Annual report pursuant to Section 13 and 15(d)

EMPLOYEE BENEFITS AND STOCK BASED COMPENSATION (Narrative) (Details)

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EMPLOYEE BENEFITS AND STOCK BASED COMPENSATION (Narrative) (Details) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Apr. 20, 2015
Defined Benefit Plan Disclosure [Line Items]        
Deferred compensation plans obligation to Board of Directors $ 11,800,000 $ 11,100,000    
Maximum term of stock options 10 years      
Stock options granted 0 0    
Stock options term from the grant date 2 years 6 months 14 days      
Number of stock option awards exercised 72,743 63,476 88,409  
Intrinsic value of stock options exercised $ 1,900,000 $ 1,200,000 $ 1,200,000  
Fair value of stock options exercised 2,800,000 2,200,000 2,600,000  
Cash received from the exercise of stock options 983,000 1,000,000 1,400,000  
Tax benefit from exercise of equity-based awards $ 390,000 370,000 381,000  
Fair value of stock options vested   47,000 159,000  
Restricted stock vesting percentage 50.00%      
Intrinsic value of stock options outstanding $ 656,238 $ 2,700,000 $ 3,900,000  
Unamortized compensation costs $ 11,265,000      
Minimum        
Defined Benefit Plan Disclosure [Line Items]        
Hours of service required for eligibility under plan 1000 hours      
Stock and Incentive Plan        
Defined Benefit Plan Disclosure [Line Items]        
Number of shares authorized to be issued, maximum 2,500,000      
Number of shares available for future issuance 1,300,663      
2011 Plan        
Defined Benefit Plan Disclosure [Line Items]        
Number of shares authorized to be issued, maximum       1,000,000
Restricted Stock | Minimum        
Defined Benefit Plan Disclosure [Line Items]        
Vesting period of restricted stock awards and performance stock units 3 years      
Restricted Stock | Maximum        
Defined Benefit Plan Disclosure [Line Items]        
Vesting period of restricted stock awards and performance stock units 4 years      
1% through 3%        
Defined Benefit Plan Disclosure [Line Items]        
Percentage of employer's match for 401(k) plan 100.00%      
1% through 3% | Minimum        
Defined Benefit Plan Disclosure [Line Items]        
Percentage of employee's gross pay for 401(k) plan 1.00%      
1% through 3% | Maximum        
Defined Benefit Plan Disclosure [Line Items]        
Percentage of employee's gross pay for 401(k) plan 3.00%      
4% through 5%        
Defined Benefit Plan Disclosure [Line Items]        
Percentage of employer's match for 401(k) plan 50.00%      
4% through 5% | Minimum        
Defined Benefit Plan Disclosure [Line Items]        
Percentage of employee's gross pay for 401(k) plan 4.00%      
4% through 5% | Maximum        
Defined Benefit Plan Disclosure [Line Items]        
Percentage of employee's gross pay for 401(k) plan 5.00%