the lessor. Excludes residential leases due to their short-term nature.
Summary of Reconciliation of Lease Liabilities	The following table provides a reconciliation of lease liabilities from our undiscounted cash flows for minimum rent payments as of September 30, 2019 (amounts in thousands): 2019 Total minimum rent payments $ 1,102,359 Less: Lease discount 769,047 Lease liabilities $ 333,312

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Schedule of Unsecured Revolving Credit Facility	The following table presents the availability on the Company’s unsecured revolving credit facility as of September 30, 2019 (amounts in thousands): September 30, 2019 Unsecured revolving credit facility commitment $ 2,000,000 Commercial paper balance outstanding (355,000 ) Unsecured revolving credit facility balance outstanding — Other restricted amounts (100,929 ) Unsecured revolving credit facility availability $ 1,544,071

Derivative and Other Fair Val_2

Derivative and Other Fair Value Instruments (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Summary of Carrying and Fair Values of Financial Instruments	The September 30, 2019 December 31, 2018 Carrying Value Estimated Fair Value (Level 2) Carrying Value Estimated Fair Value (Level 2) Mortgage notes payable, net $ 1,962,471 $ 1,961,120 $ 2,385,470 $ 2,352,502 Unsecured debt, net 7,029,465 7,599,742 6,432,469 6,481,426 Total debt, net $ 8,991,936 $ 9,560,862 $ 8,817,939 $ 8,833,928
Summary of Fair Value Measurements for Each Major Category of Assets and Liabilities Measured at Fair Value on Recurring Basis	The Fair Value Measurements at Reporting Date Using Description Balance Sheet Location 9/30/2019 Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Supplemental Executive Retirement Plan Other Assets $ 146,542 $ 146,542 $ — $ — Liabilities Supplemental Executive Retirement Plan Other Liabilities $ 146,542 $ 146,542 $ — $ — Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners Mezzanine $ 494,999 $ — $ 494,999 $ — Fair Value Measurements at Reporting Date Using Description Balance Sheet Location 12/31/2018 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: Forward Starting Swaps Other Assets $ 2,000 $ — $ 2,000 $ — Supplemental Executive Retirement Plan Other Assets 134,088 134,088 — — Total $ 136,088 $ 134,088 $ 2,000 $ — Liabilities Derivatives designated as hedging instruments: Interest Rate Contracts: Fair Value Hedges Other Liabilities $ 2,277 $ — $ 2,277 $ — Forward Starting Swaps Other Liabilities 9,851 — 9,851 — Supplemental Executive Retirement Plan Other Liabilities 134,088 134,088 — — Total $ 146,216 $ 134,088 $ 12,128 $ — Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners Mezzanine $ 379,106 $ — $ 379,106 $ —
Summary of Effect of Fair Value Hedges on the Accompanying Consolidated Statements of Operations and Comprehensive Income	The September 30, 2019 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 $ 2,277 Fixed rate debt Interest expense $ (2,277 ) Total $ 2,277 $ (2,277 ) September 30, 2018 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 $ (1,491 ) Fixed rate debt Interest expense $ 1,491 Total $ (1,491 ) $ 1,491
Summary of Effect of Cash Flow Hedges on the Accompanying Consolidated Statements of Operations and Comprehensive Income	The Effective Portion September 30, 2019 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/(Loss) Reclassified from Accumulated OCI into Income Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps $ (33,765 ) Interest expense $ (14,659 ) Total $ (33,765 ) $ (14,659 ) Effective Portion Ineffective Portion September 30, 2018 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/(Loss) Reclassified from Accumulated OCI into Income Location of Gain/(Loss) Recognized in Income on Derivative Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income Derivatives designated as hedging instruments: Interest Rate Contracts: Forward Starting Swaps $ 24,021 Interest expense $ (13,902 ) N/A $ — Total $ 24,021 $ (13,902 ) $ —

Earnings Per Share and Earnin_2

Earnings Per Share and Earnings Per Unit (Tables)	9 Months Ended
	Sep. 30, 2019
Schedule of Calculation of Numerator and Denominator in Earnings Per Share and Earnings Per Unit	The Nine Months Ended September 30, Quarter Ended September 30, 2019 2018 2019 2018 Numerator for net income per share – basic: Net income $ 708,402 $ 562,804 $ 277,846 $ 223,846 Allocation to Noncontrolling Interests – Operating Partnership (25,339 ) (20,517 ) (9,910 ) (8,159 ) Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties (2,450 ) (1,939 ) (830 ) (750 ) Preferred distributions (2,318 ) (2,318 ) (773 ) (773 ) Numerator for net income per share – basic $ 678,295 $ 538,030 $ 266,333 $ 214,164 Numerator for net income per share – diluted: Net income $ 708,402 $ 562,804 $ 277,846 $ 223,846 Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties (2,450 ) (1,939 ) (830 ) (750 ) Preferred distributions (2,318 ) (2,318 ) (773 ) (773 ) Numerator for net income per share – diluted $ 703,634 $ 558,547 $ 276,243 $ 222,323 Denominator for net income per share – basic and diluted: Denominator for net income per share – basic 370,227 367,920 370,768 368,028 Effect of dilutive securities: OP Units 12,915 12,871 12,941 12,884 Long-term compensation shares/units 3,035 2,642 3,187 2,972 Denominator for net income per share – diluted 386,177 383,433 386,896 383,884 Net income per share – basic $ 1.83 $ 1.46 $ 0.72 $ 0.58 Net income per share – diluted $ 1.82 $ 1.46 $ 0.71 $ 0.58
ERPOP [Member]
Schedule of Calculation of Numerator and Denominator in Earnings Per Share and Earnings Per Unit	The following tables set forth the computation of net income per Unit – basic and net income per Unit – diluted for the Operating Partnership (amounts in thousands except per Unit amounts): Nine Months Ended September 30, Quarter Ended September 30, 2019 2018 2019 2018 Numerator for net income per Unit – basic and diluted: Net income $ 708,402 $ 562,804 $ 277,846 $ 223,846 Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties (2,450 ) (1,939 ) (830 ) (750 ) Allocation to Preference Units (2,318 ) (2,318 ) (773 ) (773 ) Numerator for net income per Unit – basic and diluted $ 703,634 $ 558,547 $ 276,243 $ 222,323 Denominator for net income per Unit – basic and diluted: Denominator for net income per Unit – basic 383,142 380,791 383,709 380,912 Effect of dilutive securities: Dilution for Units issuable upon assumed exercise/vesting of the Company’s long-term compensation shares/units 3,035 2,642 3,187 2,972 Denominator for net income per Unit – diluted 386,177 383,433 386,896 383,884 Net income per Unit – basic $ 1.83 $ 1.46 $ 0.72 $ 0.58 Net income per Unit – diluted $ 1.82 $ 1.46 $ 0.71 $ 0.58

