XML 83 R63.htm IDEA: XBRL DOCUMENT v3.8.0.1
FAIR VALUE MEASUREMENTS (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
item
Dec. 31, 2016
USD ($)
Fair value of financial assets and liabilities carried at fair value    
Aggregate carrying value of total debt $ 1,600,000 $ 1,600,000
Estimated fair value of total debt $ 1,700,000 1,600,000
Interest rate swap    
Fair value of financial assets and liabilities carried at fair value    
Number of counterparties to derivative contracts who experienced significant downgrades in 2017 | item 0  
Level 2    
Fair value of financial assets and liabilities carried at fair value    
Total liabilities at fair value $ 406 2,280
Level 2 | Interest rate swap    
Fair value of financial assets and liabilities carried at fair value    
Derivative Liabilities $ 406 $ 2,280