NOTES PAYABLE AND LONG-TERM DEBT - Narrative (Details)		6 Months Ended
	Jun. 29, 2018 USD ($)	Dec. 31, 2018 USD ($)
Performance bonds
Line of Credit Facility [Line Items]
Performance bonds outstanding, financial assurance		$ 1,200,000.0
Credit Agreement
Line of Credit Facility [Line Items]
Maturity extension period	2 years
Maximum borrowing capacity	$ 14,000,000.0
Percentage of eligible accounts receivable considered for borrowing base	80.00%
Percentage of eligible inventory considered for borrowing base	50.00%
Borrowing base, monetary benchmark	$ 3,000,000
Basis spread of variable rate (as a percent)	0.00%
Interest rate		5.00%
Unused capacity, commitment fee percentage		0.25%
Remaining borrowing capacity		$ 12,300,000
Credit Agreement | Maximum
Line of Credit Facility [Line Items]
Debt cash flow leverage ratio	3.0
Credit Agreement | Minimum
Line of Credit Facility [Line Items]
Debt service coverage ratio	1.15
Credit Agreement | Term Loan
Line of Credit Facility [Line Items]
Maturity period	5 years
Credit Agreement | Working Capital
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 6,000,000.0
Remaining borrowing capacity		6,000,000
Credit Agreement | Letter of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	2,000,000.0
Amount outstanding		40,000
Credit Agreement | Acquisitions
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 8,000,000.0
Percentage of portion allocated to acquisition purchase price	75.00%
Remaining borrowing capacity		$ 6,300,000
Credit Agreement | LIBOR
Line of Credit Facility [Line Items]
Basis spread of variable rate (as a percent)	2.50%
Debt instrument, term of variable rate	1 month
Credit Agreement | LIBOR | Maximum
Line of Credit Facility [Line Items]
Basis spread of variable rate (as a percent)	3.00%