Related Parties - Additional Information (Details) - USD ($)		12 Months Ended
	Mar. 27, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Fee and other income		$ 35,222,000	$ 34,246,000	$ 30,533,000
Accounts and other receivables, net		17,502,000	19,231,000
Property management, asset management, leasing and other related services fee income		28,070,000	22,744,000	18,629,000
Transaction related costs		1,096,000	1,999,000	1,471,000
Accounts payable and accrued expenses		101,901,000	117,356,000
Due from Affiliates			217,918,000
Repayment of amounts due from affiliates		$ 36,918,000	181,000,000
Fund X [Member]
Related Party Transaction [Line Items]
Due from Affiliates			36,918,000
Note receivables basis spread on variable rate		2.20%
Repayment of amounts due from affiliates	$ 36,918,000
Repayment of accrued interest	$ 349,000
712 Fifth Avenue [Member]
Related Party Transaction [Line Items]
Equity method paramount ownership percentage		50.00%
CNBB-RDF Holdings Otto Family [Member] | Management Agreements [Member]
Related Party Transaction [Line Items]
Fee and other income		$ 1,227,000	842,000	838,000
Accounts and other receivables, net		34,000
Unconsolidated Joint Ventures and Real Estate Funds [Member] | Management Agreements [Member]
Related Party Transaction [Line Items]
Accounts and other receivables, net		5,011,000	2,734,000
Property management, asset management, leasing and other related services fee income		$ 22,986,000	17,466,000	15,231,000
Hamburg Trust Consulting GMBH ("HTC") [Member]
Related Party Transaction [Line Items]
Mark-up cost percentage		10.00%
Transaction related costs		$ 512,000	796,000	240,000
Accounts payable and accrued expenses		$ 123,000	38,000
Hamburg Trust Consulting GMBH ("HTC") [Member] | Chairman, Chief Executive Officer and President [Member]
Related Party Transaction [Line Items]
Percentage of ownership		100.00%
Mannheim Trust [Member] | Board of Director [Member] | 712 Fifth Avenue [Member]
Related Party Transaction [Line Items]
Equity method paramount ownership percentage		50.00%
Lease rental income		$ 362,000	360,000	$ 366,000
Kramer Design Services [Member]
Related Party Transaction [Line Items]
Accounts payable and accrued expenses		0
Development expenses		$ 187,000
Kramer Design Services [Member] | 712 Fifth Avenue [Member]
Related Party Transaction [Line Items]
Equity method paramount ownership percentage		50.00%
Expense recognized		$ 29,000	$ 325,000