CONSOLIDATED BALANCE SHEETS OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Investment in real estate
Land	$ 4,384,200,000	$ 4,367,816,000
Depreciable property	15,606,315,000	15,554,740,000
Projects under development	185,621,000	160,190,000
Land held for development	360,955,000	325,200,000
Investment in real estate	20,537,091,000	20,407,946,000
Accumulated depreciation	(4,658,994,000)	(4,539,583,000)
Investment in real estate, net	15,878,097,000	15,868,363,000
Cash and cash equivalents	219,628,000	383,921,000
Investments in unconsolidated entities	14,803,000	12,327,000
Deposits - restricted	182,182,000	152,237,000
Escrow deposits - mortgage	11,428,000	10,692,000
Deferred financing costs, net	45,861,000	44,608,000
Other assets	129,248,000	187,155,000
Total assets	16,481,247,000	16,659,303,000
Liabilities:
Mortgage notes payable	4,056,976,000	4,111,487,000
Notes, net	5,355,590,000	5,609,574,000
Lines of credit	0	0
Accounts payable and accrued expenses	77,055,000	35,206,000
Accrued interest payable	79,489,000	88,121,000
Other liabilities	261,448,000	291,289,000
Security deposits	65,468,000	65,286,000
Distributions payable	109,043,000	179,079,000
Total liabilities	10,005,069,000	10,380,042,000
Partners' Capital:
Accumulated other comprehensive (loss)	(189,973,000)	(196,718,000)
Noncontrolling Interests - Partially Owned Properties	73,915,000	74,306,000
Total liabilities and equity	16,481,247,000	16,659,303,000
OPERATING PARTNERSHIP
Investment in real estate
Land	4,384,200,000	4,367,816,000
Depreciable property	15,606,315,000	15,554,740,000
Projects under development	185,621,000	160,190,000
Land held for development	360,955,000	325,200,000
Investment in real estate	20,537,091,000	20,407,946,000
Accumulated depreciation	(4,658,994,000)	(4,539,583,000)
Investment in real estate, net	15,878,097,000	15,868,363,000
Cash and cash equivalents	219,628,000	383,921,000
Investments in unconsolidated entities	14,803,000	12,327,000
Deposits - restricted	182,182,000	152,237,000
Escrow deposits - mortgage	11,428,000	10,692,000
Deferred financing costs, net	45,861,000	44,608,000
Other assets	129,248,000	187,155,000
Total assets	16,481,247,000	16,659,303,000
Liabilities:
Mortgage notes payable	4,056,976,000	4,111,487,000
Notes, net	5,355,590,000	5,609,574,000
Lines of credit	0	0
Accounts payable and accrued expenses	77,055,000	35,206,000
Accrued interest payable	79,489,000	88,121,000
Other liabilities	261,448,000	291,289,000
Security deposits	65,468,000	65,286,000
Distributions payable	109,043,000	179,079,000
Total liabilities	10,005,069,000	10,380,042,000
Redeemable Limited Partners	457,224,000	416,404,000
Partners' Capital:
Preferred Units Value Outstanding	200,000,000	200,000,000
General Partner	5,811,981,000	5,665,733,000
Limited Partners	123,031,000	119,536,000
Accumulated other comprehensive (loss)	(189,973,000)	(196,718,000)
Total partners' capital	5,945,039,000	5,788,551,000
Noncontrolling Interests - Partially Owned Properties	73,915,000	74,306,000
Total capital	6,018,954,000	5,862,857,000
Total liabilities and equity	$ 16,481,247,000	$ 16,659,303,000