GOODWILL AND OTHER INTANGIBLE ASSETS - Other intangible assets - (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Other intangible assets:
Cost	$ 12,420,000	$ 12,466,000
Accumulated amortization	4,388,000	4,207,000
Net book value	8,032,000	8,259,000
Customer Relationships [Member]
Other intangible assets:
Cost	7,809,000	7,825,000
Accumulated amortization	2,879,000	2,724,000
Net book value	$ 4,930,000	$ 5,101,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	8 years 6 months	8 years 8 months 12 days
Trademarks and trade names one [Member]
Other intangible assets:
Cost	$ 2,351,000	$ 2,375,000
Accumulated amortization	0	0
Net book value	$ 2,351,000	$ 2,375,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 years 3 months 18 days	11 years 6 months
Trademarks and Trade Names Two [Member]
Other intangible assets:
Cost	$ 200,000	$ 200,000
Accumulated amortization	49,000	45,000
Net book value	151,000	155,000
Engineering drawings [Member]
Other intangible assets:
Cost	330,000	330,000
Accumulated amortization	229,000	225,000
Net book value	$ 101,000	$ 105,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 10 months 24 days	7 years 1 month 6 days
Non-compete agreements [Member]
Other intangible assets:
Cost	$ 325,000	$ 331,000
Accumulated amortization	235,000	235,000
Net book value	$ 90,000	$ 96,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years 7 months 6 days	3 years 8 months 12 days
Patents [Member]
Other intangible assets:
Cost	$ 1,405,000	$ 1,405,000
Accumulated amortization	996,000	978,000
Net book value	$ 409,000	$ 427,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 10 months 24 days	7 years 1 month 6 days