STOCK COMPENSATION PLANS (Details)				12 Months Ended
	May 06, 2020 $ / shares shares	May 08, 2019 $ / shares shares	May 02, 2018 $ / shares shares	Dec. 31, 2020 USD ($) Director $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares
Stock Compensation Plans [Abstract]
Number of directors in committee | Director				3
Shares [Abstract]
Granted (in shares) | shares				0	0	0
Weighted Average Exercise [Abstract]
Total intrinsic value of options exercised | $				$ 620,000	$ 334,000	$ 176,000
Received cash from the exercise of options | $				695,000
Tax benefit realized during the period | $				799,000
Unrecognized expense related to non-vested option shares | $				59,900
Weighted Average Exercise Price [Abstract]
Intrinsic value of awards | $				$ 178,250
$19.01 - $20.46 [Member] | Employee and Director [Member]
Options Outstanding [Abstract]
Range of Exercise Price, Minimum (in dollars per shares)				$ 19.01
Range of Exercise Price, Maximum (in dollars per shares)				$ 20.46
Shares Outstanding (in shares) | shares				48,847
Weighted Average Remaining Life				11 months 1 day
Weighted Average Exercise Price (in dollars per shares)				$ 19.03
Aggregate Intrinsic Value | $				$ 881,573
Options Exercisable [Abstract]
Range of Exercise Price, Minimum (in dollars per shares)				$ 19.01
Range of Exercise Price, Maximum (in dollars per shares)				20.46
$20.47 - $22.66 [Member] | Employee and Director [Member]
Options Outstanding [Abstract]
Range of Exercise Price, Minimum (in dollars per shares)				20.47
Range of Exercise Price, Maximum (in dollars per shares)				$ 22.66
Shares Outstanding (in shares) | shares				67,500
Weighted Average Remaining Life				2 years 10 months 6 days
Weighted Average Exercise Price (in dollars per shares)				$ 22.26
Aggregate Intrinsic Value | $				$ 1,000,350
Options Exercisable [Abstract]
Range of Exercise Price, Minimum (in dollars per shares)				$ 20.47
Range of Exercise Price, Maximum (in dollars per shares)				$ 22.66
Non-vested Option [Member]
Weighted Average Exercise [Abstract]
Unrecognized expense related to non-vested option shares | $				$ 0
Restricted Stock Awards [Member] | 2015 Equity Compensation Plan [Member]
Weighted Average Exercise [Abstract]
Unrecognized expense related to non-vested option shares | $				$ 59,900
Weighted Average Exercise Price [Abstract]
Award vesting period				4 months 6 days
Class A Stock [Member] | Stock Options [Member]
Shares [Abstract]
Outstanding at beginning of year (in shares) | shares				153,250	168,750	176,802
Granted (in shares) | shares				0	0	0
Exercised/vested and released, option shares (in shares) | shares				(36,903)	(15,500)	(8,052)
Expired (in shares) | shares				0	0	0
Outstanding at end of year (in shares) | shares				116,347	153,250	168,750
Options exercisable at year end (in shares) | shares				116,347	153,250	168,750
Weighted Average Exercise [Abstract]
Outstanding at beginning of year (in dollars per shares)				$ 20.40	$ 20.11	$ 19.91
Granted, weighted average exercise price (in dollars per share)				0	0	0
Exercised/vested and released, weighted average exercise price (in dollars per shares)				18.83	17.15	15.77
Expired/cancelled, weighted average exercise price (in dollars per share)				0	0	0
Outstanding at end of year (in dollars per shares)				20.90	20.40	20.11
Options exercisable at year end (in dollars per shares)				$ 20.90	$ 20.40	$ 20.11
Class A Stock [Member] | Restricted Stock Awards [Member]
Shares [Roll Forward]
Outstanding at beginning of year (in shares) | shares				5,000	5,000	5,000
Granted (in shares) | shares	5,000	5,000	5,000	5,000	5,000	5,000
Vested/Released (in shares) | shares				(5,000)	(5,000)	(5,000)
Cancelled (in shares) | shares				0	0	0
Unvested Outstanding at end of year (in shares) | shares				5,000	5,000	5,000
Weighted Average Grant Date Fair Value [Abstract]
Outstanding at beginning of year (in dollars per shares)				$ 36.11	$ 38.51
Granted (in dollars per shares)				35.01	36.11
Vested/Released (in dollars per shares)				36.11	38.51
Cancelled (in dollars per shares)				0	0
Unvested Outstanding at end of year (in dollars per shares)				$ 35.01	36.11	$ 38.51
Weighted Average Exercise Price [Abstract]
Outstanding at beginning of year (in dollars per shares)					$ 38.51	38.10
Granted (in dollars per shares)						38.51
Vested/Released (in dollars per shares)						38.10
Cancelled (in dollars per shares)						0
Unvested Outstanding at end of year (in dollars per shares)						$ 38.51
Fair market value (in dollars per share)	$ 35.01	$ 36.11	$ 38.51