XML 50 R39.htm IDEA: XBRL DOCUMENT v3.6.0.2
Significant Accounting Policies - Rent Receivables (Details) - USD ($)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Tenant Rent Receivables and Straight-line Rent Receivable      
Period within which tenant rent receivables are expected to be collected 1 year    
Straight-line rent receivable $ 50,930,000 $ 48,502,000  
Allowance for doubtful accounts - Tenant rent receivables      
Tenant Rent Receivables and Straight-line Rent Receivable      
Receivables written-off 108,000 89,000 $ 119,000
Increase (decrease) in allowance $ 78,000 (106,000) 394,000
Allowance for doubtful accounts - Straight-line rent receivable      
Tenant Rent Receivables and Straight-line Rent Receivable      
Receivables written-off   112,000  
Increase (decrease) in allowance   $ (112,000) $ 27,000