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Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 | Jun. 30, 2025
ASSETS |  |  |
Total real estate |  | $ 21,050,255 | $ 21,262,840
Total assets |  | 26,084,980 | 25,621,190
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Mortgage and notes payable, net |  | 4,276,609 | 4,278,788
Other Liabilities |  | 450,796 | 416,838
Members’/Partners’ equity |  | 5,413,306 | 5,258,786
Total liabilities and equity / capital |  | 26,084,980 | 25,621,190
Carying value of the Company's investment in unconsolidated joint ventures |  | 1,093,583 | 1,161,036
Operating Lease, Right-of-Use Asset |  | 334,767 | 325,670
Lease Liabilities - Operating Leases |  | 392,686 | 399,174
Unconsolidated Joint Ventures [Member] |  |  |
ASSETS |  |  |
Total real estate | [1] | 5,748,198 | 5,838,787
Other assets | [2] | 703,096 | 726,052
Total assets |  | 6,451,294 | 6,564,839
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Mortgage and notes payable, net |  | 3,206,723 | 3,214,062
Other Liabilities | [3] | 292,125 | 244,381
Members’/Partners’ equity |  | 2,952,446 | 3,106,396
Total liabilities and equity / capital |  | 6,451,294 | 6,564,839
Company's share of equity |  | 1,344,543 | 1,388,350
Basis differentials | [4] | (284,469) | (275,446)
Carying value of the Company's investment in unconsolidated joint ventures | [5] | 1,060,074 | 1,112,904
Operating Lease, Right-of-Use Asset |  | 19,000 | 18,400
Sales-type lease receivable, net |  | 14,100 | 14,300
Lease Liabilities - Operating Leases |  | 30,500 | 30,500
Unconsolidated Joint Ventures [Member] |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Other Liabilities |  | 33,500 | 48,100
Colorado Center |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | 127,632 | 129,524
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 65,000 | 70,222
Impairment loss on investment |  | 168,400 |
200 Fifth Avenue JV LLC |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | 49,656 | 49,459
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 70,673 | 74,446
Gateway Commons Complex [Member] |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | (74,500) | (72,366)
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 272,000 | 271,454
Impairment loss on investment |  | 126,100 |
Safeco Plaza REIT LLC |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | (75,576) | (74,043)
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 0 | 43
Impairment loss on investment |  | 46,800 |
Dock 72 |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Other Liabilities | [6] | 9,889 | 11,961
Basis differentials |  | (92,054) | (90,263)
360 Park Avenue South |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | (113,265) | (111,530)
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 74,592 | 89,769
Platform 16 |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | (142,698) | (142,676)
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 56,265 | 57,805
Remaining Other Investment |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | $ 36,336 | $ 36,449
[1] | At June 30, 2025 and December 31, 2024, this amount included right of use assets - operating leases totaling approximately $18.4 million and $19.0 million, respectively.
[2] | At June 30, 2025 and December 31, 2024, this amount included sales-type lease receivable, net totaling approximately $14.3 million and $14.1 million, respectively.
[3] | At June 30, 2025 and December 31, 2024, this amount included lease liabilities - operating leases totaling approximately $30.5 million.
[4] | 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 result from impairments of investments, acquisitions through joint ventures with no change in control and upon the transfer of assets that were previously owned by the Company into a joint venture. During the year ended December 31, 2024, the Company recognized an other-than-temporary impairment loss on its investments in Colorado Center, Gateway Commons and Safeco Plaza of approximately $168.4 million, $126.1 million, and $46.8 million, respectively. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level. The Company’s basis differences include:
| June 30, 2025 |  | December 31, 2024
Property | (in thousands)
Colorado Center | $ | 129,524 |  |  | $ | 127,632 |
200 Fifth Avenue | 49,459 |  |  | 49,656 |
Gateway Commons | (72,366) |  |  | (74,500) |
Safeco Plaza | (74,043) |  |  | (75,576) |
Dock 72 | (90,263) |  |  | (92,054) |
360 Park Avenue South | (111,530) |  |  | (113,265) |
Platform 16 | (142,676) |  |  | (142,698) |
Other basis differentials | 36,449 |  |  | 36,336 |
Total basis differentials | (275,446) |  |  | (284,469) |
These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities.
[5] | Investments with deficit balances aggregating approximately $48.1 million and $33.5 million at June 30, 2025 and December 31, 2024, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.
[6] | Investments with deficit balances aggregating approximately $48.1 million and $33.5 million at June 30, 2025 and December 31, 2024, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.

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