Long-Term Debt (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Line of Credit Facility [Line Items]
Interest Expense, Debt	$ 14,000	$ 73,000	$ 33,000	$ 240,000
Revolving Credit Facility [Member] | Wells Fargo Bank, N.A. [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	50,000,000		50,000,000
Line of credit facility, discretionary amount available	50,000,000		50,000,000
Line of Credit Facility, Remaining Borrowing Capacity	88,500,000		$ 88,500,000
Debt Instrument, Maturity Date			Sep. 01, 2019
Letters of Credit Outstanding, Amount	$ 11,500,000		$ 11,500,000