CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Comprehensive income:
Net income	$ 108,315	$ 581,753	$ 260,482	$ 714,819
Other comprehensive (loss) - derivative instruments:
Unrealized holding (losses) arising during the period	(11,860)	(31,201)	(8,642)	(25,119)
Losses reclassified into earnings from other comprehensive income	3,640	935	7,203	1,891
Other comprehensive income - other instruments:
Unrealized holding gains arising during the period	118	347	82	493
Other Comprehensive (loss)	(8,102)	(29,919)	(1,357)	(22,735)
Comprehensive income	100,213	551,834	259,125	692,084
Comprehensive (income), Net of Tax, Attributable to Noncontrolling Interest	(5,051)	(25,829)	(11,919)	(31,564)
Comprehensive income attributable to controlling interests	95,162	526,005	247,206	660,520
OPERATING PARTNERSHIP
Comprehensive income:
Net income	108,315	581,753	260,482	714,819
Other comprehensive (loss) - derivative instruments:
Unrealized holding (losses) arising during the period	(11,860)	(31,201)	(8,642)	(25,119)
Losses reclassified into earnings from other comprehensive income	3,640	935	7,203	1,891
Other comprehensive income - other instruments:
Unrealized holding gains arising during the period	118	347	82	493
Other Comprehensive (loss)	(8,102)	(29,919)	(1,357)	(22,735)
Comprehensive income	100,213	551,834	259,125	692,084
Comprehensive (income), Net of Tax, Attributable to Noncontrolling Interest	(319)	(71)	(769)	(31)
Comprehensive income attributable to controlling interests	$ 99,894	$ 551,763	$ 258,356	$ 692,053