Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details)

v3.10.0.1
FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($)
Jun. 30, 2018
Dec. 31, 2017
Line of Credit    
Short-term Debt [Line Items]    
Maximum borrowing capacity $ 175,000,000.0  
Outstanding borrowings 0 $ 0
Letter of Credit    
Short-term Debt [Line Items]    
Maximum borrowing capacity 75,000,000.0  
Swingline Credit Facility    
Short-term Debt [Line Items]    
Maximum borrowing capacity $ 25,000,000.0