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 58 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2016
Apr. 20, 2015
Jan. 01, 2014
Defined Benefit Plan Disclosure [Line Items]            
Deferred compensation plans obligation to Board of Directors $ 10,400,000 $ 9,100,000   $ 10,400,000    
Salaries and benefit expense for incentive compensation $ 2,700,000 $ 1,200,000 $ 898,000      
Maximum term of stock options 10 years          
Stock options granted 0 0   0    
Stock options term from the grant date 3 years 8 months 1 day          
Number of stock option awards exercised 88,409 60,637 75,282      
Intrinsic value of stock options exercised $ 1,200,000 $ 544,000 $ 573,000      
Fair value of stock options exercised 2,600,000 1,400,000 1,800,000      
Cash received from the exercise of stock options 1,400,000 886,000 1,200,000      
Tax benefit from exercise of equity-based awards 381,000 178,000 187,000      
Fair value of stock options vested $ 159,000 316,000 313,000      
Restricted stock vesting percentage 50.00%          
Intrinsic value of stock options outstanding $ 3,915,988 $ 2,800,000 $ 3,100,000 $ 3,915,988    
Unamortized compensation costs $ 6,548,000     $ 6,548,000    
Minimum            
Defined Benefit Plan Disclosure [Line Items]            
Hours of service required for eligibility under plan 1000 hours          
Vesting period of stock options 3 years          
Maximum            
Defined Benefit Plan Disclosure [Line Items]            
Vesting period of stock options 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%          
Stock and Incentive Plan            
Defined Benefit Plan Disclosure [Line Items]            
Number of shares authorized to be issued, maximum 2,500,000     2,500,000    
Number of shares available for future issuance 1,666,637     1,666,637    
2011 Plan            
Defined Benefit Plan Disclosure [Line Items]            
Number of shares authorized to be issued, maximum         1,000,000  
StellarOne Bank            
Defined Benefit Plan Disclosure [Line Items]            
Number of shares equivalent to each share of acquired entity           0.9739