CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 29, 2013	Dec. 29, 2012	Jun. 30, 2012
CONSOLIDATED BALANCE SHEETS
Property and equipment, accumulated depreciation (in dollars)	$ 28,205	$ 25,123	$ 22,284
Intangible assets, accumulated amortization (in dollars)	$ 3,810	$ 3,810	$ 3,810
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized	45,000,000	45,000,000	45,000,000
Common stock, shares issued	16,655,023	16,302,007	16,271,118
Common stock, shares outstanding	16,655,023	16,302,007	16,271,118
Undesignated preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Undesignated preferred stock, shares authorized	5,000,000	5,000,000	5,000,000
Undesignated preferred stock, shares issued	0	0	0
Undesignated preferred stock, shares outstanding	0	0	0