Investments in Partially Owned Entities - Partially Owned Property Balance Sheet Schedule (Details) $ in Thousands	Mar. 31, 2018 USD ($) Property ApartmentUnit	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)
Partially Owned Property Balance Sheet Schedule
Total properties | Property	303
Apartment Units | ApartmentUnit	78,399
ASSETS
Investment in real estate	$ 25,958,617	$ 26,026,896
Accumulated depreciation	(6,173,047)	(6,040,378)
Investment in real estate, net	19,785,570	19,986,518
Cash and cash equivalents	44,453	50,647	$ 42,139
Investments in unconsolidated entities	59,091	58,254
Restricted deposits	50,258	50,115	$ 144,084
Other assets	444,498	425,065
Total assets	20,383,870	20,570,599
LIABILITIES AND EQUITY
Mortgage notes payable, net	2,894,344	3,618,722
Accounts payable and accrued expenses	167,481	114,766
Accrued interest payable	69,753	58,035
Other liabilities	335,957	341,852
Security deposits	64,748	65,009
Total liabilities	9,504,210	9,729,781
Partially Owned Properties	1,293	4,708
Total equity	10,525,093	10,473,863
Total liabilities and equity/capital	$ 20,383,870	$ 20,570,599
Unconsolidated Non-VIE
Partially Owned Property Balance Sheet Schedule
Total properties | Property	2
Apartment Units | ApartmentUnit	945
ASSETS
Investment in real estate	$ 236,854
Accumulated depreciation	(46,190)
Investment in real estate, net	190,664
Cash and cash equivalents	6,587
Investments in unconsolidated entities	0
Restricted deposits	258
Other assets	243
Total assets	197,752
LIABILITIES AND EQUITY
Mortgage notes payable, net	145,424
Accounts payable and accrued expenses	1,361
Accrued interest payable	691
Other liabilities	261
Security deposits	525
Total liabilities	148,262
Partially Owned Properties	51,079
Company equity/General and Limited Partners’ Capital	(1,589)
Total equity	49,490
Total liabilities and equity/capital	$ 197,752
Consolidated VIE
Partially Owned Property Balance Sheet Schedule
Total properties | Property	17
Apartment Units | ApartmentUnit	3,535
ASSETS
Investment in real estate	$ 875,187
Accumulated depreciation	(235,426)
Investment in real estate, net	639,761
Cash and cash equivalents	13,061
Investments in unconsolidated entities	43,926
Restricted deposits	381
Other assets	25,879
Total assets	723,008
LIABILITIES AND EQUITY
Mortgage notes payable, net	302,656
Accounts payable and accrued expenses	3,344
Accrued interest payable	1,037
Other liabilities	3,683
Security deposits	2,470
Total liabilities	313,190
Partially Owned Properties	1,293
Company equity/General and Limited Partners’ Capital	408,525
Total equity	409,818
Total liabilities and equity/capital	$ 723,008
Unconsolidated VIE
Partially Owned Property Balance Sheet Schedule
Total properties | Property	0
Apartment Units | ApartmentUnit	0
ASSETS
Investment in real estate	$ 172,995
Accumulated depreciation	(51,420)
Investment in real estate, net	121,575
Cash and cash equivalents	225
Investments in unconsolidated entities	0
Restricted deposits	0
Other assets	320
Total assets	122,120
LIABILITIES AND EQUITY
Mortgage notes payable, net	0
Accounts payable and accrued expenses	115
Accrued interest payable	0
Other liabilities	15
Security deposits	0
Total liabilities	130
Partially Owned Properties	84,038
Company equity/General and Limited Partners’ Capital	37,952
Total equity	121,990
Total liabilities and equity/capital	$ 122,120
Partially Owned Properties – Unconsolidated
Partially Owned Property Balance Sheet Schedule
Total properties | Property	2
Apartment Units | ApartmentUnit	945
ASSETS
Investment in real estate	$ 409,849
Accumulated depreciation	(97,610)
Investment in real estate, net	312,239
Cash and cash equivalents	6,812
Investments in unconsolidated entities	0
Restricted deposits	258
Other assets	563
Total assets	319,872
LIABILITIES AND EQUITY
Mortgage notes payable, net	145,424
Accounts payable and accrued expenses	1,476
Accrued interest payable	691
Other liabilities	276
Security deposits	525
Total liabilities	148,392
Partially Owned Properties	135,117
Company equity/General and Limited Partners’ Capital	36,363
Total equity	171,480
Total liabilities and equity/capital	$ 319,872