Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Details)

v3.19.1
Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Jan. 01, 2019
Property, Plant and Equipment [Line Items]        
Other $ 98,000 $ 122,000    
Asset Impairment Charges $ 0 0    
Maturity of highly liquid investments 90 days      
Insurance coverage amount $ 250,000      
Past due rent charge term 5 days      
Allowance for uncollectible accounts $ 1,030,000   $ 1,260,000  
Tenant recoveries realized from previous charge-offs 0 0    
Finite-lived intangible assets, accumulated amortization 52,160,000   50,550,000  
Amortization of intangible assets $ 2,630,000 4,300,000    
Property management fee, percent fee 3.00%      
Asset management fee, percent fee 2.00%      
Minimum percentage of taxable income to be distributed to stockholders (as percent) 90.00%      
Advertising $ 49,000 43,000    
Provision for federal income taxes $ (22,000)   $ 13,000  
Term of disqualification to be taxed as a REIT due to loss of REIT status 5 years      
Common Stock, Par or Stated Value Per Share $ 0.01   $ 0.01  
Increase in cash provided by operating activities $ 2,697,000 6,474,000    
Reduction in cash from investing activities (3,318,000) 23,465,000    
ROU assets 11,833,000   $ 0  
Provision for credit losses $ 90,000 $ 98,000    
ASU 2016-02        
Property, Plant and Equipment [Line Items]        
ROU assets       $ 11,900,000
Lease liability       $ 11,990,000
Incremental borrowing rate on leases       4.84%
Building and building improvements | Minimum        
Property, Plant and Equipment [Line Items]        
Property, Plant and Equipment, Useful Life 5 years      
Building and building improvements | Maximum        
Property, Plant and Equipment [Line Items]        
Property, Plant and Equipment, Useful Life 40 years      
Rent and other tenant receivables        
Property, Plant and Equipment [Line Items]        
Recoveries related to tenant receivables $ 3,540,000   $ 3,120,000  
New Lease [Member]        
Property, Plant and Equipment [Line Items]        
Commission fee, percent fee 6.00%      
Renewed Lease [Member]        
Property, Plant and Equipment [Line Items]        
Commission fee, percent fee 3.00%