Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands		Mar. 31, 2024	Dec. 31, 2023
ASSETS
Total real estate		$ 20,768,288	$ 20,593,459
Total assets		25,525,978	26,026,149
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable, net		4,368,367	4,166,379
Other Liabilities		417,978	445,947
Members’/Partners’ equity		5,857,699	5,876,697
Total liabilities and equity / capital		25,525,978	26,026,149
Carying value of the Company's investment in unconsolidated joint ventures		1,399,824	1,377,319
Right-of-use assets - finance leases		401,486	401,680
Operating Lease, Right-of-Use Asset	[1]	344,255	324,298
Lease liabilities - finance leases		415,888	417,961
Lease Liabilities - Operating Leases		377,667	350,391
Unconsolidated Joint Ventures [Member]
ASSETS
Total real estate	[2]	5,740,545	5,811,763
Other assets	[3]	619,559	682,291
Total assets		6,360,104	6,494,054
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable, net		3,162,545	3,351,873
Other Liabilities	[4]	318,708	361,357
Members’/Partners’ equity		2,878,851	2,780,824
Total liabilities and equity / capital		6,360,104	6,494,054
Company's share of equity		1,313,484	1,278,483
Basis differentials	[5]	56,963	58,933
Carying value of the Company's investment in unconsolidated joint ventures	[6]	1,370,447	1,337,416
Operating Lease, Right-of-Use Asset		19,800	20,100
Sales-type lease receivable, net		14,000	13,900
Lease Liabilities - Operating Leases		30,500	30,500
Unconsolidated Joint Ventures [Member]
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Other Liabilities		29,400	39,900
Colorado Center
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		298,190	298,906
Carying value of the Company's investment in unconsolidated joint ventures	[7]	235,143	237,815
200 Fifth Avenue JV LLC
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		56,193	58,308
Carying value of the Company's investment in unconsolidated joint ventures	[7]	76,728	75,718
Gateway Commons Complex [Member]
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		49,593	48,971
Carying value of the Company's investment in unconsolidated joint ventures	[7]	385,568	376,834
Safeco Plaza REIT LLC
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		(29,432)	(29,678)
Carying value of the Company's investment in unconsolidated joint ventures	[7]	43,860	44,734
360 PAS Holdco LLC
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		(116,188)	(116,534)
Carying value of the Company's investment in unconsolidated joint ventures	[7]	49,888	42,988
Dock 72
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Other Liabilities	[7]	12,501	11,890
Basis differentials		(94,586)	(95,521)
Platform 16
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		(142,671)	(143,052)
Carying value of the Company's investment in unconsolidated joint ventures	[7]	$ 51,349	$ 45,564

[1] See Note 4.

[2] At March 31, 2024 and December 31, 2023, this amount included right of use assets - operating leases totaling approximately $19.8 million and $20.1 million, respectively.

[3] At March 31, 2024 and December 31, 2023, this amount included sales-type lease receivable, net totaling approximately $14.0 million and $13.9 million, respectively.

[4] At March 31, 2024 and December 31, 2023, 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, 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. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level. The majority of the Company’s basis differences are as follows: March 31, 2024December 31, 2023Property(in thousands)Colorado Center$298,190 $298,906 200 Fifth Avenue56,193 58,308 Gateway Commons49,593 48,971 Safeco Plaza(29,432)(29,678)360 Park Avenue South(116,188)(116,534)Dock 72(94,586)(95,521)Platform 16(142,671)(143,052) These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities.

[6] Investments with deficit balances aggregating approximately $29.4 million and $39.9 million at March 31, 2024 and December 31, 2023, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

[7] Investments with deficit balances aggregating approximately $29.4 million and $39.9 million at March 31, 2024 and December 31, 2023, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.