Reportable Segments (Tables)

Reportable Segments (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Schedule of Reconciliation of NOI from Rental Real Estate Specific to Continuing Operations	The Nine Months Ended September 30, Quarter Ended September 30, 2019 2018 2019 2018 Rental income $ 2,016,796 $ 1,925,128 $ 685,120 $ 652,677 Property and maintenance expense (338,497 ) (322,487 ) (114,966 ) (110,541 ) Real estate taxes and insurance expense (270,434 ) (268,784 ) (87,546 ) (87,388 ) Total operating expenses (608,931 ) (591,271 ) (202,512 ) (197,929 ) Net operating income $ 1,407,865 $ 1,333,857 $ 482,608 $ 454,748
Schedule of NOI for Each Segment from Rental Real Estate Specific to Continuing Operations	The following tables present NOI for each segment from our rental real estate for the nine months and quarters ended September 30, 2019 and 2018, Nine Months Ended September 30, 2019 Nine Months Ended September 30, 2018 Rental Income Operating Expenses NOI Rental Income Operating Expenses NOI Same store (1) Los Angeles $ 350,841 $ 102,851 $ 247,990 $ 337,047 $ 96,431 $ 240,616 Orange County 78,522 18,583 59,939 75,595 18,434 57,161 San Diego 71,088 18,532 52,556 68,640 17,988 50,652 Subtotal - Southern California 500,451 139,966 360,485 481,282 132,853 348,429 San Francisco 359,867 87,104 272,763 346,485 84,581 261,904 Washington D.C. 330,944 101,969 228,975 323,549 100,575 222,974 New York 340,828 142,047 198,781 332,474 133,001 199,473 Boston 169,576 46,645 122,931 163,292 45,473 117,819 Seattle 154,453 41,517 112,936 150,103 42,084 108,019 Other Markets 1,560 545 1,015 1,453 503 950 Total same store 1,857,679 559,793 1,297,886 1,798,638 539,070 1,259,568 Non-same store/other (2) (3) Non-same store 136,353 43,801 92,552 69,334 25,322 44,012 Other (3) 22,764 5,337 17,427 57,156 26,879 30,277 Total non-same store/other 159,117 49,138 109,979 126,490 52,201 74,289 Totals $ 2,016,796 $ 608,931 $ 1,407,865 $ 1,925,128 $ 591,271 $ 1,333,857 (1) For the nine months ended September 30, 2019 and 2018, same store primarily includes all properties acquired or completed that were stabilized prior to January 1, 2018, less properties subsequently sold, which represented 72,979 apartment (2) For the nine months ended September 30, 2019 and 2018, non-same store primarily includes properties acquired after January 1, 2018, plus any properties in lease-up and not stabilized as of January 1, (3) Other includes development, other corporate operations and operations prior to disposition for properties sold. Quarter Ended September 30, 2019 Quarter Ended September 30, 2018 Rental Income Operating Expenses NOI Rental Income Operating Expenses NOI Same store (1) Los Angeles $ 122,506 $ 36,666 $ 85,840 $ 118,864 $ 34,683 $ 84,181 Orange County 26,636 6,382 20,254 25,599 6,203 19,396 San Diego 24,064 6,447 17,617 23,215 6,234 16,981 Subtotal - Southern California 173,206 49,495 123,711 167,678 47,120 120,558 San Francisco 127,104 31,438 95,666 122,075 30,420 91,655 Washington D.C. 111,712 34,797 76,915 108,979 34,549 74,430 New York 117,382 48,293 69,089 114,407 45,143 69,264 Boston 59,354 16,243 43,111 56,724 16,124 40,600 Seattle 60,434 16,086 44,348 58,107 16,062 42,045 Other Markets 520 168 352 484 164 320 Total same store 649,712 196,520 453,192 628,454 189,582 438,872 Non-same store/other (2) (3) Non-same store 32,171 9,676 22,495 8,160 2,785 5,375 Other (3) 3,237 (3,684 ) 6,921 16,063 5,562 10,501 Total non-same store/other 35,408 5,992 29,416 24,223 8,347 15,876 Totals $ 685,120 $ 202,512 $ 482,608 $ 652,677 $ 197,929 $ 454,748 (1) For the quarters ended September 30, 2019 and 2018, same store primarily includes all properties acquired or completed that were stabilized prior to July 1, 2018, less properties subsequently sold, which repres ented 75,290 apartment units. (2) For the quarters ended September 30, 2019 and 2018, non-same store primarily includes properties acquired after July 1, 2018, plus any properties in lease-up and not stabilized as of July 1, (3) Other includes development, other corporate operations and operations prior to disposition for properties sold. Nine Months Ended September 30, 2019 Total Assets Capital Expenditures Same store (1) Los Angeles $ 3,002,609 $ 23,301 Orange County 409,559 7,460 San Diego 394,352 3,161 Subtotal - Southern California 3,806,520 33,922 San Francisco 3,267,869 19,422 Washington D.C. 3,600,267 16,517 New York 3,915,125 17,532 Boston 1,479,159 18,191 Seattle 1,304,042 14,162 Other Markets 12,867 165 Total same store 17,385,849 119,911 Non-same store/other (2) (3) Non-same store 3,109,994 7,757 Other (3) 558,213 667 Total non-same store/other 3,668,207 8,424 Totals $ 21,054,056 $ 128,335 (1) Same store primarily includes all properties acquired or completed that were stabilized prior to January 1, 2018, less properties subsequently sold, which represented 72,979 apartment (2) Non-same store primarily includes properties acquired after January 1, 2018, plus any properties in lease-up and not stabilized as of January 1, (3) Other includes development, other corporate operations and capital expenditures for properties

Business - Additional Informati

Business - Additional Information (Details)	Sep. 30, 2019StatePropertyApartmentUnit
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of states in which entity operates | State	10
Properties | Property	308
Apartment units | ApartmentUnit	80,299
ERPOP [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Noncontrolling interest, ownership percentage by parent	96.40%

Business - Ownership Breakdown

Business - Ownership Breakdown (Details)	Sep. 30, 2019PropertyApartmentUnit
Property/Unit schedule
Properties | Property	308
Apartment Units | ApartmentUnit	80,299
Wholly Owned Properties
Property/Unit schedule
Properties | Property	290
Apartment Units | ApartmentUnit	76,602
Master-Leased Properties - Consolidated
Property/Unit schedule
Properties | Property	1
Apartment Units | ApartmentUnit	162
Partially Owned Properties - Consolidated
Property/Unit schedule
Properties | Property	17
Apartment Units | ApartmentUnit	3,535

