Shareholders' Equity (Details) - USD ($) $ / shares in Units, shares in Thousands			3 Months Ended			6 Months Ended
	Dec. 22, 2017	Jun. 30, 2017	Jun. 29, 2018	Mar. 30, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017
Equity, Class of Treasury Stock [Line Items]
Amount available under repurchase plan			$ 7,200,000			$ 7,200,000
Additional repurchase under plan			5,000,000
Total authorized amount under stock repurchase plan			$ 142,200,000			$ 142,200,000
Shares repurchased for employee net vesting obligations, shares			11		21	184	195
Shares repurchased for employee net vesting obligations, value			$ 200,000		$ 400,000	$ 3,100,000	$ 3,300,000
Annual cash dividend per share	$ 0.30	$ 0.26
Dividend payment	$ 4,700,000	$ 4,600,000	$ 5,400,000
Dividend declared			$ 0.17	$ 0.34
Dividend declared, date of record			Jun. 29, 2018
Dividend declared, date of payment			Jul. 11, 2018
Share Repurchase Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock					507	53	566
Purchase price per share					$ 15.01	$ 18.33	$ 15.55
Total cost					$ 7,600,000	$ 1,000,000	$ 8,800,000
Stock Appreciation Rights (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