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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, 2025 | Dec. 31, 2024 | Dec. 31, 2023
ASSETS |  |  |  |  |  |
Total real estate |  | $ 20,899,879 |  | $ 21,050,255 |  |
Total assets |  | 26,166,164 |  | 26,084,980 |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Mortgage and notes payable, net |  | 4,280,067 |  | 4,276,609 |  |
Other Liabilities |  | 386,074 |  | 450,796 |  |
Members’/Partners’ equity |  | 5,147,190 |  | 5,413,306 |  |
Total liabilities and equity / capital |  | 26,166,164 |  | 26,084,980 |  |
Carying value of the Company's investment in unconsolidated joint ventures |  | 999,309 |  | 1,093,583 |  |
Right of use assets - operating leases |  | 325,841 |  | 334,767 |  |
Sales-type lease receivable, net |  | 15,929 |  | 14,923 |  |
Lease Liabilities - Operating Leases |  | 389,213 |  | 392,686 |  |
Impairment loss |  | 85,803 |  | 13,615 |  | $ 0
Gateway Commons Complex [Member] | Unconsolidated Properties |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Impairment loss |  | 425,800 |  |  |  |
Safeco Plaza | Unconsolidated Properties |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Impairment loss |  | 319,500 |  |  |  |
Unconsolidated Joint Ventures [Member] |  |  |  |  |  |
ASSETS |  |  |  |  |  |
Total real estate | [2] | 4,786,058 | [1] | 5,748,198 |  |
Other assets | [3] | 672,776 |  | 703,096 |  |
Total assets |  | 5,458,834 |  | 6,451,294 |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Mortgage and notes payable, net |  | 2,905,065 |  | 3,206,723 |  |
Other Liabilities | [4] | 189,125 |  | 292,125 |  |
Members’/Partners’ equity |  | 2,364,644 |  | 2,952,446 |  |
Total liabilities and equity / capital |  | 5,458,834 |  | 6,451,294 |  |
Company's share of equity |  | 1,084,806 |  | 1,344,543 |  |
Basis differentials | [5] | (101,096) | [1] | (284,469) |  |
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 983,710 |  | 1,060,074 |  |
Right of use assets - operating leases |  | 17,900 |  | 19,000 |  |
Sales-type lease receivable, net |  | 14,400 |  | 14,100 |  |
Lease Liabilities - Operating Leases |  | 30,500 |  | 30,500 |  |
Impairment loss |  | 745,224 | [7] | 0 |  | 0
Equity Method Investment, Other-than-Temporary Impairment | [8] | 145,133 |  | 341,338 |  | 272,603
Unconsolidated Joint Ventures [Member] |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Other Liabilities |  | 15,600 |  | 33,500 |  |
Colorado Center |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Basis differentials |  | 131,356 |  | 127,632 |  |
Carying value of the Company's investment in unconsolidated joint ventures | [9] | 69,959 |  | 65,000 |  |
Equity Method Investment, Other-than-Temporary Impairment |  |  |  | 168,400 |  |
Colorado Center | Unconsolidated Joint Ventures [Member] | Unconsolidated Properties |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Equity Method Investment, Other-than-Temporary Impairment |  |  |  | 168,400 |  |
200 Fifth Avenue JV LLC |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Basis differentials |  | 48,289 |  | 49,656 |  |
Carying value of the Company's investment in unconsolidated joint ventures | [9] | 74,747 |  | 70,673 |  |
200 Fifth Avenue JV LLC | Unconsolidated Joint Ventures [Member] |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Equity Method Investment, Other-than-Temporary Impairment |  |  |  |  |  | 33,400
Gateway Commons Complex [Member] |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Basis differentials |  | (700) |  | (74,500) |  |
Carying value of the Company's investment in unconsolidated joint ventures | [9] | 125,576 |  | 272,000 |  |
Equity Method Investment, Other-than-Temporary Impairment |  | 145,100 |  | 126,100 |  |
Gateway Commons Complex [Member] | Unconsolidated Joint Ventures [Member] | Unconsolidated Properties |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Equity Method Investment, Other-than-Temporary Impairment |  |  |  | 126,100 |  |
Safeco Plaza REIT LLC |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Other Liabilities | [9] | 2,557 |  |  |  |
Basis differentials |  | 32,905 |  | (75,576) |  |
Carying value of the Company's investment in unconsolidated joint ventures | [9] |  |  | 0 |  |
Equity Method Investment, Other-than-Temporary Impairment |  |  |  | 46,800 |  |
Safeco Plaza REIT LLC | Unconsolidated Joint Ventures [Member] |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Equity Method Investment, Other-than-Temporary Impairment |  |  |  |  |  | 29,900
Safeco Plaza REIT LLC | Unconsolidated Joint Ventures [Member] | Unconsolidated Properties |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Equity Method Investment, Other-than-Temporary Impairment |  |  |  | 46,800 |  |
