Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 26, 2020	Dec. 27, 2019
Statement Of Financial Position [Abstract]
Account receivable, allowance for doubtful accounts	$ 0.2	$ 0.3
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10.0	10.0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	90.0	90.0
Common stock, shares issued	40.3	40.3
Common stock, shares outstanding	39.9	39.9
Treasury stock, shares	0.6	0.6

Amount of allowance for credit loss on accounts receivable, classified as current.

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