STOCK OPTIONS - Summary of status of Salisbury's outstanding stock options (Details) - Stock options $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Number, beginning of period | shares	55,350
Weighted average exercise price, beginning of period | $ / shares	$ 22.86
Number of options, granted | shares
Weighted average exercise price, granted | $ / shares
Number of options, exercised | shares	(12,150)
Weighted average exercise price, exercised | $ / shares	$ 25.93
Number of options, forfeited or expired | shares	(2,700)
Weighted average exercise price, forfeited or expired | $ / shares	$ 25.93
Number, end of period | shares	40,500
Weighted average exercise price, end of period | $ / shares	$ 21.73
Weighted average remaining contractual term	4 years 3 months 29 days
Aggregate intrinsic value | $	$ 928