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019
Provision for income tax	$ 265,000	$ 280,000	$ 749,000	$ 767,000
Percentage of rental income excluded from accounting standard adoption			94.00%
Percentage of total revenue subject to revenue recognition standard			6.00%
Right-of-use assets	481,044,000		$ 481,044,000		$ 434,201,000
Lease liabilities	$ 333,312,000		333,312,000		$ 278,287,000
Federal [Member]
Provision for income tax			$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Computation of Initial Right-of-use Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
Leases [Line Items]
Lease liabilities	$ 333,312	$ 278,287
Reclassifications:
Right-of-use assets	$ 481,044	434,201
Other Assets [Member]
Reclassifications:
Prepaid ground leases		17,886
Ground lease intangibles – below market, net		166,230
Other Liabilities [Member]
Reclassifications:
Ground lease intangibles – above market, net		(2,110)
Straight line rent liabilities		$ (26,092)

Equity, Capital and Other Int_3

Equity, Capital and Other Interests - Changes in Issued and Outstanding Common Shares and Units (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Equity Capital And Other Interests [Abstract]
Common Stock, Shares, Outstanding	369,405,161	368,018,082
Common Shares Issued:
Conversion of OP Units	294,400	12,510
Exercise of share options	1,430,048	194,796
Employee Share Purchase Plan (ESPP)	37,263	61,321
Restricted share grants, net	160,460	122,877
Common Stock, Shares, Outstanding	371,327,332	368,409,586
Units
Total Units Outstanding	13,904,035	13,768,438
Restricted unit grants, net	140,055	267,074
Conversion of OP Units to Common Shares	(294,400)	(12,510)
Total Units Outstanding	13,749,690	14,023,002
Common Shares And Units Outstanding	385,077,022	382,432,588
Units Ownership Interest in Operating Partnership	3.60%	3.70%

Equity, Capital and Other Int_4

Equity, Capital and Other Interests - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Redeemable noncontrolling interests - operating partnership	$ 494,999	$ 379,106	$ 381,239	$ 366,955
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, par or stated value per share	$ 0.01	$ 0.01
ERPOP [Member]
Class Of Stock [Line Items]
Redeemable Limited Partners	$ 494,999	$ 379,106	$ 381,239	$ 366,955

Equity, Capital and Other Int_5

Equity, Capital and Other Interests - Changes in Redemption Value of Redeemable Noncontrolling Interests - Operating Partnership (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Equity Capital And Other Interests [Abstract]
Redeemable Noncontrolling Interests - Operating Partnership	$ 379,106	$ 366,955
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	114,936	14,361
Change in carrying value of Redeemable Noncontrolling Interests - Operating Partnership	957	(77)
Redeemable Noncontrolling Interests - Operating Partnership	$ 494,999	$ 381,239

Equity, Capital and Other Int_6

Equity, Capital and Other Interests - Issued and Outstanding Preferred Shares and Preference Units (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of September 30, 2019 and December 31, 2018	$ 37,280	$ 37,280
ERPOP [Member]
Class Of Stock [Line Items]
8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of September 30, 2019 and December 31, 2018	$ 37,280	37,280
Preferred Stock
Class Of Stock [Line Items]
Preferred Stocks Preference Units Call Date	Dec. 10, 2026
Annual Dividend Per Preferred Share Preference Unit	$ 4.145
8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of September 30, 2019 and December 31, 2018	$ 37,280	37,280
Preferred Stock | ERPOP [Member]
Class Of Stock [Line Items]
Preferred Stocks Preference Units Call Date	Dec. 10, 2026
Annual Dividend Per Preferred Share Preference Unit	$ 4.145
8.29% Series K Cumulative Redeemable Preferred; liquidation value $50 per share; 745,600 shares issued and outstanding as of September 30, 2019 and December 31, 2018	$ 37,280	$ 37,280

Equity, Capital and Other Int_7

Equity, Capital and Other Interests - Issued and Outstanding Preferred Shares and Preference Units (Parenthetical) (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	100,000,000	100,000,000
Preferred Stock
Class Of Stock [Line Items]
Preferred Stock Preference Units Issued	745,600	745,600
Preferred Stock Preference Units Outstanding	745,600	745,600
Preferred Stock Preference Units Redemption Price Per Share	$ 50	$ 50
Preferred Stock Preference Units Dividend Rate Percentage	8.29%	8.29%
Preferred Stock | ERPOP [Member]
Class Of Stock [Line Items]
Preferred Stock Preference Units Issued	745,600	745,600
Preferred Stock Preference Units Outstanding	745,600	745,600
Preferred Stock Preference Units Redemption Price Per Share	$ 50	$ 50
Preferred Stock Preference Units Dividend Rate Percentage	8.29%	8.29%

Equity, Capital and Other Int_8

Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding Units (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
General and Limited Partner Units
Exercise of share options	1,430,048	194,796
Employee Share Purchase Plan (ESPP)	37,263	61,321
Restricted share grants, net	160,460	122,877
Restricted unit grants, net	140,055	267,074
Common Shares And Units Outstanding	385,077,022	382,432,588
LIMITED PARTNERS
Total Units Outstanding	13,904,035	13,768,438
Restricted unit grants, net	140,055	267,074
Conversion of Limited Partner OP Units to EQR Common Shares	(294,400)	(12,510)
Total Units Outstanding	13,749,690	14,023,002
Units Ownership Interest in Operating Partnership	3.60%	3.70%
ERPOP [Member]
General and Limited Partner Units
Common Shares And Units Outstanding	383,309,196	381,786,520
Exercise of share options	1,430,048	194,796
Employee Share Purchase Plan (ESPP)	37,263	61,321
Restricted share grants, net	160,460	122,877
Restricted unit grants, net	140,055	267,074
Common Shares And Units Outstanding	385,077,022	382,432,588
LIMITED PARTNERS
Total Units Outstanding	13,904,035	13,768,438
Restricted unit grants, net	140,055	267,074
Conversion of Limited Partner OP Units to EQR Common Shares	(294,400)	(12,510)
Total Units Outstanding	13,749,690	14,023,002
Units Ownership Interest in Operating Partnership	3.60%	3.70%

Equity, Capital and Other Int_9

Equity, Capital and Other Interests - Changes in Redemption Value of Redeemable Limited Partners Interest (Details) - ERPOP [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Redeemable Limited Partners	$ 379,106	$ 366,955
Limited Partners Change In Redemption Value	114,936	14,361
Limited Partners Change In Carrying Value	957	(77)
Redeemable Limited Partners	$ 494,999	$ 381,239

Equity, Capital and Other In_10

Equity, Capital and Other Interests - Other - Additional Information (Details)	9 Months Ended
	Sep. 30, 2019shares
Equity Capital And Other Interests [Abstract]
Additional common shares authorized	13,000,000
Stock repurchase program, number of shares authorized to be repurchased	13,000,000
Stock open market repurchased and retired during period, shares	0
Stock repurchase program, remaining number of shares authorized to be repurchased	13,000,000

