Construction Finance Liabilities - Additional Information (Details)
$ in Thousands
1 Months Ended 9 Months Ended 12 Months Ended
Mar. 08, 2021
USD ($)
Oct. 31, 2019
USD ($)
Oct. 31, 2019
USD ($)
Option
Oct. 31, 2019
USD ($)
Jul. 31, 2019
USD ($)
Jul. 31, 2019
USD ($)
Option
Jul. 31, 2019
USD ($)
Sep. 30, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Construction Finance Liability [Line Items]                    
Tenant improvements allowance                 $ 16,700  
Construction finance liability               $ 92,021 82,047 $ 22,956
Percentage at which one twelfth of tenant improvement allowance dispersed for first 5.0 million       12.75%            
Percentage at which one twelfth of tenant improvement allowance dispersed after 5.0 million up to 21.0 million       13.75%            
Massachusetts                    
Construction Finance Liability [Line Items]                    
Proceeds from sale of property         $ 3,500          
Tenant improvements allowance         $ 40,000 $ 40,000 $ 40,000   40,000 2,500
Finance lease liability, initial term         10 years 10 years 10 years      
Finance lease liability, extended term         5 years 5 years 5 years      
Number of options to extend finance lease           2 2      
Percentage of purchase price of property as initial payment for finance lease             11.00%      
Percentage increase in finance lease liability payment             3.00%      
Construction finance liability               44,400 43,900 6,100
Florida                    
Construction Finance Liability [Line Items]                    
Proceeds from sale of property   $ 17,000                
Finance lease liability, initial term   10 years 10 years 10 years            
Finance lease liability, extended term   5 years 5 years 5 years            
Number of options to extend finance lease     2 2            
Percentage of purchase price of property as initial payment for finance lease       11.00%            
Percentage increase in finance lease liability payment       3.00%            
Construction finance liability               17,400 17,200 $ 16,900
Sale and lease back transaction amount payable after year four                 23,000  
Pennsylvania                    
Construction Finance Liability [Line Items]                    
Proceeds from sale of property   $ 5,000                
Tenant improvements allowance $ 36,500 $ 21,000 $ 21,000 $ 21,000         36,500  
Tenant improvements allowance received               25,600    
Finance lease liability, initial term   15 years 15 years 15 years            
Finance lease liability, extended term   5 years 5 years 5 years            
Number of options to extend finance lease     2 2            
Construction finance liability               $ 30,200    
Threshold minimum tenant improvement allowance for calculating interest rate                 $ 21,000  
Percentage at which one twelfth of tenant improvement allowance dispersed for first 5.0 million       12.75%            
Percentage at which one twelfth of tenant improvement allowance dispersed after 5.0 million up to 21.0 million       13.75%            
Percentage at which one twelfth of tenant improvement allowance dispersed in excess 21.0 million 10.75%               10.75%