Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 27, 2019	Dec. 28, 2018
Statement Of Financial Position [Abstract]
Account receivable, allowance for doubtful accounts	$ 0.3	$ 0.1
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	39.9	39.1
Common stock, shares outstanding	39.9	39.1
Treasury stock, shares	0.6	0.6