INVESTMENT SECURITIES HELD TO MATURITY - Amortized cost and fair value (Details) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Amortized cost of held-to-maturity securities, by contractual maturity    
Within one year $ 861  
One to five years 22,915  
Five to ten years 42,080  
After ten years 12,816  
Amortized cost 78,672 $ 87,521
Fair Value of held-to-maturity securities, by contractual maturity    
Within one year 865  
One to five years 23,537  
Five to ten years 44,547  
After ten years 13,003  
Fair value $ 81,952 $ 92,816