Debt - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 29, 2019	Mar. 30, 2018	Dec. 31, 2017	Dec. 31, 2018
Line of Credit Facility [Line Items]
Line of Credit Facility, Initiation Date			Oct. 30, 2015
Long-term debt	$ 13,318,000	$ 9,000,000.0		$ 3,640,000
Maximum amount outstanding	18,000,000.0	12,800,000
Average amount outstanding	$ 10,300,000	$ 6,200,000
Weighted-average interest rate	3.00%	3.00%
Debt covenants, Maximum leverage ratio	1.10%
Debt covenants, Minimum tangible net worth	$ 5,000,000.0
Debt covenants, Maximum capital expenditures	5,000,000.0
Debt covenants threshold limit to test fixed charge coverage ratio	5,625,000
Total available borrowings	21,900,000
Debt covenants, EBITDA	8,400,000
Capital expenditures	$ 300,000
Federal Funds Effective Swap Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.50%
Minimum [Member] | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.50%
Minimum [Member] | Adjusted London Interbank Offered Rate L I B O R
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.50%
Maximum [Member] | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on variable rate			2.00%
Maximum [Member] | Adjusted London Interbank Offered Rate L I B O R
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.00%
Credit and Security Agreement [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, term			3 years
Line of Credit Facility, Maximum Borrowing Capacity			$ 45,000,000.0
Line of credit facility, expiration date			2020-12
Letters of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 10,000,000.0
Swing Line Loans [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 10,000,000.0