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Commitments and Contingencies - Additional Information (Details)
12 Months Ended
Dec. 31, 2019
ft²
Feb. 16, 2018
USD ($)
Nov. 23, 2014
ft²
Other Commitments [Line Items]      
Area of office properties | ft² 13,100,000    
Minimum [Member] | New York State Division Of Taxation And Finance [Member]      
Other Commitments [Line Items]      
Loss Contingency, Estimate of Possible Loss | $   $ 0  
Maximum [Member] | New York State Division Of Taxation And Finance [Member]      
Other Commitments [Line Items]      
Loss Contingency, Estimate of Possible Loss | $   $ 43,500,000  
718 Fifth Avenue [Member]      
Other Commitments [Line Items]      
Percentage of tenancy-in-common interest in property     50.00%
Put right notice period 12 months    
712 Fifth Avenue [Member]      
Other Commitments [Line Items]      
Percentage of ownership interest in new joint venture 50.00%    
Owned by Affiliate [Member] | 718 Fifth Avenue [Member] | Third Party Affiliate [Member]      
Other Commitments [Line Items]      
Percentage of ownership interest in new joint venture     25.00%
Owned by Affiliate [Member] | Parent Company [Member] | Put Right Exercised [Member] | 718 Fifth Avenue [Member]      
Other Commitments [Line Items]      
Pre IPO ownership percentage 25.00%    
Owned by Affiliate [Member] | Retail Type Space [Member] | 718 Fifth Avenue [Member]      
Other Commitments [Line Items]      
Area of office properties | ft²     19,050