Summary of Significant Accounting Policies: (Details 2) (USD $)	3 Months Ended								12 Months Ended
	Jan. 03, 2012	Sep. 27, 2011	Jun. 28, 2011	Mar. 29, 2011	Dec. 28, 2010	Sep. 28, 2010	Jun. 29, 2010	Mar. 30, 2010	Jan. 03, 2012	Dec. 28, 2010	Dec. 29, 2009
Advertising Costs
Advertising costs									$ 6,200,000	$ 7,300,000	$ 7,700,000
Income Taxes
Threshold for recognition of uncertain income tax position, minimum (as a percent)									50.00%
Net income per share, basic and diluted
Net income	$ 29,942,000	$ 20,574,000	$ 24,748,000	$ 20,456,000	$ 21,865,000	$ 21,953,000	$ 19,229,000	$ 18,666,000	$ 95,720,000	$ 81,713,000	$ 42,833,000
Basic weighted average shares outstanding									56,378,000	58,905,000	59,362,000
Dilutive effect of equity awards (in shares)									1,812,000	1,541,000	720,000
Diluted weighted average shares outstanding									58,190,000	60,446,000	60,082,000
Basic net income per share (in dollars per share)	$ 0.55	$ 0.37	$ 0.44	$ 0.35	$ 0.37	$ 0.38	$ 0.32	$ 0.31	$ 1.70	$ 1.39	$ 0.72
Diluted net income per share (in dollars per share)	$ 0.54	$ 0.36	$ 0.42	$ 0.34	$ 0.36	$ 0.37	$ 0.32	$ 0.31	$ 1.64	$ 1.35	$ 0.71
Shares of common stock not included in the diluted calculation due to their anti-dilutive effect									3,400,000	4,400,000	9,300,000
Restricted Shares and Restricted Share Units
Net Income Per Share
Unvested shares of restricted stock issued to employees	826,000				537,000				826,000	537,000	600,000