Shareholders' Equity (Details) - USD ($)					1 Months Ended		2 Months Ended		12 Months Ended					156 Months Ended
	Dec. 28, 2015	Jun. 29, 2015	Dec. 10, 2014	Oct. 15, 2013	Dec. 31, 2013	Dec. 31, 2012	Mar. 14, 2016	Mar. 14, 2016	Jan. 01, 2016	Dec. 31, 2015	Jan. 02, 2015	Dec. 31, 2014	Dec. 27, 2013	Jan. 02, 2015	Sep. 26, 2013	Aug. 28, 2013	Jul. 30, 2002
Stockholders Equity [Line Items]
Stock repurchase authorized							$ 100,000,000	$ 100,000,000	$ 95,000,000								$ 5,000,000
Common stock, par value									$ 0.001		$ 0.001			$ 0.001
Stock repurchase cost of tender offer net of fees and expenses related to tender offer									$ 1,400,000		$ 11,000,000		$ 7,170,000
Percentage of eligble compensation allowed, per grant purchase									10.00%
Interval between employee stock purchases									6 months
Employee purchase price as percentage of trading value									95.00%
Annual share repurchase authorized, value									$ 25,000
Employee stock purchase plan, expiration date									Jul. 01, 2018
Common stock available for issuance employee stock purchase plans									4,275,000
Shares available for issuance, per offering period									400,000
Shares issued under ESPP									48,356		94,333		113,905
Additional stock repurchase authorized								$ 5,000,000						$ 90,000,000
Repurchase of common stock									100,000		1,800,000
Purchase price per share									$ 9.10		$ 6.07
Total cost									$ 1,356,000		$ 10,929,000		$ 5,962,000
Cumulative purchases									92,700,000
Amount available under repurchase plan									$ 2,300,000
Dividend declared						$ 0.10			$ 0.20	$ 0.20		$ 0.12
Annual dividend							$ 0.26
Annual cash dividend per share			$ 0.12		$ 0.10	$ 0.10
Dividend payment	$ 3,200,000	$ 3,100,000	$ 3,500,000		$ 3,100,000	$ 3,100,000			$ 6,266,000		$ 3,508,000		$ 3,096,000
Minimum [Member]
Stockholders Equity [Line Items]
Period of service qualification									3 months
2013 Tender Offer [Member]
Stockholders Equity [Line Items]
Stock repurchase authorized															$ 25,000,000	$ 35,750,000
Common stock, par value																$ 0.001
Number of stock repurchased in tender offer				1,000,000
Price per share repurchased in tender offer				$ 7.00
Stock repurchase cost of tender offer net of fees and expenses related to tender offer				$ 6,900,000
Percentage of issued and outstanding shares repurchased in tender offer				3.00%
2013 Tender Offer [Member] | Minimum [Member]
Stockholders Equity [Line Items]
Stock repurchase authorized, per share															$ 6.50	5.75
2013 Tender Offer [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Stock repurchase authorized, per share															$ 7.00	$ 6.50
Tax Withholding [Member]
Stockholders Equity [Line Items]
Treasury stock held							253,000	253,000	297,000		435,000			435,000
Treasury shares withheld and not issued							$ 3,500,000	$ 3,500,000	$ 2,500,000		$ 2,700,000			$ 2,700,000
Cumulative [Member]
Stockholders Equity [Line Items]
Purchase price per share									$ 3.84		$ 3.81
Treasury stock held									24,100,000		24,000,000			24,000,000
Subsequent Event [Member]
Stockholders Equity [Line Items]
Repurchase of common stock							300,000
Purchase price per share							$ 13.83
Total cost							$ 4,200,000
Amount available under repurchase plan							$ 3,100,000	$ 3,100,000
Annual dividend							$ 0.26