Quarterly report pursuant to Section 13 or 15(d)

RELATED PARTY TRANSACTIONS (Details)

v3.8.0.1
RELATED PARTY TRANSACTIONS (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Related Party Transaction [Line Items]    
Payroll and related costs reimbursed to the PROs by the Company $ 25,226 $ 19,749
Supervisory and Administrative Fee Agreement | Management | Participating Regional Operator (PRO)    
Related Party Transaction [Line Items]    
Supervisory and administrative fees paid to the PROs $ 4,100 3,300
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 $ 7,300 5,800
Due Diligence Costs | Management | Participating Regional Operator (PRO)    
Related Party Transaction [Line Items]    
Due diligence expenses payable to the PROs 200 $ 100
NSA OP, LP | Affiliated Entity    
Related Party Transaction [Line Items]    
Value of co-investment in acquisition $ 300  
Subordinated performance units | NSA OP, LP | Affiliated Entity    
Related Party Transaction [Line Items]    
Subordinated performance units issued to an affiliate of Personal Mini 11,490