Quarterly report pursuant to Section 13 or 15(d)

RELATED PARTY TRANSACTIONS (Details)

v3.19.2
RELATED PARTY TRANSACTIONS (Details) - USD ($)
$ in Thousands
1 Months Ended 3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Jun. 01, 2019
Related Party Transaction [Line Items]            
Payroll and related costs reimbursed to the PROs by the Company   $ 27,190 $ 25,184 $ 53,647 $ 50,410  
Ownership interest in reinsurance company acquired (percent)           5.50%
Equity interest in reinsurance company $ 500 500   500    
Supervisory and Administrative Fee Agreement | Management | Participating Regional Operator (PRO)            
Related Party Transaction [Line Items]            
Supervisory and administrative fees paid to the PROs   4,900 4,200 $ 9,600 8,200  
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   7,900 7,200 $ 15,700 14,500  
Due Diligence Costs | Management | Participating Regional Operator (PRO)            
Related Party Transaction [Line Items]            
Due diligence expenses payable to the PROs   300 $ 100 $ 600 $ 300  
Real Estate Purchases | Corporate Joint Venture            
Related Party Transaction [Line Items]            
Number of properties acquired       1    
Consideration in acquisition transaction       $ 4,100    
Acquisition of Interest in Reinsurance Company            
Related Party Transaction [Line Items]            
Consideration in acquisition transaction 15,100          
Cash paid in acquisition 6,600          
Acquisition of Interest in Reinsurance Company | Management            
Related Party Transaction [Line Items]            
Cash paid in acquisition 2,200          
Tenant reinsurance intangible            
Related Party Transaction [Line Items]            
Recognized fair value allocated to intangible assets $ 14,600 $ 14,600   $ 14,600    
Weighted average remaining useful life (in years)       25 years    
OP units | NSA OP, LP | Acquisition of Interest in Reinsurance Company            
Related Party Transaction [Line Items]            
OP units issued in acquisition (in shares) 285,512          
Value of OP units issued in acquisition $ 8,500          
OP units | NSA OP, LP | Acquisition of Interest in Reinsurance Company | Management            
Related Party Transaction [Line Items]            
OP units issued in acquisition (in shares) 95,170          
Value of OP units issued in acquisition $ 2,800