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, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Comprehensive income:
Net income	$ 336,732	$ 108,315	$ 1,397,766	$ 260,482
Other comprehensive (loss) - derivative instruments:
Unrealized holding (losses) arising during the period	9,523	(11,860)	12,337	(8,642)
Losses reclassified into earnings from other comprehensive income	3,826	3,640	12,098	7,203
Other comprehensive income - other instruments:
Unrealized holding gains arising during the period	501	118	928	82
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	1,814	0	941	0
Other comprehensive income (loss)	15,664	(8,102)	26,304	(1,357)
Comprehensive income	352,396	100,213	1,424,070	259,125
Comprehensive (income) attributable to Noncontrolling Interests	(11,973)	(5,051)	(55,321)	(11,919)
Comprehensive income attributable to controlling interests	340,423	95,162	1,368,749	247,206
OPERATING PARTNERSHIP
Comprehensive income:
Net income	336,732	108,315	1,397,766	260,482
Other comprehensive (loss) - derivative instruments:
Unrealized holding (losses) arising during the period	9,523	(11,860)	12,337	(8,642)
Losses reclassified into earnings from other comprehensive income	3,826	3,640	12,098	7,203
Other comprehensive income - other instruments:
Unrealized holding gains arising during the period	501	118	928	82
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	1,814	0	941	0
Other comprehensive income (loss)	15,664	(8,102)	26,304	(1,357)
Comprehensive income	352,396	100,213	1,424,070	259,125
Comprehensive (income) attributable to Noncontrolling Interests	815	(319)	790	(769)
Comprehensive income attributable to controlling interests	$ 353,211	$ 99,894	$ 1,424,860	$ 258,356