RELATED PARTIES BALANCES AND TRANSCATIONS - Compensation of Key Management Personnel (Details)
12 Months Ended
Dec. 31, 2015
shares
Jul. 16, 2015
shares
Apr. 30, 2015
USD ($)
shares
Dec. 31, 2017
USD ($)
shares
Dec. 31, 2016
USD ($)
shares
Dec. 31, 2015
USD ($)
shares
Disclosure of transactions between related parties [line items]            
Amount incurred by entity for provision of key management personnel services provided by separate management entity       $ 4,507,000 $ 4,432,000 $ 4,211,000
Key management personnel compensation       $ 4,507,000 $ 4,432,000 $ 4,211,000
Number of share options granted in share-based payment arrangement (in shares) | shares 545,649 43,857 30,000 85,000 1,003,250  
Weighted average exercise price of share options granted in share-based payment arrangement (in usd per share)     $ 21.01 $ 39.69 $ 31.89  
Grant One [Member]            
Disclosure of transactions between related parties [line items]            
Number of share options granted in share-based payment arrangement (in shares) | shares       12,836 260,000 30,000
Weighted average exercise price of share options granted in share-based payment arrangement (in usd per share)       $ 34.96 $ 29.01 $ 22.77
Grant Two [Member]            
Disclosure of transactions between related parties [line items]            
Number of share options granted in share-based payment arrangement (in shares) | shares       62,162 82,500 273,000
Weighted average exercise price of share options granted in share-based payment arrangement (in usd per share)       $ 37.00 $ 32.36 $ 28.31