Dock 72 |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Other Liabilities |  | 400 |  | 9,889 | [9] |
Basis differentials |  | (88,420) |  | (92,054) |  |
Carying value of the Company's investment in unconsolidated joint ventures | [9] | 83,547 |  |  |  |
360 Park Avenue South |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Basis differentials |  | (110,815) |  | (113,265) |  |
Carying value of the Company's investment in unconsolidated joint ventures | [9] | 104,778 |  | 74,592 |  |
360 Park Avenue South | Unconsolidated Joint Ventures [Member] |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Equity Method Investment, Other-than-Temporary Impairment |  |  |  |  |  | 54,000
Platform 16 |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Basis differentials |  | (142,677) |  | (142,698) |  |
Carying value of the Company's investment in unconsolidated joint ventures | [9] | 58,561 |  | 56,265 |  |
Platform 16 | Unconsolidated Joint Ventures [Member] |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Equity Method Investment, Other-than-Temporary Impairment |  |  |  |  |  | $ 155,200
Remaining Other Investment |  |  |  |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |  |  |  |
Basis differentials |  | $ 28,966 |  | $ 36,336 |  |
[1] | During the year ended December 31, 2025, the joint ventures that own Safeco Plaza and Gateway Commons recognized property level impairment losses in accordance with ASC 360 (See Note 2). In prior periods, the Company had impaired its equity method investment to the estimated fair value for these joint ventures and therefore this is recognized as a basis difference.
[2] | At December 31, 2025 and December 31, 2024, this amount included right of use assets - operating leases totaling approximately $17.9 million and $19.0 million, respectively.
[3] | At December 31, 2025 and December 31, 2024, this amount included sales-type lease receivable, net totaling approximately $14.4 million and $14.1 million, respectively.
[4] | At December 31, 2025 and December 31, 2024, this amount included lease liabilities - operating leases totaling approximately $30.5 million.
[5] | 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, impairments at the property level, 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, 2025, the joint ventures that own Gateway Commons and Safeco Plaza recognized property level impairments of approximately $425.8 million and $319.5 million, respectively. During the year ended December 31, 2025, the Company recognized an other-than-temporary impairment loss on its investment in Gateway Commons of approximately $145.1 million. 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:
| December 31, 2025 |  | December 31, 2024
Property | (in thousands)
Colorado Center | $ | 131,356 |  |  | $ | 127,632 |
200 Fifth Avenue | 48,289 |  |  | 49,656 |
Gateway Commons | (700) |  |  | (74,500) |
Safeco Plaza | 32,905 |  |  | (75,576) |
Dock 72 | (88,420) |  |  | (92,054) |
360 Park Avenue South | (110,815) |  |  | (113,265) |
Platform 16 | (142,677) |  |  | (142,698) |
Other basis differentials | 28,966 |  |  | 36,336 |
Total basis differentials | $ | (101,096) |  |  | $ | (284,469) |
These basis differentials (excluding land, which does not depreciate) will be amortized over the remaining lives of the related assets and liabilities.
[6] | Investments with deficit balances aggregating approximately $15.6 million and $33.5 million at December 31, 2025 and December 31, 2024, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.
[7] | (3)During the year ended December 31, 2025, the joint ventures that own Safeco Plaza and Gateway Commons recognized property level impairment losses in accordance with ASC 360 (See Note 2). In prior periods, the Company had impaired its equity method investment to the estimated fair value for these joint ventures and therefore this is recognized as a basis difference and does not impact Loss from Unconsolidated Joint Ventures on the Consolidated Statements of Operations.
[8] | During the year ended December 31, 2025, the Company recognized an other-than-temporary impairment loss on its investment in Gateway Commons of approximately $145.1 million. 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. During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investments in Platform 16, 360 Park Avenue South, 200 Fifth Avenue and Safeco Plaza of approximately $155.2 million, $54.0 million, $33.4 million and $29.9 million, respectively.
[9] | Investments with deficit balances aggregating approximately $15.6 million and $33.5 million at December 31, 2025 and December 31, 2024, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.

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