CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME OF ERP OPERATING LIMITED PARTNERSHIP (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Comprehensive income:
Net income	$ 1,905,353	$ 881,204	$ 935,197
Other comprehensive income (loss) - derivative instruments:
Unrealized holding gains (losses) arising during the year	18,771	(11,772)	(143,598)
Losses reclassified into earnings from other comprehensive income	20,141	14,678	4,343
Other comprehensive income (loss) - other instruments:
Unrealized holding gains arising during the year	583	664	355
Gain on Sale of Securities, Net	(2,122)	0	0
Other comprehensive income – foreign currency:
Currency translation adjustments arising during the year	613	0	0
Other comprehensive income (loss)	37,986	3,570	(138,900)
Comprehensive income	1,943,339	884,774	796,297
Comprehensive (income) attributable to Noncontrolling Interests	(74,740)	(39,485)	(41,612)
Comprehensive income attributable to controlling interests	1,868,599	845,289	754,685
OPERATING PARTNERSHIP
Comprehensive income:
Net income	1,905,353	881,204	935,197
Other comprehensive income (loss) - derivative instruments:
Unrealized holding gains (losses) arising during the year	18,771	(11,772)	(143,598)
Losses reclassified into earnings from other comprehensive income	20,141	14,678	4,343
Other comprehensive income (loss) - other instruments:
Unrealized holding gains arising during the year	583	664	355
Gain on Sale of Securities, Net	(2,122)	0	0
Other comprehensive income – foreign currency:
Currency translation adjustments arising during the year	613	0	0
Other comprehensive income (loss)	37,986	3,570	(138,900)
Comprehensive income	1,943,339	884,774	796,297
Comprehensive (income) attributable to Noncontrolling Interests	538	(844)	(832)
Comprehensive income attributable to controlling interests	$ 1,943,877	$ 883,930	$ 795,465