Annual report pursuant to Section 13 and 15(d)

Summary Of Significant Accounting Policies (Narrative) (Details)

v3.20.4
Summary Of Significant Accounting Policies (Narrative) (Details)
12 Months Ended
Feb. 19, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
property
Dec. 31, 2020
USD ($)
item
Dec. 31, 2020
USD ($)
shares
Dec. 31, 2020
USD ($)
segment
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Jan. 01, 2018
Dec. 31, 2017
USD ($)
Summary Of Significant Accounting Policies [Line Items]                        
Common units in operating partnership | shares             7,305,355          
Land and building held for development, net   $ 43,014,000 $ 43,014,000 $ 43,014,000 $ 43,014,000 $ 43,014,000 $ 43,014,000 $ 43,014,000 $ 28,110,000      
Cash and cash equivalents maximum benchmark (in months)   3 months                    
Restricted cash included in Land and building held for development, net   $ 1,088,000 1,088,000 1,088,000 1,088,000 1,088,000 1,088,000 1,088,000 1,088,000 $ 1,088,000   $ 1,100,000
Minimum expected future benefit period on expenditures cost to be capitalized and depreciated (in years)   2 years                    
Minimum expected future benefit period on transaction cost to be capitalized and depreciated (in years)   1 year                    
Length of time criteria for expected sale of assets to be classified as properties held for disposition   12 months                    
Below market lease, net   $ 2,200,000 2,200,000 2,200,000 2,200,000 2,200,000 2,200,000 2,200,000 2,400,000      
Below market leases, accumulated amortization   12,200,000 12,200,000 12,200,000 12,200,000 12,200,000 12,200,000 12,200,000 11,400,000      
Impairment on assets     0           0 0    
Operating lease, right-of-use asset   1,500,000 1,500,000 1,500,000 1,500,000 1,500,000 1,500,000 1,500,000 1,600,000      
Accumulated amortization   200,000 200,000 $ 200,000 200,000 $ 200,000 200,000 $ 200,000 100,000      
Accounts receivable, write-off     1,600,000                  
Deferred rent receivable, write-off     3,100,000                  
Rental income     415,623,000           429,846,000 413,516,000    
Rental income, operating leases     319,200,000           333,300,000 322,300,000    
Rental income, variable lease payments     96,400,000           96,500,000 $ 91,200,000    
Income tax expense     0                  
Tax benefit for uncertain tax positions     0           0      
Number of operating segments | segment               2        
Number of reportable segments | segment               1        
Properties held for sale, net                 15,264,000      
COVID-19 [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Deferral agreement, number of customers | item           393            
Deferral agreement, percentage of customers on a percentage of total rental income basis       11.00%                
Deferred rent receivable     5,700,000                  
Rent receivable abated     1,300,000                  
Reclassification [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Properties held for sale, net                 3,800,000      
Above Market Leases [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Finite-lived intangible assets, net   1,200,000 1,200,000 $ 1,200,000 1,200,000 $ 1,200,000 1,200,000 $ 1,200,000 1,200,000      
Finite-lived intangible assets, accumulated amortization   (11,100,000) (11,100,000) (11,100,000) (11,100,000) (11,100,000) (11,100,000) (11,100,000) (10,600,000)      
Acquired In Place Leases [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Finite-lived intangible assets, net   5,300,000 5,300,000 5,300,000 5,300,000 5,300,000 5,300,000 5,300,000 5,700,000      
Finite-lived intangible assets, accumulated amortization   $ 7,200,000 $ 7,200,000 $ 7,200,000 $ 7,200,000 $ 7,200,000 $ 7,200,000 $ 7,200,000 $ 4,100,000      
Minimum [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Estimated useful life (in years)   5 years                    
Operating lease, expiration date   2029                    
Operating lease, remaining lease term   8 years 9 months 18 days                    
Maximum [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Estimated useful life (in years)   30 years                    
Operating lease, expiration date   2030                    
Operating lease, remaining lease term   9 years 1 month 6 days                    
Highgate at the Mile [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Number of units to be developed | property         395              
Highgate at the Mile [Member] | JV Partner [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Consolidated entity ownership percentage   5.00% 5.00% 5.00% 5.00% 5.00% 5.00% 5.00%     5.00%  
Brentford at The Mile [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Number of units to be developed         411 411            
Brentford at The Mile [Member] | JV Partner [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Consolidated entity ownership percentage   1.80% 1.80% 1.80% 1.80% 1.80% 1.80% 1.80%        
Investment in Joint Venture [Member] | Highgate at the Mile [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Consolidated entity ownership percentage   95.00% 95.00% 95.00% 95.00% 95.00% 95.00% 95.00%        
Investment in Joint Venture [Member] | Brentford at The Mile [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Consolidated entity ownership percentage   98.20% 98.20% 98.20% 98.20% 98.20% 98.20% 98.20%        
Land and building held for development, net   $ 15,100,000 $ 15,100,000 $ 15,100,000 $ 15,100,000 $ 15,100,000 $ 15,100,000 $ 15,100,000        
Subsequent Event [Member] | COVID-19 [Member]                        
Summary Of Significant Accounting Policies [Line Items]                        
Deferred rent receivable $ 5,700,000                      
Deferred payments received $ 3,700,000                      
Collection rate percentage on deferral repayments 97.10%