Investments in Partially Owned Entities - Partially Owned Property Balance Sheet Schedule (Details) $ in Thousands	Jun. 30, 2017 USD ($) Property ApartmentUnit	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)
Partially Owned Property Balance Sheet Schedule
Total properties | Property	301
Total apartment units | ApartmentUnit	77,034
ASSETS
Investment in real estate	$ 25,489,817	$ 25,386,425
Accumulated depreciation	(5,671,510)	(5,360,389)
Investment in real estate, net	19,818,307	20,026,036
Cash and cash equivalents	37,719	77,207	$ 497,843	$ 42,276
Investments in unconsolidated entities	59,246	60,141
Deposits – restricted	254,378	76,946
Other assets	445,909	398,883
Total assets	20,636,575	20,704,148
LIABILITIES AND EQUITY
Mortgage notes payable, net	3,743,363	4,119,181
Accounts payable and accrued expenses	137,920	147,482
Accrued interest payable	48,823	60,946
Other liabilities	324,002	350,466
Security deposits	63,648	62,624
Total liabilities	9,730,199	9,801,072
Partially Owned Properties	6,303	10,609
Total equity	10,525,857	10,460,984
Total liabilities and equity/capital	$ 20,636,575	$ 20,704,148
Unconsolidated Non-VIE
Partially Owned Property Balance Sheet Schedule
Total properties | Property	2
Total apartment units | ApartmentUnit	945
ASSETS
Investment in real estate	$ 236,332
Accumulated depreciation	(38,177)
Investment in real estate, net	198,155
Cash and cash equivalents	5,886
Investments in unconsolidated entities	0
Deposits – restricted	258
Other assets	576
Total assets	204,875
LIABILITIES AND EQUITY
Mortgage notes payable, net	145,424
Accounts payable and accrued expenses	1,382
Accrued interest payable	691
Other liabilities	333
Security deposits	480
Total liabilities	148,310
Partially Owned Properties	55,881
Company equity/General and Limited Partners' Capital	684
Total equity	56,565
Total liabilities and equity/capital	$ 204,875
Consolidated VIE
Partially Owned Property Balance Sheet Schedule
Total properties | Property	17
Total apartment units | ApartmentUnit	3,215
ASSETS
Investment in real estate	$ 648,047
Accumulated depreciation	(221,433)
Investment in real estate, net	426,614
Cash and cash equivalents	17,431
Investments in unconsolidated entities	45,688
Deposits – restricted	361
Other assets	25,300
Total assets	515,394
LIABILITIES AND EQUITY
Mortgage notes payable, net	301,728
Accounts payable and accrued expenses	1,550
Accrued interest payable	1,024
Other liabilities	922
Security deposits	2,010
Total liabilities	307,234
Partially Owned Properties	6,303
Company equity/General and Limited Partners' Capital	201,857
Total equity	208,160
Total liabilities and equity/capital	$ 515,394
Unconsolidated VIE
Partially Owned Property Balance Sheet Schedule
Total properties | Property	0
Total apartment units | ApartmentUnit	0
ASSETS
Investment in real estate	$ 172,995
Accumulated depreciation	(47,295)
Investment in real estate, net	125,700
Cash and cash equivalents	176
Investments in unconsolidated entities	0
Deposits – restricted	0
Other assets	176
Total assets	126,052
LIABILITIES AND EQUITY
Mortgage notes payable, net	0
Accounts payable and accrued expenses	107
Accrued interest payable	0
Other liabilities	55
Security deposits	0
Total liabilities	162
Partially Owned Properties	85,202
Company equity/General and Limited Partners' Capital	40,688
Total equity	125,890
Total liabilities and equity/capital	$ 126,052
Partially Owned Properties – Unconsolidated
Partially Owned Property Balance Sheet Schedule
Total properties | Property	2
Total apartment units | ApartmentUnit	945
ASSETS
Investment in real estate	$ 409,327
Accumulated depreciation	(85,472)
Investment in real estate, net	323,855
Cash and cash equivalents	6,062
Investments in unconsolidated entities	0
Deposits – restricted	258
Other assets	752
Total assets	330,927
LIABILITIES AND EQUITY
Mortgage notes payable, net	145,424
Accounts payable and accrued expenses	1,489
Accrued interest payable	691
Other liabilities	388
Security deposits	480
Total liabilities	148,472
Partially Owned Properties	141,083
Company equity/General and Limited Partners' Capital	41,372
Total equity	182,455
Total liabilities and equity/capital	$ 330,927