Condensed consolidated balance sheets (Parenthetical) (USD $)	Mar. 30, 2013	Dec. 29, 2012
Condensed consolidated balance sheets
Preferred stock, shares authorized	15,000,000	15,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	46,723,723	46,627,064
Common stock, shares outstanding	46,711,323	46,627,064
Treasury stock, shares	12,400	0