CONSOLIDATED STATEMENTS OF CASH FLOWS OF ERP OPERATING LIMITED PARTNERSHIP - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 1,396,714	$ 962,501	$ 1,009,708
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	838,272	820,832	831,083
Amortization of deferred financing costs	8,737	8,939	11,670
Amortization of above/below market lease intangibles	(154)	(71)	(71)
Amortization of discounts and premiums on debt	5,302	5,231	11,780
Amortization of deferred settlements on derivative instruments	9,382	35,075	21,176
Amortization of right-of-use assets	13,266	11,682	11,764
Impairment	16,769
Write-off of pursuit costs	6,526	6,869	5,529
(Income) loss from investments in unconsolidated entities	3,398	3,284	(65,945)
Distributions from unconsolidated entities – return on capital	56	100	2,621
Net (gain) loss on sales of real estate properties	(1,072,183)	(531,807)	(447,637)
Net (gain) loss on sales of land parcels	(5)	(34,234)	(2,044)
Net (gain) loss on debt extinguishment		26,150	13,647
Realized/unrealized (gain) loss on derivative instruments		50
Realized (gain) loss on sale of investment securities	(23,432)
Compensation paid with Company Common Shares	27,810	23,174	24,449
Other operating activities, net		1,805	(287)
Changes in assets and liabilities:
(Increase) decrease in other assets	5,906	(53,021)	6,278
Increase (decrease) in accounts payable and accrued expenses	15,381	470	5,116
Increase (decrease) in accrued interest payable	3,614	(956)	4,230
Increase (decrease) in lease liabilities	(5,122)	(2,204)	(2,269)
Increase (decrease) in other liabilities	4,286	(8,751)	13,382
Increase (decrease) in security deposits	5,661	(9,582)	2,804
Net cash provided by operating activities	1,260,184	1,265,536	1,456,984
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in real estate – acquisitions	(1,712,131)	(48,898)	(1,518,878)
Investment in real estate – development/other	(206,421)	(230,332)	(195,692)
Capital expenditures to real estate	(151,019)	(135,979)	(178,423)
Non-real estate capital additions	(1,696)	(20,100)	(4,955)
Interest capitalized for real estate and unconsolidated entities under development	(15,932)	(10,165)	(6,884)
Proceeds from disposition of real estate, net	1,707,747	1,113,972	1,064,619
Investments in unconsolidated entities – acquisitions	(48,534)
Investments in unconsolidated entities – other	(31,257)	(5,775)	(9,604)
Distributions from unconsolidated entities – return of capital	1,516	1,636	78,262
Purchase of investment securities and other investments	(168,291)	(773)	(269)
Proceeds from sale of investment securities	191,398
Net cash provided by (used for) investing activities	(434,620)	663,586	(771,824)
CASH FLOWS FROM FINANCING ACTIVITIES:
Debt financing costs	(6,446)	(2,923)	(19,812)
Mortgage notes payable, net:
Proceeds	58,428	519,204	295,771
Lump sum payoffs	(156,815)	(160,522)	(743,021)
Scheduled principal repayments	(7,465)	(7,759)	(6,808)
Notes, net:
Proceeds	497,470		1,194,468
Lump sum payoffs		(750,000)	(1,050,000)
Line of credit and commercial paper:
Line of credit proceeds	10,000	1,870,000	6,010,000
Line of credit repayments	(10,000)	(1,890,000)	(5,990,000)
Commercial paper proceeds	7,590,200	7,450,997	15,944,800
Commercial paper repayments	(7,690,000)	(8,034,000)	(15,446,150)
Proceeds from (payments on) settlement of derivative instruments		(1,240)	(41,616)
Prepaid finance ground lease			(34,734)
Finance ground lease principal payments	(365)
Proceeds from Employee Share Purchase Plan (ESPP)	4,265	4,508	3,116
Proceeds from exercise of EQR options	85,445	12,275	77,785
Payment of offering costs	(428)		(991)
Other financing activities, net	(63)	(63)	(80)
Contributions – Noncontrolling Interests – Partially Owned Properties	1,394	417	7,337
Contributions – Limited Partners		13	2
Distributions:
OP Units – General Partner	(900,468)	(883,938)	(831,111)
Preference Units	(3,090)	(3,090)	(3,090)
OP Units – Limited Partners	(31,316)	(32,403)	(29,615)
Noncontrolling Interests – Partially Owned Properties	(5,802)	(11,719)	(7,078)
Net cash provided by (used for) financing activities	(565,056)	(1,946,393)	(684,474)
Net increase (decrease) in cash and cash equivalents and restricted deposits	260,508	(17,271)	686
Cash and cash equivalents and restricted deposits, beginning of year	99,728	116,999	116,313
Cash and cash equivalents and restricted deposits, end of year	360,236	99,728	116,999
Cash and cash equivalents	123,832	42,591	45,753
Restricted deposits	236,404	57,137	71,246
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized	252,838	320,854	342,048
