Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands		3 Months Ended						9 Months Ended
	Dec. 20, 2019	Sep. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Sep. 27, 2019	Sep. 28, 2018
Equity, Class of Treasury Stock [Line Items]
Total cost			$ 1,440,000	$ 1,616,000			$ 964,000
Amount available under repurchase plan		$ 3,900,000						$ 3,900,000
Stock repurchase authorized		$ 142,200,000						$ 142,200,000
Shares repurchased for employee net vesting obligations, shares		5			8			129	191
Shares repurchased for employee net vesting obligations, value		$ 88,000			$ 100,000			$ 2,500,000	$ 3,300,000
Dividend declared			$ 0.18
Dividend payment			$ 5,789,000			$ 5,396,000
Dividend declared, date of payment			Jul. 10, 2019
Forecast [Member]
Equity, Class of Treasury Stock [Line Items]
Dividend declared	$ 0.18
Dividend declared, date of payment	Jan. 07, 2020
Dividends payable, date of record	Dec. 20, 2019
Minimum [Member]
Equity, Class of Treasury Stock [Line Items]
Dividend declared								$ 0.34
Maximum [Member]
Equity, Class of Treasury Stock [Line Items]
Dividend declared								$ 0.36
Share Repurchase Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock		0						193	53
Purchase price per share								$ 15.80	$ 18.33
Total cost								$ 3,100,000	$ 1,000,000
SARs [Member]
Equity, Class of Treasury Stock [Line Items]
SARs outstanding		2,900						2,900
Exercise price		$ 4.00						$ 4.00
Expiration date								Feb. 28, 2022