Quarterly report pursuant to Section 13 or 15(d)

RELATED PARTY TRANSACTIONS (Details)

v3.19.1
RELATED PARTY TRANSACTIONS (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Related Party Transaction [Line Items]    
Payroll and related costs reimbursed to the PROs by the Company $ 26,457 $ 25,226
Supervisory and Administrative Fee Agreement | Management | Participating Regional Operator (PRO)    
Related Party Transaction [Line Items]    
Supervisory and administrative fees paid to the PROs $ 4,700 4,100
Supervisory and Administrative Fee Agreement | Management | Participating Regional Operator (PRO) | Minimum    
Related Party Transaction [Line Items]    
Supervisory and administrative fee agreement of gross revenue, percent 5.00%  
Supervisory and Administrative Fee Agreement | Management | Participating Regional Operator (PRO) | Maximum    
Related Party Transaction [Line Items]    
Supervisory and administrative fee agreement of gross revenue, percent 6.00%  
Payroll Services | Management | Participating Regional Operator (PRO)    
Related Party Transaction [Line Items]    
Payroll and related costs reimbursed to the PROs by the Company $ 7,800 7,300
Due Diligence Costs | Management | Participating Regional Operator (PRO)    
Related Party Transaction [Line Items]    
Due diligence expenses payable to the PROs $ 300 $ 200
Real Estate Purchases | Corporate Joint Venture    
Related Party Transaction [Line Items]    
Number of properties acquired 1  
Estimated fair value of acquired self storage properties $ 4,100