GOODWILL AND OTHER INTANGIBLE ASSETS - Other intangible assets - (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Other intangible assets:
Cost	$ 10,784,000	$ 12,466,000
Accumulated amortization	4,272,000	4,207,000
Net book value	6,512,000	8,259,000
Hy-Tech Customer relationships [Member]
Other intangible assets:
Cost	6,475,000	7,825,000
Accumulated amortization	2,763,000	2,724,000
Net book value	$ 3,712,000	$ 5,101,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	8 years	8 years 8 months 12 days
Trademarks and trade names one [Member]
Other intangible assets:
Cost	$ 2,169,000	$ 2,375,000
Accumulated amortization	0	0
Net book value	$ 2,169,000	$ 2,375,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 years	11 years 6 months
Trademarks and Trade Names Two [Member]
Other intangible assets:
Cost	$ 200,000	$ 200,000
Accumulated amortization	52,000	45,000
Net book value	148,000	155,000
Engineering drawings [Member]
Other intangible assets:
Cost	330,000	330,000
Accumulated amortization	232,000	225,000
Net book value	$ 98,000	$ 105,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 7 months 6 days	7 years 1 month 6 days
Non-compete agreements [Member]
Other intangible assets:
Cost	$ 324,000	$ 331,000
Accumulated amortization	242,000	235,000
Net book value	$ 82,000	$ 96,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years 4 months 24 days	3 years 8 months 12 days
NUMATX[Member]
Other intangible assets:
Cost	$ 1,286,000	$ 1,405,000
Accumulated amortization	983,000	978,000
Net book value	$ 303,000	$ 427,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years 7 months 6 days	7 years 1 month 6 days