NET INCOME PER COMMON SHARE AND EQUITY PER COMMON SHARE (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
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)	9,462,000	9,394,000	9,327,000
Dilutive effect of employee stock options and awards (in shares)	19,000	32,000	42,000
Weighted average common shares outstanding during the period for Diluted computation (in shares)	9,481,000	9,426,000	9,369,000
Earnings Per Share [Abstract]
Equity per common share (in dollars per share)	$ 1.9	$ 1.79	$ 1.8
Common Stock [Member]
Earnings Per Share [Abstract]
Equity per common share (in dollars per share)	$ 19.86	$ 18.94	$ 18.16
Common Stock [Member] | Class A Stock [Member]
Common Stock [Abstract]
Common stock, shares authorized (in shares)	15,000,000	15,000,000	15,000,000
Common stock, shares issued (in shares)	8,621,415	8,532,795	8,475,452
Common stock, shares outstanding (in shares)	8,621,415	8,532,795	8,475,452
Common stock, par value (in dollars per share)	$ 1
Common Stock [Member] | Class B Stock [Member]
Common Stock [Abstract]
Common stock, shares authorized (in shares)	1,040,000	1,040,000	1,040,000
Common stock, shares issued (in shares)	881,452	881,452	881,452
Common stock, shares outstanding (in shares)	881,452	881,452	881,452
Common stock, par value (in dollars per share)	$ 1
Stock Option [Member]
Common Stock [Abstract]
Shares excluded from calculations of diluted net income per share (in shares)	0	0	0
Restricted Stock [Member]
Common Stock [Abstract]
Shares excluded from calculations of diluted net income per share (in shares)	0	0	0