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Schedule III - Real Estate and Accumulated Depreciation-Overall Summary (Details) | Dec. 31, 2018 USD ($) Property ApartmentUnit | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
--- | --- | --- | --- | ---
Overall summary of real estate and accumulated depreciation |  |  |  |
Investment in Real Estate, Gross | $ 26,511,022,000 | $ 26,026,896,000 | $ 25,386,425,000 | $ 28,542,697,000
Accumulated Depreciation | $ (6,696,281,000) | $ (6,040,378,000) | $ (5,360,389,000) | $ (6,084,616,000)
Investment in Real Estate - Wholly Owned Unencumbered [Member] |  |  |  |
Overall summary of real estate and accumulated depreciation |  |  |  |
Properties | Property | 240 |  |  |
Units | ApartmentUnit | 62,862 |  |  |
Investment in Real Estate, Gross | $ 21,609,130,732 |  |  |
Accumulated Depreciation | (5,400,484,879) |  |  |
Investment in Real Estate, Net | 16,208,645,853 |  |  |
Encumbrances | $ 0 |  |  |
Investment in Real Estate - Wholly Owned Encumbered [Member] |  |  |  |
Overall summary of real estate and accumulated depreciation |  |  |  |
Properties | Property | 48 |  |  |
Units | ApartmentUnit | 12,140 |  |  |
Investment in Real Estate, Gross | $ 4,023,117,169 |  |  |
Accumulated Depreciation | (1,039,436,780) |  |  |
Investment in Real Estate, Net | 2,983,680,389 |  |  |
Encumbrances | $ 2,081,887,149 |  |  |
Wholly Owned Properties |  |  |  |
Overall summary of real estate and accumulated depreciation |  |  |  |
Properties | Property | 288 |  |  |
Units | ApartmentUnit | 75,002 |  |  |
Investment in Real Estate, Gross | $ 25,632,247,901 |  |  |
Accumulated Depreciation | (6,439,921,659) |  |  |
Investment in Real Estate, Net | 19,192,326,242 |  |  |
Encumbrances | $ 2,081,887,149 |  |  |
Investment in Real Estate - Partially Owned Unencumbered [Member] |  |  |  |
Overall summary of real estate and accumulated depreciation |  |  |  |
Properties | Property | 9 |  |  |
Units | ApartmentUnit | 1,847 |  |  |
Investment in Real Estate, Gross | $ 516,719,235 |  |  |
Accumulated Depreciation | (116,736,579) |  |  |
Investment in Real Estate, Net | 399,982,656 |  |  |
Encumbrances | $ 0 |  |  |
Investment in Real Estate - Partially Owned Encumbered [Member] |  |  |  |
Overall summary of real estate and accumulated depreciation |  |  |  |
Properties | Property | 8 |  |  |
Units | ApartmentUnit | 1,688 |  |  |
Investment in Real Estate, Gross | $ 362,054,538 |  |  |
Accumulated Depreciation | (139,622,501) |  |  |
Investment in Real Estate, Net | 222,432,037 |  |  |
Encumbrances | $ 303,583,335 |  |  |
NONCONTROLLING INTERESTS - PARTIALLY OWNED PROPERTIES |  |  |  |
Overall summary of real estate and accumulated depreciation |  |  |  |
Properties | Property | 17 |  |  |
Units | ApartmentUnit | 3,535 |  |  |
Investment in Real Estate, Gross | $ 878,773,773 |  |  |
Accumulated Depreciation | (256,359,080) |  |  |
Investment in Real Estate, Net | 622,414,693 |  |  |
Encumbrances | $ 303,583,335 |  |  |
Unencumbered Properties [Member] |  |  |  |
Overall summary of real estate and accumulated depreciation |  |  |  |
Properties | Property | 249 |  |  |
Units | ApartmentUnit | 64,709 |  |  |
Investment in Real Estate, Gross | $ 22,125,849,967 |  |  |
Accumulated Depreciation | (5,517,221,458) |  |  |
Investment in Real Estate, Net | 16,608,628,509 |  |  |
Encumbrances | $ 0 |  |  |
Encumbered Properties [Member] |  |  |  |
Overall summary of real estate and accumulated depreciation |  |  |  |
Properties | Property | 56 |  |  |
Units | ApartmentUnit | 13,828 |  |  |
Investment in Real Estate, Gross | $ 4,385,171,707 |  |  |
Accumulated Depreciation | (1,179,059,281) |  |  |
Investment in Real Estate, Net | 3,206,112,426 |  |  |
Encumbrances | $ 2,385,470,484 |  |  |
Total Consolidated Investment in Real Estate [Member] |  |  |  |
Overall summary of real estate and accumulated depreciation |  |  |  |
Properties | Property | 305 |  |  |
Units | ApartmentUnit | 78,537 |  |  |
Investment in Real Estate, Gross | $ 26,511,021,674 |  |  |
Accumulated Depreciation | (6,696,280,739) |  |  |
Investment in Real Estate, Net | 19,814,740,935 |  |  |
Encumbrances | $ 2,385,470,484 |  |  |

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