GOODWILL AND OTHER INTANGIBLE ASSETS - Gross Amount and Amortization (Details) - USD ($)
9 Months Ended 12 Months Ended
Sep. 30, 2016
Dec. 30, 2016
Jan. 01, 2016
Jan. 02, 2015
Goodwill and other intangible assets        
Gross Amount   $ 9,036,000 $ 2,716,000  
Accumulated Amortization   3,095,000 1,171,000  
Amortization expense for acquired identifiable intangible assets   1,900,000 1,200,000 $ 0
Decreased other receivables $ 300,000      
Estimated amortization expense for acquired identifiable intangible assets        
2017   2,120,000    
2018   1,951,000    
2019   1,087,000    
2020   674,000    
2021   109,000    
Total estimated amortization expense   5,941,000    
Goodwill impairment        
Goodwill impairment   0 0 $ 0
Backlog        
Goodwill and other intangible assets        
Gross Amount   1,398,000 348,000  
Accumulated Amortization   $ 639,000 340,000  
Amortization Period (in years)   5 years    
Tradename        
Goodwill and other intangible assets        
Gross Amount   $ 2,739,000 1,049,000  
Accumulated Amortization   $ 1,142,000 329,000  
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 1,011,000  
Accumulated Amortization   $ 463,000 194,000  
Non-compete agreements | Minimum        
Goodwill and other intangible assets        
Amortization Period (in years)   4 years    
Non-compete agreements | Maximum        
Goodwill and other intangible assets        
Amortization Period (in years)   5 years    
License to bid        
Goodwill and other intangible assets        
Gross Amount   $ 308,000 308,000  
Accumulated Amortization   308,000 $ 308,000  
Customer relationships        
Goodwill and other intangible assets        
Gross Amount   3,260,000    
Accumulated Amortization   $ 543,000    
Amortization Period (in years)   5 years