Real Estate - Summary of Carryi

Real Estate - Summary of Carrying Amounts of Investment in Real Estate (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Land	$ 5,955,121	$ 5,875,803
Depreciable property:
Buildings and improvements	18,796,370	18,232,625
Furniture, fixtures and equipment	1,875,121	1,722,231
In-Place lease intangibles	496,764	481,045
Projects under development:
Construction-in-progress	143,434	109,409
Land held for development:
Land	91,017	89,909
Construction-in-progress	143,434	109,409
Investment in real estate	27,357,827	26,511,022
Accumulated depreciation	(7,171,876)	(6,696,281)
Investment in real estate, net	20,185,951	19,814,741
Projects under development [Member]
Projects under development:
Land	23,531	25,429
Construction-in-progress	119,903	83,980
Land held for development:
Construction-in-progress	119,903	83,980
Land held for development [Member]
Projects under development:
Construction-in-progress	26,357	28,871
Land held for development:
Land	64,660	61,038
Construction-in-progress	$ 26,357	$ 28,871

Real Estate - Acquired Properti

Real Estate - Acquired Properties From Unaffiliated Parties (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)PropertyApartmentUnit
Properties acquired | Property	10
Property Units acquired | ApartmentUnit	2,728
Purchase Price	$ 1,144,412
Rental Properties - Consolidated [Member]
Properties acquired | Property	10
Property Units acquired | ApartmentUnit	2,728
Purchase Price	$ 1,124,580
Land Parcels [Member]
Purchase Price	$ 19,832

Real Estate - Acquired Proper_2

Real Estate - Acquired Properties From Unaffiliated Parties (Parenthetical) (Details) $ in Thousands	Sep. 30, 2019USD ($)
Purchase Price	$ 1,144,412
Land Parcels [Member]
Purchase Price	19,832
Land [Member]
Purchase Price	193,400
Depreciable Property [Member]
Purchase Price	933,300
Vacant Land [Member]
Purchase Price	16,700
Construction in Progress [Member]
Purchase Price	$ 3,800

Real Estate - Disposed Properti

Real Estate - Disposed Properties to Unaffiliated Parties (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)PropertyApartmentUnit
Properties disposed | Property	11
Property Units disposed | ApartmentUnit	2,147
Sales Price	$ 1,103,075
Rental Properties - Consolidated [Member]
Properties disposed | Property	9
Property Units disposed | ApartmentUnit	1,202
Sales Price	$ 706,675
Rental Properties - Unconsolidated [Member]
Properties disposed | Property	2
Property Units disposed | ApartmentUnit	945
Sales Price	$ 394,500
Land Parcels [Member]
Sales Price	$ 1,900

Real Estate - Disposed Proper_2

Real Estate - Disposed Properties to Unaffiliated Parties (Parenthetical) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Net sales proceeds of unconsolidated rental properties	$ 692,649	$ 691,526
Rental Properties - Unconsolidated [Member]
Ownership percentage	20.00%
Net sales proceeds of unconsolidated rental properties	$ 78,300

Real Estate - Additional Inform

Real Estate - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Real Estate [Abstract]
Net gain on sales of real estate properties	$ 130,565	$ 114,672	$ 269,400	$ 256,834
Net gain on sales of unconsolidated entities			69,500
Net gain on sales of land parcels	$ 1,899		$ 2,077	$ 995

Commitments to Acquire_Dispos_3

Commitments to Acquire/Dispose of Real Estate - Separate Agreements to Dispose (Details) $ in Thousands	Sep. 30, 2019USD ($)PropertyApartmentUnit
Property/Unit schedule
Properties | Property	1
Apartment Units | ApartmentUnit	939
Sales Price	$ 309,350
Rental Properties Disposed [Member] | Consolidated [Member]
Property/Unit schedule
Properties | Property	1
Apartment Units | ApartmentUnit	939
Sales Price	$ 254,000
Land [Member]
Property/Unit schedule
Sales Price	$ 55,350

Investments in Partially Owne_3

Investments in Partially Owned Entities - Consolidated Variable Interest Entities ("VIEs") - Additional Information (Details) $ in Thousands	Sep. 30, 2019USD ($)PropertyApartmentUnit	Dec. 31, 2018USD ($)
Variable Interest Entity [Line Items]
Properties | Property	308
Apartment units | ApartmentUnit	80,299
Total assets	$ 21,054,056	$ 20,394,209
Total liabilities	$ 10,152,058	9,615,454
Consolidated VIE [Member]
Variable Interest Entity [Line Items]
Properties | Property	17
Apartment units | ApartmentUnit	3,535
Total assets	$ 711,500	713,600
Total liabilities	$ 325,500	$ 313,900
Consolidated VIE [Member] | Consolidated Joint Venture [Member]
Variable Interest Entity [Line Items]
Ownership Percentage	90.00%
Consolidated VIE [Member] | General Partner and Developer [Member] | Consolidated Joint Venture [Member]
Variable Interest Entity [Line Items]
Ownership Percentage	10.00%

Investments in Partially Owne_4

Investments in Partially Owned Entities - Summary of Companys Investment in Unconsolidated Entities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Investments in Unconsolidated Entities	$ 52,474	$ 58,349
Operating Property [Member] | Unconsolidated Non-VIE [Member]
Variable Interest Entity [Line Items]
Investments in Unconsolidated Entities		10,494
Ownership Percentage	20.00%
Real Estate Technology/Other [Member]
Variable Interest Entity [Line Items]
Investments in Unconsolidated Entities	$ 11,578	5,490
Consolidated VIE [Member] | Wisconsin Place Developer [Member]
Variable Interest Entity [Line Items]
Investments in Unconsolidated Entities	$ 40,896	$ 42,365
Ownership Percentage	33.30%

Investments in Partially Owne_5

Investments in Partially Owned Entities - Summary of Companys Investment in Unconsolidated Entities (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2018ApartmentUnitJointVenture	Sep. 30, 2019ApartmentUnit
Variable Interest Entity [Line Items]
Apartment units		80,299
Operating Property [Member] | Unconsolidated Non-VIE [Member]
Variable Interest Entity [Line Items]
Apartment units	945
Number of joint ventures under agreements | JointVenture	2

Restricted Deposits - Restricte

Restricted Deposits - Restricted Deposits (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Mortgage escrow deposits:
Real estate taxes and insurance		$ 876
Replacement reserves	$ 8,523	8,641
Mortgage principal reserves/sinking funds	8,758	9,754
Other		852
Mortgage escrow deposits	17,281	20,123
Restricted cash:
Earnest money on pending acquisitions		5,000
Restricted deposits on real estate investments	665	540
Resident security and utility deposits	36,888	35,659
Other	985	7,549
Restricted cash	38,538	48,748
Restricted deposits	$ 55,819	$ 68,871	$ 55,755

