EMPLOYEE BENEFIT PLANS - Fair Value Hierarchy (Details) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value $ 15,090 $ 14,223 $ 13,906
Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 15,090 14,223  
Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 987 1,218  
Cash and cash equivalents | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 987 1,218  
Mutual funds - taxable fixed income      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 1,379 1,467  
Mutual funds - taxable fixed income | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 1,379 1,467  
Mutual funds - domestic equity      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 8,944 8,150  
Mutual funds - domestic equity | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 8,944 8,150  
Mutual funds - international equity      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 835 631  
Mutual funds - international equity | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 835 631  
Inflation Hedges/Real Assets      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 838 715  
Inflation Hedges/Real Assets | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 838 715  
Hedged Strategies      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value 2,107 2,042  
Hedged Strategies | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Assets at fair value $ 2,107 $ 2,042