Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Common Stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Retained earnings	Treasury Stock
Beginning Balance at Jan. 02, 2009	$ 128,094	$ 16	$ 72,734	$ (345)	$ 127,127	$ (71,438)
Beginning Balance (in shares) at Jan. 02, 2009		16,427				2,737
Employee stock purchase plan (in shares)						(33)
Employee stock purchase plan	848		146			702
Exercise of stock options, net of swaps (in shares)						(392)
Exercise of stock options, net of swaps	2,839		(227)		(5,185)	8,251
Tax benefit for stock option plans	3,282		3,282
Amortization of unrecognized stock-based compensation	4,134		4,134
Purchase of treasury shares (in shares)						540
Purchase of treasury shares	(13,121)					(13,121)
Foreign currency translation adjustments	(122)			(122)
Grant of restricted stock units to settle accrued bonus	3,739		3,739
Settlement of restricted stock units (in shares)						(162)
Settlement of restricted stock units	(1,849)				(4,463)	2,614
Unrealized gain (loss) on investments	100			100
Net income	22,127				22,127
Ending Balance at Jan. 01, 2010	150,071	16	83,808	(367)	139,606	(72,992)
Ending 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
Ending Balance at Dec. 31, 2010	183,800	16	96,089	(451)	156,086	(67,940)
Ending 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
Ending Balance at Dec. 30, 2011	$ 186,715	$ 16	$ 108,071	$ (471)	$ 179,432	$ (100,333)
Ending Balance (in shares) at Dec. 30, 2011		16,427				3,127