GOODWILL AND OTHER INTANGIBLE ASSETS - Gross Amount and Amortization (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016	Dec. 30, 2016
Goodwill and other intangible assets
Gross Amount	$ 15,688,000		$ 15,688,000		$ 8,728,000
Accumulated Amortization	4,543,000		4,543,000		2,787,000
Amortization expense for acquired identifiable intangible assets	700,000	$ 400,000	1,800,000	$ 1,400,000
Remainder of fiscal year 2017	700,000		700,000
Estimated amortization expense for acquired identifiable intangible assets
2018	2,823,000		2,823,000
2019	1,959,000		1,959,000
2020	1,546,000		1,546,000
2021	981,000		981,000
2022	872,000		872,000
Thereafter	2,236,000		2,236,000
Total estimated amortization expense	10,417,000		10,417,000
Backlog
Goodwill and other intangible assets
Gross Amount	1,398,000		1,398,000		1,398,000
Accumulated Amortization	901,000		$ 901,000		639,000
Backlog | Maximum
Goodwill and other intangible assets
Amortization Period (in years)			5 years
Tradename
Goodwill and other intangible assets
Gross Amount	3,779,000		$ 3,779,000		2,739,000
Accumulated Amortization	1,818,000		$ 1,818,000		1,142,000
Tradename | Minimum
Goodwill and other intangible assets
Amortization Period (in years)			2 years 6 months
Tradename | Maximum
Goodwill and other intangible assets
Amortization Period (in years)			6 years
Non-compete agreements
Goodwill and other intangible assets
Gross Amount	1,331,000		$ 1,331,000		1,331,000
Accumulated Amortization	674,000		$ 674,000		463,000
Amortization Period (in years)			4 years
Developed Technology
Goodwill and other intangible assets
Gross Amount	2,760,000		$ 2,760,000
Accumulated Amortization	58,000		$ 58,000
Amortization Period (in years)			8 years
In-process Technology
Goodwill and other intangible assets
Gross Amount	1,650,000		$ 1,650,000
Accumulated Amortization	28,000		$ 28,000
Amortization Period (in years)			10 years
Customer relationships
Goodwill and other intangible assets
Gross Amount	4,770,000		$ 4,770,000		3,260,000
Accumulated Amortization	$ 1,064,000		$ 1,064,000		$ 543,000
Customer relationships | Minimum
Goodwill and other intangible assets
Amortization Period (in years)			5 years
Customer relationships | Maximum
Goodwill and other intangible assets
Amortization Period (in years)			8 years