GOODWILL AND OTHER INTANGIBLE ASSETS - Gross Amount and Amortization (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Apr. 01, 2016	Dec. 30, 2016
Goodwill and other intangible assets
Gross Amount	$ 8,728,000		$ 8,728,000
Accumulated Amortization	3,335,000		2,787,000
Amortization expense for acquired identifiable intangible assets	500,000	$ 300,000
Remainder of fiscal year 2017	1,600,000
Estimated amortization expense for acquired identifiable intangible assets
2018	1,951,000
2019	1,087,000
2020	674,000
2021	109,000
Total estimated amortization expense	3,821,000
Backlog
Goodwill and other intangible assets
Gross Amount	1,398,000		1,398,000
Accumulated Amortization	$ 726,000		639,000
Backlog | Maximum
Goodwill and other intangible assets
Amortization Period (in years)	5 years
Tradename
Goodwill and other intangible assets
Gross Amount	$ 2,739,000		2,739,000
Accumulated Amortization	$ 1,370,000		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)	3 years 6 months
Non-compete agreements
Goodwill and other intangible assets
Gross Amount	$ 1,331,000		1,331,000
Accumulated Amortization	$ 533,000		463,000
Amortization Period (in years)	4 years
Customer relationships
Goodwill and other intangible assets
Gross Amount	$ 3,260,000		3,260,000
Accumulated Amortization	$ 706,000		$ 543,000
Amortization Period (in years)	5 years