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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 | Mar. 31, 2025
ASSETS |  |  |
Total real estate |  | $ 21,050,255 | $ 21,119,163
Total assets |  | 26,084,980 | 25,436,521
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Mortgage and notes payable, net |  | 4,276,609 | 4,277,710
Other Liabilities |  | 450,796 | 450,165
Members’/Partners’ equity |  | 5,413,306 | 5,319,942
Total liabilities and equity / capital |  | 26,084,980 | 25,436,521
Carying value of the Company's investment in unconsolidated joint ventures |  | 1,093,583 | 1,137,732
Operating Lease, Right-of-Use Asset |  | 334,767 | 330,129
Lease Liabilities - Operating Leases |  | 392,686 | 395,638
Unconsolidated Joint Ventures [Member] |  |  |
ASSETS |  |  |
Total real estate | [1] | 5,748,198 | 5,820,435
Other assets | [2] | 703,096 | 700,641
Total assets |  | 6,451,294 | 6,521,076
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Mortgage and notes payable, net |  | 3,206,723 | 3,213,566
Other Liabilities | [3] | 292,125 | 251,826
Members’/Partners’ equity |  | 2,952,446 | 3,055,684
Total liabilities and equity / capital |  | 6,451,294 | 6,521,076
Company's share of equity |  | 1,344,543 | 1,371,939
Basis differentials | [4] | (284,469) | (282,392)
Carying value of the Company's investment in unconsolidated joint ventures | [5] | 1,060,074 | 1,089,547
Operating Lease, Right-of-Use Asset |  | 19,000 | 18,700
Sales-type lease receivable, net |  | 14,100 | 14,200
Lease Liabilities - Operating Leases |  | 30,500 | 30,500
Unconsolidated Joint Ventures [Member] |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Other Liabilities |  | 33,500 | 48,200
Colorado Center |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | 127,632 | 128,562
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 65,000 | 68,235
Impairment loss on investment |  | 168,400 |
200 Fifth Avenue JV LLC |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | 49,656 | 48,017
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 70,673 | 67,165
Gateway Commons Complex [Member] |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | (74,500) | (73,693)
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 272,000 | 272,872
Impairment loss on investment |  | 126,100 |
Safeco Plaza REIT LLC |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | (75,576) | (74,822)
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 0 | 132
Impairment loss on investment |  | 46,800 |
Dock 72 |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Other Liabilities | [6] | 9,889 | 12,477
Basis differentials |  | (92,054) | (91,159)
360 Park Avenue South |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | (113,265) | (112,372)
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 74,592 | 79,883
Platform 16 |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | (142,698) | (142,683)
Carying value of the Company's investment in unconsolidated joint ventures | [6] | 56,265 | 57,775
Other Unconsolidated JVS |  |  |
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY |  |  |
Basis differentials |  | $ 36,300 | $ 35,800
[1] | At March 31, 2025 and December 31, 2024, this amount included right of use assets - operating leases totaling approximately $18.7 million and $19.0 million, respectively.
[2] | At March 31, 2025 and December 31, 2024, this amount included sales-type lease receivable, net totaling approximately $14.2 million and $14.1 million, respectively.
[3] | At March 31, 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:
| March 31, 2025 |  | December 31, 2024
Property | (in thousands)
Colorado Center | $ | 128,562 |  |  | $ | 127,632 |
200 Fifth Avenue | 48,017 |  |  | 49,656 |
Gateway Commons | (73,693) |  |  | (74,500) |
Safeco Plaza | (74,822) |  |  | (75,576) |
Dock 72 | (91,159) |  |  | (92,054) |
360 Park Avenue South | (112,372) |  |  | (113,265) |
Platform 16 | (142,683) |  |  | (142,698) |
These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities. An additional $35.8 million and $36.3 million of other basis differentials are not included above at March 31, 2025 and December 31, 2024, respectively.
[5] | Investments with deficit balances aggregating approximately $48.2 million and $33.5 million at March 31, 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 $48.2 million and $33.5 million at March 31, 2025 and December 31, 2024, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.

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