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EMPLOYEE BENEFITS AND STOCK BASED COMPENSATION (Narrative) (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Apr. 20, 2015
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Deferred compensation plans obligation to Board of Directors | $ 15,800,000 | $ 15,700,000 |  |
Maximum term of stock options | 10 years |  |  |
Stock options granted | 0 |  |  |
Vesting period of stock awards | 5 years |  |  |
Number of stock option awards exercised | 46,278 | 56,619 | 72,743 |
Intrinsic value of stock options exercised | $ 555,000 | $ 684,000 | $ 1,900,000 |
Fair value of stock options exercised | 1,600,000 | 2,100,000 | 2,800,000 |
Cash received from the exercise of stock options | 1,000,000.0 | 1,400,000 | 983,000 |
Tax benefit from exercise of equity-based awards | $ 112,000 | 127,000 | 390,000 |
Restricted stock vesting percentage | 33.33% |  |  |
Intrinsic value of stock options outstanding | $ 798,340 | $ 2,300,000 | $ 656,000 |
Unamortized compensation costs | $ 10,990,000 |  |  |
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 | 666,858 |  |  |
2011 Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Number of shares authorized to be issued, maximum |  |  |  | 1,000,000
Restricted Stock |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Restricted stock units, vesting terms | RSAs vest one-third on each of the first, second and third anniversaries from the date of the grant |  |  |
Restricted Stock and Performance Stock Awards | Minimum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Vesting period of stock awards | 3 years |  |  |
Restricted Stock and Performance Stock Awards | Maximum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Vesting period of stock awards | 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% |  |  |
Access National Bank |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Maximum term of stock options |  | 5 years |  |
Vesting period of stock awards |  | 4 years |  |

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