Net Income (Loss) Per Share - Numerators and Denominators of Basic and Diluted Net Income (Loss) Per Share Computations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2020	Sep. 27, 2019	Sep. 25, 2020	Sep. 27, 2019
Numerator:
Net income (loss)	$ (5,381)	$ 11,657	$ (42,736)	$ (11,494)
Basic	97,563	89,964	96,623	89,030
Effect of dilutive securities from stock options, restricted stock units and ESPP	0	1,855	0	0
Effect of dilutive securities from convertible debt	0	3,468	0	0
Effect of dilutive securities from warrant	0	2,309	0	0
Diluted shares	97,563	97,596	96,623	89,030
Net income (loss) per share:
Basic	$ (0.06)	$ 0.13	$ (0.44)	$ (0.13)
Diluted	$ (0.06)	$ 0.12	$ (0.44)	$ (0.13)