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)PropertyCorporateOfficeLease	Sep. 30, 2019USD ($)PropertyCorporateOfficeLease	Jan. 01, 2019USD ($)
Operating Leased Assets [Line Items]
Lease liabilities	$ 333,312	$ 333,312	$ 278,287
Right-of-use assets	$ 481,044	$ 481,044	$ 434,201
Corporate Office Leases [Member]
Operating Leased Assets [Line Items]
Number of operating leases | CorporateOfficeLease		9
Number of office lease modified | CorporateOfficeLease	2
Lease liabilities	$ 45,237	$ 45,237
Right-of-use assets	$ 43,739	$ 43,739
Lease expiration date		Nov. 30, 2032
Number of option to extend | CorporateOfficeLease	2	2
Lease renewal term	5 years	5 years
Amount incurred for leased office space	$ 700	$ 2,000
Ground Leases [Member]
Operating Leased Assets [Line Items]
Unsecured borrowing rates for actual pricing period used for calculating discount rate		30 years
Lease liabilities	264,865	$ 264,865
Right-of-use assets	$ 414,104	$ 414,104
Number of operating properties | Property	14	14
Finance lease, liability	$ 23,210	$ 23,210
Finance lease,ROU asset	23,201	23,201
Modified Corporate Office leases [Member]
Operating Leased Assets [Line Items]
Lease liabilities	29,100	29,100
Right-of-use assets	29,100	29,100
Ground Lease Under Development [Member]
Operating Leased Assets [Line Items]
Finance lease, liability	23,200	23,200
Finance lease,ROU asset	$ 23,200	$ 23,200
Minimum [Member] | Corporate Office Leases [Member]
Operating Leased Assets [Line Items]
Discount rate	3.30%	3.30%
Remaining lease terms (inclusive of applicable extension options)		1 year
Minimum [Member] | Ground Leases [Member]
Operating Leased Assets [Line Items]
Discount rate	4.40%	4.40%
Operating lease expiration year		2042
Maximum [Member] | Corporate Office Leases [Member]
Operating Leased Assets [Line Items]
Discount rate	3.90%	3.90%
Remaining lease terms	10 years	10 years
Remaining lease terms (inclusive of applicable extension options)		23 years
Maximum [Member] | Ground Leases [Member]
Operating Leased Assets [Line Items]
Discount rate	5.50%	5.50%
Operating lease expiration year		2113
Residential Apartment Leases [Member]
Operating Leased Assets [Line Items]
Percentage of rental income		97.10%
Retail Commercial Leases [Member]
Operating Leased Assets [Line Items]
Percentage of rental income		2.90%
Retail Commercial Leases [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Retail/commercial leases term	5 years	5 years
Retail Commercial Leases [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Retail/commercial leases term	10 years	10 years

Leases - Summary of Lease Incom

Leases - Summary of Lease Income Types Relating to Lease Payments (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Operating Leased Assets [Line Items]
Total lease revenue	$ 642,854	$ 1,896,059
Residential Leases [Member]
Operating Leased Assets [Line Items]
Total lease revenue	624,281	1,841,133
Retail Lease [Member]
Operating Leased Assets [Line Items]
Total lease revenue	18,573	54,926
Residential and Retail Rent [Member]
Operating Leased Assets [Line Items]
Total lease revenue	629,473	1,856,365
Residential and Retail Rent [Member] | Residential Leases [Member]
Operating Leased Assets [Line Items]
Total lease revenue	611,020	1,801,749
Residential and Retail Rent [Member] | Retail Lease [Member]
Operating Leased Assets [Line Items]
Total lease revenue	18,453	54,616
Parking Rent [Member]
Operating Leased Assets [Line Items]
Total lease revenue	9,505	28,133
Parking Rent [Member] | Residential Leases [Member]
Operating Leased Assets [Line Items]
Total lease revenue	9,405	27,874
Parking Rent [Member] | Retail Lease [Member]
Operating Leased Assets [Line Items]
Total lease revenue	100	259
Storage Rent [Member]
Operating Leased Assets [Line Items]
Total lease revenue	960	2,847
Storage Rent [Member] | Residential Leases [Member]
Operating Leased Assets [Line Items]
Total lease revenue	940	2,796
Storage Rent [Member] | Retail Lease [Member]
Operating Leased Assets [Line Items]
Total lease revenue	20	51
Pet Rent [Member]
Operating Leased Assets [Line Items]
Total lease revenue	2,916	8,714
Pet Rent [Member] | Residential Leases [Member]
Operating Leased Assets [Line Items]
Total lease revenue	$ 2,916	$ 8,714

Leases - Summary of Lease Inc_2

Leases - Summary of Lease Income Types Relating to Lease Payments (Parenthetical) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating Leased Assets [Line Items]
Other rental income	$ 685,120	$ 652,677	$ 2,016,796	$ 1,925,128
Rental [Member]
Operating Leased Assets [Line Items]
Other rental income	$ 42,200		$ 120,700

Leases - Summary of Right-of-Us

Leases - Summary of Right-of-Use Assets and Related Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
Operating Leased Assets [Line Items]
Right-of-use assets	$ 481,044	$ 434,201
Lease liabilities	333,312	$ 278,287
Corporate Office Leases [Member]
Operating Leased Assets [Line Items]
Right-of-use assets	43,739
Lease liabilities	45,237
Ground Leases [Member]
Operating Leased Assets [Line Items]
Right-of-use assets	414,104
Finance lease, right-of-use asset	23,201
Lease liabilities	264,865
Finance lease, liabilities	$ 23,210

Leases - Summary of Quantitativ

Leases - Summary of Quantitative Disclosures for Lessees (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Lease cost:
Interest on lease liabilities (capitalized)	$ 55	$ 55
Total lease cost	$ 7,837	23,331
Cash paid for amounts included in the measurement of lease liabilities:
Investing cash flows from finance leases (capitalized)		47
ROU assets obtained in exchange for new finance lease liabilities		$ 23,201
Weighted-average remaining lease term – finance leases	19 years 10 months 24 days	19 years 10 months 24 days
Weighted-average discount rate – finance leases	3.00%	3.00%
Corporate Office Leases [Member]
Lease cost:
Operating lease cost	$ 935	$ 2,753
Short-term lease cost	56	168
Variable lease cost	$ 361	1,130
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from Operating leases		4,128
ROU assets obtained in exchange for new operating lease liabilities		$ 45,791
Weighted-average remaining lease term – operating leases	19 years 2 months 12 days	19 years 2 months 12 days
Weighted-average discount rate – operating leases	3.20%	3.20%
Ground Leases [Member]
Lease cost:
Operating lease cost	$ 5,550	$ 16,650
Variable lease cost	$ 880	2,575
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from Operating leases		12,035
ROU assets obtained in exchange for new operating lease liabilities		$ 422,018
Weighted-average remaining lease term – operating leases	56 years 4 months 24 days	56 years 4 months 24 days
Weighted-average discount rate – operating leases	5.00%	5.00%