Net cash paid (received) for income and other taxes	1,179	(1,038)	(585)
Amortization of deferred financing costs:
Investment in real estate, net	(353)	(240)	(120)
Other assets	2,338	2,338	2,987
Mortgage notes payable, net	2,743	1,815	3,934
Notes, net	4,009	5,026	4,869
Amortization of discounts and premiums on debt:
Mortgage notes payable, net	2,764	2,234	8,618
Notes, net	2,538	2,997	3,162
Amortization of deferred settlements on derivative instruments:
Other liabilities	(12)	(12)	(12)
Accumulated other comprehensive income	9,394	35,087	21,188
Write-off of pursuit costs:
Investment in real estate, net	5,918	6,566	5,451
Other assets	582	271	62
Accounts payable and accrued expenses	26	32	16
(Income) loss from investments in unconsolidated entities:
Investments in unconsolidated entities	2,122	1,995	(67,268)
Other liabilities	1,276	1,289	1,323
Realized/unrealized (gain) loss on derivative instruments:
Other assets			2,002
Notes, net			2,277
Other liabilities		1,240	29,486
Accumulated other comprehensive income		(1,190)	(33,765)
Interest capitalized for real estate and unconsolidated entities under development:
Investment in real estate, net	15,318	10,165	6,884
Investments in unconsolidated entities	(614)
Investments in unconsolidated entities – other:
Investment in real estate, net	1,395
Investments in unconsolidated entities	(30,642)	(4,275)	(7,504)
Other liabilities	(2,010)	(1,500)	(2,100)
Debt financing costs:
Other assets	229	(231)	(6,909)
Mortgage notes payable, net	(2,344)	(2,692)	(2,354)
Notes, net	(4,331)		(10,549)
Right-of-use assets and lease liabilities initial measurement and reclassifications:
Right-of-use assets	11,308		(489,517)
Other assets			184,116
Lease liabilities	(11,308)		333,603
Other liabilities			(28,202)
Non-cash share distribution from unconsolidated entities:
Investments in unconsolidated entities	1,430
Other assets	(1,430)
Mortgage Notes Payable, Net [Member]
Mortgage notes payable, net:
Net gain (loss) on debt extinguishment		(327)	(3,381)
Notes, net:
Net gain (loss) on debt extinguishment		(327)	(3,381)
Notes, Net [Member]
Mortgage notes payable, net:
Net gain (loss) on debt extinguishment		(25,823)	(10,266)
Notes, net:
Net gain (loss) on debt extinguishment		(25,823)	(10,266)
ERPOP [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	1,396,714	962,501	1,009,708
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	838,272	820,832	831,083
Amortization of deferred financing costs	8,737	8,939	11,670
Amortization of above/below market lease intangibles	(154)	(71)	(71)
Amortization of discounts and premiums on debt	5,302	5,231	11,780
Amortization of deferred settlements on derivative instruments	9,382	35,075	21,176
Amortization of right-of-use assets	13,266	11,682	11,764
Impairment	16,769
Write-off of pursuit costs	6,526	6,869	5,529
(Income) loss from investments in unconsolidated entities	3,398	3,284	(65,945)
Distributions from unconsolidated entities – return on capital	56	100	2,621
Net (gain) loss on sales of real estate properties	(1,072,183)	(531,807)	(447,637)
Net (gain) loss on sales of land parcels	(5)	(34,234)	(2,044)
Net (gain) loss on debt extinguishment		26,150	13,647
Realized/unrealized (gain) loss on derivative instruments		50
Realized (gain) loss on sale of investment securities	(23,432)
Compensation paid with Company Common Shares	27,810	23,174	24,449
Other operating activities, net		1,805	(287)
Changes in assets and liabilities:
(Increase) decrease in other assets	5,906	(53,021)	6,278
Increase (decrease) in accounts payable and accrued expenses	15,381	470	5,116
Increase (decrease) in accrued interest payable	3,614	(956)	4,230
Increase (decrease) in lease liabilities	(5,122)	(2,204)	(2,269)
Increase (decrease) in other liabilities	4,286	(8,751)	13,382
Increase (decrease) in security deposits	5,661	(9,582)	2,804
Net cash provided by operating activities	1,260,184	1,265,536	1,456,984
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in real estate – acquisitions	(1,712,131)	(48,898)	(1,518,878)
Investment in real estate – development/other	(206,421)	(230,332)	(195,692)
Capital expenditures to real estate	(151,019)	(135,979)	(178,423)
Non-real estate capital additions	(1,696)	(20,100)	(4,955)
Interest capitalized for real estate and unconsolidated entities under development	(15,932)	(10,165)	(6,884)
Proceeds from disposition of real estate, net	1,707,747	1,113,972	1,064,619
Investments in unconsolidated entities – acquisitions	(48,534)
