CONSOLIDATED STATEMENTS OF OPERATIONS OF ERP OPERATING LIMITED PARTNERSHIP (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
REVENUES
Rental income	$ 2,605,311,000	$ 2,378,004,000	$ 1,737,929,000
Fee and asset management	9,437,000	9,698,000	9,573,000
Total revenues	2,614,748,000	2,387,702,000	1,747,502,000
EXPENSES
Property and maintenance	473,098,000	449,427,000	332,219,000
Real estate taxes and insurance	325,401,000	293,999,000	206,723,000
Property management	79,636,000	84,342,000	81,902,000
Fee and asset management	5,429,000	6,460,000	4,663,000
Depreciation	758,861,000	978,973,000	560,669,000
General and administrative	50,948,000	62,179,000	47,233,000
Total expenses	1,693,373,000	1,875,380,000	1,233,409,000
Operating income	921,375,000	512,322,000	514,093,000
Interest and other income	4,462,000	5,283,000	151,060,000
Other expenses	(9,073,000)	(29,630,000)	(27,796,000)
Interest:
Expense incurred, net	(457,191,000)	(586,854,000)	(455,236,000)
Amortization of deferred financing costs	(11,088,000)	(22,197,000)	(21,295,000)
Income (loss) before income and other taxes, (loss) from investments in unconsolidated entities, net gain on sales of real estate properties and land parcels and discontinued operations	448,485,000	(121,076,000)	160,826,000
Income and other tax (expense) benefit	(1,394,000)	(1,169,000)	(514,000)
(Loss) from investments in unconsolidated entities	(7,952,000)	(58,156,000)	(14,000)
Net gain on sales of real estate properties	212,685,000	0	0
Net gain on sales of land parcels	5,277,000	12,227,000	0
Income (loss) from continuing operations	657,101,000	(168,174,000)	160,298,000
Discontinued operations, net	1,582,000	2,073,527,000	720,906,000
Net income	658,683,000	1,905,353,000	881,204,000
Net (income) loss attributable to Noncontrolling Interests - Partially Owned Properties	(2,544,000)	538,000	(844,000)
Net income attributable to controlling interests	631,308,000	1,830,613,000	841,719,000
ALLOCATION OF NET INCOME:
Preference Units	(4,145,000)	(4,145,000)	(10,355,000)
Premium on redemption of Preference Units	0	0	5,152,000
Earnings per Unit – basic:
Income (loss) from continuing operations	$ 1.732	$ (0.466)	$ 0.454
Net income available to Units	$ 1.736	$ 5.155	$ 2.729
Earnings per Unit – diluted:
Income (loss) from continuing operations available to Units	$ 1.722	$ (0.466)	$ 0.450
Net income available to Units	$ 1.726	$ 5.155	$ 2.705
Distributions declared per Unit outstanding	$ 2.000	$ 1.850	$ 1.780
Partnership Interest [Member]
REVENUES
Rental income	2,605,311,000	2,378,004,000	1,737,929,000
Fee and asset management	9,437,000	9,698,000	9,573,000
Total revenues	2,614,748,000	2,387,702,000	1,747,502,000
EXPENSES
Property and maintenance	473,098,000	449,427,000	332,219,000
Real estate taxes and insurance	325,401,000	293,999,000	206,723,000
Property management	79,636,000	84,342,000	81,902,000
Fee and asset management	5,429,000	6,460,000	4,663,000
Depreciation	758,861,000	978,973,000	560,669,000
General and administrative	50,948,000	62,179,000	47,233,000
Total expenses	1,693,373,000	1,875,380,000	1,233,409,000
Operating income	921,375,000	512,322,000	514,093,000
Interest and other income	4,462,000	5,283,000	151,060,000
Other expenses	(9,073,000)	(29,630,000)	(27,796,000)
Interest:
Expense incurred, net	(457,191,000)	(586,854,000)	(455,236,000)
Amortization of deferred financing costs	(11,088,000)	(22,197,000)	(21,295,000)
Income (loss) before income and other taxes, (loss) from investments in unconsolidated entities, net gain on sales of real estate properties and land parcels and discontinued operations	448,485,000	(121,076,000)	160,826,000
Income and other tax (expense) benefit	(1,394,000)	(1,169,000)	(514,000)
(Loss) from investments in unconsolidated entities	(7,952,000)	(58,156,000)	(14,000)
Net gain on sales of real estate properties	212,685,000	0	0
Net gain on sales of land parcels	5,277,000	12,227,000	0
Income (loss) from continuing operations	657,101,000	(168,174,000)	160,298,000
Discontinued operations, net	1,582,000	2,073,527,000	720,906,000
Net income	658,683,000	1,905,353,000	881,204,000
Net (income) loss attributable to Noncontrolling Interests - Partially Owned Properties	(2,544,000)	538,000	(844,000)
Net income attributable to controlling interests	656,139,000	1,905,891,000	880,360,000
ALLOCATION OF NET INCOME:
Preference Units	4,145,000	4,145,000	10,355,000
Premium on redemption of Preference Units	0	0	5,152,000
General Partner	627,163,000	1,826,468,000	826,212,000
Limited Partners	24,831,000	75,278,000	38,641,000
Net income available to Units	$ 651,994,000	$ 1,901,746,000	$ 864,853,000
Earnings per Unit – basic:
Income (loss) from continuing operations	$ 1.732	$ (0.466)	$ 0.454
Net income available to Units	$ 1.736	$ 5.155	$ 2.729
Weighted average Units outstanding	374,899	368,038	316,554
Earnings per Unit – diluted:
Income (loss) from continuing operations available to Units	$ 1.722	$ (0.466)	$ 0.450
Net income available to Units	$ 1.726	$ 5.155	$ 2.705
Weighted average Units outstanding	377,735	368,038	319,766
Distributions declared per Unit outstanding	$ 2.000	$ 1.850	$ 1.780