Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands		Dec. 31, 2021		Dec. 31, 2020
ASSETS
Real estate and development in process, net		$ 18,275,954		$ 17,818,807
Total assets		22,365,258		22,858,190
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable, net		3,267,914		2,909,081
Other Liabilities		391,441		412,084
Members’/Partners’ equity		5,834,020		5,996,083
Total liabilities and equity / capital		22,365,258		22,858,190
Carying value of the Company's investment in unconsolidated joint ventures		1,482,997		1,310,478
Right-of-use assets - finance leases		237,507		237,393
Right of use assets - operating leases		169,778	[1]	146,406
Lease liabilities - finance leases		244,421		236,492
Lease liabilities - operating leases		204,561		201,713
Unconsolidated Joint Ventures [Member]
ASSETS
Real estate and development in process, net	[2]	5,579,218		4,708,571
Other assets		586,470		531,071
Total assets		6,165,688		5,239,642
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable, net		3,214,961		2,637,911
Other Liabilities	[3]	652,135		650,433
Members’/Partners’ equity		2,298,592		1,951,298
Total liabilities and equity / capital		6,165,688		5,239,642
Company's share of equity		1,104,175		936,087
Basis differentials	[4]	341,751		337,832
Carying value of the Company's investment in unconsolidated joint ventures	[5]	1,445,926		1,273,919
Right-of-use assets - finance leases		248,900		248,900
Right of use assets - operating leases		22,300		22,500
Lease liabilities - finance leases		385,500		388,700
Lease liabilities - operating leases		30,400		29,000
Unconsolidated Joint Ventures [Member]
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Other Liabilities		37,100		36,600
Colorado Center
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		304,776		307,328
Carying value of the Company's investment in unconsolidated joint ventures	[6]	231,479		227,671
Gateway Commons Complex [Member]
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		51,009		51,875
Carying value of the Company's investment in unconsolidated joint ventures	[6]	327,148		336,206
Dock 72
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		(50,051)		(52,243)
Carying value of the Company's investment in unconsolidated joint ventures	[6]	$ 27,343		$ 29,536

[1] See Note 4.

[2] At December 31, 2021 and December 31, 2020, this amount included right of use assets - finance leases totaling approximately $248.9 million. At December 31, 2021 and December 31, 2020, this amount included right of use assets - operating leases totaling approximately $22.3 million and $22.5 million, respectively.

[3] At December 31, 2021 and December 31, 2020, this amount included lease liabilities - finance leases totaling approximately $385.5 million and $388.7 million, respectively, and lease liabilities - operating leases totaling approximately $30.4 million and $29.0 million, respectively.

[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. 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: December 31, 2021December 31, 2020Property(in thousands)Colorado Center$304,776 $307,328 Gateway Commons51,009 51,875 Dock 72(50,051)(52,243) 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 $37.1 million and $36.6 million at December 31, 2021 and 2020, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

[6] Investments with deficit balances aggregating approximately $37.1 million and $36.6 million at December 31, 2021 and December 31, 2020, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.