CONSOLIDATED STATEMENTS OF OPERATIONS OF ERP OPERATING LIMITED PARTNERSHIP - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
REVENUES
Rental income	$ 2,700,691	$ 2,577,681	$ 2,470,689
Fee and asset management	$ 384	$ 753	$ 717
Type of Revenue [Extensible List]	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember
Total revenues	$ 2,701,075	$ 2,578,434	$ 2,471,406
EXPENSES
Property and maintenance	446,845	429,335	405,281
Real estate taxes and insurance	366,139	357,814	335,495
Property management	95,344	92,485	85,493
General and administrative	52,757	53,813	52,224
Depreciation	831,083	785,725	743,749
Total expenses	1,792,168	1,719,172	1,622,242
Net gain (loss) on sales of real estate properties	447,637	256,810	157,057
Impairment		(702)	(1,693)
Operating income	1,356,544	1,115,370	1,004,528
Interest and other income	2,817	15,317	6,136
Other expenses	(18,177)	(17,267)	(5,186)
Interest:
Expense incurred, net	(390,076)	(413,360)	(383,890)
Amortization of deferred financing costs	(11,670)	(11,310)	(8,526)
Income before income and other taxes, income (loss) from investments in unconsolidated entities and net gain (loss) on sales of land parcels	939,438	688,750	613,062
Income and other tax (expense) benefit	2,281	(878)	(478)
Income (loss) from investments in unconsolidated entities	65,945	(3,667)	(3,370)
Net gain (loss) on sales of land parcels	2,044	987	19,167
Net income	1,009,708	685,192	628,381
Partially Owned Properties	(3,297)	(2,718)	(2,323)
Net income attributable to controlling interests	$ 970,377	$ 657,535	$ 603,454
Earnings per Unit – basic:
Net income available to Units	$ 2.61	$ 1.78	$ 1.64
Earnings per Unit – diluted:
Net income available to Units	$ 2.60	$ 1.77	$ 1.63
Weighted average Units outstanding	386,333	383,695	382,678
ERPOP [Member]
REVENUES
Rental income	$ 2,700,691	$ 2,577,681	$ 2,470,689
Fee and asset management	384	$ 753	$ 717
Type of Revenue [Extensible List]		us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember
Total revenues	2,701,075	$ 2,578,434	$ 2,471,406
EXPENSES
Property and maintenance	446,845	429,335	405,281
Real estate taxes and insurance	366,139	357,814	335,495
Property management	95,344	92,485	85,493
General and administrative	52,757	53,813	52,224
Depreciation	831,083	785,725	743,749
Total expenses	1,792,168	1,719,172	1,622,242
Net gain (loss) on sales of real estate properties	447,637	256,810	157,057
Impairment		(702)	(1,693)
Operating income	1,356,544	1,115,370	1,004,528
Interest and other income	2,817	15,317	6,136
Other expenses	(18,177)	(17,267)	(5,186)
Interest:
Expense incurred, net	(390,076)	(413,360)	(383,890)
Amortization of deferred financing costs	(11,670)	(11,310)	(8,526)
Income before income and other taxes, income (loss) from investments in unconsolidated entities and net gain (loss) on sales of land parcels	939,438	688,750	613,062
Income and other tax (expense) benefit	2,281	(878)	(478)
Income (loss) from investments in unconsolidated entities	65,945	(3,667)	(3,370)
Net gain (loss) on sales of land parcels	2,044	987	19,167
Net income	1,009,708	685,192	628,381
Partially Owned Properties	(3,297)	(2,718)	(2,323)
Net income attributable to controlling interests	1,006,411	682,474	626,058
ALLOCATION OF NET INCOME:
Preference Units	3,090	3,090	3,091
General Partner	967,287	654,445	600,363
Limited Partners	36,034	24,939	22,604
Net income available to Units	$ 1,003,321	$ 679,384	$ 622,967
Earnings per Unit – basic:
Net income available to Units	$ 2.61	$ 1.78	$ 1.64
Weighted average Units outstanding	383,368	380,921	379,869
Earnings per Unit – diluted:
Net income available to Units	$ 2.60	$ 1.77	$ 1.63
Weighted average Units outstanding	386,333	383,695	382,678