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Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands | Jun. 30, 2016 | Dec. 31, 2015
--- | --- | ---
ASSETS |  |  |
Real estate and development in process, net |  | $ 15,740,152 | $ 15,555,641
Liabilities and Members'/Partners' Equity [Abstract] |  |  |
Mortgage notes payable, net |  | 3,189,013 | 3,435,242
Other Liabilities |  | 508,952 | 483,601
Total liabilities and equity / capital |  | 18,963,965 | 18,351,486
Carrying value of the Company's investments in unconsolidated joint ventures |  | 252,618 | 235,224
Unconsolidated Joint Ventures [Member] |  |  |
ASSETS |  |  |
Real estate and development in process, net |  | 1,124,267 | 1,072,412
Other assets |  | 237,196 | 252,285
Total assets |  | 1,361,463 | 1,324,697
Liabilities and Members'/Partners' Equity [Abstract] |  |  |
Mortgage notes payable, net |  | 827,987 | 830,125
Other Liabilities |  | 47,685 | 44,549
Members'/Partners' equity |  | 485,791 | 450,023
Total liabilities and equity / capital |  | 1,361,463 | 1,324,697
Company's share of equity |  | 255,362 | 237,070
Basis differentials | [1] | (26,673) | (27,047)
Carrying value of the Company's investments in unconsolidated joint ventures | [2],[3] | 228,689 | 210,023
Unconsolidated Joint Ventures [Member] |  |  |
Liabilities and Members'/Partners' Equity [Abstract] |  |  |
Carrying value of the Company's investments in unconsolidated joint ventures |  | $ (23,900) | $ (25,200)
[1] | (1)This amount represents the aggregate difference between the Company’s historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from impairment of investments and upon the transfer of assets that were previously owned by the Company into a joint venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level.
[2] | Investments with deficit balances aggregating approximately $23.9 million and $25.2 million at June 30, 2016 and December 31, 2015, respectively, have been reflected within Other Liabilities on the Company’s Consolidated Balance Sheets.
[3] | Investments with deficit balances aggregating approximately $23.9 million and $25.2 million at June 30, 2016 and December 31, 2015, respectively, have been reflected within Other Liabilities on the Company’s Consolidated Balance Sheets.

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- Definition This amount represents the aggregate difference between the Company's historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from impairment of investments and upon the transfer of assets that were previously owned by the Company into a joint venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level. + References No definition available. + Details
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- Definition Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(d)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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