Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands		Mar. 31, 2022	Dec. 31, 2021
ASSETS
Real estate and development in process, net		$ 18,313,215	$ 18,275,954
Total assets		22,475,634	22,365,258
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable, net		3,268,745	3,267,914
Other Liabilities		396,283	391,441
Members’/Partners’ equity		5,843,602	5,834,020
Total liabilities and equity / capital		22,475,634	22,365,258
Carying value of the Company's investment in unconsolidated joint ventures		1,518,622	1,482,997
Right-of-use assets - finance leases		237,501	237,507
Right of use assets - operating leases		169,248	169,778
Lease liabilities - finance leases		245,554	244,421
Lease liabilities - operating leases		204,677	204,561
Unconsolidated Joint Ventures [Member]
ASSETS
Real estate and development in process, net	[1]	5,649,181	5,579,218
Other assets		628,608	586,470
Total assets		6,277,789	6,165,688
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable, net		3,370,649	3,214,961
Other Liabilities	[2]	644,127	652,135
Members’/Partners’ equity		2,263,013	2,298,592
Total liabilities and equity / capital		6,277,789	6,165,688
Company's share of equity		1,112,465	1,104,175
Basis differentials	[3]	343,085	341,751
Carying value of the Company's investment in unconsolidated joint ventures	[4]	1,455,550	1,445,926
Right-of-use assets - finance leases		248,900	248,900
Right of use assets - operating leases		22,000	22,300
Lease liabilities - finance leases		384,700	385,500
Lease liabilities - operating leases		30,400	30,400
Unconsolidated Joint Ventures [Member]
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Other Liabilities		63,100	37,100
Colorado Center
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		304,045	304,776
Carying value of the Company's investment in unconsolidated joint ventures	[5]	232,384	231,479
Gateway Commons Complex [Member]
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		51,530	51,009
Carying value of the Company's investment in unconsolidated joint ventures	[5]	342,021	327,148
Dock 72
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Basis differentials		(49,600)	(50,051)
Carying value of the Company's investment in unconsolidated joint ventures	[5]	$ 25,856	$ 27,343

[1] At March 31, 2022 and December 31, 2021, this amount included right of use assets - finance leases totaling approximately $248.9 million. At March 31, 2022 and December 31, 2021, this amount included right of use assets - operating leases totaling approximately $22.0 million and $22.3 million, respectively.

[2] At March 31, 2022 and December 31, 2021, this amount included lease liabilities - finance leases totaling approximately $384.7 million and $385.5 million, respectively. At March 31, 2022 and December 31, 2021, this amount included lease liabilities - operating leases totaling approximately $30.4 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: March 31, 2022December 31, 2021Property(in thousands)Colorado Center$304,045 $304,776 Gateway Commons51,530 51,009 Dock 72(49,600)(50,051) 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 $63.1 million and $37.1 million at March 31, 2022 and December 31, 2021, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

[5] Investments with deficit balances aggregating approximately $63.1 million and $37.1 million at March 31, 2022 and December 31, 2021, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.