NET INCOME PER COMMON SHARE AND EQUITY PER COMMON SHARE (Details) - $ / shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Shares used in computing basic and diluted net income per share [Abstract]
Weighted average common shares outstanding during the period for Basic computation (in shares)	8,960,000	8,898,000	8,935,000	8,876,000
Dilutive effect of employee stock options (in shares)	40,000	32,000	37,000	43,000
Weighted average common shares outstanding during the period for Diluted computation (in shares)	9,000,000	8,930,000	8,972,000	8,919,000
Common stock excluded from calculations of diluted net income per share (in shares)	33,750		67,500
Class A Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	15,000,000		15,000,000
Common stock, shares issued (in shares)	72,200	8,722	89,104	70,344
Common stock, shares outstanding (in shares)	8,119,781	8,018,913	8,119,781	8,018,913
Common stock, par value (in dollars per share)	$ 1.00		$ 1.00
Common stock, shares issued during period (in shares)	72,200	8,722	89,104	70,344
Equity per common share (in dollars per share)			$ 14.45		$ 14.14
Class B Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	1,040,000		1,040,000
Common stock, shares outstanding (in shares)	881,452	881,452	881,452	881,452
Common stock, par value (in dollars per share)	$ 1.00		$ 1.00