Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 28, 2021	Dec. 29, 2020
Condensed Consolidated Balance Sheets
Receivables, allowance for doubtful accounts (in dollars)	$ 14	$ 11
Property and equipment, accumulated depreciation (in dollars)	842,686	763,700
Intangible assets, accumulated amortization (in dollars)	$ 14,911	$ 14,341
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	69,735,401	69,561,861
Common stock, shares outstanding	69,735,401	69,561,861