Leases - Summary of Undiscounte

Leases - Summary of Undiscounted Cash Flows for Contractual Obligations for Minimum Rent Payments/Receipts (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
Remaining 2019	$ (141)
2020	(567)
2021	(578)
2022	(590)
2023	(601)
2024	(614)
Thereafter	(33,850)
Total	(36,941)
Remaining 2019	(4,175)
2020	(16,840)
2021	(16,862)
2022	(16,602)
2023	(16,687)
2024	(17,014)
Thereafter	(977,238)
Total	(1,065,418)
Remaining 2019	16,194
2020	63,409
2021	60,140
2022	56,624
2023	49,150
2024	41,950
Thereafter	149,208
Total	$ 436,675

Leases - Summary of Reconciliat

Leases - Summary of Reconciliation of Lease Liabilities (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
Total minimum rent payments	$ 1,102,359
Less: Lease discount	769,047
Lease liabilities	$ 333,312

Debt - Mortgage Notes Payable -

Debt - Mortgage Notes Payable - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Mortgage notes payable	$ 1,962,471	$ 2,385,470
Debt instrument, maturity date	Jan. 10, 2022
Mortgages [Member]
Debt Instrument [Line Items]
Mortgage notes payable	$ 4,900
Debt instrument, maturity date	May 28, 2061
Write off of deferred debt issuance cost	$ 2,300
Write off unamortized (premium) discount	$ 6,200
Weighted average interest rate	3.90%
Mortgages [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	0.10%
Mortgages [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	5.29%
Variable Rate Construction Mortgage [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date	Jun. 25, 2022
Variable rate of construction mortgage debt	$ 7,600
Total commitment amount	67,600
Bonds [Member]
Debt Instrument [Line Items]
Repayments of long-term debt	$ 132,600
Debt instrument maturity year start	2032
Debt instrument maturity year, end	2036
Conventional Floating-rate Mortgage Loans [Member]
Debt Instrument [Line Items]
Repayments of long-term debt	$ 5,900
Debt instrument maturity year start	2032
Debt instrument maturity year, end	2035
Mortgages Debt [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.79%
Repayments of long-term debt	$ 84,500
Debt instrument, maturity date	2053
Prepayment penalty charges	$ 3,400
Credit enhanced debt [Member]
Debt Instrument [Line Items]
Mortgage notes payable	301,700
Fannie Mae Pool 3 [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt	$ 288,100
Debt instrument, maturity date	Mar. 1, 2029
Debt instrument, interest rate, stated percentage	3.94%
Freddie Mac Loan Pool [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date	Jul. 1, 2020
Debt instrument, interest rate, stated percentage	5.78%
Repayments of long-term debt	$ 500,000

Debt - Notes - Additional Infor

Debt - Notes - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Unsecured notes	$ 6,675,084,000	$ 5,933,286,000
Repayments of unsecured debt	$ 450,000,000
Debt instrument, maturity date	Jan. 10, 2022
Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date	Aug. 1, 2047
Weighted average interest rate	4.26%
Notes Payable, Other Payables [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.50%
Notes Payable, Other Payables [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	7.57%
3.00% Notes [Member]
Debt Instrument [Line Items]
Proceeds from issuance of unsecured debt	$ 600,000,000
Debt instrument, interest rate, stated percentage	3.00%
Proceeds from debt, net of issuance costs	$ 597,500,000
2.50% Notes [Member]
Debt Instrument [Line Items]
Proceeds from issuance of unsecured debt	$ 600,000,000
Debt instrument, interest rate, stated percentage	2.50%
Proceeds from debt, net of issuance costs	$ 597,000,000
2.375% Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.375%
Repayments of unsecured debt	$ 450,000
Debt instrument, basis spread on variable rate	0.61%
2.375% Notes [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument, description of variable rate basis	90-Day LIBOR plus 0.61%

Debt - Line of Credit and Comme

Debt - Line of Credit and Commercial Paper - Additional Information (Details)	9 Months Ended
	Sep. 30, 2019USD ($)
Line of Credit Facility [Line Items]
Debt instrument, maturity date	Jan. 10, 2022
Commercial Paper [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility	$ 500,000,000
Weighted average interest rate	2.61%
Weighted average amount outstanding	$ 384,700,000
Commercial paper weighted average days outstanding	28 days
Commercial paper principal outstanding	$ 500,000,000
Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Unsecured revolving credit facility	2,000,000,000
Ability to increase LOC facility	$ 750,000,000
Debt instrument, basis spread on variable rate	0.825%
Percentage points of line of credit facility commitment fee	0.125%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Weighted average interest rate	3.14%

Debt - Line of Credit and Com_2

Debt - Line of Credit and Commercial Paper - Schedule of Unsecured Revolving Credit Facility (Details) - Unsecured Revolving Credit Facility	9 Months Ended
	Sep. 30, 2019USD ($)
Line of Credit Facility [Line Items]
Unsecured revolving credit facility	$ 2,000,000,000
Commercial paper balance outstanding	(355,000,000)
Other restricted amounts	(100,929,000)
Unsecured revolving credit facility availability	$ 1,544,071,000

Debt - Other - Additional Infor

Debt - Other - Additional Information (Details) $ in Millions	Sep. 30, 2019USD ($)
Debt Disclosure [Abstract]
Letters of credit outstanding	$ 9

Derivative and Other Fair Val_3

Derivative and Other Fair Value Instruments - Summary of Carrying and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, net	$ 8,991,936	$ 8,817,939
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, net	9,560,862	8,833,928
Mortgage Notes Payable, Net [Member] | Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, net	1,962,471	2,385,470
Mortgage Notes Payable, Net [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, net	1,961,120	2,352,502
Unsecured Debt [Member] | Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, net	7,029,465	6,432,469
Unsecured Debt [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total debt, net	$ 7,599,742	$ 6,481,426

