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RETIREMENT PLANS (Detail)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
USD ($)
plan
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Retirement Benefits [Abstract]      
Employer contribution expense $ 432 $ 334 $ 361
Deferred compensation arrangement      
Defined Benefit Plan Disclosure [Line Items]      
Age at which a director or his beneficiaries will receive a monthly retirement benefit 65 years    
Estimated present value of future benefits to be paid $ 94 105  
Plan expense 11 12 12
Supplemental discretionary deferred compensation plans      
Defined Benefit Plan Disclosure [Line Items]      
Plan expense 10 15 30
Trust account balance 1,571 1,483  
Supplemental retirement and salary continuation plans      
Defined Benefit Plan Disclosure [Line Items]      
Estimated present value of future benefits to be paid 6,109 5,662  
Plan expense $ 739 727 626
Number of supplemental retirement and salary continuation plans | plan 2    
Life insurance coverage post-retirement      
Defined Benefit Plan Disclosure [Line Items]      
Estimated present value of future benefits to be paid $ 937 860  
Plan expense $ 77 $ 61 $ 129