Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands		Jun. 30, 2023	Dec. 31, 2022
ASSETS
Total real estate		$ 19,598,101	$ 19,496,442
Total assets		25,341,680	24,207,669
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable, net		3,274,764	3,272,368
Other Liabilities		418,813	450,918
Members’/Partners’ equity		6,040,052	6,132,919
Total liabilities and equity / capital		25,341,680	24,207,669
Carying value of the Company's investment in unconsolidated joint ventures		1,780,959	1,715,911
Right-of-use assets - finance leases		237,526	237,510
Right of use assets - operating leases		166,421	167,351
Lease liabilities - finance leases		251,874	249,335
Lease liabilities - operating leases		204,826	204,686
Unconsolidated Joint Ventures [Member]
ASSETS
Total real estate	[1]	6,748,400	6,537,554
Other assets		779,220	756,786
Total assets		7,527,620	7,294,340
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable, net		4,056,181	4,022,746
Other Liabilities	[2]	724,078	716,271
Members’/Partners’ equity		2,747,361	2,555,323
Total liabilities and equity / capital		7,527,620	7,294,340
Company's share of equity		1,301,827	1,238,929
Basis differentials	[3]	401,205	391,556
Carying value of the Company's investment in unconsolidated joint ventures	[4]	1,703,032	1,630,485
Right-of-use assets - finance leases		248,900	248,900
Right of use assets - operating leases		20,600	21,200
Lease liabilities - finance leases		379,700	382,200
Lease liabilities - operating leases		30,500	30,500
Unconsolidated Joint Ventures [Member]
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Other Liabilities		77,900	85,400
Colorado Center
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		300,370	301,820
Carying value of the Company's investment in unconsolidated joint ventures	[5]	235,846	233,862
200 Fifth Avenue JV LLC
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		96,837	94,497
Carying value of the Company's investment in unconsolidated joint ventures	[5]	116,335	120,083
Gateway Commons Complex [Member]
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		48,078	47,808
Carying value of the Company's investment in unconsolidated joint ventures	[5]	349,055	324,038
Dock 72
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Other Liabilities	[5]	13,511	19,921
Basis differentials		$ (97,232)	$ (98,980)

[1] At June 30, 2023 and December 31, 2022, this amount included right of use assets - finance leases totaling approximately $248.9 million. At June 30, 2023 and December 31, 2022, this amount included right of use assets - operating leases totaling approximately $20.6 million and $21.2 million, respectively.

[2] At June 30, 2023 and December 31, 2022, this amount included lease liabilities - finance leases totaling approximately $379.7 million and $382.2 million, respectively. At June 30, 2023 and December 31, 2022, this amount included lease liabilities - operating leases totaling approximately $30.5 million.

[3] 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: June 30, 2023December 31, 2022Property(in thousands)Colorado Center$300,370 $301,820 200 Fifth Avenue96,837 94,497 Gateway Commons48,078 47,808 Dock 72(97,232)(98,980) These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities.

[4] Investments with deficit balances aggregating approximately $77.9 million and $85.4 million at June 30, 2023 and December 31, 2022, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

[5] Investments with deficit balances aggregating approximately $77.9 million and $85.4 million at June 30, 2023 and December 31, 2022, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.