CONSOLIDATED STATEMENTS OF OPERATIONS OF ERP OPERATING LIMITED PARTNERSHIP - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
REVENUES
Rental income	$ 2,577,681	$ 2,470,689	$ 2,422,233
Fee and asset management	$ 753	$ 717	$ 3,567
Type of Revenue [Extensible List]	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember
Total revenues	$ 2,578,434	$ 2,471,406	$ 2,425,800
EXPENSES
Property and maintenance	429,335	405,281	406,823
Real estate taxes and insurance	357,814	335,495	317,387
Property management	92,485	85,493	82,015
General and administrative	53,813	52,224	57,840
Depreciation	785,725	743,749	705,649
Impairment	702	1,693	0
Total expenses	1,719,874	1,623,935	1,569,714
Operating income	858,560	847,471	856,086
Interest and other income	15,317	6,136	65,773
Other expenses	(17,267)	(5,186)	(10,368)
Interest:
Expense incurred, net	(413,360)	(383,890)	(482,246)
Amortization of deferred financing costs	(11,310)	(8,526)	(12,633)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations	431,940	456,005	416,612
Income and other tax (expense) benefit	(878)	(478)	(1,613)
Income (loss) from investments in unconsolidated entities	(3,667)	(3,370)	4,801
Net gain (loss) on sales of real estate properties	256,810	157,057	4,044,055
Net gain (loss) on sales of land parcels	987	19,167	15,731
Income from continuing operations	685,192	628,381	4,479,586
Discontinued operations, net	0	0	518
Net income	685,192	628,381	4,480,104
Partially Owned Properties	(2,718)	(2,323)	(16,430)
Net income attributable to controlling interests	$ 657,535	$ 603,454	$ 4,292,163
Earnings per Unit – basic:
Income from continuing operations available to Units	$ 1.78	$ 1.64	$ 11.75
Net income available to Units	1.78	1.64	11.75
Earnings per Unit – diluted:
Income from continuing operations available to Units	1.77	1.63	11.68
Net income available to Units	$ 1.77	$ 1.63	$ 11.68
Weighted average Units outstanding	383,695	382,678	381,992
ERPOP [Member]
REVENUES
Rental income	$ 2,577,681	$ 2,470,689	$ 2,422,233
Fee and asset management	$ 753	$ 717	$ 3,567
Type of Revenue [Extensible List]	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember	us-gaap:ManagementServiceMember
Total revenues	$ 2,578,434	$ 2,471,406	$ 2,425,800
EXPENSES
Property and maintenance	429,335	405,281	406,823
Real estate taxes and insurance	357,814	335,495	317,387
Property management	92,485	85,493	82,015
General and administrative	53,813	52,224	57,840
Depreciation	785,725	743,749	705,649
Impairment	702	1,693
Total expenses	1,719,874	1,623,935	1,569,714
Operating income	858,560	847,471	856,086
Interest and other income	15,317	6,136	65,773
Other expenses	(17,267)	(5,186)	(10,368)
Interest:
Expense incurred, net	(413,360)	(383,890)	(482,246)
Amortization of deferred financing costs	(11,310)	(8,526)	(12,633)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations	431,940	456,005	416,612
Income and other tax (expense) benefit	(878)	(478)	(1,613)
Income (loss) from investments in unconsolidated entities	(3,667)	(3,370)	4,801
Net gain (loss) on sales of real estate properties	256,810	157,057	4,044,055
Net gain (loss) on sales of land parcels	987	19,167	15,731
Income from continuing operations	685,192	628,381	4,479,586
Discontinued operations, net			518
Net income	685,192	628,381	4,480,104
Partially Owned Properties	(2,718)	(2,323)	(16,430)
Net income attributable to controlling interests	682,474	626,058	4,463,674
ALLOCATION OF NET INCOME:
Preference Units	3,090	3,091	3,091
General Partner	654,445	600,363	4,289,072
Limited Partners	24,939	22,604	171,511
Net income available to Units	$ 679,384	$ 622,967	$ 4,460,583
Earnings per Unit – basic:
Income from continuing operations available to Units	$ 1.78	$ 1.64	$ 11.75
Net income available to Units	$ 1.78	$ 1.64	$ 11.75
Weighted average Units outstanding	380,921	379,869	378,829
Earnings per Unit – diluted:
Income from continuing operations available to Units	$ 1.77	$ 1.63	$ 11.68
Net income available to Units	$ 1.77	$ 1.63	$ 11.68
Weighted average Units outstanding	383,695	382,678	381,992