STOCK COMPENSATION PLANS (Details)		3 Months Ended
	May 08, 2019 $ / shares shares	Mar. 31, 2020 USD ($) Director $ / shares shares	Mar. 31, 2019 USD ($)
Stock Compensation Plans [Abstract]
Compensation expense		$ 45,000	$ 47,000
Number of directors in committee | Director		3
Total intrinsic value of options exercised		$ 70,000
Shares of Class A Non-Voting Common Stock under option [Abstract]
Exercised/vested and released, aggregate intrinsic value		70,000
Class A Stock [Member] | Stock Options [Member]
Stock Compensation Plans [Abstract]
Total intrinsic value of options exercised		$ 70,000
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		(4,750)
Expired/cancelled, option shares (in shares) | shares		0
Outstanding at end of period, option shares (in shares) | shares		148,500
Exercisable/vested at end of period, option share (in shares) | shares		148,500
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		18.61
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		20.46
Options exercisable at year end (in dollars per shares) | $ / shares		$ 20.46
Shares of Class A Non-Voting Common Stock under option [Abstract]
Outstanding at end of period, weighted average remaining life		2 years 4 months 18 days
Exercisable/vested at end of period, weighted average remaining life		2 years 4 months 18 days
Outstanding at beginning of period, aggregate intrinsic value		$ 2,575,000
Granted, aggregate intrinsic value		0
Exercised/vested and released, aggregate intrinsic value		70,000
Expired/cancelled, aggregate intrinsic value		0
Outstanding at end of period, aggregate intrinsic value		2,512,000
Exercisable/vested at end of period, aggregate intrinsic value		2,512,000
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
Class A Stock [Member] | Restricted Stock [Member]
Stock Compensation Plans [Abstract]
Compensation expense		$ 45,000	$ 47,000
Fair value per share (in dollars per share) | $ / shares	$ 36.11
Shares [Roll Forward]
Outstanding at beginning of year (in shares) | shares		5,000
Granted (in shares) | shares	5,000	0
Exercised/vested and released, restricted stock awards (in shares) | shares		0
Cancelled (in shares) | shares		0
Unvested Outstanding at end of year (in shares) | shares		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		0
Vested and released, weighted average grant date fair value (in dollars per shares) | $ / shares		0
Cancelled, weighted average grant date fair value (in dollars per share) | $ / shares		0
Unvested Outstanding at end of year (in dollars per shares) | $ / shares		$ 36.11
Class A Stock [Member] | Restricted Stock [Member] | 2015 Equity Compensation Plan [Member]
Stock Compensation Plans [Abstract]
Unrecognized expense related to non-vested option shares		$ 18,000
Period over which unvested options cost will recognized		1 month 6 days