Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies - Additional Information (Details)

v3.10.0.1
Commitments and Contingencies - Additional Information (Details) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Jun. 28, 2018
Sep. 01, 2011
Other Commitments [Line Items]          
Ground lease expenses $ 812,000 $ 555,000 $ 441,000    
Preferred stock, liquidation preference per share (in dollars per share) $ 1,000        
Harbor Pointe Associates, LLC [Member] | Grove Economic Development Authority [Member] | Guarantor Subsidiaries [Member] | Notes Payable, Other Payables [Member] | Grove Economic Development Authority Tax Increment Revenue Note [Member]          
Other Commitments [Line Items]          
Amount of debt issued         $ 2,415,000
Debt number of semi-annual installments         50
Company's future total principal obligation under the agreement         $ 2,280,000
Amounts funded as debt service shortfalls $ 73,000 58,000 49,000    
Accrued liability of future debt service shortfalls (inestimable) 0        
Minimum [Member] | Harbor Pointe Associates, LLC [Member] | Grove Economic Development Authority [Member] | Guarantor Subsidiaries [Member] | Notes Payable, Other Payables [Member] | Grove Economic Development Authority Tax Increment Revenue Note [Member]          
Other Commitments [Line Items]          
Debt interest rate         2.29%
Maximum [Member] | Harbor Pointe Associates, LLC [Member] | Grove Economic Development Authority [Member] | Guarantor Subsidiaries [Member] | Notes Payable, Other Payables [Member] | Grove Economic Development Authority Tax Increment Revenue Note [Member]          
Other Commitments [Line Items]          
Debt interest rate         14.00%
JANAF Acquisition [Member]          
Other Commitments [Line Items]          
Ground lease expenses 258,000 $ 0 $ 0    
Ground lease expense as percentage of rent $ 113,000        
Northeast [Member]          
Other Commitments [Line Items]          
Total annualized base rent percentage 4.00%        
Mid Atlantic [Member]          
Other Commitments [Line Items]          
Total annualized base rent percentage 19.00%        
Southeast [Member]          
Other Commitments [Line Items]          
Total annualized base rent percentage 76.00%        
Southwest [Member]          
Other Commitments [Line Items]          
Total annualized base rent percentage 1.00%        
Series D Preferred Stock          
Other Commitments [Line Items]          
Preferred stock, liquidation preference per share (in dollars per share) $ 25.00     $ 25.00