Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Balance at Jan. 01, 2010	$ 150,071	$ 16	$ 83,808	$ (367)	$ 139,606	$ (72,992)
Balance (in shares) at Jan. 01, 2010		16,427				2,690
Employee stock purchase plan (in shares)						(26)
Employee stock purchase plan	796		125			671
Exercise of stock options,net of swaps (in shares)						(330)
Exercise of stock options, net of swaps	2,079		(82)		(6,059)	8,220
Tax benefit for stock option plans	3,972		3,972
Amortization of unrecognized stock-based compensation	4,724		4,724
Purchase of treasury shares (in shares)						244
Purchase of treasury shares	(6,899)					(6,899)
Foreign currency translation adjustments	(53)			(53)
Grant of restricted stock units to settle accrued bonus	3,566		3,566
Settlement of restricted stock units (in shares)						(147)
Settlement of restricted stock units	(1,946)		(24)		(4,982)	3,060
Unrealized gain (loss) on investments	(31)			(31)
Net income	27,521				27,521
Balance at Dec. 31, 2010	183,800	16	96,089	(451)	156,086	(67,940)
Balance (in shares) at Dec. 31, 2010		16,427				2,431
Employee stock purchase plan (in shares)						(21)
Employee stock purchase plan	894		222			672
Exercise of stock options,net of swaps (in shares)						(102)
Exercise of stock options, net of swaps	1,336		(162)		(1,484)	2,982
Tax benefit for stock option plans	2,378		2,378
Amortization of unrecognized stock-based compensation	5,044		5,044
Purchase of treasury shares (in shares)						1,002
Purchase of treasury shares	(40,573)					(40,573)
Foreign currency translation adjustments	(72)			(72)
Grant of restricted stock units to settle accrued bonus	4,538		4,538
Settlement of restricted stock units (in shares)						(183)
Settlement of restricted stock units	(3,377)		(38)		(7,865)	4,526
Unrealized gain (loss) on investments	52			52
Net income	32,695				32,695
Balance at Dec. 30, 2011	186,715	16	108,071	(471)	179,432	(100,333)
Balance (in shares) at Dec. 30, 2011		16,427				3,127
Employee stock purchase plan (in shares)						(20)
Employee stock purchase plan	1,008		400			608
Exercise of stock options,net of swaps (in shares)						(200)
Exercise of stock options, net of swaps	2,607		(358)		(3,123)	6,088
Tax benefit for stock option plans	3,948		3,948
Amortization of unrecognized stock-based compensation	6,289		6,289
Purchase of treasury shares (in shares)						480
Purchase of treasury shares	(23,395)					(23,395)
Foreign currency translation adjustments	249			249
Grant of restricted stock units to settle accrued bonus	5,343		5,343
Settlement of restricted stock units (in shares)						(166)
Settlement of restricted stock units	(3,532)				(7,477)	3,945
Unrealized gain (loss) on investments	(28)			(28)
Net income	37,225				37,225
Balance at Dec. 28, 2012	$ 216,429	$ 16	$ 123,693	$ (250)	$ 206,057	$ (113,087)
Balance (in shares) at Dec. 28, 2012		16,427				3,221