STOCK COMPENSATION PLANS (Details)	3 Months Ended	6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2016 USD ($) $ / shares shares	Sep. 30, 2016 USD ($) Director $ / shares shares	Sep. 30, 2015 USD ($)	Dec. 31, 2014	May 04, 2016 $ / shares shares	Dec. 18, 2015 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of directors in committee | Director			3
Non-vested shares of Class A Stock under option [Abstract]
Vesting period for granted option			1 year
Options granted term			10 years
Weighted-average assumptions used for grants issued [Abstract]
Expected Dividend Yield					3.88%
Expected Stock Price Volatility					26.50%
Weighted Average Risk-Free Interest Rate					2.24%
Weighted Average Expected Life of Options					7 years 6 months 7 days
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award Nonvested Options Outstanding [Roll Forward]
Outstanding at beginning of period, Non-vested option shares (in shares) | shares		0	0
Granted, option shares (in shares) | shares			5,000
Vested, option shares (in shares) | shares			0
Cancelled, option shares (in shares) | shares			0
Outstanding at end of period, Non-vested option shares (in shares) | shares	5,000		5,000
Non-vested shares of Class A Stock under option [Abstract]
Outstanding at beginning of period, weighted average grant-date fair value per option (in dollars per share) | $ / shares		$ 0	$ 0
Granted, weighted average grant-date fair value per option (in dollars per share) | $ / shares			27.7
Vested, weighted average grant-date fair value per option (in dollars per share) | $ / shares			0
Cancelled, weighted average grant-date fair value per option (in dollars per share) | $ / shares			0
Outstanding at end of period, weighted average grant-date fair value per option (in dollars per share) | $ / shares	$ 27.7		$ 27.7
Class A Stock [Member] | 2005 Equity Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense | $				$ 46,000
Class A Stock [Member] | 2015 Equity Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense | $	$ 35,000		$ 57,000
Unrecognized expense related to non-vested option shares | $	$ 0		$ 0
Number of shares authorizes under the plan (in shares) | shares						5,000	5,000
Fair market value (in dollars per share) | $ / shares						$ 27.7	$ 27.38
Class A Stock [Member] | Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period, option shares (in shares) | shares		270,000	270,000
Granted, option shares (in shares) | shares			0
Exercised/vested and released, option shares (in shares) | shares			(33,750)
Expired, option shares (in shares) | shares			0
Outstanding at end of period, option shares (in shares) | shares	236,250		236,250
Exercisable/vested at end of period, option share (in shares) | shares	236,250		236,250
Shares of Class A Non-Voting Common Stock under option [Abstract]
Outstanding at beginning of period, weighted average exercise price (in dollars per shares) | $ / shares		$ 19.34	$ 19.34
Granted, weighted average exercise price (in dollars per share) | $ / shares			0
Exercised/vested and released, weighted average exercise price (in dollars per shares) | $ / shares			19.64
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	$ 19.30		19.30
Exercisable/vested at end of period, weighted average exercise price (in dollars per shares) | $ / shares	$ 19.30		$ 19.30
Outstanding at end of period, weighted average remaining life			4 years 7 months 2 days
Exercisable/vested at end of period, weighted average remaining life			4 years 7 months 2 days
Outstanding at beginning of period, aggregate intrinsic value | $		$ 2,256,000	$ 2,256,000
Granted, aggregate intrinsic value | $			0
Exercised/ vested and released, aggregate intrinsic value | $			286,000
Expired/cancelled, aggregate intrinsic value | $		$ 0
Outstanding at end of period, aggregate intrinsic value | $	$ 2,182,000		2,182,000
Exercisable/vested at end of period, aggregate intrinsic value | $	$ 2,182,000		$ 2,182,000
Class A Stock [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period, option shares (in shares) | shares		0	0
Granted, option shares (in shares) | shares		5,000
Exercised/vested and released, option shares (in shares) | shares		0
Expired, option shares (in shares) | shares		0
Outstanding at end of period, option shares (in shares) | shares	5,000		5,000
Exercisable/vested at end of period, option share (in shares) | shares	0		0
Shares of Class A Non-Voting Common Stock under option [Abstract]
Outstanding at beginning of period, weighted average exercise price (in dollars per shares) | $ / shares		$ 0	$ 0
Granted, weighted average exercise price (in dollars per share) | $ / shares			27.70
Exercised/vested and released, weighted average exercise price (in dollars per shares) | $ / shares			0
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	$ 27.70		27.70
Exercisable/vested at end of period, weighted average exercise price (in dollars per shares) | $ / shares	$ 0		$ 0
Class A Stock [Member] | Restricted Stock [Member] | 2015 Equity Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense related to non-vested option shares | $	$ 82,000		$ 82,000
Period over which unvested options cost will recognized			7 months 2 days