Accumulated Other Comprehensive Income (Loss) and Shareholders' Equity (Narrative) (Details)	1 Months Ended	12 Months Ended
	Aug. 31, 2019 USD ($)	Dec. 28, 2019 USD ($) hour shares	Dec. 29, 2018 USD ($)	Mar. 31, 2016 USD ($)	May 31, 2007 shares	Jan. 01, 2007 shares
Schedule of Shareholders' Equity [Line Items]
Derivative asset			$ 300,000
Accumulated other comprehensive income (loss)		$ (8,073,000)	$ (3,599,000)
Term of employment agreement		2 years
Certain officers
Schedule of Shareholders' Equity [Line Items]
Change in control percentage		20.00%
Percent of board members		0.3333
Term of employment agreement		2 years
Number of times annual salary		200.00%
Corporation's Chairman, President and CEO
Schedule of Shareholders' Equity [Line Items]
Number of times annual salary		300.00%
Director plan
Schedule of Shareholders' Equity [Line Items]
Available for future issuance (shares) | shares					300,000
Purchase Plan
Schedule of Shareholders' Equity [Line Items]
Available for future issuance (shares) | shares						800,000
Rights to purchase stock, minimum working hours per week | hour		20
Rights to purchase stock, minimum working months per year		5 months
Price of repurchased stock as percent of closing price on the exercise date		85.00%
Maximum amount fair value for purchase of common stock		$ 25,000
Shares available for future issuance (shares) | shares		593,223
Interest rate swap
Schedule of Shareholders' Equity [Line Items]
Derivative notional amount	$ 75,000,000			$ 150,000,000
Fixed interest rate	1.42%			1.29%
Proceeds from derivative instrument	$ 500,000
Gain (loss) on derivative	$ 500,000
Accumulated other comprehensive income (loss)		$ 500,000
Common Stock
Schedule of Shareholders' Equity [Line Items]
Remaining authorized repurchase amount		$ 164,700,000