Unvested Stock Options (Detail) (USD $)	12 Months Ended
	Dec. 28, 2012	Dec. 30, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested options Outstanding, Balance	103,878	136,000	163,750
Unvested Options Outstanding, Granted	25,000	30,000	42,500
Unvested Options Outstanding, Vested	(44,624)	(62,122)	(70,250)
Unvested Options Outstanding, Forfeited	0	0	0
Unvested Options Outstanding, Balance	84,254	103,878	136,000
Weighted Average Fair Value, Balance	$ 12.58	$ 10.64	$ 9.31
Weighted Average Fair Value, Granted	$ 19.51	$ 16.51	$ 11.70
Weighted Average Fair Value, Vested	$ 12.27	$ 10.23	$ 8.19
Weighted Average Fair Value, Forfeited	$ 0	$ 0	$ 0
Weighted Average Fair Value, Balance	$ 14.80	$ 12.58	$ 10.64