CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Comprehensive income:
Net income	$ 236,323	$ 112,977	$ 496,805	$ 827,796
Other comprehensive (loss) - derivative instruments:
Unrealized holding (losses) arising during the period	(3,695)	(105,248)	(12,337)	(130,367)
Losses reclassified into earnings from other comprehensive income	3,704	951	10,907	2,842
Other comprehensive income - other instruments:
Unrealized holding gains arising during the period	312	(182)	394	311
Other Comprehensive (loss)	321	(104,479)	(1,036)	(127,214)
Comprehensive income	236,644	8,498	495,769	700,582
Comprehensive (income), Net of Tax, Attributable to Noncontrolling Interest	(10,184)	(5,129)	(22,103)	(36,693)
Comprehensive income attributable to controlling interests	226,460	3,369	473,666	663,889
OPERATING PARTNERSHIP
Comprehensive income:
Net income	236,323	112,977	496,805	827,796
Other comprehensive (loss) - derivative instruments:
Unrealized holding (losses) arising during the period	(3,695)	(105,248)	(12,337)	(130,367)
Losses reclassified into earnings from other comprehensive income	(3,704)	(951)	(10,907)	(2,842)
Other comprehensive income - other instruments:
Unrealized holding gains arising during the period	312	(182)	394	311
Other Comprehensive (loss)	321	(104,479)	(1,036)	(127,214)
Comprehensive income	236,644	8,498	495,769	700,582
Comprehensive (income), Net of Tax, Attributable to Noncontrolling Interest	312	(387)	(457)	(418)
Comprehensive income attributable to controlling interests	$ 236,956	$ 8,111	$ 495,312	$ 700,164