Derivative and Other Fair Val_4

Derivative and Other Fair Value Instruments - Summary of Fair Value Measurements for Each Major Category of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Fair Value Of SERP Investments	$ 146,542	$ 134,088
Assets, Fair Value Disclosure		136,088
Other Liabilities, Fair Value Disclosure	146,542	134,088
Liabilities, Fair Value Disclosure		146,216
Redeemable Noncontrolling Interests - Operating Partnership/Redeemable Limited Partners	494,999	379,106	$ 381,239	$ 366,955
Forward Starting Swaps [Member]
Derivatives, Fair Value [Line Items]
Forward Starting Swaps		2,000
Forward Starting Swaps		9,851
Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value		2,277
Fair Value, Inputs, Level 1 [Member]
Derivatives, Fair Value [Line Items]
Fair Value Of SERP Investments	146,542	134,088
Assets, Fair Value Disclosure		134,088
Other Liabilities, Fair Value Disclosure	146,542	134,088
Liabilities, Fair Value Disclosure		134,088
Redeemable Noncontrolling Interests - Operating Partnership/Redeemable Limited Partners	0	0
Fair Value, Inputs, Level 1 [Member] | Forward Starting Swaps [Member]
Derivatives, Fair Value [Line Items]
Forward Starting Swaps		0
Forward Starting Swaps		0
Fair Value, Inputs, Level 1 [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value		0
Fair Value, Inputs, Level 2 [Member]
Derivatives, Fair Value [Line Items]
Fair Value Of SERP Investments	0	0
Assets, Fair Value Disclosure		2,000
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure		12,128
Redeemable Noncontrolling Interests - Operating Partnership/Redeemable Limited Partners	494,999	379,106
Fair Value, Inputs, Level 2 [Member] | Forward Starting Swaps [Member]
Derivatives, Fair Value [Line Items]
Forward Starting Swaps		2,000
Forward Starting Swaps		9,851
Fair Value, Inputs, Level 2 [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value		2,277
Fair Value, Inputs, Level 3 [Member]
Derivatives, Fair Value [Line Items]
Fair Value Of SERP Investments	0	0
Assets, Fair Value Disclosure		0
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure		0
Redeemable Noncontrolling Interests - Operating Partnership/Redeemable Limited Partners	$ 0	0
Fair Value, Inputs, Level 3 [Member] | Forward Starting Swaps [Member]
Derivatives, Fair Value [Line Items]
Forward Starting Swaps		0
Forward Starting Swaps		0
Fair Value, Inputs, Level 3 [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value		$ 0

Derivative and Other Fair Val_5

Derivative and Other Fair Value Instruments - Summary of Effect of Fair Value Hedges on the Accompanying Consolidated Statements of Operations and Comprehensive Income (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in Income on Derivative	$ 2,277	$ (1,491)
Amount of Gain/(Loss) Recognized in Income on Hedged Item	(2,277)	1,491
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in Income on Derivative	2,277	(1,491)
Amount of Gain/(Loss) Recognized in Income on Hedged Item	$ (2,277)	$ 1,491

Derivative and Other Fair Val_6

Derivative and Other Fair Value Instruments - Summary of Effect of Cash Flow Hedges on the Accompanying Consolidated Statements of Operations and Comprehensive Income (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Effective Portion - Amount of Gain/(Loss) Recognized in OCI on Derivative	$ (33,765)	$ 24,021
Effective Portion - Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income	(14,659)	(13,902)
Ineffective Portion - Amount of Gain/ (Loss) Reclassified from Accumulated OCI into Income		0
Forward Starting Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Effective Portion - Amount of Gain/(Loss) Recognized in OCI on Derivative	(33,765)	24,021
Effective Portion - Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income	$ (14,659)	(13,902)
Ineffective Portion - Amount of Gain/ (Loss) Reclassified from Accumulated OCI into Income		$ 0

Derivative and Other Fair Val_7

Derivative and Other Fair Value Instruments - Additional Information (Details) $ in Thousands	1 Months Ended		9 Months Ended	12 Months Ended
	Jul. 31, 2019USD ($)DerivativeInstrument	Jun. 30, 2019USD ($)DerivativeInstrument	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)
Derivative [Line Items]
Unrealized gain (loss) on interest rate cash flow hedges, pretax, accumulated other comprehensive income (loss)			$ 84,100	$ 65,000
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net			25,600
Number of interest rate swaps matured | DerivativeInstrument	6
Repayments of unsecured debt			$ 450,000
2.375% Notes [Member]
Derivative [Line Items]
Repayments of unsecured debt	$ 450,000
Debt instrument, interest rate, stated percentage	2.375%
Forward Starting Swaps [Member]
Derivative [Line Items]
Forward starting swaps settled | DerivativeInstrument		10
Debt instrument, term		10 years
Proceeds from settlement of derivative instruments		$ 41,800
Public notes, face value		600,000
Interest expense		200
Increase (decrease) in charges hedge termination activities		$ 41,600

Earnings Per Share and Earnin_3

Earnings Per Share and Earnings Per Unit - Computation of Net Income per Share Basic and Net Income per Share Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 277,846	$ 223,846	$ 708,402	$ 562,804
Allocation to Noncontrolling Interests – Operating Partnership	(9,910)	(8,159)	(25,339)	(20,517)
Partially Owned Properties	(830)	(750)	(2,450)	(1,939)
Preferred distributions	(773)	(773)	(2,318)	(2,318)
Net income available to Common Shares	266,333	214,164	678,295	538,030
Numerator for net income per share – diluted	$ 276,243	$ 222,323	$ 703,634	$ 558,547
Weighted average Common Shares outstanding	370,768	368,028	370,227	367,920
OP Units	12,941	12,884	12,915	12,871
Dilutive Securities Options	3,187	2,972	3,035	2,642
Denominator for net income per share – diluted	386,896	383,884	386,177	383,433
Net income per share – basic	$ 0.72	$ 0.58	$ 1.83	$ 1.46
Net income per share – diluted	$ 0.71	$ 0.58	$ 1.82	$ 1.46

Earnings Per Share and Earnin_4

Earnings Per Share and Earnings Per Unit - Computation of Net Income per Unit Basic and Net Income per Unit Diluted for Operating Partnership (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income	$ 277,846	$ 223,846	$ 708,402	$ 562,804
Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties	$ (830)	$ (750)	$ (2,450)	$ (1,939)
Dilutive Securities Options	3,187	2,972	3,035	2,642
Denominator for net income per share – diluted	386,896	383,884	386,177	383,433
Net income per Unit – basic	$ 0.72	$ 0.58	$ 1.83	$ 1.46
Net income per Unit – diluted	$ 0.71	$ 0.58	$ 1.82	$ 1.46
ERPOP [Member]
Net income	$ 277,846	$ 223,846	$ 708,402	$ 562,804
Net (income) loss attributable to Noncontrolling Interests – Partially Owned Properties	(830)	(750)	(2,450)	(1,939)
Allocation to Preference Units	(773)	(773)	(2,318)	(2,318)
Numerator for net income per Unit – basic and diluted	$ 276,243	$ 222,323	$ 703,634	$ 558,547
Denominator for net income per Unit – basic	383,709	380,912	383,142	380,791
Dilutive Securities Options	3,187	2,972	3,035	2,642
Denominator for net income per share – diluted	386,896	383,884	386,177	383,433
Net income per Unit – basic	$ 0.72	$ 0.58	$ 1.83	$ 1.46
Net income per Unit – diluted	$ 0.71	$ 0.58	$ 1.82	$ 1.46