Investments in unconsolidated entities – other	(31,257)	(5,775)	(9,604)
Distributions from unconsolidated entities – return of capital	1,516	1,636	78,262
Purchase of investment securities and other investments	(168,291)	(773)	(269)
Proceeds from sale of investment securities	191,398
Net cash provided by (used for) investing activities	(434,620)	663,586	(771,824)
CASH FLOWS FROM FINANCING ACTIVITIES:
Debt financing costs	(6,446)	(2,923)	(19,812)
Mortgage notes payable, net:
Proceeds	58,428	519,204	295,771
Lump sum payoffs	(156,815)	(160,522)	(743,021)
Scheduled principal repayments	(7,465)	(7,759)	(6,808)
Notes, net:
Proceeds	497,470		1,194,468
Lump sum payoffs		(750,000)	(1,050,000)
Line of credit and commercial paper:
Line of credit proceeds	10,000	1,870,000	6,010,000
Line of credit repayments	(10,000)	(1,890,000)	(5,990,000)
Commercial paper proceeds	7,590,200	7,450,997	15,944,800
Commercial paper repayments	(7,690,000)	(8,034,000)	(15,446,150)
Proceeds from (payments on) settlement of derivative instruments		(1,240)	(41,616)
Prepaid finance ground lease			(34,734)
Finance ground lease principal payments	(365)
Proceeds from Employee Share Purchase Plan (ESPP)	4,265	4,508	3,116
Proceeds from exercise of EQR options	85,445	12,275	77,785
Payment of offering costs	(428)		(991)
Other financing activities, net	(63)	(63)	(80)
Contributions – Noncontrolling Interests – Partially Owned Properties	1,394	417	7,337
Contributions – Limited Partners		13	2
Distributions:
OP Units – General Partner	(900,468)	(883,938)	(831,111)
Preference Units	(3,090)	(3,090)	(3,090)
OP Units – Limited Partners	(31,316)	(32,403)	(29,615)
Noncontrolling Interests – Partially Owned Properties	(5,802)	(11,719)	(7,078)
Net cash provided by (used for) financing activities	(565,056)	(1,946,393)	(684,474)
Net increase (decrease) in cash and cash equivalents and restricted deposits	260,508	(17,271)	686
Cash and cash equivalents and restricted deposits, beginning of year	99,728	116,999	116,313
Cash and cash equivalents and restricted deposits, end of year	360,236	99,728	116,999
Cash and cash equivalents	123,832	42,591	45,753
Restricted deposits	236,404	57,137	71,246
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized	252,838	320,854	342,048
Net cash paid (received) for income and other taxes	1,179	(1,038)	(585)
Amortization of deferred financing costs:
Investment in real estate, net	(353)	(240)	(120)
Other assets	2,338	2,338	2,987
Mortgage notes payable, net	2,743	1,815	3,934
Notes, net	4,009	5,026	4,869
Amortization of discounts and premiums on debt:
Mortgage notes payable, net	2,764	2,234	8,618
Notes, net	2,538	2,997	3,162
Amortization of deferred settlements on derivative instruments:
Other liabilities	(12)	(12)	(12)
Accumulated other comprehensive income	9,394	35,087	21,188
Write-off of pursuit costs:
Investment in real estate, net	5,918	6,566	5,451
Other assets	582	271	62
Accounts payable and accrued expenses	26	32	16
(Income) loss from investments in unconsolidated entities:
Investments in unconsolidated entities	2,122	1,995	(67,268)
Other liabilities	1,276	1,289	1,323
Realized/unrealized (gain) loss on derivative instruments:
Other assets			2,002
Notes, net			2,277
Other liabilities		1,240	29,486
Accumulated other comprehensive income		(1,190)	(33,765)
Interest capitalized for real estate and unconsolidated entities under development:
Investment in real estate, net	(15,318)	(10,165)	(6,884)
Investments in unconsolidated entities	(614)
Investments in unconsolidated entities – other:
Investment in real estate, net	1,395
Investments in unconsolidated entities	(30,642)	(4,275)	(7,504)
Other liabilities	(2,010)	(1,500)	(2,100)
Debt financing costs:
Other assets	229	(231)	(6,909)
Mortgage notes payable, net	(2,344)	(2,692)	(2,354)
Notes, net	(4,331)		(10,549)
Right-of-use assets and lease liabilities initial measurement and reclassifications:
Right-of-use assets	11,308		(489,517)
Other assets			184,116
Lease liabilities	(11,308)		333,603
Other liabilities			(28,202)
Non-cash share distribution from unconsolidated entities:
Investments in unconsolidated entities	1,430
Other assets	$ (1,430)
ERPOP [Member] | Mortgage Notes Payable, Net [Member]
Mortgage notes payable, net:
Net gain (loss) on debt extinguishment		(327)	(3,381)
Notes, net:
Net gain (loss) on debt extinguishment		(327)	(3,381)
ERPOP [Member] | Notes, Net [Member]
Mortgage notes payable, net:
Net gain (loss) on debt extinguishment		(25,823)	(10,266)
Notes, net:
Net gain (loss) on debt extinguishment		$ (25,823)	$ (10,266)