Annual report pursuant to Section 13 and 15(d)

Related Party Transactions (Narrative) (Details)

v3.20.4
Related Party Transactions (Narrative) (Details)
1 Months Ended 12 Months Ended
Apr. 30, 2021
USD ($)
Jan. 31, 2021
USD ($)
Nov. 30, 2020
USD ($)
Sep. 30, 2020
USD ($)
item
Dec. 31, 2020
USD ($)
ft²
property
item
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Related Party Transaction [Line Items]              
Revenue from leases         $ 272,970,000 $ 302,409,000 $ 323,793,000
Reimbursement expense       $ 6,100,000      
General and administrative         73,641,000 59,805,000 53,869,000
Number of payments | item       3      
Mack [Member]              
Related Party Transaction [Line Items]              
Due from related parties         0 0  
Marshall [Member]              
Related Party Transaction [Line Items]              
Due from related parties         99,000    
Due to related party, Current           120,000 148,000
Accounts payable to related parties         0 0  
RG [Member]              
Related Party Transaction [Line Items]              
Related party revenue         0 674,000 1,114,000
Bow Street LLC [Member]              
Related Party Transaction [Line Items]              
Reimbursement expense       $ 6,100,000      
General and administrative       $ 6,100,000 $ 6,100,000    
Number of payments | item         3    
Payments for fees and expenses     $ 2,100,000        
Leased Office Space 1 [Member] | Mack [Member]              
Related Party Transaction [Line Items]              
Area Of Real Estate Property | ft²         5,930    
Number of real estate properties | property         1    
Lease expiration date         January 2025    
Previously Leased [Member]              
Related Party Transaction [Line Items]              
Number of real estate properties | property         1    
Previously Leased [Member] | Mack [Member]              
Related Party Transaction [Line Items]              
Area Of Real Estate Property | ft²         7,034    
Revenue from leases         $ 48,000 $ 18,000 $ 193,000
Scenario, Forecast [Member] | Bow Street LLC [Member]              
Related Party Transaction [Line Items]              
Payments for fees and expenses $ 2,000,000.0            
Subsequent Event [Member] | Bow Street LLC [Member]              
Related Party Transaction [Line Items]              
Payments for fees and expenses   $ 2,000,000.0