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)PropertyApartmentUnit
Commitments And Contingencies [Abstract]
Projects in various stages of development	2
Partially owned projects in various stages of development	1
Units in various stages of development | ApartmentUnit	824
Consolidated project under development commitment fund | $	$ 459.4
Various stages of development with estimated completion dates ranging through September 30, 2021	Sep. 30, 2021

Reportable Segments - Additiona

Reportable Segments - Additional Information (Details) - Customer	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Disclosure Of Entitys Reportable Segments [Abstract]
Number of customer contributed 10% or more of total revenue	0	0

Reportable Segments - Reconcili

Reportable Segments - Reconciliation of NOI from Rental Real Estate Specific to Continuing Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Rental income	$ 685,120	$ 652,677	$ 2,016,796	$ 1,925,128
Property and maintenance expense	(114,966)	(110,541)	(338,497)	(322,487)
Real estate taxes and insurance expense	(87,546)	(87,388)	(270,434)	(268,784)
Operating income	368,363	339,403	947,592	896,088
Same Store, Non-same Store and Other
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Rental income	685,120	652,677	2,016,796	1,925,128
Property and maintenance expense	(114,966)	(110,541)	(338,497)	(322,487)
Real estate taxes and insurance expense	(87,546)	(87,388)	(270,434)	(268,784)
Total operating expenses	(202,512)	(197,929)	(608,931)	(591,271)
Operating income	$ 482,608	$ 454,748	$ 1,407,865	$ 1,333,857

Reportable Segments - NOI for E

Reportable Segments - NOI for Each Segment from Our Rental Real Estate Specific to Continuing Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Rental income	$ 685,120	$ 652,677	$ 2,016,796	$ 1,925,128
Operating income	368,363	339,403	947,592	896,088
Total Assets	21,054,056		21,054,056		$ 20,394,209
Capital Expenditures			128,335
Same store
Segment Reporting Information [Line Items]
Rental income	649,712	628,454	1,857,679	1,798,638
Operating expenses	196,520	189,582	559,793	539,070
Operating income	453,192	438,872	1,297,886	1,259,568
Total Assets	17,385,849		17,385,849
Capital Expenditures			119,911
Non-same store/other
Segment Reporting Information [Line Items]
Rental income	35,408	24,223	159,117	126,490
Operating expenses	5,992	8,347	49,138	52,201
Operating income	29,416	15,876	109,979	74,289
Total Assets	3,668,207		3,668,207
Capital Expenditures			8,424
Same Store, Non-same Store and Other
Segment Reporting Information [Line Items]
Rental income	685,120	652,677	2,016,796	1,925,128
Operating expenses	202,512	197,929	608,931	591,271
Operating income	482,608	454,748	1,407,865	1,333,857
Other markets | Same store
Segment Reporting Information [Line Items]
Rental income	520	484	1,560	1,453
Operating expenses	168	164	545	503
Operating income	352	320	1,015	950
Total Assets	12,867		12,867
Capital Expenditures			165
Los Angeles | Same store
Segment Reporting Information [Line Items]
Rental income	122,506	118,864	350,841	337,047
Operating expenses	36,666	34,683	102,851	96,431
Operating income	85,840	84,181	247,990	240,616
Total Assets	3,002,609		3,002,609
Capital Expenditures			23,301
Orange County | Same store
Segment Reporting Information [Line Items]
Rental income	26,636	25,599	78,522	75,595
Operating expenses	6,382	6,203	18,583	18,434
Operating income	20,254	19,396	59,939	57,161
Total Assets	409,559		409,559
Capital Expenditures			7,460
San Diego | Same store
Segment Reporting Information [Line Items]
Rental income	24,064	23,215	71,088	68,640
Operating expenses	6,447	6,234	18,532	17,988
Operating income	17,617	16,981	52,556	50,652
Total Assets	394,352		394,352
Capital Expenditures			3,161
Subtotal - Southern California | Same store
Segment Reporting Information [Line Items]
Rental income	173,206	167,678	500,451	481,282
Operating expenses	49,495	47,120	139,966	132,853
Operating income	123,711	120,558	360,485	348,429
Total Assets	3,806,520		3,806,520
Capital Expenditures			33,922
San Francisco | Same store
Segment Reporting Information [Line Items]
Rental income	127,104	122,075	359,867	346,485
Operating expenses	31,438	30,420	87,104	84,581
Operating income	95,666	91,655	272,763	261,904
Total Assets	3,267,869		3,267,869
Capital Expenditures			19,422
Washington DC | Same store
Segment Reporting Information [Line Items]
Rental income	111,712	108,979	330,944	323,549
Operating expenses	34,797	34,549	101,969	100,575
Operating income	76,915	74,430	228,975	222,974
Total Assets	3,600,267		3,600,267
Capital Expenditures			16,517
New York | Same store
Segment Reporting Information [Line Items]
Rental income	117,382	114,407	340,828	332,474
Operating expenses	48,293	45,143	142,047	133,001
Operating income	69,089	69,264	198,781	199,473
Total Assets	3,915,125		3,915,125
Capital Expenditures			17,532
Boston | Same store
Segment Reporting Information [Line Items]
Rental income	59,354	56,724	169,576	163,292
Operating expenses	16,243	16,124	46,645	45,473
Operating income	43,111	40,600	122,931	117,819
Total Assets	1,479,159		1,479,159
Capital Expenditures			18,191
Seattle | Same store
Segment Reporting Information [Line Items]
Rental income	60,434	58,107	154,453	150,103
Operating expenses	16,086	16,062	41,517	42,084
Operating income	44,348	42,045	112,936	108,019
Total Assets	1,304,042		1,304,042
Capital Expenditures			14,162
Non-same store | Non-same store/other
Segment Reporting Information [Line Items]
Rental income	32,171	8,160	136,353	69,334
Operating expenses	9,676	2,785	43,801	25,322
Operating income	22,495	5,375	92,552	44,012
Total Assets	3,109,994		3,109,994
Capital Expenditures			7,757
Other | Non-same store/other
Segment Reporting Information [Line Items]
Rental income	3,237	16,063	22,764	57,156
Operating expenses	(3,684)	5,562	5,337	26,879
Operating income	6,921	$ 10,501	17,427	$ 30,277
Total Assets	$ 558,213		558,213
Capital Expenditures			$ 667

Reportable Segments - NOI for_2

Reportable Segments - NOI for Each Segment from Our Rental Real Estate Specific to Continuing Operations (Parenthetical) (Details) - Property	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Disclosure Of Entitys Reportable Segments [Abstract]
Units in same store properties	75,290	75,290	72,979	72,979

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - Bonds [Member] - USD ($) $ in Millions	Oct. 01, 2019	Sep. 30, 2019
Subsequent Event [Line Items]
Repayments of long-term debt		$ 132.6
Subsequent Event
Subsequent Event [Line Items]
Repayments of long-term debt	$ 20