GOODWILL AND OTHER INTANGIBLE ASSETS - Other intangible assets - (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Other intangible assets:
Cost	$ 12,466,000	$ 11,297,000
Accumulated amortization	4,207,000	3,497,000
Net book value	8,259,000	7,800,000
Customer Relationships [Member]
Other intangible assets:
Cost	7,825,000	6,821,000
Accumulated amortization	2,724,000	2,135,000
Net book value	$ 5,101,000	$ 4,686,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	8 years 8 months 12 days	9 years 3 months 18 days
Trademarks and trade names one [Member]
Other intangible assets:
Cost	$ 2,375,000	$ 2,308,000
Accumulated amortization	0	0
Net book value	$ 2,375,000	$ 2,308,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 years 6 months	12 years 6 months
Trademarks and Trade Names Two [Member]
Other intangible assets:
Cost	$ 200,000	$ 200,000
Accumulated amortization	45,000	32,000
Net book value	155,000	168,000
Engineering drawings [Member]
Other intangible assets:
Cost	330,000	330,000
Accumulated amortization	225,000	202,000
Net book value	$ 105,000	$ 128,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years 1 month 6 days	7 years 8 months 12 days
Non-compete agreements [Member]
Other intangible assets:
Cost	$ 331,000	$ 233,000
Accumulated amortization	235,000	223,000
Net book value	$ 96,000	$ 10,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years 8 months 12 days	2 years 3 months 18 days
Patents [Member]
Other intangible assets:
Cost	$ 1,405,000	$ 1,405,000
Accumulated amortization	978,000	905,000
Net book value	$ 427,000	$ 500,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years 1 month 6 days	7 years 10 months 24 days