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STOCK COMPENSATION PLANS (Details) |  |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | --- | ---
May 06, 2020 $ / shares shares | May 08, 2019 $ / shares shares | Sep. 30, 2020 USD ($) $ / shares shares | Sep. 30, 2019 USD ($) | Sep. 30, 2020 USD ($) Director $ / shares shares | Sep. 30, 2019 USD ($)
Stock Compensation Plans [Abstract] |  |  |  |  |  |
Compensation expense |  |  |  |  | $ 134,000 | $ 136,000
Number of directors in committee | Director |  |  |  |  | 3 |
Total intrinsic value of options exercised |  |  | $ 391,000 |  |  |
Shares of Class A Non-Voting Common Stock under option [Abstract] |  |  |  |  |  |
Exercised/vested and released, aggregate intrinsic value |  |  | $ 391,000 |  |  |
Class A Stock [Member] | Stock Options [Member] |  |  |  |  |  |
Stock Compensation Plans [Abstract] |  |  |  |  |  |
Total intrinsic value of options exercised |  |  |  |  | $ 391,000 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Outstanding at beginning of period, option shares (in shares) | shares |  |  |  |  | 153,250 |
Granted, option shares (in shares) | shares |  |  |  |  | 0 |
Exercised/vested and released, option shares (in shares) | shares |  |  |  |  | (25,000) |
Expired/cancelled, option shares (in shares) | shares |  |  |  |  | 0 |
Outstanding at end of period, option shares (in shares) | shares |  |  | 128,250 |  | 128,250 |
Exercisable/vested at end of period, option share (in shares) | shares |  |  | 128,250 |  | 128,250 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] |  |  |  |  |  |
Outstanding at beginning of period, weighted average exercise price (in dollars per shares) | $ / shares |  |  |  |  | $ 20.40 |
Granted, weighted average exercise price (in dollars per share) | $ / shares |  |  |  |  | 0 |
Exercised/vested and released, weighted average exercise price (in dollars per shares) | $ / shares |  |  |  |  | 18.73 |
Expired/cancelled, weighted average exercise price (in dollars per share) | $ / shares |  |  |  |  | 0 |
Outstanding at end of period, weighted average exercise price (in dollars per shares) | $ / shares |  |  | $ 20.73 |  | 20.73 |
Options exercisable at year end (in dollars per shares) | $ / shares |  |  | $ 20.73 |  | $ 20.73 |
Shares of Class A Non-Voting Common Stock under option [Abstract] |  |  |  |  |  |
Outstanding at end of period, weighted average remaining life |  |  |  |  | 2 years 2 months 7 days |
Exercisable/vested at end of period, weighted average remaining life |  |  |  |  | 2 years 2 months 7 days |
Outstanding at beginning of period, aggregate intrinsic value |  |  |  |  | $ 2,575,000 |
Granted, aggregate intrinsic value |  |  |  |  | 0 |
Exercised/vested and released, aggregate intrinsic value |  |  |  |  | 391,000 |
Expired/cancelled, aggregate intrinsic value |  |  |  |  | 0 |
Outstanding at end of period, aggregate intrinsic value |  |  | $ 1,762,000 |  | 1,762,000 |
Exercisable/vested at end of period, aggregate intrinsic value |  |  | 1,762,000 |  | 1,762,000 |
Class A Stock [Member] | Stock Options [Member] | 2015 Equity Compensation Plan [Member] |  |  |  |  |  |
Stock Compensation Plans [Abstract] |  |  |  |  |  |
Unrecognized expense related to non-vested option shares |  |  | 0 |  | 0 |
Class A Stock [Member] | Restricted Stock [Member] |  |  |  |  |  |
Stock Compensation Plans [Abstract] |  |  |  |  |  |
Compensation expense |  |  | $ 44,000 | $ 45,000 | $ 134,000 | $ 136,000
Fair value per share (in dollars per share) | $ / shares | $ 35.01 | $ 36.11 |  |  |  |
Shares [Roll Forward] |  |  |  |  |  |
Outstanding at beginning of year (in shares) | shares |  |  |  |  | 5,000 |
Granted (in shares) | shares | 5,000 | 5,000 |  |  | 5,000 |
Exercised/vested and released, restricted stock awards (in shares) | shares |  |  |  |  | (5,000) |
Cancelled (in shares) | shares |  |  |  |  | 0 |
Unvested Outstanding at end of year (in shares) | shares |  |  | 5,000 |  | 5,000 |
Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Outstanding at beginning of year (in dollars per shares) | $ / shares |  |  |  |  | $ 36.11 |
Granted, weighted average grant date fair value (in dollars per share) | $ / shares |  |  |  |  | 35.01 |
Vested and released, weighted average grant date fair value (in dollars per shares) | $ / shares |  |  |  |  | 36.11 |
Cancelled, weighted average grant date fair value (in dollars per share) | $ / shares |  |  |  |  | 0 |
Unvested Outstanding at end of year (in dollars per shares) | $ / shares |  |  | $ 35.01 |  | $ 35.01 |
Class A Stock [Member] | Restricted Stock [Member] | 2015 Equity Compensation Plan [Member] |  |  |  |  |  |
Stock Compensation Plans [Abstract] |  |  |  |  |  |
Unrecognized expense related to non-vested option shares |  |  | $ 104,000 |  | $ 104,000 |
Period over which unvested options cost will recognized |  |  |  |  | 21 days |

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